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I'm in the early stages of picking a new DIY project.
Presently I'm using a stock Hafler XL280 mosfet power amp. It's not a bad amp and it seems reasonably happy driving a pair of Acoustat 2+2's. It replaced a pair of Curcio premium level modified Dyna MK III's. (One was stepped upon by a burglar a couple of years ago, breaking tubes and the driver board.)
I miss the "glow". I've always felt that electrostats and tubes have a beautiful relationship, each bringing the best out of the other. I've heard Audio Research D-79 amps and 2+2's make magic ... but, even on the used market adequately powered tube equipment is expensive and, even if you get the product "as advertised" you're still probably going to have to re-tube and perhaps replace some electrolytics. This also doesn't truly satisfy any DIY jones... sometimes you just want to make something ...
That said, I'm leaning heavily towards building a pair of Curcio MQ-100 mono blocks.
I've always been a huge fan of Joe Curcio's work and he's been a strong supporter of DIY audio for 30+ years starting with Audio Amateur. I've built almost every circuit he has published and some he hasn't and, most importantly, his audio tastes are very similar to mine.
The schematics are on his web site. It's a 100 watt pentode design using a constant current cascade driver. All stages are regulated except the raw B+ feeding the output transformer.
http://www.curcioaudio.com/padvrsch.gif
http://www.curcioaudio.com/mqsch.gif
Most of the amps that I have built used Dyna transformers. The MQ-100 has Magnequest iron specifically designed for this amp, Output, power and choke. A real plus. My intention is to purchase just the iron and the PC boards.
My question... the MQ-100 's have been out for 8 or 10 years yet there is very little record of builders/users. What little there is seems very favorable, there just isn't much of it. It would seem to fill a niche that has only one other comparable component ( the Dyna VTA M-125, a less expensive 125 watt ultra-linear kit) and while I admire Bob Latino, I think there is more of an opportunity to customize the Curcio product.
Whatca think?
Is the utilization of custom designed Magnequest coils worth the increased price? Why do we see little record of the Mq-100?
Follow Ups:
Though I would recommend taking your time and paying special attention to the physical build. Get a nice case or have a box custom done. Since you do not have to worry about creating the circuit you can spend your time making a physically nice amp.
Don't short this part as the aesthetics of your build will be the determination of the long term satisfaction. This might be the time you buy a drill press or learn Front Panel Express. Neither is that expensive.
Go with your plan an build it EXACTLY as designed and I am very confident you will be a happy camper for a very long time!
Chris O,
Love the enthusiasm!
Good advice ... I have a modest shop and "Front Panel Express" is your friend!
Earlier project :
http://www.audiocircle.com/index.php?topic=63343.0
Hey, common sense. I think you need to HEAR the amp, before you jump into the fire financially on a big DIY build project.It would be better to spend the money on an airline ticket and HEAR the amp somewhere, or even MUCH better yet, have someone ship theirs to you to use temporarily on YOUR speaker load.
AS to MQ iron, I think it is a real "plus" in the realm of output trannies, because Mikey is as good as it gets in that area of design and execution. Get them!!
For chokes and power transformers, I would suggest to use Hammond. There is a new (two years old) line of Hammond 300 series power trannies, that have DCRs across the entire HV secondary as low as 21 and 11 Ohms, and THOSE would be "the ones" to use, typically rated at 500 mA or more, look them up !! Those would have fabulous self-regulation.
Don't let anyone tell you that because you are regulating everything, the trannie and choke DCRs won't matter, because the self regulation and DCR of the iron ( PT and Ls ) is clearly HEARD through the active regulators. Also, of course, your Finals are unregulated, so ONLY use the Hammond pieces with the lowest DCR you can find.
There is one other factor, before you spend a lot of effort pondering what to do, you better check with Curcio to see if the iron is still available, and IN STOCK, because if its a low demand amplifier, you will be on the hook waiting for it to be wound.
I really shudder about you embarking upon this without FIRST hearing the amps on your speaker load !!!
Have you ever heard Paoli 60Ms with GE6550s? Its a Mark 3 Dyna variant, with a good reputation, that does well on ESLs. I have all the original schematics, Patent papers, and fully-developed ideas to improve the unit, already documented. It uses a SIMPLE circuit, with NO regulators, which is a sonic plus.
Note, any time someone actively regulates the screen on a Pentode, the regulator leaves its signature on the music, in a negative way. None of the active regulators are good enough, transparent sounding enough, for that super sensitive area, G2.
We know how to treat G2 fabulously well in 2012, using passive components for a superbly performing screen supply. I'd be happy to share such design data with you.
Jeff Medwin
Edits: 08/05/12
Jeff,
Thanks for the rapid feedback.
Fully agree on hearing before purchase but that only works for me with mass produced, identical items. If you and I each built a component having only the transformers and circuit boards in common, they would sound differently. Perhaps subtly, maybe dramatically but most probably not indistinguishable from one another.
BUT... I can get close in that the driver circuitry is, essentially, identical to the driver board I installed in the premium Dyna MKIII's I used (and loved!) for some 20 years. The outputs are 6550's (again, as in the MKIII's) only doubled in numbers. It's almost a test bed of doubling the power and improving the quality of all of the coils, with a minimal alteration of the supporting circuitry.
I see your point about the Hammond transformers/chokes but it seems that this Magnequest line is proprietarily designed for this amp and available only from Curcio Audio. This doesn't overly bother me in that the price for 2 power transformers, 2 output transformers, and 2 chokes while high, (WAY more than I have ever spent for such items!!) it's very much in sync wit other Magnequest products.
In for a penny, in for a pound?
Bob Roemer
I would stick with the Magnequest power iron also. Hammonds aren't designed for the higher line voltages seen in the U.S. now, and every transformer I've bought from them has run extremely hot.
--------------------------
Buy Chinese. Bury freedom.
Correction.
Hammonds ARE now designed for higher line voltages, (for the last two years), all the primaries on their classic 200 series PTs come as 115 AND 125 VAC tapped.
I suggested a 500 mA. plus PT for a quad of 6550s running at 240 mA., so where is the strain , it will loaf at one half draw.
Jeff Medwin
I have had no problems at all with the Hammond 300 series power transformers and I have used at least 10 in projects over the last couple years.
I second that and I have bought the cheapest Hammonds as well as the more expensive.
I think keeping the current demand way down from the transformer current output helps to keep it running cooler. I have run it close to the allowable current rating and it never got any where near hot. Maybe warm to the touch but never hot.
The ones I've used ran hot at idle with no load at all. The problem appears to be insufficient primary inductance for the line voltage here (~125V).
--------------------------
Buy Chinese. Bury freedom.
Hi Bob,
You (and I) are getting older, and its time for you (and I) to stop messing around and DIY something really good !!
First of all, you should build a amp with NO circuit boards, point to point using REAL wire, made for audio !!! THAT sounds better.
Secondly, if a Pentode amp, I vote for NO COMPROMISE, a totally separate passive power supply for G2 on the Finals, as it is positively the NICEST way to run a pentode !!
Third, ALL the supply iron (PTs and Ls) need to be 20 Ohms DCR or less, if you want it to honor the music dynamically. I doubt the Curcio / MQ power supply iron will fit that criteria. You can do better on your own.
Our posts, and my revision above (which brought up a couple of other factors), crossed !!
Do you have any Paoli 60m experience ? I have reviews somewhere.
You could always PM me, and we can talk on the phone.
Jeff Medwin
Jeff,
I know you are big on the modern power supplies but is it really noticeable in PP as compared to SET?
Hi Paul,
Not a bad question. I believe it would also be very important on P-P, yes. You have TWO tubes to the Finals, each pulling on the B+ filter
The "modern" aspect is just using low HY Ls and low uF Cs to the low DCR iron, sorta like icing on the cake that needs to be there as part of the recipe.
In my first twenty years of DIY building, I built P-P tube amps, and I found the power supply design is critical. For example, I NEVER EVER got a P-P amp to perform to standards I could live with, with Ls over 20 Ohms, and power trannies over 20 Ohms.
Jeff Medwin
Jeff,
I would love to build a Paoli 60M, or at the very least see a schematic of the final, debugged, version.
You know we are on the same page here. Curcio/Paoli/Acoustat ... common engineering threads. I remember reading Holt's review of the 60M when it first came out. ( you are correct Jeff ... we are old) I read your correspondence back in ... 2004(?) concerning this very subject. Did you ever get a schematic?
Bob Roemer
Bob,I have the earlier and later 60M schematics, and prefer the earlier schematic. I also have done extensive PSUD 2 modeling of the B+ and G2 supplies. Contact me by private email, and I will be happy to email all the information to you as attachments. IAR (Peter Goodgrief, Editor) gave the 60M a great write up in his amp reviews.
One year at CES, many years ago, Dayton Wright had their ESL speakers powered by their new ultra high wattage Dayton Wright Solid State amp. My audio buddy, Dr. Gary Vart, a now-retired OB-Gyn, walked into their room and noticed something funny. He opened their attached bedroom door, and found out that the guys were powering their Dayton Wright ESLs from a pair of Paoli 60Ms, hidden from sight in their bedroom. They asked Dr. Vart to leave the demo room!! TRUE story. LMAO.
Check your email, incoming, you have mail, my 60M files.
Jeff Medwin
Edits: 08/06/12 08/06/12
See the comparisons (in both cases with a stock Dynaco power transformer), of the original Paoli 60M B+ supply filter (which settles slowly - in about 550 mS.) and a "modern" supply filter using a small and inexpensive Triad C-56U and the new style open frame Edcor choke.
The new supply settles quite a bit quicker, in well under John Swenson's sought-after 50 mS., to a 15% current step.
The original 60M supply uses the 1970's "big final cap" of 1,000 uF, and the "modern" supply uses 68 uF as C2, and has lower B+ ripple.
Cheers.
Jeff Medwin
Edits: 08/07/12 08/08/12
Intelligently in the 1970's, designed with a TOTALLY SEPARATE G2 supply, the stock Paoli 60M used a 62 Ohm DCR 230 VAC G2 power trannie. The Dynamic Z of the supply PSUD 2 simulates to 511 Ohms Z, and it settles in 550 mS. (see top PSUD 2 screen shot).I have applied "modern" power supply technology for G2, and we can use off-the-shelf iron, (from Signal Transformer Co. and Edcor) to obtain a G2 supply that settles TEN TIMES faster, (about 60 mS. - much closer to John Swenson's 50 mS. threshold), and has a reduced Dynamic Z of 177 Ohms.
All this is passively designed and executed, with NO add-on active regulators (ugh, ugh) to leave their sonic thumbprint on G2. A bold new world of audio is here.
G2's treatment is "everything" in Pentode Finals, it requires a separate supply, and we are maximizing performance with the above design. This will be VERY VERY bold and authoritative sounding, yet ultra-detailed, and the 60M amps will be a whole LOT of FUN to hear. Enjoy them Bob.
Jeff Medwin
Edits: 08/07/12 08/07/12 08/07/12
For G2 supplies :Here are ALL the magnetic parts, off the shelf stuff, no part truly "audiophile inflated" in cost, just Jeff's picks, "the real deal" :
(1) 6 Ohm DCR Power Transformer; Signal Transformer Co., Model A41-175-230. Digikey P/N 595-1307-ND, rated 175 VA, or 760 mA !!! $49.42 for an "under ten Ohm, Ultra High Fidelity" part.
All I will tell you is, "don't live this life without a UNDER ten Ohm DCR PT in your tube audio amp."
(2) L1, 72 mHY is a Signal Transformer Co, dual choke, Model Number CL-1-2. Rated at 1 A. and ONLY 1.4 Ohms DCR as configured, it won't buzz. Digikey P/N 395-14307-ND, only $19.77, one of the biggest bargains in audio, under 10 Ohms = "Ultra High Fi ". Weighs UNDER one pound. Low in stored energy.
(3) L2, 1.5 HY at 17 Ohms, EDCOR model XC75-1.5 HY at 250 mA., lists at $26.13. Small, low in mass/stored energy, and beneficially, open frame, no end bells to mess it up. Three week delivery.
(4) L3, 2 HY at 29 Ohms, EDCOR model XC75-2 HY at 200 mA., lists at $26.13. Small, low in mass / stored energy, and beneficially open frame, no end bells to mess it up. Three week delivery.
We should consider this : ALL THREE of these industrial-made and priced Ls are less than the cost of just ONE high mass and high DCR, clunky "audiophile" LuXXXhl choke. Audio "give-away" here, like a JJ-2A3-40.
(5) The current-drawing resistor MUST ONLY be a Mills MRA-12, of proper Ohmic value. Michael Percy, 5 or 6 dollars.
(6) The 54 uF part can be a (newly designed 105 degree C) Nichicon KX audio-grade cap, value is 56 uF at 450 VDC. and it is INexpensive, a few dollars. Parallel two more for the 110 uF final cap in this G2 filter.
(7) Double Kimber Kable TCSS wire this entire supply, right to the G2 pin on the tube socket.
(8) One other circuit twist .....DO not forget to put a John Swenson snubber, between the power transformer's secondary HV winding, (a C and R, connected in series, and then placed in parallel across the HV winding) and the solid state rectifiers.
(THIS SNUBBER IS NOT SHOWN IN PSUD SIMULATION SCHEMATIC !!)
It will be John's suggested values : 0.022 uF and 330 Ohms. Wima nicely makes a 4,000 VDC rated part, 5 or 6 dollars, BUY that one, which should NEVER fail.
Hey, hey, hey, we are putting a power supply on a GRID, so this snubber is justified, 'will be audible improvement on G2 - big time !!
--------------------------------------------
Now buds, after about 80 years, there is NO more excuses for you to be listening to that nasty sounding, perturbated U.L. (ultra NON linear) connection on your G2......OR, that nasty and non-transparent-sounding actively regulated G2.
William Z., do you ever read my posts ?? This could be ideal for your big "Reference" series amp.
Wake up everyone and smell 'de roses. Circuit suggestions are welcomed and encouraged.
Cheers.
Jeff Medwin
BTW, my friend JLH could also use this separate G2 supply advantageously in his pentode LCR preamp.
Edits: 08/10/12 08/10/12 08/10/12 08/10/12 08/10/12 08/11/12 08/12/12
IMPO:
Will this Drlowmu G2 supply work? YES
Will this supply sound good? YES
Is it overkill? YES
Will it hurt anything other than cost money and space? NO. (The use of doubled up silver wire however is simply absurd! A real waste of money)OK, since your project is a DIY build and not mass production there is no problem with using it. However based on common knowledge of Pentode operation it's not necessary.
Now there is one minor flaw. It is not a true regulated supply. The low DCR secondary does impart good rough load regulation. The current draw is miniscule compared to the capacity so signal loading won't be an issue. However it will vary with AC line voltage changes by a factor of two. I don't like that but many areas have good utility AC stability.
Now about regulated power supplies. It is true if not designed properly they do impart a sonic deficiency to the amplified signal. And design is difficult to do at high current levels - especially in SS amps. That phenomenon however is only an issue with power amps, specifically the output stages. Preamps, signal processing devices, and even the power amps driver stages benefit greatly from active regulation. In my builds of three KT88 PP amps for midrange service I found the best compromise was unregulated finals but a regulated driver stage.
The problems with regulators is rising impedance with rising frequency AND rising current demands. Exactly what happens on a power output stage. The entire audio industry finally acknowledged back in the 70s that the best power supply for amps is a simple rectifier/filter. Remember the Dynaco 120? This is a great example of a bad regulator design but with respect to Dynaco it was an achievement for the time with the low HFE power transistors of the day.
Saying that regulators "sound bad" is a very sweeping broad statement. While not untrue in some cases, the theory and therefore applied practice of good audio regulator design is beyond the novice hobbiest as well as theater projectionist, irrigation mechanic, fashion audio product builder. Without the deeper understanding of electronic theory it's probably to just best avoid regulation period. Note this has nothing to do with university education as is often ridiculed by some here. Especially with the internet today, anyone determined can learn this stuff. There are many good articles published on this very subject of audio power supply regulation.
Edits: 08/10/12 08/10/12 08/10/12 08/10/12
Countless expensive brands with tall tales of impossible performance claims. Don't have time to keep up with all that.
Hey, I DO USE SILVER PLATED TEFLON WIRE! It's great, solders beautifully, no insulation creep, no danger if scorching next to a power resistor or heat sink. But sounds better within an average chassis length? Nah, I don't buy that.
Oh and the most important reason, I can buy 500ft rolls by the pound which is less than $10 here. http://www.apexelectronic.com/image/tid/48. As silver plated teflon wire was very common in the cold war, there are huge stocks all over the US available just a cheap. Look on line. No need to pay Percy prices. (Percy is a great resource though for many other things)
Gusser,
Do not worry about protecting "Mr.Bob". Look up the Curcio kit costs.
Kimber Kable TCSS is not "expensive silver wire".
It is multi strand copper wire whose strands are various gauges, unplated, effectively about 19 gauge, teflon outer jacket, retails at about $1.10 to 1.20 a foot, and as a manufacturer, I get it at a reduced cost.
One other thing, I have always found, over the last 34 years, the "goodness" in terms of DCR of the power transformer, and L1 and L2 chokes preceding ANY active regulator, is heard through the regulator.
The "iron" has to be 20 Ohms or less, to musically satisfy "me" on a long term basis. YMMV, fine !!
Jeff Medwin
Regulating the screen with a VR tube produces exceptionally fine results. No more complication (such as a separate supply) is necessary.
--------------------------
Buy Chinese. Bury freedom.
Hi Triode Kingdom :
Incorrect. Speaking from direct experience, I have owned and heard MANY highly regarded high quality tube amps since the 1970s with actively regulated G2 supplies. Results always left me wanting for more.
There is NO substitute for a (1) totally separate (2) low DCR supply to G2, assuming one seeks maximum performance. It brings a certain music presentation to the table, (bold, AUTHORITATIVE, vivid, detailed and nuanced) that you can NOT obtain ANY other way. Its simply the very best way to execute G2.
It is similar conceptually to building an amp with totally separate supplies for each stage, except G2 of the Pentode Finals is much more sensitive than that.
You have simply under-estimated the sensitivity (and importance) of G2 Triode Kingdom, as MOST ordinary E.E.s do.
Here are the three ways to do G2, each successively better sounding :
(1) Most E.E.s will use a cheap-o resistive voltage divider to separate G2., mediocre.
(2) Some E.E.s will add a active regulator, (unfortunately, with its own thumbprint, because G2 is sensitive).
(3) Walter Key in the 1970's, (and I), will advocate a totally separate passive G2 supply,..... cleanest sounding and simple.
Now you all have been made aware.
This is why the Paoli 60M, with a separate G2 supply, has had a following over many years.
Imagine how this new build will perform for "The Bob" - with really good sets of power supplies ( B+, G2, negative bias) supporting his circuit !! If you want an amp to perform, you need to give it really good supplies, or, you are just playing with yourself.
In 2012, we have progressed from the 1970's, and have learned how to design SUPERB passive supplies. It is PSUDED above, for anyone interested. A cheap gas tube G2 voltage regulator off an existing supply that you propose.... will never be the equal.
If it didn't make a significant difference, I would not go to the trouble to build it as I show you all.
But it DOES make a difference, and it is very audible. "The Bob" will have some real fun, and benefit tremendously.
Cheers,
Jeff Medwin
"There is NO substitute for a (1) totally separate (2) low DCR supply to G2, assuming one seeks maximum performance."
Simply untrue, and there's no evidence of this anywhere but between your mistaken eardrums. I have learned over the years that you prefer the sound of sloppy, poorly filtered supplies with peaky response and inconsistent output impedance. Nothing you could say now will ever convince me that you have the aural education necesary to discern fact from fiction.
--------------------------
Buy Chinese. Bury freedom.
Your theory, OR, results and performance, over decades.Proof of the pudding - is in the eating.
Jeff Medwin
Edits: 08/10/12
Tell 'em, Jeff! Point out the obvious so highly trained "yes" people can-- some day-- and in some way, finally understand-........------ THE OBVIOUS!Really! We're arguing about a power supply that is about to be attached to A GRID-- for !~@#$%^&* sake! A GRID!
I developed superior power supplies for plates of triodes-- and you have used parts of this information to help many forum members. And you did this without tons of engineering training. Well, it's been good anyhow!
That was S.E. triodes-- a plate supply. Made a difference-- huge.
But NOW-- we're talking G2 in a pentode or Tetrode amp! THIS application is FAR more critical than in a simple S.E. triode Plate Supply.
Hey! If you guys know ANYTHING-- you know how LARGE--- ANY--- changes on G2 will sound. IT IS OBVIOUS!
Let's just be blunt: IF any one of you install a voltage or current regulator on a G2 Supply-- you will listen to THAT-- NOT, I repeat-- NOT-- to ANY FORM of music.
AND, if that supply has High-DCR chokes and large capacitors in it-- you WILL be listening to that mess stumble all over the place-- desperately trying to salvage some small part of the musical signal.
G2 supplies are super-critical, they must be engineered to NOT interfere with the tube's TWO GRIDS-- operation-together, as a whole.
GO AHEAD! Get with it!-- all the usual bullshit and theory. HERE it comes! JEFF! Get ready!
Jeff could simply apply a decent G2 supply to any separately-powered G2 setup in any Pentode or Tetrode amp-- and the difference would be starkly obvious.
Enough is enough. We've had arguments for years about the simple requirements of two-stage triode S.E. amp's Plate Supplies-- the differences were large and obvious-- on great speakers.
BUT NOW-- you're talking about G2 power for a Tetrode or Pentode amp!
ANYTHING you do to mess up a G2 supply will be amplified-- starkly obvious and it won't be good, Dudes-- NOT VERY GOOD!! Of course, you can deny that. Just run ordinary speakers, sources, and interconnects-- and you'll never notice (as usual?)! Maybe.
Or you just might anyhow! G2 is a rather sensitive spot-- after all, it's a grid! I think you probably WILL notice THAT!
---Dennis---
Edits: 08/09/12 08/09/12
I know nothing about pentode amplifiers, but as I understand it G2 needs to be held firm at a certain constant DC voltage in relation to the grid, etc. Thus I can see why some of the alternative schemes you pose above would potentially be at least a little flawed. But since the G2 supply is not subject to signal voltage, i.e., it does not have to "recover" from anything, as far as I can tell, why is it so important that the G2 supply be "low DCR"? It would seem that any decent low noise and stiff supply would be sufficient.
Lew,G2 needs a low impedance supply, as well as a fixed voltage supply. That's especially true for Class AB1 PP pentodes, because G2 current demand can vary greatly from quiet to loud music passages - as much as 500%. That's why either very low DCR supplies or series regulation supplies have often been used for G2 (shunt regulation is not really practical with such great variation of current demand).
I personally favor a MOSFET source follower regulator with a voltage reference on the gate. This approach is "modern", using modern technology, is very simple, provides adequate regulation for the purpose, doesn't use NFB and isn't noisy. The voltage reference can be a high voltage zener, a string of gas tubes or, best of all IMHO, a CCS driving a resistor. (If using a zener, it's best to "suppress" it with a high value cap. to deal with the noise, although the tendency for such zeners to drift is a potential problem too.)
Edits: 08/11/12 08/11/12
Ray,You posted this :
G2 needs a low impedance supply, as well as a fixed voltage supply. That's especially true for Class AB1 PP pentodes, because G2 current demand can vary greatly from quiet to loud music passages - as much as 500%. That's why either very low DCR supplies or series regulation supplies have often been used for G2 (shunt regulation is not really practical with such great variation of current demand).
------------------------
Your contribution was excellent. When I look up GE 6550A tube data sheets, I read (as AB1 P-P for two tubes, 450 VDC P-K), the following specs:
G2 at idle current , 9 mA.
G2 at max power , 38 mA.So yes, that is over a 400 percent change. NO WONDER low DCR G2 supplies made a difference in stable G2 operation. Its not just a change from 1 mA. to 5 mA.
As a result of your post, I am now also viewing 500% changes in G2 current, with PSUD2 sims.
No longer only 3 mA. to 3.45 mA., or a 15% delta I.
Thanks Ray.
Jeff Medwin
Edits: 08/15/12
Lew, your question is fully relevant.Ray-- your post is outstanding-- it is 100% on the money.
As Ray relates, G2 has enormous current demand swings. The Mosfet approach has been used by several of the better P/P amp builders over the last several decades-- they used it to compensate-- partially-- for power supplies that are inadequate..
I have an old McIntosh MI-200 Industrial amp--a pair of them.
At one time, I had quite a few of them, but sold-off all the prettier ones, and kept a beat-up pair. This sported the usual "MAC" front-end-- a 12AX7 and a 12AU7-- too much gain, and too little fidelity.
The rest of the amp was really cool! The output stage was a pair of 8005 DHT's. These were operated in Class AB-Class B, depending on the output level. Standing idle current per 8005 was set at 60 ma., each, and plate supply voltage was 1000 VDC. This was from 4 5U4 tubes, operated in a Full-Wave-Bridge. Max. output was rated at a continuous 200 watts with a very wide bandwidth-- up to 200 KHZ. Peak output was over 480 watts.
WHY? It was designed as a Shaker-Table amp for Gold Mining operations. You used a signal-generator input-- you could thus select any frequency fron 2 HZ on up-- and run the transducer that shook the separation table at whatever vibration turned out the most Gold..
Usually, these had 2 ohm, 4 ohm, 8 ohm, 16 ohm, 32 ohm, and 500 ohm outputs.
Movie Theatre guys-- especially in Canada-- as in Calgary, Alberta-- had glommed onto these things to run Drive-in Theatres, and also to run indoor theatres which seated 1500 or more people.
I liked the thing, so I fixed-up the power supplies with some nice PhotoFlash caps instead of the usual soggy-sounding electrolytics. That alone really perked the thing-- it fixed a lot of output stage problems right off.
First thing I did was eliminate the input 12AX7 and 12AU7 stages-- GONE! I got rid of all NFB.
The input stage I made out of a 6BZ7 twin triode. I used a Mosfet, like Ray does-- in this case as a CCS on the common-cathode. I had connected the two cathodes together, and ran one grid grounded, the other "hot"-- that was the amp input.
The Mosfet CCS made the thing come alive more-- it was a really good amp by then.
Then, I took the Mosfet out, and VERY CAREFULLY adjusted the common-cathode resistor until I got exactly equal plate currents in both sections-- at idle.
Well, that took care of the remaining nasties-- small-signal humps and bumps due to the CCS-- which was GOOD, but now things were even better.
I still have it-- buried somewhere with enough tubes to run it for decades.
The output transformer in this thing is one of the best ever built, and it sounds like it! It sounds almost like a SET-- it's transparent, and fast-- it has dynamics and it has a very wide bandwidth.
I judge it by far THE BEST amp out there-- until-- the little 2A3 SET-- which bears zero resemblance to any other amp-- especially "usual" SETs--which are usually quite dead dynamically, and sport severely deficient bandwidth and speed. Most decent SETs do have a sort of transparency, and a certain "rightness" to the rhythm, Pace, and Timing of music, but I find them boring dynamically.
The SET I use has overcome all of these problems, and is dead-reliable and its performance is always repeatable. It TRASHES the Big MAC in every listenable musical parameter. It is FAR more dynamic than any other amplifier, period. Another unusual thing about it is that this terrific sense of unlimited power is present right down into-- and through-- the lowest Octaves, yet they are blazing fast and super-lively. Also, the entire range, including the bottom octaves has all the colors and dynamics that are present in the recording being played.
That's why I have the MAC buried somewhere---.
The MAC Finals Supply was choke-input. There were 4 separate supplies--the other 3 were the usual Center-Tap arrangements... I recall one might have been choke-input, the others CLC. 5Y3's were in abundance.
The finals were driven by a T.V. Horizontal-amp tube-- for all practical purposes, consider it a KT-88.
A great feature of that MAC amp was its output transformer-- which had windings that loaded all the driving stages. That is why it sounds close to a good SET-- all the time-delays caused by having too many stages had been compensated-for--- timing-wise-- by designing the output transformer windings with the needed reverse-delays. It all came out just like a single stage!
MAC made this thing in the 50's-- it is BY FAR their best-ever amp, but is also a 4-chassis monster and a great Room-Heater. Two channels of it occupy 4 chassis-- with umbilicals-- total weight is just under 200 lbs.
As busy as this thing is-- it is quite reliable. It can run for 2 or 3 years more or less continuously, and can be switched on-and-off at will with no tube problems and without tube servicing-- something few enjoy today.
I think it is about 300% better than any SET today-- except for the one that was actually designed right. That SET resembles no other amplifier.
A lot of discussion has ranged over Ripple, Hum and noise.
I realize that one can obtain very low Ripple, and a very quiet background by using lots of inductance, High-DCR, and large capacitors in a Power Supply.
This can be a matter of preference. If you're after just TONE-- you can get it right with any kind of power supply, and you may wish a "quiet" background. If you want a Female voice to sound like the Lady-- you can get that also.
What you don't have is DYNAMICS-- all kinds, Micro and Macro.
But, you CAN compensate, and GET BACK the MACRO-- by using an amplifier that has a lot of watt-power. To get it that way, you must utilize an inefficient speaker that will USE all that power. A lot of it will go to waste heat-- but there will still be plenty enough to Hard-Drive the speaker.
While this can be impressive, it is not real dynamic life-- as in REAL life! It's just a Power-Driven approximation-- a false POWER PRODUCED dynamic-- it's not what the musician actually did.
The other way is to decide what is an ideal power supply. That would have NO inductance, NO capacitors, and ZERO DCR.
It would also have NO FORCED way of providing Low-Impedance-- that is-- by regulator. Instead, it really needs NATURAL occurrence of the same parameters. Those should be designed-in, not forced into compliance after the fact.
The difference in sound quality is simply staggering if you haven't heard it happen.
Low Ripple, Low hum, and Low Noise are all things that we all want.The problem arises when we seek to obtain those admirable characteristics by wrecking the amp's performance. We're fixing one thing by CAUSING other problems.
An interesting case is HUM. Long ago, while building movie theatres for special theatre owners who wanted cost-no-object performance (yes, that is rare), it was discovered that a small amount of A.C. Hum acted as a signal carrier-- that is, the HUM keeps everything in a system-- all the parts, all the wiring, all the solder joints, all the transducers IN A READY STATE. It is a signal carrier of the best possible kind.
Since the entire audio system is ALREADY IN MOTION-- when a small cue that is either alone, or is buried in signal, occurs-- it is simply and effortlessly carried by the entire system. Nothing has to "stop and start"-- as it has to do with a system that has a totally "black" background.
People get fooled by this. In a "quiet" system, NOTHING happens UNTIL a threshold of signal has built up-- and THEN-- it lets go. Many mistake this phenomenon as "fast", and say that the amp has "speed". Actually, it can be VERY SLOW and STILL APPEAR to be fast because once the threshold is hit, you do get sudden energy release.
Trouble is, you just missed MOST of the music! Ir simply isn't there!
So, what to do about HUM? Simple: tolerate as much as possible, but don't overdo it. The sound quality difference will amaze you!
---Dennis---
Edits: 08/12/12
"Lew, your question is fully relevant.
"Ray-- your post is outstanding-- it is 100% on the money.
"As Ray relates, G2 has enormous current demand swings. The Mosfet approach has been used by several of the better P/P amp builders over the last several decades-- they used it to compensate-- partially-- for power supplies that are inadequate"
Dennis,
Thanks for your kind words. They may help to protect me from the fury of our mutual buddy, who is probably currently loading both barrels.
Ray,
I actually thought you posted a superb response on variations of G2 current.
I just didn't acknowledge it, because it isn't right for a fellow from Great Britain to get too conceited. Being brash is for the uncouth Americans.
Egads, jolly good job Ray.
Jeff
And an elegant solution. A truly modern approach using a MOSFET regulator. Much better than an unregulated supply.And it's obvious to me Ray has a good electrical engineering background. He outlined his circuit quite well. Not the same old goobly gook we get from Dennis based on farm irrigation principles.
Edits: 08/14/12
The WHOLE POINT of this thread by me is that G2 is sensitive, and it always sounds best, has the highest audio performance, with NO active regulator what so ever, just a well-executed "modern" supply works best.
As soon as you put any active regulator on the G2, you have a degrade versus the supply I have outlined. The basic supply has to be pristine, and that alone is all that is needed.
Funny, I thought the thread was by TheBob, not you, but you think it's all about your agenda? This has happened before.
The type of regulation I would recommend does NOT degrade anything. It is much better than your recommended so-called "modern" supply. It provides a rock-steady voltage regardless of the G2 current dcemand. Your approach was the way things used to be done decades ago, before modern technology became available. Why live in the past when you can do so much better?
How will that work well, if the current demand is swinging up and down? Isn't that the antithesis of low DCR? (I am sure I am missing something obvious.)
Thanks for the explanation, by the way. I had not appreciated the the extent to which the current on G2 might vary.
The CCS (constant current source) can be, as in this example, a two-transistor cascode. (The zener is 6.2v, the most stable and least noisy) It takes its current through a (high stability) fixed resistor. Fixed current through a fixed resistor = fixed voltage. This acts as a voltage reference for the gate of a suitable MOSFET. The source of the MOSFET is also at that reference voltage because of the extremely low gate-source impedance. The current for G2 is taken from the source via the drain. The variability of G2 current has nothing to do with the CCS current.Incidentally, the regulator shown includes a slow-srart, to ramp up the G2 voltage (the 1.5Meg and 2uF capacitor). This helps to ensure tnat the fixed bias reaches its required level well before the pentodes start taking current.
Edits: 08/12/12
I learned something.
"...why is it so important that the G2 supply be 'low DCR'"?
It's not important at all. This is non-scientific hooey that hasn't been verified by any reputable source.
--------------------------
Buy Chinese. Bury freedom.
Hi Lew,Hell if I know anything my friend.
Yes, and you notice, my test is at 3 mA. with my usual 15% step, to 3.45 mA.
A stiff supply IS a low DCR supply. It seems from my listening experiments, that Pentode G2 is super critical. Walter Key got it right in the 1970s by using a totally separate G2 supply. Later attempts at the Paoli 60M, with a different E.E., used more and more regulation, and the amps died (Paoli S.O.B. etc.). Dennis Fraker and I have discussed this over the past two decades, and we believe a separate supply, a clean one, IS the very best way to do G2.
What ever I did to improve the G2 supply, seemed to lock-in the amp's music making ability, just as much, (actually - perhaps more), than as if I was using 10 Ohm power trannies on the B+.
Honestly, it blew my mind how wonderfully the amp responded, on the speaker load (Fulton Premieres, P-12s), to my G2 power supply improvements.
I don't know all the theory, but that didn't hinder me from getting decent results !! I listened a LOT !! Tried a LOT of configurations, I had a LOT of fun doing that.
Jeff Medwin
Edits: 08/09/12
Makes perfect sense that a completely separate and dedicated supply might be optimal and also rarely used because of the complication involved. I was only wondering about the "low DCR" mandate. I guess you base that on your listening to amps you have built.Who was the (somewhat infamous) audio dealer who was a central figure in the development of the Paoli amplifier, so named because his shop was in Paoli, PA? I cannot remember, but I believe he was also an IMF loudspeaker and Audio Research dealer. (Bud Fried's business was located in Phila.)
Edits: 08/09/12
Hello Lew,Eugene Coggins is the guy, nice man, also the sole USA Decca cartridge distributor !! Mel Schilling got his start in Philly too. I grew up in Trenton, NJ and in Bucks County, PA.
The 1970's Paoli amp patent holders are named as Eugene Coggins and Walter Key, Walter being the engineer who really did the original circuit, with a totally separate G2 supply, schematics all on line, US Patent Office.
Dennis Fraker has been building separate G2 power supplies, low DCR, since about the 1950's! When he was 12 years old, in Billings MT, he used to walk across town and daily raid the Western Electric (four blocks big) Billings Service Center trash bins. All the EEs liked seeing this "only 12 year old" kid, and GAVE him cool stuff. He knew back then, separate G2 supplies, LOW in DCR, (he used retard coils) was the ONLY design that was sonically palpable.
Coggins' later Paoli amps unfortunately morphed into a "designed by an typical EE nightmare", active regulators, and they sounded worse and worse. All of my own PSUD 2 above-posted ("modern") power supply improvements can be directly applied to the Walter Key supply, and should REALLY be a wonderful thing to hear. I already know it will kick a** and take no survivors.
Jeff Medwin
Edits: 08/09/12 08/09/12
is definitely the guy I was thinking of. He was a "noted authority" back in the day and a bit sharp around the edges.
When I was 12, G2 might have meant something to me, but I doubt it would have had anything to do with pentodes. If I ever raided a trash bin at that age, it was for discarded Playboy or Esquire magazines.
Dennis MADE from scratch, a radio station in his family's basement when he was still in High School, and he and his class mates would broadcast after school, all over Billings, MT.
Good point on Playboy. Hormones 'a popping. My Dad had a new Altec 604B in the wall of our basement Rec Room, when I was eight. Listened a lot to My Fair Lady, Rex Harrison.
Jeff
My mom was an opera singer and opera buff. For her benefit, my dad put together an Altec corner cabinet, probably using a 604, that I think he bought as a kit from Radio Shack. I remember watching him build it in our basement. He mated that with a Harman Kardon Festival mono receiver and a Garrard record changer. Not only was I exposed thereby to Maria Callas, etc, but also to South Pacific, etc. Later, I played my first copy of KOB on that same system, and Take Five, and yes, Johnny Mathis. Also, I believe that system led me down the path of being an audiophile, much later. And this was way before Mel Schilling and the Paoli amplifier. Until this thread, I never realized the Paoli had endured as such a "classic".
Mel Schilling had very little to do with the Paoli amp, other than maybe he sold it at Music and Sound in PA. It was nice-guy Eugene Coggins (of Paoli Hi Fi Consultant's) baby 100%, with Walter Key as the EE, and later, Coggins with another EE.Jeff
Edits: 08/10/12
You have done all this G2 experimentation, surely you documented the results in terms of standard electrical parameters and also included the musical passages you used in subjective testing.
We would like to see them if we are to heed your sole advice.
Please don't tell us all this extensive testing was done by circuit modification and re-listening a half hour or more apart? That's a highly flawed approach.
BTW, is this Walter Key still alive so anyone interested can try and contact him? You have a track record here of quoting famous but dead industry figures. Difficult to verify the claim isn't it.
LMAO.
You bet your sweet bubbkies I used my ears !! "Deeply flawed"... right.
I also use my imagination and a whole LOT of intuition in selecting parts configurations, and I LISTEN to what they do and how they effect the music' presentation.
All the truly great creative audio people do this, and we are ALL endowed to do this, if self-motivated. How do we assign "numbers" to humans' imagination, enthusiasm, aesthetic concern? Edison employed high school kids who were NOT trained, so they would use their imaginations.
Can something designed by ear sound good? If so, the numbered method may not be needed. Lets paint by numbers Gusser, Monet did so, look at Waterlillies at Giverny.
And the biggest question of all, is, what numbers?? What is the BEST piece of audio test gear to generate those numbers? Is it a o'sillyscope of high bandwidth, how high is needed? You, as a college trained EE, does not have this answer at all, and you will go to your grave not really knowing, although, most sadly, you THINK you may know.
Gee, maybe the numbers need to come from my spectrum analyzer, and not my Tek scope!!
Or, is the best audio test gear our human brain and our ears which has been undergoing development over millions of years?
The proof of the pudding is in the eating. Number that, my friend !!
Jeff Medwin
To speak out that math and science are of limited or secondary value in electrical engineering.
Foolish!
You think that's absurd? See if you can find any of the schematics or circuit descriptions for the "Low DCR" supplies that have been posted here. They're absolute junk, not designed to any standard of electrical performance, intended only to be sufficiently different to attract the interest of those who are unable to discern their failings. Pandering to the unknowing and uneducated appears to be a consistent trend in this forum now.
--------------------------
Buy Chinese. Bury freedom.
Triode Kingdom,Looks like I have suitably "pressed your buttons" and you have gone off-the-scale BOINKERS !! Sad, sad, sorry to do that.
Hey, wanna schematic, just look again at my PSUD sims, its all there !!!
Seems funny, these supplies seem to be LIKED by some EEs on this Forum.
We have had Henry Pasternak, John L. Hasquin, and John Swenson writing positively on various aspects of it, besides Dennis Fraker who builds the world's best SE 2A3 amp. Ask Dave of Raleigh Audio about the amps. NONE of these people are not discerning and unknowing. Au contraire, they may be all way smarter than you.Are you BLIND to that?
How about Larry D. Moore, Esq. of "Ultra Fi", using it in his new Monoco 845 amps and saying that is ALL he will use to Finals, now that he has tried it. How about Drummerwill??? And how about Mr. John Jacob Gingleheimerschmidt??? None of these end users are novices .
Get "real" TK, 'smell de roses.
Jeff Medwin
Edits: 08/11/12 08/11/12 08/11/12
Like most of your posts, there's nothing of substance in this reply. I've analyzed several of your designs, I know how they perform, and you won't bully me into shutting up. There may be instances where a designer can get by using a supply with limited filtering and poor dynamics, but that doesn't validate this defective concept. Use all the voodoo engineering you want; just don't expcet those of us who know better to stand by while you publish junk and rubbish in the guise of scientific research.
--------------------------
Buy Chinese. Bury freedom.
These supplies do produce hum due to the minimal ripple filtering. Both Drlowmu and Dennis have acknowledged that. They claim however since the output triode has a low mu, hum on the B+ is not amplified all that much.OK, I'll agree to that.
But here's the rub. Due to the flea power of these SET's you must use very efficient speakers. Well doesn't a sensitive speaker reproduce background hum at a higher level than a not so efficient speaker. Yes, the hum level is very low in these "modern" power supply SETs. But then the speaker efficiency is that much higher too.
And here's the bigger rub: Dennis in particular goes on and on about "micro dynamics" and "timing". He further states that you need really good internal wiring and other extreme construction techniques to be able to reproduce them. That's why us so called "mid fi" people can't hear them and don't think they exist. OK then. How does Dennis and Drlowmu reproduce the subtle "micro dymanics" with the signal riding on top of rather high power supply ripple? If you are going to try and reproduce "micro" anything in an audio signal you need the background noise as low as possible. That would mean virtually no measurable AC ripple just as a start.
Edits: 08/11/12 08/11/12 08/11/12
This is a good post and a seemingly logical set of questions.The problem is one of application-- the theory is OK-- the application requires a careful balance of real-life factors in order to get a whole that is superior overall-- in reproduced musical results.
One of those Real-Life factors is that a resistance in series with a power supply seriously blunts that power supply's dynamic response. (After all, it IS a resistor!).
Another obvious one is that the larger the power supply capacitors, the less power the supply can deliver into instantaneous, intermittent demand. It is obvious that the recharging capacitor is competing with the load for the available current. OBVIOUS result? Large capacitors equals current starvation in the load.
The most obvious to me is that an ideal power supply has NO resistance, NO capacitance, and NO Inductance.
When someone understands this, and builds as close to this ideal as possible, it should be obvious that it is the right thing to do.This requirement ALSO demands the utmost in good wiring? This isn't extreme, it's a MINIMAL REQUIREMENT! When you have a system that can resolve the sonic differences, then ordinary wiring, used commonly by Industry-- is sadly lacking.
So-Called "boutique" wire builders are some of the smartest, best engineers that we have today. They are combining good materials with a good understanding of what the wire is being asked to do in audio.
One thing the best wire builders have done is give us large conductors.
For even the smallest, instantaneous musical signals, these wires make all the difference in the Low-End of a given system. NOT just how low in HZ. it goes-- you could prove that the HZ Low-End will be the same with a smaller wire-- if all you do is measure it and apply known wire conductivity tables.
Trouble is- the larger conductor is ALSO handling certain obscure Energy Peaks-- which NO ONE is measuring, but you can hear the results of. RESULT? The larger conductor is more efficient at conducting Low-End Energy PEAKS. What a surprise.
So, how does one get-- say-- a 10 gauge conductor to do well at H.F. Audio frequencies? Just ask Siltech or Audio Revelations, or Pranawire!
They get better "highs" than ANY wire. Do YOU understand how this is done-- that it is, and must be a balance of factors-- not just an Industry Wire Table?Look, I have plenty of Belden wire also-- but only one product is any good! I have plenty of THAT one! I found ONE product that they make, which I used in my new 12V. D.C. computer power supply. It's Tin-Plated, double-shielded, twisted 2-conductor/double Teflon insulated 12 ga. Why the double-Teflon? It's designed for FIRE ALARMS!
People seeking a usable, cheap A.C. Power Cord like it. Why did Belden design it this way, since it is good wire (must be an accident!)? FIRE CODE demanded it-- the stuff is also colored RED.
Since we're not in the 50's anymore, maybe they could make their FIRST usable AUDIO WIRE!
Try an analogy-- Will the Porsche 911 run better with the tires that worked best for it-- in actual driver preferences-- or should one apply theory and include Bicycle Tires? After all-- they're theoretically better.
If you'd like to operate an OSHA Lawn Mower-- be my guest-- that's what all Vintage and most DIY amps are!
There's better to be had-- and you can buy or build it. All you have to do is apply common sense, and then build that way.
---Dennis---
Edits: 08/12/12 08/12/12
The only thing 12v is used for in even a 10 year old computer is fans and the hard disk motor. The primary power rails are 5v and 3.3v From that the processor core has several dedicated regulators that supply 1.8v, 2.6v, and other component specific voltages.So what exactly is your 12v supply accomplishing?
Want to impress me, build me a full ATX power supply that plugs into the mother board. Try and meet those regulation and current requirements with your cowboy engineering. Sure real engineers have mastered that all for $30 these days. But don't let that price fool you into thinking it's junk. Just try to build one from scratch.
Edits: 08/12/12 08/12/12 08/12/12
Sorry to disappoint. We found circuit cards that were all 12v!They're just becoming available. Also, S/S Hard Drives have come down a lot in price lately-- so that's helpful..
We're using 3 separate 12V. supplies-- one for the Mother Board, One for the Processor, and one for the USB card. We had to look to find all 12v. stuff. It's out there!
I got started on this at RMAF where I thought another demo room sounded better than ours. They were using an Apple computer-- the entire thing was run on a 12V. auto battery.
My setup is newer, and it is a P.C. which is what I wanted so I could use Media Center the way I wanted to. The kind guys at Berkeley Audio Design and Al at Goodwin's High End steered me to the right implementations. I got a lot of help from Jeff Fox at Command Performance Audio-Visual..
I built a power supply for these things only because there are NO good ones that I can buy-- which is what I prefer-- I'd rather BUY!. Anyhow, the new P.S. is a real beauty.
I am using BAD's Alpha-DAC2, and their USB link with this system.
Audio drive is direct from the Alpha-DAC2 straight into my amps.
I also bring along my trusty Pioneer Blu-Ray player-- all 33 pounds of it. This was built as the top of the "Elite" Series. I liked the way-strong transport in it.
At shows, we will run the SPDIF output into the Berkeley Alpha-DAC2.
This performance is close to being as good as the computer. On musicals such as "Celtic Thunder", the sound is very, very good.
I did this once before-- even had the Plasma Panel at Denver. No computer, and only Pioneer DVD players. Today, those are unlistenable.
I could show up with a Turntable one of these days, but although I have good tables, tonearms, cartridges and wiring, I find ALL Phono stages that can be bought-- really, really bad, and linestages even worse.
A guy could spend $150,000.00 on L.P. playback and still not get there.
Vinyl freaks! You need some PREAMPS!
I would have to build one. Until I do, the computer is King.
---Dennis---
Edits: 08/12/12 08/12/12 08/12/12
While it's possible you have found a motherboard designed for mobile applications that runs on a single 12v supply, I guarantee you there is a switching regulator fed directly from that 12v producing all the required voltages.
No processor core or memory these days runs directly from 12v. Some PCI cards also take in 12v as it's convenient from a drive connector. But again, it's feeding a switching regulator on the board.
Dennis you are not an electrical engineer by any stretch of the word. The crap you post is just that. You have no clue what is going on within
the circuits you copy from others and slap together. Because of this lack of understanding you resort to magic and voodoo.You are really a dis-service to this forum!
Tell me, why isn't all this great modern theory and practice you claim to have solely discovered applied anywhere in the commercial market. Why is it just restricted to your one hit product?
I am an IEEE member. I get the journal. I have yet to see any of this crap you promote published in any form.
Edits: 08/12/12 08/12/12 08/12/12
Hi Gusser,
You ask this :
"How does Dennis and Drlowmu reproduce the subtle "micro dynamics" with the signal riding on top of rather high power supply ripple? If you are going to try and reproduce "micro" anything in an audio signal you need the background noise as low as possible. That would mean virtually no measurable AC ripple just as a start."
OK Gusser, good honest question, 'deserves an answer.
- - - - - - - - - - - - - - - - - - - -
We see the 2A3 SE output stage, in a DC two stage amp, as somewhat like a unity buffer. (A mu of 4 triode driving a 2.5K to 8 Ohm step-down trannie.)
This means we are hearing mostly the driver tube, be it a 7B4 in Dennis' case, or half a Telefunken smooth plate 12AX7 in my case.
The driver tube's B+, therefore, must (as you have surmised above), be SCRUPULOUSLY optimized and it IS, "an engineering tour de force" compliments of Dennis' total design.
The two stage DC amp beneficially allows us to have a super clean, low ripple B+ driver supply, with only about a millivolt of AC ripple on it, with no power supply cap in the amp over 50 uF.
Further more, this low ripple driver supply is shunt regulated with a ONE PART no-negative-feedback shunt regulator. The shunt draws at least 15 TIMES what the audio circuit draws, so perturbations of audio content, the musical information, has VERY LITTLE interaction with the shunt regulated driver supply.
Additionally, there are other power supply optimizations employed, that I am simply not free to divulge, but my post gives you a legitimate answer to what you asked, I believe.
I hope this made sense to you :
(a) about a mVAC B+ ripple in the first stage and
(b) a 15 times shunt regulator,
.... helps keep the music intact as to micro detailing, etc. Layout, wiring, also helps.
I am not able to offer any more details of his circuit, but the whole amp is a "total design", in every sense of the word total. His supply is located "all over the amp", and is integral with the audio circuit. It has been very well thought-out, in 1989, by Dennis Fraker. My friend Dennis, he IS the "real deal".
Gusser, book a plane now, for RMAF October 2012 Denver, and catch the show. We would like to meet you.
Jeff Medwin, audio amateur
Did any of the Fraker "critics" step up to the challenge Dennis issued?
Is anyone bringing an amp to battle with the Serious Stereo 2A3 monoamp at RMAF 2012?
dt 667
Now there's a potential deal breaker. I can think of a few CDs I have that will break a 1w amp at concert volume levels no matter how efficient the speakers.And one more thing. Do we get to run a frequency sweep of Dennis's amp first. Why? Well I for one want to make sure his amp is reasonably flat and that he is not compensating for something in the speaker or even the source material. We know he runs a music server. It is very easy in Windows to loop in all kinds of background realtime processing with the audio stream before it hits the DAC. I will want to fully inspect the computers running services as well.
Edits: 08/12/12
For your information, we do not use any form of tone controls.
We usually have both Blu-Ray player and computer to play music. In an earlier post, I just explained to you that the Berkeley converter is directly driven by a Pioneer Elite Series Blu-Ray player. Do you think there are tone controls in the Blu-Ray player?
Our computers are run wide-open-- NO reprogramming or tone control-- or signal attenuation is applied in the computer because NONE of these things can do anything but seriously degrade performance.
I do not believe in, or build synergistic systems. My philosophy has been stated on this forum countless times-- EACH PART or component is allowed to do what IT does-- with NO control on its behavior of ANY kind.
EACH part of any good system MUST be neutral. If you skew ANY component in a system to compensate for anything else, you've created a monster that will only play "certain tunes" well. That is the DIRECT OPPOSITE of what we do.
Most owners of our amps have their own signal sources and speakers, until they find out that those are better also. Most people gradually build-up their systems-- they get better with time.
You're off the hook anyhow. My setup and security guys have read all of your posts-- and have decided they want no part of it. You're EXCUSED.
---Dennis---
Gusser,
Why don't you just contact Dennis if you are seriously thinking about attending RMAF and bring an amp.
Then you can get the rules for the competition established.
You could even assemble a team of guys from this forum to come up with a reasonable design.
dt 667
My issue here as well as others is not about how Dennis's amps sound. It's about all the junk science he promotes. He has no clue why his amps sound the way the way they do good or bad period!I'm just pointing out in the above post that his amps may sound better than some other amp based on factors beyond the amp's actual performance. Magnavox did this with their stereo consoles. They did sound very good. But they had total control with the exception of room acoustics. They designed the amps, source device and speakers as a unit. Break it apart and you may be disappointed.
Edits: 08/12/12 08/12/12 08/12/12 08/12/12
I wonder if you know that people all over the world are reading this.
I hope you don't think they're stupid!
---Dennis---
"I wonder if you know that people all over the world are reading this."
"An interesting case is HUM. Long ago, while building movie theatres for special theatre owners who wanted cost-no-object performance (yes, that is rare), it was discovered that a small amount of A.C. Hum acted as a signal carrier-- that is, the HUM keeps everything in a system-- all the parts, all the wiring, all the solder joints, all the transducers IN A READY STATE. It is a signal carrier of the best possible kind.
Since the entire audio system is ALREADY IN MOTION-- when a small cue that is either alone, or is buried in signal, occurs-- it is simply and effortlessly carried by the entire system. Nothing has to "stop and start"-- as it has to do with a system that has a totally "black" background." - Dennis Fraker
"A great feature of that MAC amp was its output transformer-- which had windings that loaded all the driving stages. That is why it sounds close to a good SET-- all the time-delays caused by having too many stages had been compensated-for--- timing-wise-- by designing the output transformer windings with the needed reverse-delays. It all came out just like a single stage!" - Dennis Fraker
Indeed people all over the world are in fact reading this.
I especially like the transformer that can "reverse time". Expect a lot of calls from prestigious research centers on that one!
Prestigious! Wow. I think they get it-- no hard feelings here-- or there!
Incidentally-- on the 12V. P.C. cards. You're right in that all the voltages required in a P.C. are not just 12V.
There ARE voltage converters on these cards that are running 12V. inputs- in some cases.
Listening tests were in favor of the cards with the local converters-- instead of feeding the individual voltages into the computer. Also, in most cases, the Solid-State Hard-Drives sounded better than mechanicals.
We found that, by providing these 12v. cards with a really good 12v. supply-- even though some have local converters-- sound quality improved quite a bit-- hence the power supply that I built. WE GOT RESULTS.
That's just it. We don't build circuit boards for computers-- we're at the mercy of what's available to actually buy-- and so is everyone else.
Well, my best wishes to you-- there's no call for silly, deep, dark suspicions about creative people and how they're getting results.
Real engineers-- of all people-- can't afford to jump to conclusions.
---Dennis---
Gusser,
There is only two things we all need to know about electricity :
(1) It can kill you
(2) If you don't pay the bill, they shut it off.
Cheers.
Jeff Medwin
Thanks for the recent update.
If statists flee at a the sight of a Medwin SE 2A3, it is not a suprise that nobody wants to accept the Serious Stereo team challenge at RMAF 2012.
It is a good thing Dennis has a security detail for the event.
Way too many mentally unbalanced people running around these days to take chances.
dt 667
We are not allowed to measure the frequency flatness of the Serious 2A3 yet is is being demoed in a cohesive system all from the same manufacture?As I said before I will want to be sure the amp is reasonable flat. It's quite possible the speaker is compensating for peaks or dips in the 2A3 amps response. That would be unfair to test against a flat response amplifier.
Now may we measure the 2A3 amp or not? If not, then the shootout is potentially skewed.
Of course the challengers amp will also be subject to the same measurements and tests. That's only fair.
Edits: 08/14/12 08/14/12
Perhaps your online demeanor caused the Serious Stereo team to black list you from the event.
The content and tenor of your posts would be the only thing they could be evaluating.
No offense intended, that is just a guess.
You would have to ask Dennis why they changed their minds.
dt 667
Gus is the name of a deceased dog of mine! So if I do go to RMAF, I don't think "Gusser" will be on my name tag. IOW, I'm not "blacklisted" from anything.The tenor of my posts is a reaction to the BS. Perhaps not a civil reaction by far but it is what it is. Though I see nowhere where I threatened or even hinted any damage to Dennis's products? Can you show me? If running a frequency sweep of his amp is a threat, well then what can I say.
I find his response to this issue laughable....
"My setup and security guys have read all of your posts-- and have decided they want no part of it. You're EXCUSED."His setup and security guys???? Who does he think he is? The Apple or Panasonic booth at CES? LOL!
Edits: 08/14/12 08/14/12 08/14/12
Gusser,
This has been covered. The amp was tested in a Montana University, already discussed up here.
The testing was done in their EE Lab, not in a Fraternity dorm room on a Saturday night !!
Jeff
Then may we see the results? And still I would want to test the exact amp being compared. Revisions to the circuit since the lab test, etc.You seriously don't expect the challenger to participate in such a test based on a sketchy lab test report we cannot inspect? What world do you live in?
And all one needs is a laptop based audio analyzer and dummy load. Don't need a full lab to do such a simple test.
Edits: 08/14/12
Nope, already explained and covered previously, besides, there is no challenge, also previously covered. Thats all there is, Ta Ta.
Jeff Medwin
So a potential challenger asks for some basic controls to be implemented in the test and the offer is withdrawn?
That's fine sportsmanship - Montanna style!
Gusser-- this is for general information to anyone who happens to be reading this.
Audio shows are places where people who love music get together and play music that is deemed excellent BY THE ROOM OWNER.
This is the best thing that happens at shows-- by going into different demo rooms, one can find music that he's not aware of-- that's THE POINT of a good audio show-- to find great music that you weren't aware of.
Occasionally, a visitor to a demo room might ask to have a tune of his played. This is a potential turn-off for the people present, who are happily enjoying the music being played, and are picking out tunes from the exhibitor's list, and playing those. NOTHING can clear out a demo room faster than switching the music style on people present who are enjoying what's being played. You want trouble-- that will guarantee it.
I have made exceptions to this at times. But ONLY when a really interested person has visited the room several times, and obviously likes the sound. We then look at the tune, then we ask the people present if they'd like to hear the guy's tune. They'll usually agree, and we'll play it. If it drives people out-- we will graciously play all of that tune-- and then, it's over for the guy and ourselves until we can get good music going again and more people enter the room. That could take a while. The people who left will talk it down in the Hallways-- and we'll have fewer visitors.
Why do I do it at all? MOST exhibitors DO NOT ALLOW that, but I have found some great music that way, and have added it to my personal collection, so I take the risk.
For this reason, we choose music we know to be enjoyable with very few exceptions. We DO run ordinary CDs even though people chide us that any idiot should play only Hi-Res material. We don't forget why we're here--to play GOOD music-- even if it's on an Edison cylinder.
For those reasons, experienced exhibitors don't play games with the public-- they RESPECT and LIKE the public.
For this same reason, equipment, interconnects, cables, etc., ARE NOT fiddled with AT ALL when the public is enjoying a demo room. They ARE NOT TOUCHED unless absolutely necessary.
Any decent demo room will call Security if someone tries to interrupt a demo room-- with anything.
It is a great honor to have ANY manufacturer's room request and play your equipment.. This IS NOT NORMALLY DONE-- EVER. For the reason that most exhibitors respect the public that visits their rooms, and are not going to turn that room into a Circus.
When I offer a fellow forum member a chance to hear his equipment on our system-- which is very high accuracy-- he will be able to tell what he has, and so will others. LISTENING, NOT LAB WORK-- is done at shows because there's simply no time whatsoever to do anything else.
In order to make it possible for a fellow to try his amps in our system, we will have to come back into the Hotel after hours and set up for HIM. The Hotel assumes all rooms are closed after hours, but will tolerate music up until about 9- 9:30 P.M. Others, curious, may or may not come in also, and enjoy it.
Such an effort requires that my people want to do it on their own time..... most exhibitors and helpers would rather talk with people at the bar, or go out to Dinner. If they are going to help run a room after hours-- but detect a touch of animosity or doubt-- well, they're done with that-- this is SUPPOSED to be a time to ENJOY and RELAX.
We go to shows to HAVE FUN-- and we all love music. That's all there is to it-- it's simple. Nobody sells much, if anything-- at audio shows unless it's CES-- which is a SALES event. Denver is a LISTENING event.
The atmosphere at Denver has always been-- and we will make certain that it stays that way-- a time of good guys and gals having fun together with each other and music. No one is trying to have a scientific pissing contest-- pissing is done with Beer.
It's all in fun. When you attacked me personally, you signalled to my crew that it would not be fun anymore.
THAT WILL NOT BE TOLERATED at Denver.
I am getting ready to do this show as well as I can-- for this reason, my comments on this forum are closed until AFTER the Oct. Denver show.
Good wishes to all of you!
---Dennis---
Great post by Dennis.
The DIY tube hobby should be fun.
If it is not fun or if differences in design philosophy with other builders cause great mental distress, it is time to take a break or find another hobby to persue.
Best luck at RMAF 2012 to the Serious Stereo audio team.
dt 667
Is a business, not a hobby. And that's OK if we didn't have the constant pimping of their wears here. It's not just Dennis either. You are a frequent promoter of their line along with Jeff. Just look at the steel chassis post today. Jeff made sure he got a plug in for Serious Stereo.
I have never been contracted by Dennis Fraker or Serious Stereo agents to "promote" any of their product lines for my personal monetary gain.I have mentioned Serious Stereo as the prototype or benchmark for modern low powered SE tube amplifiers out of respect for Dennis and his design philosophy.
That is all there is to it.
Edits: 08/16/12
I remember finding a schematic a few years ago, posted by another junk science promoter, that showed a superflous single diode in series with the B+ from the power supply. A note was scribbled next to the diode that read "Halves the ripple." Too funny!
--------------------------
Buy Chinese. Bury freedom.
We are looking at a total voltage difference of 0.22v in the upper example and 0.1v in the lower. This is from a nominal voltage of 318 volts!
This will not be even the least bit audible in a G2 supply. Hardly worth the extra expense and chassis real estate to build the "better" version.
"We are looking at a total voltage difference of 0.22v in the upper example and 0.1v in the lower."
Actually we are looking at .021 for the upper and .045 for the lower in the first 12.5ms
This stepped response has little to do with the behaviour of a power supply operating audio vacuum tubes.
Having said that;
The longest, slowest, most sustained current draw increase would be the first 1/4 wave of the lowest frequency of interest or 20Hz.
The first 1/4 wave increases the current draw but the increase takes time, 12ms.
The second 1/4 wave decreases the current draw back to the idle current level with the third 1/4 wave decreasing the current draw and the last 1/4 wave increasing the current draw back to the idle current level.
If we look to see what happens to the voltage in both given examples, the supply that is the slowest to "settle" is the supply that drops the least voltage in the first 12.5ms which is the voltage drop within the time frame we are interested in.
P.S. The first PS example sims very quickly (only takes a few seconds to complete) using PSUD2 while the second PS sims very slowly (it took over 480 seconds to complete). This indicates a inherent flaw with the design of the second PS filter.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
It certainly indicates something. I don't know that it indicates a flaw in the power supply, certainly something going on there.
All sims done with "modern supplies" sim slower vs traditional. (small low resistance/inductance chokes)... "flywheel input" certainly slows simulations down, regardless of second choke.
adding an R-c stage and current tap makes it even slower.
when I get off my ass and learn spice maybe I'll learn more.
this has been a great thread... I'd searched previously for Jeff's G2 supply stuff, however this is one stop shopping.
I've got a simple SS regulator setup to try here, will screw around with what jeff has put up here and compare.. (soonish)
Here's the bottom of the current wave form into C1 of a normal, critical inductance choke input filter.
Here's the bottom of the current wave form into C1 on a "modern" power supply filter.
I think that's what is taking all the time to simulate. I think that's non-stable filter performance.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 08/10/12 08/10/12
rage
It indicates reaching for straws.
A more complex input takes longer for a computer program to process, that is all. Notice, the modern supply's results, the waveform fully settles dynamically ten or eleven times faster, and within John Swenson's 50 mS. guideline.
Jeff Medwin
rage,The people who brought us the modern power supply, (that would be "the originator" Mr. Dennis Fraker, and initial followers such as myself, and contributors Henry Pasternak, John Hasquin, and John Swenson), pay close attention to ALL sections of a L/C multi-section B+ filter.
The above-mentioned individuals focus on the ENTIRE supply and filter, and how it performs dynamically at the POINT OF USE.
Each section is carefully designed to work with the OTHER sections in the filter, either as a two stage filter (L1/C1/L2/C2 - my favored to the finals) OR as a three stage filter (L1/C1/L2/C2/L3/C3).
Henry Pasternak has proven to us that a non L-critical filter has superior regulation to a L-Critical input filter, superior dynamic characteristics, (although he would use either, but has never heard what we discuss.)
In my above-posted G2 supply, the G2 point of use is obviously "at C3". Observe waveforms in the 18 mS window above. Both the C3 current AND voltage waveforms appear virtually "perfect" (sinusoidal and very clean). About 2-3 mVAC of ripple.
To consider current waveforms in "C1 ONLY" (of a multi-section filter), is like highlighting an explosive noise level in the combustion chamber of a Lamborghini's cylinder head at ignition, whereas we are really primarily concerned with the noise level after the vehicle's mufflers, AND....most importantly, .........how well the Lambo engine pulls !!
(Jeff's Question #1) Can someone beat that G2 supply...if NOT made with aspects of a "modern" power supply design?
(Jeff's Answer #1) Unlikely in a million years.
Never say never.
Jeff Medwin .... Cheers.
Edits: 08/11/12 08/11/12 08/11/12 08/11/12
oh I notice...and certainly the modern supply performs better according to those specific parameters......and kicks ass in my own amp.
Hi rage,See, it really exists. No telling what the Reserve is, and I would re-do the supplies in 2012.
Jeff
Edits: 08/10/12 08/10/12
hi i have been reading all i can about the paoli amps I have the pair that you posted pics of they were dropped by ups and now are broke i need all the info I can get like what driver tubes were in them I know the power tubes were 6550 and what is the bias settings . they have the bias pots for each tube i sure could use a manual and any info om any upgrads that should be done and do these have the g2 i dont really understand it but all i know is when somthing sounds good i have been to;ld I have a great ear but so what right now i could sure use some help h.....e.....l.....p..... thanks David if you like give me a call at 318 734 8659
Gusser,You are really not understanding this Gusser.
I have about twenty years direct experience with building and LISTENING to separate G2 supply configurations, on high quality full range speakers, and I expect you have very little practical experience, if any at all.
So I would not be so eager to post your hugely uninformed "opinion" up here. You are the one who is looking silly about this, Mr. College-Graduated E.E., not me !! LMAO.
Jeff Medwin
Edits: 08/07/12 08/07/12 08/07/12
Let's cut the crap here. As an EE with over 30 years in broadcast grade systems and product development are you saying I lack the back ground to understand a simple G2 supply? And as I have shown you and others before I am not just a desk engineer. I have a deep hobby as well as professional construction skills to draw on.You are a hack. You have no real clue what is really going on inside these circuits. Slapping parts together and listening to the result may be a fun hobby but it sure ain't engineering on any level.
The issue is your promoting yourself here as a expert to novices enticing them to spend substantial sums of money and waste time on configurations that yield no audible benefit. If someone still wants to try it, that's fine. I am just pointing out these ideas are not accepted by the electrical engineering community at large.
Edits: 08/07/12 08/07/12
Gusser,
My comments (in my above post) stands 100%.
I will refrain from posting any additional negative comments. No one wants to see them.
I was discussing G2, and didn't expect to get so maliciously and erroneously engaged by you !!
Cheers to all Forum readers,
Jeff Medwin
Jeff,
Do you really understand the difference between triode, ultralinear, and true pentode operation? Do you know why G2 in pentode operation requires high stability - typically from a regulated supply?
Jeff, schoolyard-style ranting against EEs doesn't alter the fact that what Gusser said was true. You were talking in your post about minuscule voltage changes that would be of no practical consequence in the real world in which most of us live.
Baloney, baloney, baloney.
How much TIME have you and Gusser spent building and listening to amps and changing G2 supplies, on close to world-class high-end high fi systems? Answer that honestly !!
( You won't address that !!)
I have spent lots of time building and listening to G2 supplies, over many years, (actually decades), whereas, YOU and GUSSER are only talking "theoretically", with zero (or little) practical build and LISTENING experience.
G2 is super critical. In my experience and opinion, G2 shouldn't even be actively regulated, because the active regulators all add their own thumbprint to the sonics. I have displayed, in the PSUD 2 simulations above, a simple way to execute a G2 supply. It sounds superb to me. If others want to show me their favorite G2 designs, I will be happy to see them.
I posted to be "on record", and show any interested individuals an alternative way to build a G2 supply, that has been done on the basis of my extensive listening to G2 supplies, which you two dudes simply have not done!
I rest my case. Flame on, keep "theorizing and guessing" boys.
Jeff Medwin
no text
--------------------------
Buy Chinese. Bury freedom.
But you need to get the numbers right first then listen. Listening should be the final step.And most will find that if the numbers are right it will sound good too. There are exceptions where good numbers don't sound good, but still one cannot design good circuits by rote alone.
And if the numbers are good and it sounds bad, one can always find the technical reason if one digs deep enough.
Edits: 08/08/12 08/08/12
Right, so HOW MUCH work (engineering and LISTENING) have YOU done on G2 supplies specifically Gusser (and not your home theatre), and on what KIND of audio systems were you making subjective evaluations, source, electronics, speakers?Ray Moth has already answered honestly.
Jeff Medwin
Edits: 08/08/12 08/08/12
I just showed you in the post below. I tested many pentode designs and I have always liked ultra linear the best. I have tried both unregulated and regulated G2 pentode designs.I think the difference is I don't need to waste time prototyping circuits I know won't work. Thats one place an understanding of electronic theory comes in handy.
As for "high end" audio equipment, well I have years of professional experience with studio mastering equipment. It doesn't get any higher end than that.
Edits: 08/08/12
You state this about G2
"I don't need to waste time prototyping circuits I know won't work".
How ironic, because you really DON'T know at all!!! And you NEVER did any work in that area !!
So you like cheap-o "Ultra-NON-Linear", that figures !!
Re : G2, separate low DCR G2 supplies are very audible and superior, I thought "everyone" who was informed knew that, but, I suppose if you don't have the imagination to build and listen to it, you will remain stymied, and encased in your dead-end rigid mold.
You dance all over the place, as I read between the lines. "I got the mastering equipment at work". If you work for a Steinway distributor, does that make you a concert pianist?
It is EXACTLY as I suspected, B.S., theories, and NO work done!!!
I should remember to ignore certain posters entirely. That is where I erred.
Jeff Medwin
Well I think other members here can look at the pages I posted and determine for themselves if I have any experience with G2 configurations. The pictures of my KT88 amps on the bench don't lie.I don't care if you ignore me or not. I just care that new novice members hear the other points of view as well. You obviously have a problem with that. You have also been told before by others here that going around and trashing experienced engineers while you yourself openly admitted you have no formal electronics background labels you a fool.
Your Steinway example is stupid. To parallel your analogy I did not claim to be a mixer, editor, or colorist. I am an engineer not an artist. You implied I have no experience listening to high end audio equipment. Anybody in our facilities including the receptionist has the listening experience you mandate. Just sit in one of the rooms. I addition to that, in my case some of that equipment was designed and built by myself and my team.
Edits: 08/08/12
http://home.earthlink.net/~tubesforht/
http://home.earthlink.net/hdtv101/This set up is in my HOME! The HT pictures are a bit dated as i am now all server based versus the DVHS decks and DVD. But a lot of the digital audio gear and video switching was fabricated at home in my lab.
As you can see Bob, there is nothing wrong with PC boards in tube gear. I agree if one lacks the facilities to make boards, point to point is fine. Even though you can get hobbiest prototype boards made these days for less than $100, tube gear still lends it's self quite well to point to point wiring. But anyone saying PC boards "sound bad" has no idea what they are talking about. Ask them why a PC board sounds "bad" and see what kind of answer you get. I can guarantee it won't be backed up by any scientific evidence or tests data. Quite to the contrary www.tubelab.com has found that his designs actually performed better after being taken from a point to point model to a PC board. This is right in line with known electrical engineering practice. PC boards do make mass production possible but at the same time they also make precision repeatable results possible. BTW, the guy at tubelab is an EE designing cell phones for a living.
And for you Jeff, want to participate in a construction / packaging contest? Don't forget I do this for a living too.
Have you or Dennis ever designed and built a device where wire length and component placement really does matter? Like high speed digital image processing gear. I have! So let's just say your theories on wire length and critical component placement in a 1920s design SE amplifier is just that. A theory which has been dis-proven ages ago.
Edits: 08/08/12 08/08/12 08/08/12
I want to thank all for your input.
This entire exchange has altered my plans significantly. Jeff brought out that it was time to abandon the PC boards and try some "point to point" construction.
He's right, I've wanted to for some time but just hadn't found the right vehicle.
Jeff also brought up the legendary 60M. I've wanted to build a 60M since I saw it's grainy picture in a 1974(?) issue of Stereophile headlining a very positive review.
I have two Dyna MKIII transformers.
Kismet!
It will take me months, many months, but I intend to build a pair of 60M's.
Again thanks to all for the spirited exchange, it's the passion that drives this hobby and it is both helpful and informative. I especially want to thank Jeff Medwin for his time and effort concerning the 60M!
Stay tuned!!
I have no complaints with UL design in general, but I prefer not to use it due to the inherent power limitations. If you ever get the itch to build a non-UL pentode amp, try a VR tube on the screens. This is an inexpensive way to get good regulation, and it gives a nice purple glow as well. :)
--------------------------
Buy Chinese. Bury freedom.
TK,
A Paoli 60M that "The Bob" will build is NOT a "UL" or Ultra Linear amp. It features a totally separate G2 supply, circa 1970s, and was a well regarded amplifier back then. Uses NO active regulators on G2. Nothing to glow.
Jeff Medwin
I agree that Jeff goes to great lengths to help. I tend to take issue with him on points where I think he goes to extremes, but I wouldn't argue with his ability to design and build a very good G2 supply. He's right when he says I don't have anything approaching his experience in this sphere (but I'm not totally clueless, either).
Edits: 08/08/12
This has become a tutorial on several fronts: construction techniques, filtering vs. regulation, audibility of details, and (my personal favorite part) using the 60M as the vehicle of choice.
If one has any interest in this at all, you gotta love this!
If you have ever thought of building a tube amp that wont cost a jillion dollars, this might be the time. Think about it. Look at the pictures of the underside of this 60M on Ebay.
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=320959933877&item=320959933877&lgeo=1&vectorid=229466
Seriously, This amp sounded great then. Keep in mind that this was a company attempting to make a profit on an extensive modification. If you (we) are building from the output transformer up ... well, there's plenty of room for improvement there.
Lots of improvement!
This has become a tutorial on several fronts: construction techniques, filtering vs. regulation, audibility of details, and (my personal favorite part) using the 60M as the vehicle of choice.
If one has any interest in this at all, you gotta love this!
If you have ever thought of building a tube amp that wont cost a jillion dollars, this might be the time. Think about it. Look at the pictures of the underside of this 60M on Ebay.
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=320959933877&item=320959933877&lgeo=1&vectorid=229466
Seriously, This amp sounded great then. Keep in mind that this was a company attempting to make a profit on an extensive modification. If you (we) are building from the output transformer up ... well, there's plenty of room for improvement there.
Lots of improvement!
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