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Sure looks like non-critical L-input filter to me. He states "L1/C1/L2/C2" and seems to LOVE the amp. Tube rectifier !! Live and Learn !!! Welcome, DH !!Inspire Headphone Amp :
Jeff Medwin
Edits: 01/26/15Follow Ups:
Since you're wrong as usual.
...because I am sick of this shit.In fact, over the years the whole tweako, golden-ear, one-upping nonsense has made me sick of the whole hobby.
I now focus on music... and motorcycles... and find both of them to be far more satisfying and infinitely less infuriating.
It is time for LSES hype to DIE.
-Henry
Edits: 01/27/15
...Probably not going to happen. Look at the post count for this thread and a recent related one. The interest on both sides of the argument is intense and unrelenting. It (opinion/discussion of LSES) has become a point of commonality amongst the diverse membership of AA Tube DIY. Something like this is increasingly rare in today's internet enabled inward looking individualism.
Another follower.
GEO,
Was today ( 1-28-15) a break-out gap ........or an exhaustion-gap ??
Ha, what does Ichan know, .... nada.
Jeff
Jeff,Thanks for the update on AAPL. I don't own the stock but I am sure others here may benefit from your wisdom. When did you complete the CFA exam and what are your thoughts on the value of pursuing the CFA path, an MBA or both?
Edits: 01/29/15
...cathode or anode? Or maybe even source?
I am just beaten down by all the nonsensical posturing.
There are different ways to formulate beliefs. I cannot prove that science is superior to faith, or vice-versa. The respective axioms of scientific and faith-based belief are different. But I can judge arguments that purport to come from one belief system in terms of their self-consistency and logical completeness.
The crap that spews so vehemently and self-seriously on this forum just makes me want to shout, "No! No! No!" As I've argued before, these discussions verge into the realm of serious philosophy -- and in that respect well beyond my credentials, to be honest. But I know enough to recognize bullshit when I see it, from both sides.
In the end you have to decide if you want your hobby to make your life simpler or more complicated, and if by pursuing it you want to get closer to intellectual clarity, or further away.
Ironically, the bullshit-spewers actually believe they are coming closer to the TRVTH. This is the central paradox of humanity, I think. It is metaphysically impossible to prove to a stupid person that he is stupid, because if he could understand the proof, the proof would be invalid.
I try to remind myself constantly that I AM stupid. I hope it keeps me honest.
I just don't know. Thinking about it twists my brain in a knot and makes my head hurt.
Better to think about motorcycles.
Gorgeous. I want one. Drive carefully.
I recognize that motorcycle talk is off-topic for this forum.
I find myself with a few nice bikes, much to my wife's consternation.
The R100 recently finished a five-figure dollar rebuild/restoration. I had some bumps along the way, but it's looking and running very nicely now.
I picked the R1100S up over Christmas break. My first non-airhead boxer. Impressive machine.
The Ducati is lovely, finicky, and demanding...
-Henry
Sure like that Beemer. Selling my Triumph this spring, the traffic has finally beat me down. :(
--------------------------
Buy Chinese. Bury freedom.
Six different chassis connection points for signal grounds and you are in love with this amp?
Six various grounds or not, the Inspire series are not crap at $1.2K.
So if you spend more money, you don't deserve something resembling a star ground?
I see less than $200 of parts. $1,200 is a boatload for this. How much do you have to spend on this before it can be classified as crap? $3,000? $5,000?
Close to LSES, but likely violates your low DCR rule with the second choke. On the other hand the current demand from the power supply is low.Dennis Had started in the electronics business with a company called Dentron, then followed up with Amp Supply Company. These businesses built RF linear amplifiers and antenna tuners (Dentron) for ham radio operators. The amplifier designs are fine products. However, Dennis did not follow that 2.5 PIV times the operating voltage rule regarding the diodes in the power supply in some products. Although failures were minimal, the later designs did raise the bridge rectifier PIV ratings.
As you know Cary Audio Design violated tube manufactures recommended maximum capacitance specifications using tube rectifiers in a CLC or CRC filter circuit. So, it is fair to state it appears a learning curve has been completed by Dennis Had.
Dennis Had designs resulted in a substantial impact with hobbyists in the ham radio and audio industry.
Edits: 01/27/15
Is anyone who uses one now a devotee of DF and JM? Just curious, because I use them in everything I build, from low voltage SS to 2.5kV tube amps, decidedly CRITICAL inductance, or else it's just a cap input filter, whatever YOU decide to call it.
Mr Had says in the auction description that it's a dual pi filter and you can see the small electrolytic first cap, likely a 10uF - 450V, on the left side of the rectifier socket. The cap and the first choke connect to pin 2 of the rectifier. The 6SN7's look to be paralleled so a Hammond 154EA choke would work and be about the size pictured.
Looks like a CLCLC, dual Pi filter as described.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
Paralleled triodes, cap input PS, the grounding arrangement through the chassis that you mentioned and non-optimal wire color.
It doesn't seem very modern but I'll bet it works just fine.
How can you be sure the supply are not critical L input ? The chokes look to me to be cheap Hammonds , not many values in this range would apply to the 'low everything' concept . It's a headphone amp so no doubt the LCLC supply is to provide low ripple...
Al
Al,
I am not sure of anything, but I am having FUN posting. Hey, I never noticed the small "c" Kyle pointed out, but its there. Looks to be "c/L1/C1/L2/C2" for a filter.
Am not sure whose chokes they are, look to be custom wound or ???, not Hammonds.
Certainly Ls are SMALL in mass.
Cheers,
Jeff Medwin
I just bought a couple 450V/47u caps to fill out an order, and they're about that same size. Seriously, no legitimate designer is using the weak PS designs you're publishing here.
--------------------------
Buy Chinese. Bury freedom.
The amp uses a 274B rectifier which has a maximum input capacitor of 4uF according to the WE data sheets. That would make it a cap input supply regardless of the relative size of capacitor compared to other amps/rectifiers.
The small sized cap is likely full size for the application.
Considering that you can get a 4uF 630V film cap for $4, it's a wonder that there is a one dollar electrolytic in that spot on a $1200 headphone amp.
The ebay ad says "Dual Pi-Network".
A Pi-Netword does not use a small "c", it uses a big "C" for a cap input filter.
BTW, "big" is a relative term. As you pointed out the 274 will only take a 4uf input cap.
A little "c" in front of a critical inductance input choke is a handy trick to lower the charging current seen by the choke and increase the B+. Most times that cap will be a .1uf to 1uf or so.
The price paid for using that "trick" is, now each of the diodes are off for part of their half cycle when they would have each been on, in turn, for that whole half cycle if the filter were left as a true critical inductance choke input filter.
But the trick does work just fine and I have used it many times myself.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Jeff,some "thinking out loud" here...
What if DF went with the chokes he did as they were the closest thing to what he needed available off the shelf at that time?
the idea being that the power transformers and chokes were selected given what was available.
today we can call heyboer and custom order iron. maybe it is time to revisit L-Critical choke input power supplies. I remember you built a 4 henry on your existing core for a phono pre project... 4henries would be just about enough for choke input duty on a stereo 2a3DC amp. 8 henries would do the job for monoblocks... a different story altogether.
if you get 4 henries in a reasonable DCR (lets say 20 ohms to stick with your logic)... and you spec your PT accordingly... now you've got choke input, low mass chokes and low DCR still..
go two stages and manipulate the caps to get the dampening you like.. the second choke can be triad c40x even.
again DF didn't have the luxury of an 8 henry choke in low resistance... maybe things would be different today if he didn't have a stash of those stancor chokes or if Hammond quit making the PT he used.
TRY IT IN PSUD. I bet you'll find that you can get the same parameters you sim for with LSES.
Edits: 01/27/15
Rage,I will let YOU carry the torch on further L experimenting.
I am getting ready to try to copy DF's most recent amp / parts / implementations, and apply them to a tweaked ALTEC A7-800 system, and get my phono and 10.000 LPs spinnning again.
Over a week ago, I heard Maurizio Pollini play Beethoven's Sonata No.21 in C major, the " Waldstein " and I quickly came to realize that the music is more important to me than either the L or the C or the or the R value and type.
That particular music has been going "over and over" in my mind, it won't leave me alone, it is haunting me, can't stop thinking about it.
Today in the mail, a LP arrived, VOX / Turnabout TV-S 34394, mint - never ever played, of a young Alfred Brendel doing this same piece. It gets heard, with a co-worker friend of mine, tomorrow.
Have fun, I am. Ohh, from what I heard several years ago on my first testing of LSES , there was a BIG bass speed and transient difference between 20 Ohms and 10 Ohms and 8 Ohms of L DCRs, listening on ALTEC 515Bs and 802-Ds. That was when I coined these following terms up here :
20 Ohms or less Ls, " High Fidelity "
10 Ohms or less Ls, " Ultra High Fidelity".
There was also a huge differences heard by me back then, using one, two and three clip leads in parallel, connecting the B+ filter parts together. Hence your new 12 AWG wire from eBay.
The real question in my mind these days has been this..." How did G-d allow L.v Beethoven to write such music, and have an aging Pollini play it back so wonderfully ??
Jeff
Edits: 01/27/15
Why do you have to copy Dennis's amps? Why can't he just build you one for the cost of the parts? Or even the parts you supply. You have certainly earned that with all the free advertising you give him here.
And after all you have both said many times it's the execution that matters the most. You say only Dennis has that special black magic to spin straw into gold. Seems when anybody else buys the parts and puts a DC coupled 2 stage 2a3 amp together and is not overly impressed with the performance you always claim it wasn't built right.
So even if Dennis can't afford to buy the parts for you why can't he at least assemble a near perfect amp using the parts you supply?
Some friend he is!
.
.
I like your ms-paint work there gargoyle.
It's an interesting paradox... the one thing that has griped my ass over the whole following of Jeff's ideas... lead out surgery on transformers and chokes.
I've wrecked countless chokes and even done some damage to a nice power transformer.. Not to say the whole idea is stupid, but moreso I am just too aggressive when trimming leadouts at 1" from the transformer.
Even then, many times I've opened up the chokes and soldered the magnet wire directly to the new leadouts..then glued everything up.. most successfully with gorilla glue.
The problem is then that I have little confidence in the chokes durability when working on the new leadouts..and that bothers my OCD a bit.
Anyhow, the SILVER LINING. I was at work on a 7 tower AM array where we had trouble with a 220 volt 20 amp contactor that switched one of the towers in and out of the pattern. The problem was the leadout had broken off from the terminal strip. The other engineer being my equal or better at being destructive ripped the entire leadout out of one of the coils for this relay. $1500 to replace the whole contactor... or scrounge ebay for a coil for the 1960s EF Johnson contactor.
I burned the enamal off the magnet wire and soldered a new leadout on. Then I put a bunch of gorilla glue on the whole thing. Two years later it still works great. Drives me nuts, but hasn't failed yet! Ugly as hell but it saved the day!
Thanks Jeff!
We will carry on after DF and JM are gone.
- LSES tube amp builders of the World
"The eternal flame"
That is very clever!
The poor guy was not fortunate enough to get the "cornhole torch" as that is reserved for the most elite of LSES builders.
I think his filter chokes were too high in DCR for such an honor.
Better luck next year.
That's a CLCLC filter.
It's not choke input at all, critical or otherwise.
Input cap is on the left, purple wire, grounding under the power transformer bolt.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
This is not considered good practice in the "modern" world!
I would bet that it works just fine.
There is more than one way to "skin a cat".
Hmmmmm, skin a cat, tar and feather a wrangler....sounds like fun! :-)
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
I agree the design would likely not have any issues with multiple grounds at various locations on the chassis just like vintage amplifiers.
I build DIY amps with just one #10 copper ground wire connected to the chassis at the input jack and elevated across the chassis. The AC power line ground is connected to the chassis at one of the transformer mounting screws.
I did it after reading the tip from this forum - sorry couldn't recall the source.
I did a simple experiment with 20 gauge wire - that's what I have in hand but should have used thicker wire Wired up the ground points close by in groups and connect them to the ground of the B+ filter cap - pseudo star. That is a tremendous improvement in resolution and many other things. Will replace the skinny with Arnold.
yes I also questions this . why he want to use so many ground point on a small amp like this one ? doesn't make any sense to me .
Won't the other Dennis be jealous of your new Dennis?
Fraker is fine with that. He knows its the only thing that works.The REAL question is this :
Won't you get jealous after you hear the INSPIRE amp ??
Jeff Medwin
Edits: 01/26/15
I'm not sure, I think it would have enough joules to run some cans.
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