SET Asylum

Single Ended Triodes (SETs), the ultimate tube lovers dream.

Return to SET Asylum


Message Sort: Post Order or Asylum Reverse Threaded

Jim Smith, author of " Get Better Sound "... Tip 145

71.50.30.198

Posted on November 6, 2015 at 19:10:06
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
Quoting Jim :

"Over many years, without really ever noticing when it happened, I made a discovery that was the very opposite of what I thought I knew.

I discovered that those systems that were dead quiet - with the volume set to medium-to-loud listening level, but no source playing, and my ear close to the speaker - were often the systems that, while they had a certain technical prowess, were the LEAST INTERESTING to listen to musically.

I've tried to understand why this is almost always the case. I do know for sure that a number of other experienced listeners are coming to similar conclusions."

( Jim then speculates why, for a couple of paragraphs, and concludes ):

" One thing I know for sure - most systems that have just a bit of noise when you get closer to them ( within a meter ) usually sound livelier and more involving than those systems that are eerily quiet with the volume turned up. If you know why, please let me know ! "



Jeff Medwin

 

Hide full thread outline!
    ...
Especially if you are partly deaf, posted on November 7, 2015 at 00:34:52
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
Seriously.

 

Directly related to the jump factor from transfer efficiency flowing in a 0.35H first choke with brass washers, posted on November 7, 2015 at 06:42:32
Chip647
Audiophile

Posts: 2631
Location: The South
Joined: December 24, 2012
Or the author does not like massive amounts of global feedback.

Good sound Tip #1 - Get some decent music and play it on whatever you have available.

 

RE: Jim Smith, author of " Get Better Sound "... Tip 145, posted on November 7, 2015 at 17:42:01
ahendler
Audiophile

Posts: 5151
Location: San Antonio, Texas
Joined: January 24, 2003
When we first started using dolby A in our studio everybody felt that we were losing high frequency response. But when we took measurements the response was flat. Turn out to be a psycho acoustic effect. When you totally got rid of the noise things did not sound as good. We got rid of Dolby A and started recording at 30ips. My system is dead quite yet it is the best system I have heard in my house. I think that feeling that the quiet system does not sound that good will change with long term listening.
Alan

 

The dangers of too much shielding, posted on November 8, 2015 at 08:15:39
Posts: 3040
Location: Atlanta
Joined: December 15, 2003
Nothing will stifle the life out of a system more than that!

 

I wasn't thinking of shielding Rick ....Power Supply !!, posted on November 8, 2015 at 18:02:19
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
Rick,

I like a SET amp chassis to be all steel, 12 or 14 gauge, welded corners, for good shielding.

What I was thinking about was MORESO - the power supply configuration, to get that "DEAD QUIET B+" in a SET amp design.

As you and others may likely recall, my contention for YEARS up here : is that ANY AMP with any 10 HENRY rated 60 Ohm to 100 Ohm choke, and caps over about 50 uF in one spot, can NEVER EVER play the musical experience as good as a LSES ( low stored energy ) L1/C1/L2/C2 supplied amplifier.

As a matter of fact, just this afternoon I had a chance to compare such a LSES amp, ( a 2015-made DC Type 45 prototype ), to a well-regarded Yamomoto A-08 Type 45 SET amp.

Both amps were tested on an "amazing-to-me" ALTEC A-4 system, 110 dB efficient ( which is four 515C woofers - horn loaded into 210 enclosures - unloaded @ 440 pounds each, using two ALTEC 288s, and two ALTEC 8 cell horns ) in a spacious 25 by 45 by 14 foot high listening room, a historic 1911-designed Firehouse in Kansas City.

That lesser filtered LSES supplied amp "easily and completely" put the Japanese amp to TOTAL shame, in every area of listening I could evaluate and think of, dynamics, bandwidth, timbre, imaging and a general overall feeling of " you are there ". The LSES amp is NOT "dead quiet" .... but the Yamomoto A-08 45 amp owner now will be selling his amp. It only took him one and a half A-B passes, of vintage Muddy Waters, to hear it all.

I had to drive 580 miles to get this amplifier evaluation done, took four visits to two high efficiency audio systems over two months !! I wish Mr. Yamomoto were there to hear what we two just heard. It would have changed his life and audio priorities.

Cheers Jeff Medwin

 

Psycho acoustic? No, it's absolutely real!, posted on November 8, 2015 at 18:21:01
Triode_Kingdom
Audiophile

Posts: 10011
Location: Central Texas
Joined: September 24, 2006
The effect being discussed here is one that encompasses both filling of quiet passages with 60/120 Hz hum and noise, and the generation of intermodulation products that create a sense of fullness in undereducated ears. Both of these undesired results are artifacts of defective power supply design.

 

Hmm, perhaps Jeff... you could try an 8 henry choke loaded 35 ohm 300 ma for better sound.~nT, posted on November 8, 2015 at 18:43:53
Cleantimestream
Audiophile

Posts: 7542
Location: Kentucky
Joined: June 30, 2005
!
The Mind has No Firewall~ U.S. Army War College.

 

Ha, I certainly have done that, posted on November 8, 2015 at 20:47:58
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005



I'm getting older. I've been building, designing DHT amps since 1982.

The VERY FIRST design advice my audio mentor, Mr. Robert W. Fulton told me in 1981 was this:

" A DHT is a "direct-access-to-the-music device " and as such, ALL the chokes have to be TWENTY Ohms or less, IF I can find them ".

I've experimented and listened to many different supplies, with his guide in mind, and Robert was RIGHT ON !!

After you hear ten Ohms or less, 55 uF or less, and PROPERLY wired, its truly impossible ( for me ) to go backwards, to your suggestion.

My NEXT choke build will likely be 4 Ohms in DCR, under two pounds in mass, with the equivalent of 9 AWG of choke lead wires, in and out. Likely in December 2015. Dowdylama and I decided ... we are going for it !!

I look forward in early 2016 to "A-B compare" 4 Ohms DCR versus 10 Ohms, in " my style of DHT SET DC amp build ".

See picture of under ten Ohms L1, L2, mid-2015 implementation, with wiring, above.

L1 is a lead-wire modified -otherwise stock Stancor C-2708, measures 500 mHY, located under the white, grey, and yellow wires at the top of the chassis, and it uses ONLY 1 1/2 inches of lead length from the 5U4GB Raytheon double getter rectifier tube. The green L2 is under 8 Ohms as I recall, 2.2 HY.

Jeff Medwin

 

I certainly have done that, posted on November 9, 2015 at 02:58:29
Cleantimestream
Audiophile

Posts: 7542
Location: Kentucky
Joined: June 30, 2005
I have a 25 ohm 5 henry right here... 500ma, weighs about 15 lbs.

That WAS a definite improvement. All the Ham guys extol what you say...
Low DCR chokes... they, like myself realize critical inductance.

4.3 is the minimum for choke loading, it is no coincidence there being so many chokes starting @ 5 Henrys.
The Mind has No Firewall~ U.S. Army War College.

 

The old no hum no fun, posted on November 9, 2015 at 06:13:17
Well that I disagree with. Still many amps I have with my 110db horns do have residual noise included solid state amps.

 

Interesting., posted on November 9, 2015 at 07:16:34
So the ears and brain are "used" to hearing background level noise and IM products? And the lack of them makes the music sterile?


Right? Thanks!

 

I M H O / I M Experience, Critical inductance is NOT desirable, posted on November 9, 2015 at 08:23:57
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
I agree, Critical Inductance is cool if you are building an industrial DC power supply, but NOT ever for the highest possible performance audio amp. For audio power amps, SETs, I find Critical Inductance is NOT desirable at all. It forces you to use filters with too much energy storage, that are always EASILY out-performed by smaller Ls having NON-critical inductance.

No matter WHAT the DCR is, any 15 pound choke that you reference has too much mass and energy storage. I like Ls best - two pounds and under. Remember, I have been listening to different Ls in DHT amps since 1982, all types !!

Every Serious Stereo, state-of-the-art 2A3 monoblock is proof of this concept we are discussing, as it employs LSES ( low stored energy supply ) filters, as is any amp employing a Flywheel filter, which is typically 30 or 40 mHY as L1, 15 or 20 uF as C1, followed by L2/C2.

The LSES inductor approach is only a small part of what gets an amp to go.

The caps have to be small, low storage - under 50 uF, and they have to be multiple film cap bypassed in my SET experience. To get adequate filtering, the LSES approach to B+ filter building calls for a L1/C1/L2/C2 filter in ALL cases. The wiring has to be LARGE, because its all source-fed, and we wanna keep the peak currents, and transient nature of live music INTACT through the SET amp !!

The proof of the pudding, is in the eating. So I rest my case.

Jeff Medwin

 

RE: Interesting., posted on November 9, 2015 at 08:29:47
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
You forgot to add that the listeners who like it otherwise are UNtrained and inexperienced.

Believe that, and I have an island in the Mekong Delta for you to purchase.

JM

 

RE: I M H O / I M Experience, Critical inble, posted on November 9, 2015 at 08:32:55
Cleantimestream
Audiophile

Posts: 7542
Location: Kentucky
Joined: June 30, 2005
I have 43 microfarads... total in the entire amp...dead quiet using modified Khorns.
The Mind has No Firewall~ U.S. Army War College.

 

RE: The old no hum no fun, posted on November 9, 2015 at 08:49:42
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
You can disagree, fine with me. But alas, you have NEVER heard my implementations.

I can share with you this, just YESTERDAY, Sunday, on ALTEC A-4s ( 110 db ) in Kansas City, we compared one of my implementations, ( with L1 500 mHY and L2 2.2 HY. ) to a Yamomoto A-08 - which sports a large 10 HY inductor.

That quieter B+ amp, with a 10 HY inductor, was bested - in EVERY parameter of music, rather easily.

This K.C. A-4 owner now is selling all his amps, and going to use what I proposed herein and we both heard on his system yesterday on his A-4s. Took him 1 1/2 A-B passes, twenty minutes, to hear it all !!

Since this happened less than 24 hours ago, AND on 110 dB speakers, I thought I'd respectfully report on our listening session.

Jeff Medwin

 

RE: I M H O / I M Experience, Critical inble, posted on November 9, 2015 at 08:57:48
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
And its also a DEAD amp DYNAMICALLY !! I can guarantee you this, from years of experimenting, no, .... decades.

A dead quiet amp .............is ALWAYS a dead amp!!!!!!!!!!

Your large chokes are KILLING the dynamic performance my friend. Likely your wiring is suspect also. If you build a amp optimally, you would easily run a SET Type 45 amp, and not have to revert to a P-P Type 45 amp on K-Horns !!

Your small caps ( 47 uF total ) are only PART. one third of the solution, there is (1) choke size and (2) wiring to optimize also, to get the highest possible performance. Believe me !!

Jeff Medwin

 

RE: I M H O / I M Experience, Critical inble, posted on November 9, 2015 at 10:33:53
Cleantimestream
Audiophile

Posts: 7542
Location: Kentucky
Joined: June 30, 2005
Am sorry your perception leads you to believe your approach is the only correct one... that severely limits your progress and learning...Ihave never heard a more dynamic amplifier than the 801 I have built. Your perception is hobbled by your lack.of.vision, Jeff.
The Mind has No Firewall~ U.S. Army War College.

 

RE: Interesting., posted on November 9, 2015 at 12:09:14
Triode_Kingdom
Audiophile

Posts: 10011
Location: Central Texas
Joined: September 24, 2006
Yes, and for evaluation purposes it's important to not only listen, but also think about what we're hearing. Not everyone is capable of that.


 

RE: I M H O / I M Experience, Critical inble, posted on November 9, 2015 at 12:52:01
GEO
Audiophile

Posts: 4749
Joined: April 7, 2000
Contributor
  Since:
September 9, 2000
I love the 801.

 

RE: I M H O / I M Experience, Critical inble, posted on November 9, 2015 at 12:53:29
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
I will not criticize you, and I do not doubt your positive experience with 47 uF TOTAL in your 801 amp.

The best answer would be an A-B session on a decent high efficiency system, yours or mine. It would be informative and FUN for both of us.

We are likely located a thousand miles apart. Oh well.

Very nice corresponding with you.

Jeff Medwin

 

RE: The old no hum no fun, posted on November 11, 2015 at 05:01:50
Oface
Audiophile

Posts: 1497
Location: columbia, south carolina
Joined: May 3, 2003
Pics, or it didn't happen! ;>)

 

hum no fun, posted on November 11, 2015 at 06:24:49
Owned at least 50 SET have 3 at the moment have enjoyed both those that hum and those that don't, of the 2 I prefer no hum low noise- I run horns. I also know a 45 SET does not do so well on theater horns unless biamped I have or had in my piles Altec a4- 5- 7, RCA Shearers, Lansings about so I do know what power requirements they have so not surprised the 45 did not give its best. Even my 300b amps couldn't get the best out of 4 15 inch woofers. I currently have a 45 SET in my office even in nearfield its struggles to drive my Community Leviathans 4-515B and TAD 4001.

 

RE: hum no fun, posted on November 11, 2015 at 06:59:10
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
Kloss,

Respectfully, you have "ordinary " SET amps, and what I have running now on A-4s are totally different than anything you have experienced.

Where do you live, I'll have to let you hear it on your system. I'm near KC, MO.

Jeff Medwin

 

RE: hum no fun, posted on November 11, 2015 at 07:10:26
S WI heard a lot of bold claims from amp builders over the years but the results I hear are more similar than different. Maybe you bring something to the party I haven't heard but I have heard much and am Jaded.

 

RE: The old no hum no fun, posted on November 11, 2015 at 07:15:19
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005



Got pictures for you. L1, 500 mHY Stancor C-2708 is at the top, below three ( white , gray, yellow) doubled-up wires running horizontally, 1 1/2 inch lead length to rectifier tube. L2 is green, mid-right side of chassis.

Note my (1) extensive use of doubled-up wiring, (2) extensive film cap bypassing across every cap location, all done by my ear.

This 45 amp totally ROCKS on the A-4 ( full range, Kloss ) !! "Killed" the fella's Yamomoto A-08 last Sunday, it's wideband playing - EASILY plays an octave higher and lower, with color and HUGE dynamic range and finesse. Its in a different league.

Next time I do some more work at the A-4 site in KC, I'll take speaker photos for you. I am having A-4 owner totally rewire his A-4s, for maximum transfer efficiency. Those ALTEC 210 bass-horn enclosures weigh 440 pounds each, with no drivers in them

Jeff Medwin

 

RE: hum no fun, posted on November 11, 2015 at 08:29:38
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
I appreciate your comments. Refreshingly right on !!

I was mentored by Robert Fulton (1925-1988) and he and I concured, AMPS are the weakest link in the audio chain.

I think amps are far-worse than many speakers.

Amps are generally TURKEYS, ill-designed for a difficult task.

I've built my own amps, DHTs, since 1982, and honestly believe I DO bring something different to this audio art, to serve the music.

I'll likely put a few "out there" in the coming years. Its FUN to build and hear them.

Jeff Medwin

 

Perhaps you can consider an amp that is dead quiet AND the recording hiss that is ever present-nT, posted on November 11, 2015 at 08:41:25
Cleantimestream
Audiophile

Posts: 7542
Location: Kentucky
Joined: June 30, 2005
!
The Mind has No Firewall~ U.S. Army War College.

 

RE: Perhaps you can consider an amp that is dead quiet AND the recording hiss that is ever present-nT, posted on November 11, 2015 at 14:47:03
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
What separates live music from hi-fi playback is a lack of realistic dynamic contrasting in the later, as it was originally played.

THAT dynamic contrasting needs to be the design goal, the KEY guiding principle, in all SET designs.

Not " dead quiet ".

Any amp that is dead quiet, will NEVER be dynamically acceptable, they are mutually-exclusive design goals.

Your "dynamic amp" with 43 uF nicely addresses only one third of a troika. Good, I am very glad to hear you did it.

BUT ...Besides (1) as little capacitance as possible, you ALSO need (2) less magnetic storage in the chokes, and (3) WAY better wiring, ( transfer efficiency, wideband ) to get all three parameters optimized - and to approach the live event's dynamics.

I am not trying to attack you. Very few have figured this out, what I am discussing herein. Wish we could A-B amps in your digs one day. I am just sharing what I have discovered, with over 33 years of DHT amp building.

Regards,

Jeff Medwin

 

RE: yamamoto A-08, posted on November 12, 2015 at 06:33:38
Here is a link to a Stereophile review of those amps.

The specs indicate full bandwidth , but the circuit is a lot different from the drlowmu amps.

 

RE: The old no hum no fun, posted on November 12, 2015 at 08:20:35
SteveBrown
Audiophile

Posts: 2454
Location: Portland, OR
Joined: November 14, 2002
Curious, what is the output iron? Series or parallel feed?

 

Tip#1, posted on November 12, 2015 at 09:03:25
PakProtector
Audiophile

Posts: 12355
Joined: May 14, 2002
I do try to practice that one...:)

It is entertaining to try new stuff, though I do try to avoid the silly stuff labeled as 'The Only Way' to do something.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

RE: The old no hum no fun, posted on November 12, 2015 at 09:07:36
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005



Steve,

I am proud to report the output transformers were NOTHING SPECIAL at all !!!

Recall, myself and a designer friend, a few years ago on this Forum, saying we could build a SET with a doorbell transformer output, and it will outperform all others?? This, in a way, is it.

Only I am using an INexpensive BUDGET SE output transformer, with a multiple primaries, as I recall, 2.5K, 3.5K and 5 K. Of course, 5K used for Type 45.

With my wiring and multiple value film cap bypassing EVERYWHERE, we easily play an ocatve higher and lower, with great tone, finesse, and dynamics, that puts that fancy Yamomoto C-Core ( ?? ) output transformer into an irrelevant status. Mr. Yamomoto-San would have possibly gone into cardiac arrest Steve, it would have shaken him up, but good.

THIS was FUN to hear and do !! Wow !!

Jeff Medwin

 

RE: yamamoto A-08, posted on November 12, 2015 at 09:50:17
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
Look up Jeff Day's " glowing " review from 6 Moons on the A-08. Likely, that review made the Kansas City ALTEC A-4 owner buy the A-08. He told me it was a "big" purchase for him.

Now he will sell it !!

Jeff Medwin

 

Thanks -cool! (nt), posted on November 12, 2015 at 10:07:44
SteveBrown
Audiophile

Posts: 2454
Location: Portland, OR
Joined: November 14, 2002
nt

 

RE: yamamoto A-08, posted on November 12, 2015 at 19:25:05
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
Jeff Day waxes lyrical about most equipment he "reviews" - I don't place value in his advertorial.

The Yammy looks pretty, but does not set the bar particularly high. Reviewers have used the Yammy as an example of fine build quality (?!) - but it looks to me to be designed for simple construction and troubleshooting while looking organised... "agricultural".

Still, people praised it... before moving onto other designs. I am guessing the Yammy is an example of "impressive first impression versus long term enjoyment" type of contention.

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: yamamoto A-08, posted on November 13, 2015 at 11:02:31
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
Hello,

Very well said. I agree with you.

Jeff Medwin

 

RE: Jim Smith, author of " Get Better Sound "... Tip 145, posted on November 14, 2015 at 10:03:27
aknaydenov
Audiophile

Posts: 106
Location: Sofia, Bulgaria
Joined: September 13, 2015
My peraonal SET in the neighbour thread uses a split PSU with single LC filter per rail. 3300uF of capacitance and 10H choke for the output stage. 18H and 1000uF for the driver stage. Choke input. I can promise you this amplifier sounds very fast with a big dynamics swing.

 

RE: yamamoto A-08, posted on November 15, 2015 at 10:30:35
Wojciech
Audiophile

Posts: 4115
Joined: June 23, 2009
No, yammy 08 is really a good sounding amp with well defined voicing.The problem is in general 45 type FR amp has a very restricted usefulness due to lack of capable speaker systems. Do not forget that yamy costs $3k and Serious stereo $15k.

 

RE: yamamoto A-08, posted on November 15, 2015 at 10:42:52
PakProtector
Audiophile

Posts: 12355
Joined: May 14, 2002
One of those Yamaha amps paid a visit. I don't think you were by during its stay, but it completely delivered the verdict that flea power is not for me.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

RE: yamamoto A-08, posted on November 15, 2015 at 10:56:48
Wojciech
Audiophile

Posts: 4115
Joined: June 23, 2009
No , I wouldn't expect you to fall for Yammy 08 considering what you have there BUT keeping things in perspective , what you have there would be in a range of $50k + If it were commercially available.
I thing it is a really nice, limited purpose weekend amp. It was a hit on the market and I assume there were many sold. Not that many resurface on used market and they tend to sell quickly if the price is right.

 

RE: yamamoto A-08, posted on November 15, 2015 at 18:58:33
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
Agreed, it is pretty decent value

Cheers,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

That is where we differ..m the room IS the weakest link, followed by the speakers-nT, posted on November 16, 2015 at 03:43:07
Cleantimestream
Audiophile

Posts: 7542
Location: Kentucky
Joined: June 30, 2005
!
The Mind has No Firewall~ U.S. Army War College.

 

RE: Jim Smith, author of " Get Better Sound "... Tip 145, posted on November 16, 2015 at 09:23:15
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
No offense intended.

Some of us have learned over our life times a MUCH better way to IMPROVE upon what you have done, power-supply-wise. !!

Easily.

Write to me privately .


Jeff Medwin

 

Only because......, posted on November 16, 2015 at 09:26:38
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
You THINK you have the amplifier resolved. Not so, IMHO, from your supply's description and my experiences.

Jeff Medwin

 

One thing about Yamamoto A-08, posted on November 24, 2015 at 16:35:19
C.Y
Audiophile

Posts: 345
Location: S.Korea
Joined: September 7, 2002
I built many SETs with 45, 2A3, 300B, 845. I built some 45 SETs including direct coupled one.

After listening to A-08, again and again, my friend and I concluded that there's something strange with 6Moons, or their taste is strange, or their speakers are differently strange or strangely different.

Since A-08 was in kit form, we checked the wiring again and again. I even let other DIYer friend to check the wiring, just in case.

The sound is exaclty opposite to 'lively', we even thought that this may be the Japanese voicing. Or we talked about there is something we did not know at all about SET sound.

I think now simply that the review is exaggereated with pretty look. Do not blindly believe the review. Yes it makes sound, but I'd rather go for Jeff low DCR chokes, for similar gambling.


 

RE: One thing about Yamamoto A-08, posted on November 24, 2015 at 18:49:03
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
The Yamomoto A-08 we used had exquisite parts. It was a FACTORY built unit, and it was neatly wired, for sure.

The Yamomoto tube sockets, as one example, were lovely, and it has C-Core Output trannies, power and chokes as I recall. The speaker wire's binding posts are special also, very nice feel with a fine-thread so tightening is progressive to the touch. Lovely.

If you look at the A-08 schematic on line, you will see they specify " RN65 " resistors, vintage American military spec types I presume these to be. Where they use an RN-65, for - say, the plate resistor or cathode resistor of the front-end tube, I would now very carefully (and expensively ) employ TWO closely-matched Caddock MK-132s or TF-020s, and such resistors' end-result is HUGE in "tone, transparency and purity".

The Yamomoto sounded gray and artificial to us both, narrow band like a bad AM radio station signal playing through a cheap radio. It missed playing one octave higher and lower, versus my prototype's implementation. Also, it was TOTALLY outclassed in dynamic contrasting, and taking control of the large ALTEC A-4 speaker system. This is due to what holds almost ALL other SET amps back,

(1) poor internal wiring,

(2) high DCR chokes ( above 20 Ohms ) , and

(3) high amounts of capacitance in the power supply.


For example, the A-08 sports a "typical" / undesirable 10 HENRY ( about 80 to 100 Ohm ) choke in a C1/L1/C2 filter, ugh. Its DOA, by design, or should I more properly call it mis-design. I used L1/C1/L2/C2 - 10 Ohms and 8 Ohms for L1 and L2, 500 mHY and 1.8 HY respectively. Low Stored Energy Supply, aka LSES.

One other thing, the A-08 used an electrolytic, (as I recall) to bypass the Rks. And noisy zeners on the Pentode's extra grid. No good. However, I used about EIGHT carefully chosen Rk bypass film capacitors in parallel - across each Rk, to ARTFULLY get the amp to play wide-band and with proper musical intent.

Yes, Yamomoto-San, ( had he been in front of those ALTEC A-4s ), may have rolled over and simply puked, if he heard the A-B. But maybe, he would learn something too, to apply into the future.

This amp build has been FUN so far, and I look forward to retrieving it from those A-4s, 55 miles away, and getting it playing on my now-silent A-7s, fifteen feet away. !! Need to finish re-wiring those A-4 woofers first, ( wanna' hear them properly ) that task coming-up this Sunday I hope.

Each ALTEC 210 bass horn weighs 440 pounds, unloaded, and each ALTEC 515C must be about 30 pounds, two per bass horn, so, we need to move about 500 pounds when loaded, just to access the enclosure's rear woofers' panel. Ugh.

Jeff Medwin

 

RE: One thing about Yamamoto A-08, posted on November 25, 2015 at 00:28:22
C.Y
Audiophile

Posts: 345
Location: S.Korea
Joined: September 7, 2002
Hi Jeff,

In fact I tried your low DCR concept in some different ways. I could feel the change in dynamics, etc.
But please use gentle and considerate words, or others may only see your definite writing and stick to that wording and may try to criticize it. You know what I mean. I've seen this before and feel sorry to see this again.

If you can offer the simplest combination of power tranny and chokes with proposed circuit, that will help, both you and others who are curious after all these years that you've been suporting that idea.

Cheers,
Chul

 

RE: One thing about Yamamoto A-08, posted on November 25, 2015 at 07:45:06
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005



Hello Chul,

I much respect the fact that you are a musician, pianist.

I do not mind others criticizing me.

I speak about what "I" hear and what "I" think.

There was plenty written previously herein about Flywheel, and LSES and one can peruse a Hammond catalogue and come up with decent alternatives, with a little effort, the use of PSUD and by listening.

In recent years, I more and more modify the leads of all power supply magnetics, ( see photo above ) to play back music's awesome peak instantaneous currents.

I still do not use chokes much over two pounds in weight, and over 2 HY or over 10 Ohms DCR. In 2015, I may employ LSES over a Flywheel, and in true LSES style, it will have L1 equal L2,..... but NOT always. Fastest settle is not my key PSUD priority ( as was written by John Swenson, John Hasquin et all ), smooth settle is the priority.

I still use 50 uF as the largest cap size, and typically use a lesser uF amount on C1 - than on C2. In 2015, I use WIMA DC LINKS as a main supply cap, and bypass it with four to eight smaller value, higher quality film caps, selected by ear, for full musical expression. Bypassing main film caps I find is a "must", in all C locations for decent full-frequency playback results. It must be done by listening and its an ART form IMHO, like musical expression on your piano.

Let people experiment on their own, by listening, and come up with a circuit they are happy with, and proud of to call their own.

Most important of all, do what pleases you and have fun in the hobby. If YOU like your results, that is ALL that matters. Have FUN.

Jeff Medwin

 

RE: I M H O / I M Experience, Critical inble, posted on November 29, 2015 at 14:31:45
Tre'
Industry Professional

Posts: 17260
Location: So. Cal.
Joined: February 9, 2002
The whole point of a critical inductance input choke is keeping each diode on, in turn, for it's entire 1/2 cycle.

That keeps the current flow from the transformer to the filter cap low and steady. This gives a sinusoidal wave form ripple instead of a saw tooth wave form ripple.

With anything less than critical inductance each diode is only on for a short time. Therefore the current has to be high during it's short allotted time. These are current spikes.

They are very hard of the power transformer and the rectifier tube.

Lynn Olson says they create RF hash that can't be filtered out because it's airborne. It has to be shielded out.

BTW "Critical inductance" is the amount of inductance, for a given voltage and current, that causes the diodes to stay on, each in turn, for their entire 1/2 cycle.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: I M H O / I M Experience, Critical inble, posted on February 12, 2016 at 04:40:28
horn kid
Audiophile

Posts: 128
Joined: November 2, 2014
Wow, what an interesting opinion, at least it is presented as experiential and not dogma, though some responses venture into the dogmatic world. But what would audio be without unsubstantiated, unproven dogma? I think many participants would leave the hobby.

Let's face it, the noisiest systems usually use horns and SETs. I would put forth that it is entirely possible that the dynamic systems are not dynamic because there is low level noise, but rather, there are great things about horns and SETs that include great dynamics and life, yet a common trait is also noise....that does not mean that noise makes things sound dynamic!.

Having many SETs, I happen to have 2 that are exceedingly quiet at the exit of the 100+ db horns. These happen to be some of my more dynamic amps.

Now, wouldn't it be ridiculous for me to say "Quiet SETs are the most dynamic"? Oops, there I go again, not spewing dogmatic conclusions based on a very small sample. I have to remember to be more dogmatic, more audiophile-like.

 

Dolby vs dbx, posted on February 15, 2016 at 04:51:38
cawson@onetel.com
Audiophile

Posts: 2362
Joined: September 27, 2004
> When we first started using dolby A in our studio everybody felt that we were losing high frequency response.

As a matter of curiosity, did you find the same when using dbx sound reduction in your studio?

I have the impression that this much simpler noise reduction system is, at least in theory far superior to Dolby. It completely failed to catch on commercially in the domestic market because you NEEDED a dbx decoder to have listenable-to music - whereas Dolby was acceptable without a decoder (though its benefit was lost).

I had a cassette recorder with a dbx circuit that played back with much less tape hiss than Dolby and I could use its decoder to allow playback of my handful of dbx-encoded vinyl. I still have the vinyl - the cassette recorder is long-since gone.

Peter

 

Excuse me, posted on March 1, 2016 at 17:21:21
Tre'
Industry Professional

Posts: 17260
Location: So. Cal.
Joined: February 9, 2002
Other than the reference to Lynn Olson my entire post was pure fact, not opinion.

As to what a critical inductance choke input filter power supply does to the sound of a audio system....that might be seen as opinion. But I didn't say anything about sound.

Tre'


Have Fun and Enjoy the Music
"Still Working the Problem"

 

Page processed in 0.050 seconds.