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In Reply to: RE: Timbre posted by Tre' on April 09, 2016 at 14:10:48
in our getting timbre, and expression.
This is unsurprising when you consider that lots of instruments - with timbre and expression, just don't do continuous tones, ever.
All this has been known for a long time.
I have heard a recording of an oboe with a clarinet attack replacing the original and we all thought it was a clarinet.
This is why matching rise and settle times into real loads are so important.
I lost interest in using valve rectifiers - anywhere - a long time ago.
Who wants sag / noise in a hi-fi PSU?
Even in a bias supply.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Follow Ups:
"Who wants sag / noise in a hi-fi PSU?"
A tubed rectified, critical inductance power supply, with the appropriate amount of capacitance, feeding a Class A circuit will not sag and is as quiet as a power supply gets.
"In terms of ragged waveforms, solid-state diodes are the worst, followed by Schottky diodes and HEXFRED's, followed by conventional tube rectifiers, followed by TV damping diodes, which are the smoothest of all in terms of the AC waveform on the power trans secondary."
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Also see my response to Jeff Behr, and look in reviews at AA for LEAK St 20s.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
"Conclusion: This is a set of personal preferences"I think Lynn meant the article as a whole.
Lynn has worked for major firms and is very versed in the science behind audio electronics.
What he says about power supply noise is not his opinion, it's fact.
There are plenty of things in this hobby that are purely subjective but physical facts are physical facts.
That doesn't mean that everyone will like the sound of a stable, noise free power supply but scientific fact will tell you which ones are stable and noise free and which ones aren't.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 04/14/16
"I lost interest in using valve rectifiers - anywhere - a long time ago."
How have you resolved the issue of instant-on B+, and the effect it has on amplifier tubes with cold filaments?
--------------------------
Buy Chinese. Bury freedom.
easy peasy.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Generally speaking, power tubes warm much more slowly than thermistors. I also suspect that whatever type(s) you're using, they're still degrading the dynamics of the supply.
--------------------------
Buy Chinese. Bury freedom.
.
----------
Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Typing too fast.We also snubbed the slow, soft recovery diodes.
I wanted maximum power, given cathode bias.
I listen mostly to simply recorded acoustic classical music.
The spheres I was using for a long time are an easy load and sensitive enough to go quite LOUD in the room. So they are efficient as well. 91db/w 35-13k IE a bandwidth product of ~400,000 which is subjectively ideal. The shape produces very little waveform distortion. Very revealing of engineering in recordings. I bought them instead of a fairly new pair of black QUAD 57s.
I have heard them with two different SE amps for more than two weeks in each case:-
one was a DIY Pass Zen FET amp. Nice but not as good or as loud as the bi-amped Once-Were LEAK Stereo 20s.
second were a SE UL pair of monos using 13E1 (regulator tube) valves. 18WPc and 20 to 20Khz. Again nice enough.
In neither case were they any more 'inner glow' than the bi-amped LEAKs, and didn't play nearly as loud, not enough jump or SLAM, either!
And, they both drew more power.
One LEAK was in pentode mode 20wpc - effectively active drive as no LP on the bass-mid driver. Amps 2 in triode 6?watts, driving a passive 3rd xover/Fs trap/Eq @ 3.5 kHz into a big soft dome.
VR's? when we were doing the rebuild/mods - 1990s - there were only a few good NoS Mullard GZ34s available here in Aussie and they were too expensive. Used ones not much cheaper either and back then the Asian made varieties were not up to spec. And had interestingly colourful ways of failing.
I've never heard any evidence of the effects of down-shifted EMI/RFI from the SS diodes, so often mooted in these and other fora.
I am / should be known for my quite profound skepticism about the hard line DB testing viewpoint - because I understand the maths of stats. Just search on objectivity with my moniker.
But, I am also deeply skeptical about audio subjectivity, and expectation bias - especially among DIYers in particular. And I have always had a tight budget. A very good discipline I find.
e.g. I would rather double the wattage of signal path resistors from 1/4W to a 1/2W and so on, as this will audibly reduce noise in audio circuits, and I use a mixture of MF brands.
For signal path capacitors in these NFB (less than as OEM'd) amps I've found that Wima MKPs and a few MKS are just fine. Teflon caps are a good idea in the NFB circuits, along with Holco Rs or better. The cathode Rs are low-L packaged 20W glassy dark-blue things whose brand and catalogue numbers I forget.
LBNLeast? The job of a [properly designed] power amp's PSU is to provide an overbuilt / hopefully inexhaustible supply of DC current, which you can only hear if it's gone unstable. Audible FR ripple is way less than HJL's specs.
The amps are at least as 'quiet' as any SS PP AB1 amp I've used.
3d, nuance, wonderful timbre.
The amps and their mods are described here in Reviews at AA.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Edits: 04/13/16
My personal audio path has convinced me that tube rectifiers are the way to go and on my SET I don't lack SLAM or SPEED, compared to many SS amplifiers I've listened to, if, of course, the SET satisfies the output power needed by the speaker.
Of course I am using a choke input filter after the rectifier and the whole PSU has very good passive regulation qualities. Currently I'm using Telefunken EY83 and AZ11 of the same brand. The Telefunkens for now are the best brand I've heard. I'm in love with the sound this rectifier gives.
From experience, I think a lack of SLAM or speed can come from many other points, like a resistor's sound signature, capacitor (especially in the cathode). It's not fair to directly blame the rectifier or Rdc of PSU components.
Hello,
You end with these words :
"It's not fair to directly blame the rectifier or Rdc of PSU components."
From the schematics of your amp builds you posted, I see you use high-storage chokes, with high DC resistances. I would have to conclude you have never built of heard a L1/C1/L2/C2 filter chain using low storage and low DCR components.
Had you had this experience, you would not write about "Rdc of a power supply" as you do now in 2016 !
I have built amps BOTH ways, and I know all Ls to the Final's filter chokes need to be 20 Ohms or less ( I use 10 Ohms or less ) and all Cs 50 uF or less, and all HY's about 2 HY., or less. Above those values, audio performance, dynamic contrasting, and timing of the amp on music playback suffers in "my" DIY amp listening - 34 years worth.
We should discuss this privately. Contact me through Forum eMail please. Regards and best wishes,
Jeff Medwin
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