Gents,
So much noise here, who's actually TRIED doing what's talked about? Anything else is, honestly, just noise.
The best approach to SE amps I have ever seen is in Sound Practices #4 - from John Camille (Budda) and his buddy.
They use a 211 power tube - SHUNT regulated by another 211, and a separate shunt reg for the 6SN7 mu-F driver stage using an EL34.
I personally believe any series reg is a waste of time and materials, but SHUNTS are very worthwhile sonically - but don't listen to me - TRY THEM!
And read that article, more wisdom on SE amps has never been spoken!
Regards, Allen (Vacuum State)
So much noise here, who's actually TRIED doing what's talked about? Anything else is, honestly, just noise.
The best approach to SE amps I have ever seen is in Sound Practices #4 - from John Camille (Budda) and his buddy.
They use a 211 power tube - SHUNT regulated by another 211, and a separate shunt reg for the 6SN7 mu-F driver stage using an EL34.
I personally believe any series reg is a waste of time and materials, but SHUNTS are very worthwhile sonically - but don't listen to me - TRY THEM!
And read that article, more wisdom on SE amps has never been spoken!
Regards, Allen (Vacuum State)
Bas,
Anyone that I have ran across before that listens seriously to tube rectified circuits will chose those every time vs. SS. I have never heard of people that prefer solid state rectification in a tube circuit as much I as I see in this forum. I guess they like the way that it measures vs. how it sounds
What I meant to say is that the amp that has higher THD may be preferred because of other things than THD. Not that it is preferred because it has higher THD.
r
Well, that part I have first hand knowledge about. I made such an experiment myself. I used the original Zen (Pass), and had a group of 5 persons evaluate.
That particular amp, was easy to change distortion level on. Simply increase the bias, to lower distortion.
I got consistent results, but the test group did not agree that less is better.
Imagine these guys discussing......we don't seem too far apart
http://www.blotto-online.com/blotto/lh4.jpg
Magura
You already did comment when you LOL that someone might hear the difference between X or Y ohms output impedance.
There's little value in projecting personal views and/or personal common sense onto everyone. Just because you or those that you trust don't hear a difference, it doesn't mean there isn't. When I was kid a friend of mine could hear the bats flying by catching bugs. None of the rest of us could, but he blindfolded, in the evening, could tell when the bad flew by.
I don't have such a refined listening skills as others who can spot a higher quality cap in the audio chain, but I don't doubt that the guy next who me who says he can, he does. It's HIS experience, and yes, it's subjective. You'll have a hard time giving me an example of objective personal experience, I'm afraid, anyone.
Can we get back to technical discussion now please? I see nothing wrong in improving the output impedance of a psu, regardless of whether one can hear it or now.
Great! Shunt regs! The type that especially need gobs of evil NFB to give a reasonably low output impedance............
Without putting such a statement into context, it is actually just noise as well.
I can come up with examples of applications, that are perfectly fine with a SS series reg.(Pass style pre's comes to mind).
Applications that has no benefit of any sort of reg., and applications that sure needs a tightly regulated shunt to work at all (inductor loaded pre's for instance).
Magura
Open-minded observation and free-thought should not be a goal in itself and is not perse better than following your instinct or "closed-minded pre-determined psychological bias". (In certain situations ofcourse)
"Western science" for lack of a better word has become the de-facto standard precisely because it includes doing stuff instead of just thinking about things. Which includes constantly measuring the "reality". This is where all our discussions go awry. Because a certain part of the community thinks that they are measuring the reality. But it is only part reality IMO. To all agree upon something...we all have to agree on what we are going to test and how. Only when we all agree on that ....those who agree that this is how must be tested must and can abide by the results. But at the moment one crowd is saying...measurements are the truth. The others say listening is the truth. Unless we all agree on how we can evaluate the "truth" there will be no agreeing.
Great. I guess that vagabond that I used to chat with at the bus stop really was conversing with the Almighty. Why on earth would anyone doubt or question the underlying truth of another person’s subjective experience? It was HIS experience damn it!
Bas your comments are exactly correct. We have the one crowd that trusts measurements over what they hear and we have the others that trust what they hear over measurements. In this forum there is only room for the minority that refuses to listen.
This I find to be the most closed minded stance of either group as the listeners do not disregard what the measurement people do, just that there are still differences that have not been categorized with measurement techniques just yet.
There may be good reasons, and of course, your right as an individual to doubt anyone's subjective experience; that's because you have your own objective experience. But is the vagabond's right to have his beliefs. It's also the quantum mechanic theoretician's right to believe there is an intrinsic randomness in the fabric of the universe, never mind he's got no good explanation for it; darn it, makes everything else works so well... so why not, right?
Don't assume they don't listen. I assume that most of them actually do. But who says they hear the same thing you do? (as shown again recently during the Burning amp meet .... one guy liked Feastrex and some other guy did not care for them) Their measurements may and probably do influence what they hear. Most likely they believe in their measurements so much that they actually adjust their hearing to suit what they measure? Who cares... it works for them? (Assuming there is some truth in that, which is not what I'm saying. Rather I'm saying that it is possible just as people apparently fool themselves with their tweak of the month)
Allow me, and if I mis-state anything, Allen will surely correct me. In his designs (which are superb), he uses gain blocks that tend to have very poor power supply rejection. This is a trade-off because these gain blocks give a lot of gain, swing a lot of volts, and do so linearly. But the poor power supply rejection needs to be accommodated by heroic regulation measures, and likewise, he has engineered some excellent regulators. Indeed, though it's unclear to me exactly why it should be so, it's certainly plausible that shunt regulators will function better in this sort of use. A high Z supply would be a disaster.
Actually most do. And they should. In certain cases. For instance my home theater amp measures better than my DIY SE amp. But none of measurements actually tell me anything about tone, timbre, soundstage etc....absolutely nothing. Then again there are those who say that words like tone, timbre and soundstage mean nothing to them. Absolutely nothing.
I guess I am one of the oddballs who both listens and measures.. I'm not always sure that what I am measuring correlates with exactly what I am hearing - however in many cases and I can only talk to my own designs, improvement in measured performance usually results in an audible if subtle improvement in the way the device in question sounds. Sometimes it doesn't and in such cases I do try to dig a bit further to try and understand why. Sometimes it is as simple as a reduction in measured thd that significantly changes the distortion spectra - lower overall, but now with a preponderance of odd higher order odd harmonics as compared to the previous spectra which may have been predominantly 2nd harmonic.. It could be a subtle change in intermodulation distortion, an asymmetry or reduction in slew rate, an unexpected but subtle change in the spectral make up of the noise floor, a change in overload behavior. Ad infinitum..
I have used both shunt and series regulators in my designs, and find both work well, but for practical reasons I tend to prefer series regulators despite their current lack of street cred. (And I don't hear the purported sonic disadvantage at least in my own designs.) I guess it is as much about fashion as anything - 20 yrs ago my comments about the benefits of voltage regulation whether series or shunt were largely dismissed as the ramblings of an engineer who focused too much on the technology and not enough on the "art." (Despite the fact that I have always relied on my ears as the final arbiter.)
There was also a rather simplistic view in those days about thd and its impact on sound quality - i.e. less is always better regardless of its spectral make up. I made the argument for the relevance of harmonic spectral content well before it was fashionable, and well before I had the instrumentation to really investigate it. It was also a major reason first for my move to limited global feedback in SS electronics and the use of local current feedback where possible, and was ultimately the reason why I ended up using tubes in my designs, finally with little or no feedback in my later designs.
The fact that there are enough of us to even care about this issue today is pretty encouraging - 25yrs ago no credible electrical engineer would have even dared to admit a fascination with hollow state devices.
I believe some level of electrical accuracy is important in the ultimate listening experience and that both well thought out measurements and careful listening are required to achieve the desired result. If I am straddling two fences I think you will find a lot of very successful designers (not me unfortunately
) doing the same thing.
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I think it is absolutely great that you are experimenting and learning something along the way, and I am delighted to have been any help at all.
I would be interested (remember I am also a fence straddler) in your subjective impression of the changes if indeed (hopefully) you have some.
I found the advantages not so subtle which is why I go to such lengths with my PSU designs which ironically are usually far more complex than the simple audio circuitry I employ in my designs. (Which as SY rightly points out wrt to these types of circuitry generally have pretty bad PSRR.)
I've designed regulators like that, and they do work. If you're going to go that route, I would suggest adding a 4K7 grid stopper and a 1K screen stopper to the 6SJ7, just to be sure it'll remain stable. You also need to keep an eye on the Vhk ratings, so that you don't exceed those limits.
The 6AS7 also requires preheating before turning on the HV DC, Otherwise, these are likely to flash over internally.
If I am straddling two fences I think you will find a lot of very successful designers (not me unfortunately
I don't think you are straddling at all, instead you are just stating the obvious really. Too many folks have their heads up the butts dogmatically clinging to objective or subjective viewpoints. It's not a good / bad, black / white, objective / subjective world. The sooner they extract their heads and open their minds the better. You're spot on in my (sometimes-not-so-humble) opinion.
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