A few additional comments:
P.S.: Jan, I would dearly like to buy two boards...do you have some extra?
P.P.S.: Two things I have managed to figure out, by experimenting and by paying attention to posts here and elsewhere by those I trust:
1. For me, I now separate the power supply from the amp chassis. There's just too much EMF from power tx's and rectifier circuits to deal with inside an amp chassis; put all that junk inside a shielded separate chassis. For an eye-opener, try really scoping the hash that's generated by the classic choke input filter...it may be clean coming out, but it is nothing like clean going in, and that stuff is radiated and is picked up. And if you like DC for filaments...I do, current regulated...you CANNOT keep that DC supply in the amp chassis, it's like a 1 KW AM transmitter stuck inside an audio amp. Also, using a stethoscope was also an eye-opener, big-time!
With a stethoscope, you can clearly hear all the vibrations of the power transformer core ALL OVER THE AMP, chassis, sockets, tubes....control grids vibrate, yup, they do...
2. The best power supply is an amp that draws constant current at all frequencies. Now that I understand that...thank-you, Broskie, Pimm, Wright, Duttman, et al (please don't be offended if I left out your name
)...power supply design is much easier (ignore all my previous posts about the Maida, by the way 🙄 ): CCS everything possible in the amp, use circuit blocks that are naturally CCS (such as the tightly coupled anode-follower/cathode-follower combo), and then just CCS Shunt reg the power supply. NOW we're getting somewhere.........
P.S.: Jan, I would dearly like to buy two boards...do you have some extra?
P.P.S.: Two things I have managed to figure out, by experimenting and by paying attention to posts here and elsewhere by those I trust:
1. For me, I now separate the power supply from the amp chassis. There's just too much EMF from power tx's and rectifier circuits to deal with inside an amp chassis; put all that junk inside a shielded separate chassis. For an eye-opener, try really scoping the hash that's generated by the classic choke input filter...it may be clean coming out, but it is nothing like clean going in, and that stuff is radiated and is picked up. And if you like DC for filaments...I do, current regulated...you CANNOT keep that DC supply in the amp chassis, it's like a 1 KW AM transmitter stuck inside an audio amp. Also, using a stethoscope was also an eye-opener, big-time!
With a stethoscope, you can clearly hear all the vibrations of the power transformer core ALL OVER THE AMP, chassis, sockets, tubes....control grids vibrate, yup, they do...2. The best power supply is an amp that draws constant current at all frequencies. Now that I understand that...thank-you, Broskie, Pimm, Wright, Duttman, et al (please don't be offended if I left out your name
)...power supply design is much easier (ignore all my previous posts about the Maida, by the way 🙄 ): CCS everything possible in the amp, use circuit blocks that are naturally CCS (such as the tightly coupled anode-follower/cathode-follower combo), and then just CCS Shunt reg the power supply. NOW we're getting somewhere.........radianceaudio said:
It a little bit off-topic, but I have to totally disagree. Compared to other technologies, audio equipment is damn simple and primitive.
On April 21 1961 first man traveled into space, in 1971 first USSR probe landed the Mars. Even elementary particle like neutrinos which could cross the distance 10^18 m (~100 light years) in the water without any reaction was successfully detected in 1956.
Yet some people still claim there is some indiscoverable mystery or magic behind device with 10 vacuum tubes or 20 transistors wired to electromagnetic cone.
Individual perception can be different, but the whole trend is well known for over decade. THD number alone do not tell much of the story, but spectrum analysis of THD and IMD does.
And since there is a magic, there are of course "wizards" with paranormal abilities (beyond reach of "ordinary" people of course) which could discover something indiscoverable. Marketing ********, nothing else. All this "magic" end up with the profit in "wizard" pocket.
It's OK, feel free to totally disagree. A good, strong emotional response is needed to get the brain activated.
However, I would just...gently....point out...as one who's labored in the trenches of medicine for a long time...we still don't understand the human brain at all, at all...just a bare smidgeon of understanding...so, while amps and speakers may seem simple (they're not, but I'll let that pass)...trust me (or don't, whatever), we know virtually nothing about how we really hear music in our brain, and even which part of the brain is listening, depending upon the conditions.
If you leave out neuroacoustics, you are leaving out at least half...probably more like 80%...of the science of audio.
Since we don't have more than a teensy-weensy understanding of neuroacoustics, it follows that at least 50% to 80% of the science of audio is still not understood...so what might seem simple from the electronic standpoint, is not simple at all, at all.
I agree with you about self-appointed audio gurus who are from another dimension or perhaps frauds, but after a while...if one pays attention...the guys who really know something separate out, like cream rising to the top. Oddly enough (just kidding, of course) they turn out to be people who are passionate engineers AND who have learned how to LISTEN.
It's become like a mantra to me: Broskie, Wright, Pimm, Didden, Turner, Robinson, Duttman, Olson, Beck, Et Allllllllllll, nnnotnnecesssarrrrilllllyinnnnnthatorrrrderrrr, Ommmmmmmmmm.......Ommmmmmmmmmmm......
(even when they disagree, as they sometimes do!! 😉
(and don't forget, at the level of quantum physics, which is likely involved in neuroacoustics, "simple" amps become spiritual....🙂
best, charlie
However, I would just...gently....point out...as one who's labored in the trenches of medicine for a long time...we still don't understand the human brain at all, at all...just a bare smidgeon of understanding...so, while amps and speakers may seem simple (they're not, but I'll let that pass)...trust me (or don't, whatever), we know virtually nothing about how we really hear music in our brain, and even which part of the brain is listening, depending upon the conditions.
If you leave out neuroacoustics, you are leaving out at least half...probably more like 80%...of the science of audio.
Since we don't have more than a teensy-weensy understanding of neuroacoustics, it follows that at least 50% to 80% of the science of audio is still not understood...so what might seem simple from the electronic standpoint, is not simple at all, at all.
I agree with you about self-appointed audio gurus who are from another dimension or perhaps frauds, but after a while...if one pays attention...the guys who really know something separate out, like cream rising to the top. Oddly enough (just kidding, of course) they turn out to be people who are passionate engineers AND who have learned how to LISTEN.
It's become like a mantra to me: Broskie, Wright, Pimm, Didden, Turner, Robinson, Duttman, Olson, Beck, Et Allllllllllll, nnnotnnecesssarrrrilllllyinnnnnthatorrrrderrrr, Ommmmmmmmmm.......Ommmmmmmmmmmm......
(even when they disagree, as they sometimes do!! 😉
(and don't forget, at the level of quantum physics, which is likely involved in neuroacoustics, "simple" amps become spiritual....🙂
best, charlie
radianceaudio said:
Japanese did very deep and extensive research in this area, that's probably why their 30+ year old vintage equipment is still highly valued today. I have seen a tiny drop of this work translated to English, but lost its trace. The rest is probably archived in Japanese.
It's a problem with the U.S., especially in the human sciences: we pretty much ignore foreign research (or rip it off). I would dearly love to read all that Japanese research, wish I knew Japanese and lived in Tokyo! (not really...)
Completely by accident, to get back on-topic a little bit...heh heh heh...I said something profound in my last post - but I hasten to add I claim no credit for it, it just surfaced from re-reading Broskie, Wright, Pimm, Turner, Duttman, Elliot, Didden, et all, et alllll, notnececessarilyinnnnnthatorrderrrrrr, ommmmmmmm........:
"The best power supply is an amp that draws constant current."
That's the smartest realization I've ever had in audio, although I'm sure it dates back at least to the 1930's.....but it does put a whole new light on the debate between pass and shunt regulators, doesn't it?
best, charlie
Completely by accident, to get back on-topic a little bit...heh heh heh...I said something profound in my last post - but I hasten to add I claim no credit for it, it just surfaced from re-reading Broskie, Wright, Pimm, Turner, Duttman, Elliot, Didden, et all, et alllll, notnececessarilyinnnnnthatorrderrrrrr, ommmmmmmm........:
"The best power supply is an amp that draws constant current."
That's the smartest realization I've ever had in audio, although I'm sure it dates back at least to the 1930's.....but it does put a whole new light on the debate between pass and shunt regulators, doesn't it?
best, charlie
I'm in complete agreement with Charlie - the undiscovered element in audio is the neuroacoustic element of which there is very little known & this seems to be missed by the objectivists & the subjectivists alike - it's, in fact, what interlinks them!
I have long paid attention to all that Gary Pimm & John Swenson & Jocko Homo say, as, like Charles, I trust their ears & their engineering skills.
I also realise the importance of power supplies in all audio equipment, preamps, amps, digital or analogue and the need to prevent PS generated interference but also to use circuits that have a high PSRR as well.
I have long paid attention to all that Gary Pimm & John Swenson & Jocko Homo say, as, like Charles, I trust their ears & their engineering skills.
I also realise the importance of power supplies in all audio equipment, preamps, amps, digital or analogue and the need to prevent PS generated interference but also to use circuits that have a high PSRR as well.
Interesting posts about blind testing and neuro-psychology etc. I've some rather strong opinions on that myself, but I don't want to beat that horse to death again.😉
Just a few comments: although we indeed don't know all the details of how the brain does it sound perception tricks, we know a great deal about the input/output function, so to say. Just like you don't need to know the detailed workings of a car engine to know how to drive a car and how to manipulate the engine.
For some reason, audio is a rather backward area when it concerns scientific approach to, say, differences between amps. We could learn a lot from medicine industry that has learned very well to do controlled tests, if only to save them from bankcrupty by ligitation. Trust me, a powerfull motivator to get it right. Of course, in audio there is no such motivator; on the contrary, most of the industry carefully maintains the aura of mysticism to save the industry from collapsing.
Also, look at the marketing industry. They know a lot about processes in the brain. Have you ever seen ads from 'United Colors of Benetton'? Brilliant. Not once do they talk about the virtues of their products, about how well they are made, about the vibrant colors. No, they ONLY have the brand name and some totally unrelated attention getter like a 4-year old kid begging in a 3rd world city. Yet, people flock to the Benetton shops to spend their money. What are the brain processes that make that happen? Think about that next time you leave through an audio glossy.
Still, I think audio is a great hobby, and the smell of burning solder beats the most expensive parfume 😀
Jan Didden
Just a few comments: although we indeed don't know all the details of how the brain does it sound perception tricks, we know a great deal about the input/output function, so to say. Just like you don't need to know the detailed workings of a car engine to know how to drive a car and how to manipulate the engine.
For some reason, audio is a rather backward area when it concerns scientific approach to, say, differences between amps. We could learn a lot from medicine industry that has learned very well to do controlled tests, if only to save them from bankcrupty by ligitation. Trust me, a powerfull motivator to get it right. Of course, in audio there is no such motivator; on the contrary, most of the industry carefully maintains the aura of mysticism to save the industry from collapsing.
Also, look at the marketing industry. They know a lot about processes in the brain. Have you ever seen ads from 'United Colors of Benetton'? Brilliant. Not once do they talk about the virtues of their products, about how well they are made, about the vibrant colors. No, they ONLY have the brand name and some totally unrelated attention getter like a 4-year old kid begging in a 3rd world city. Yet, people flock to the Benetton shops to spend their money. What are the brain processes that make that happen? Think about that next time you leave through an audio glossy.
Still, I think audio is a great hobby, and the smell of burning solder beats the most expensive parfume 😀
Jan Didden
Somebody once said...(P.T., of course)...there's a new one born every minute.
The challenge in this hobby is to walk between objectivism and lunacy, because both have it wrong. Until we really understand neuroacoustics, and I submit that it's still a science in its infancy, objectivism is almost as bad a trap as lunacy, because we don't know which measurements are meaningful. We think because we can measure certain things in electronics, we know something...but since we don't really know which measurements are the most meaningful, we delude ourselves. I am stating the extreme case, but I've seen it so many times in medicine.
Things we thought we absolutely knew in the medical sciences twenty years ago we now know were wrong, and the further one goes back, the more primitive the mistakes. Remember the 60's, when the new science, the molecular biology of DNA, thought it "knew" that genes could not move around or jump in and out of DNA? It took Dr. Barbara McClintock (Nobel '83) her entire life of research to finally convince the "boys" that they were wrong...because the "boys" had never thought about the possibility of transposons.
The question that comes up in my mind when I contemplate an amp that is so well designed that it has very close to a constant current demand at all audio frequencies is, does it matter whether the reg is pass or shunt?
Probably not...but it's hard to give up the regulation idea, whether pass or shunt. I'm thinking pass for voltage and ripple rejection, followed by shunt for the rest of the ripple and noise, with a fairly constant output impedance, even if a bit higher than a pass by itself.
I'm curious...would we all agree, for the sake of argument, that the two primary qualities of an amp for allowing background detail and soundstage to be heard, would be ultra low noise and phase coherency? (I'm leaving out RF, but that may be a mistake; our brains may not be as well shielded from RF as we assume...)
If so, then stacking PSRR's could hardly hurt, no? - at least for the noise part.
Best, Charlie
janneman said:
Ah, but the designer of the car engine needs to know the details of how the car engine works, otherwise we're in deep trouble.
So, as designers of audio systems we need to know how the brain perceives what it perceives when listening to live music in order to be able to approximate the recreation of the event in our living room.
jkeny said:
Yes, but. Recreation of the live event is much more encompassing than just building the worlds greatest amp. And if we limit ourselves, just for this discussion, to the amp, there are some simple things we can do.
For instance, in the debate about series or shunt or local stage regulation, almost all of these things can be measured. Don't forget that we can measure much more detail than we can ever hope to hear. We can measure 0.005dB freq response flatness, better than 1 degree phase shift. We can measure the difference between 0.0003 and 0.00025 % THD. We can measure the difference between -120dB S/N and -116dB S/N.
And I would posit that whatever differences we hear, if they are real, they can be measured (in principle) because any audible difference MUST be caused by an electrical signal difference at the speaker terminals. It's just that you cannot measure that difference by just looking at the 1kHz THD.
Example. If you excite an amp with a 30-frequencies multitone, load it with a speaker-like complex impedance and measure the spectrum of supply ripple and distortion residue on the ground line, for instance, you measure a LOT of differences between amps that have identical 1kHz THD but sound different.
Then again, it has been noted that pretending to change from amplifier A to amplifier B but without actually changing anything, can lead to clear listener statements of 'B is definitely better'!
There are no easy answers, but approaching it in a logical, scientific way, without that hidden 'mysticism' agenda, can clarify a lot.
Home work: go to http://www.libinst.com/Audio DiffMaker.htm , Bill Waslo's latest baby, and download the program. There are two audio test files of a piece by Brahms http://www.libinst.com/diffmaker_example_files.htm (scroll down to listener challenge). Listen to both of them carefully, try to decide if you can hear a difference, and which one you like. Then listen to the difference. Don't cheat!
Jan Didden
This is very cool, I'm there.
Rod Elliot had this idea too, I think, in a different way, a circuit that would show to what extent the output of an amp differed from the input, with an LED display. But this is much better; interactive, audible. How interesting.
This might be a very valuable tool indeed. sigh, now I'll have to make at least two versions of everything, so I can use this....
It would be MOST enlightening to use this on a preamp with different power supplies: Swenson, Maida, Didden, Wright, etc....
Best, Charlie
Rod Elliot had this idea too, I think, in a different way, a circuit that would show to what extent the output of an amp differed from the input, with an LED display. But this is much better; interactive, audible. How interesting.
This might be a very valuable tool indeed. sigh, now I'll have to make at least two versions of everything, so I can use this....
It would be MOST enlightening to use this on a preamp with different power supplies: Swenson, Maida, Didden, Wright, etc....
Best, Charlie
Peter Walker of Quad and Dave Hafler of Dynaco have also attempted to isolate the I/O difference of their amps, but it's difficult with analog. You need to very carefully balance level as well as phaseshifts to get a good null. The circuits I've seen had several trims you needed to tweak carefully and then stop breathing to keep it from drifting 😉
But digitally, you can massage the numers as much as you like; Waslo even compensates for slight drift in clock speed that can occur between recordings. It's still not ideal, for instance the first test between a ceramic and a polyprop coupling cap, you can still hear part of the music come through, along with the actual distorted difference signal caused by the differences in caps.
But actually playing with these types of tools advances your understanding of audibility and audible difference much, much faster than weeks of turning around in circles on the 'net 😉 . If you can accept that preconceived notions you might have had *could* be wrong 😎
Jan Didden
But digitally, you can massage the numers as much as you like; Waslo even compensates for slight drift in clock speed that can occur between recordings. It's still not ideal, for instance the first test between a ceramic and a polyprop coupling cap, you can still hear part of the music come through, along with the actual distorted difference signal caused by the differences in caps.
But actually playing with these types of tools advances your understanding of audibility and audible difference much, much faster than weeks of turning around in circles on the 'net 😉 . If you can accept that preconceived notions you might have had *could* be wrong 😎
Jan Didden
radianceaudio said:
Probably we have very different way of thinking, but what is real usefulness of someone else impressions when it comes to very personal matters ????? My ears are connected to my brain.
Moreover, listening people who listen cables, caps, resistors, power supply rectifiers, is basically joining a lunacy club. Speakers and their placement in the room determine much more degree of sonic picture then components of amplifier. Other people listen different set of speakers, in different room, different music, and very likely from different source. Even if they are trained musicians their opinion is valid only under certain very strict circumstances.
LinuksGuru said:
I like your condensed version of the space exploration history. It avoids a lot of controversy and unsubstantiated claims. It comes as no surprise that you share an equally down to earth approach to the finer points of audio.
Yeah, that's the point. You see, humans have this habit of making the ridiculous assumption that they know which processing centers in their brain are operating at any given moment.
Where you string words together silently into what you think are your only thoughts is a very teensy-weensy part of the brain, a thin layer of cells in the cerebral cortex.
A whole lotta stuff is going on in other parts of the brain long before your cerebral cortex has any chance to formulate any opinions about whatever data is coming in - such as sounds via your ears.
Did you know, for example, that your retinas in your eyes have very sophisticated processing matrices of what are very similar to digital computer processing, made up of cells that not only respond to light at different wavelengths, but interact with each other just like brain neurons and process the visual information before it's even passed back to your numerous brain vision processing centers via the optic nerve? In fact, we have little auxiliary brains all over our bodies, of which we have NO conscious awareness or control.
How do you know which translation of what your ears are hearing is actually being conveyed to your awareness? You don't, dude. All that stuff going on is not under the control of your cerebral cortex. It's as if you were sitting in a totally isolated room, and occasionally somebody would stuff a written note through the mail-slot in the door to your room. You read the note, and you think you know what is going on in the outside world. Good luck with that. You have no idea what your servants have done with the message from the front door to your room.
Extreme example to make a point. Like any extreme example, you can reject the example, or you can focus on the point.
The point is this: there is now neuroacoustic research that suggests there are at least two distinctly different audio processing centers in our brains, and when our verbal thought center - our cerebral cortex - gets the end-result of all that processing in other parts of the brain, we don't know which auditory processing center the sounds passed through that we are listening to and forming opinions about. One of these appears to be a more primitive center that does not provide aesthetic information to the cerebral cortex, but does react in the limbic system emotionally to perceived threats from the acoustic input. This center appears to gain dominance when we don't know the source of the acoustic input. As in a BLINDED TEST.
I won't bore everyone by going on any longer, if you're interested in the whole story, read the link I posted earlier.
But stop thinking you know what's happening between your ears and your cerebral cortex in a blinded situation. You don't.
Thus, the need for educated ears in combination with passionate engineering. Criminey! What's so hard about this concept?
best, charlie
P.S. I do think this DifferenceMaker software may provide an avenue to critical evaluation of audio equipment that gets around the problem of blinding.
Charlie,
You have a somewhat abrasive way of putting it, but what I've read about these issues is largely in line with what you say.
Most people indeed feel that whatever pops up into their head has a direct line to the air vibrations on their erdrums. Which is not the case, unfortunately.
But it takes a concious step to accept that listening doesn't occur in the ears, but between the ears. Once you make that step, you learn, fast. Like opening up a new world of understanding.
Jan Didden
You have a somewhat abrasive way of putting it, but what I've read about these issues is largely in line with what you say.
Most people indeed feel that whatever pops up into their head has a direct line to the air vibrations on their erdrums. Which is not the case, unfortunately.
But it takes a concious step to accept that listening doesn't occur in the ears, but between the ears. Once you make that step, you learn, fast. Like opening up a new world of understanding.
Jan Didden
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