JPV said:
Hi JPV,
Yes, it does indeed make sense to use capacitance multipliers in the supply rails to the input stage and VAS of a solid state amplifier, as long as the resulting voltage drop can be afforded. When one uses boosted rails for the VAS and input stage, such a slight additional voltage drop is definitely affordable. If we are talking about very high quality amplifiers, no one should be complaining about the slight extra cost of boosted rails. Note that a capacitance multiplier allows really good filtering of the input and VAS rails without dumping rail noise current into a potentially sensitive ground through brute-force capacitance.
With regard to output stages, I have often thought that a MOSFET capacitance multiplier ("soft rail regulation") between the raw rectified rail and the supply for the output stage would make sense. This capacitance multiplier would still feed into a fairly large capacitance local to the output transistors themselves (perhaps 10-20,000 uF). This keeps raw ripple and RFI away from the output stage. The price paid here is some power supply rail voltage loss ( a precious commodity) and some power dissipation in the capacitance multiplier. The key advantage of this as compared with a fully regulated supply to the output stage is that the voltage provided by the capacitance multiplier tracks the available raw rail voltage, keeping regulator dissipation down and retaining the advantage of dynamic headroom.
In any approach like this, one must always consider whether the output stage would have been just better off with the greater headroom afforded by the same raw supply with the conventional approach.
Cheers,
Bob
john curl said:
I agree, and my experience is quite similar. Maybe I would say "This is not about distortion only "
I mean that distortion should be under certain level, should have certain harmonic spectrum, with only low order components. If this is fullfilled, then it is of minor importance. I still cannot admit distortion produced by vast majority of SE triode amps, not only from technical point of view, but their sound does not satisfy me.
Nelson Pass said:
This is not strictly a "yes/no" proposition, despite extreme views on either side. In my view, those who never trust their ears are probably deaf, and those who unconditionally trust their ears are probably delusional. In the real world in the middle, it's a matter of degree. If we are trying to detect some change, then the extent to which we can trust our ears depends heavily on the magnitude of that change.
I don't necessarily trust my own ears. I trust other peoples ears. Independent, but enlightened opinion, by serious music listeners, is my true feedback, beyond theory and measurement.
I, in turn, can review other designs, from serious (and maybe not so serious) audio designers.
For example, when I heard the LAMM exhibit at CES this year, I KNEW it was a winner and it was only driving a direct radiator speaker system.
The year before at CES it was a similar single ended tube amp driving a horn loaded system.
The year or so before that, we shared a listening room with my electronics driving big electrostatic speakers, that did very well.
I find it just about impossible to qualify any speaker type, or amp type, and state that it is impossible to get wonderful sound quality.
What seems to make the difference, is the care and effort in the design itself, more that the design approach.
For example, the next biggest surprise at CES was a class D amplifier exhibit based on TI modules, but sponsored by IR. It sounded pretty darn good, although I would have to have more time with it to know if something would be distractingly annoying after long term listening. Only time will tell with that one.
I, in turn, can review other designs, from serious (and maybe not so serious) audio designers.
For example, when I heard the LAMM exhibit at CES this year, I KNEW it was a winner and it was only driving a direct radiator speaker system.
The year before at CES it was a similar single ended tube amp driving a horn loaded system.
The year or so before that, we shared a listening room with my electronics driving big electrostatic speakers, that did very well.
I find it just about impossible to qualify any speaker type, or amp type, and state that it is impossible to get wonderful sound quality.
What seems to make the difference, is the care and effort in the design itself, more that the design approach.
For example, the next biggest surprise at CES was a class D amplifier exhibit based on TI modules, but sponsored by IR. It sounded pretty darn good, although I would have to have more time with it to know if something would be distractingly annoying after long term listening. Only time will tell with that one.
I ask this question about Floyd Toole and his book.
First, I have met and discussed audio with Dr. Toole. I have also attended several of his lectures.
However, what audio components has Dr. Toole found that audiophiles here, have tried and swear by? Any breakthroughs from HK or its possessions?
Let's find what Dr. Toole has found, in REAL PRODUCT, and discuss its qualities and perhaps its limitations.
Then, maybe, we might find the limits of DB testing, in that discussion.
First, I have met and discussed audio with Dr. Toole. I have also attended several of his lectures.
However, what audio components has Dr. Toole found that audiophiles here, have tried and swear by? Any breakthroughs from HK or its possessions?
Let's find what Dr. Toole has found, in REAL PRODUCT, and discuss its qualities and perhaps its limitations.
Then, maybe, we might find the limits of DB testing, in that discussion.
My comment was given in support of the fact that there is not such a thing as perfect sound.
The title of Tool's book is: Sound reproduction, loudspeakers and room.
The listening experience is a complex chain including the interaction of the loudspeaker, the room and the brain.
Toole has used of course real products to try to understand what is important, what to measure and so on.
Impact of direct sound, first reflection and diffuse field must be studied and understood. It si not so easy and Tool's book is a must read IMHO in that respect.
I am not believing that listening tests are weak, I am saying that the experience of listening is complex and the right set up of this experience is difficult if the objective is finding and understanding improvments.
His pages on carefull listening to the influence of amplitude spectral linear distortion in anechoic and room environment is a very interesting example. One observation is that voice and more femal voice is a forgiving program for amplitude response variations (resonnances) of the loudspeake because the energy is not always enough to fully excite these resonnances.
After having read this book ( and I need to reread it) I am even more convinced that you have to remain humble if you try any definitive judgment in audio
JPV
The title of Tool's book is: Sound reproduction, loudspeakers and room.
The listening experience is a complex chain including the interaction of the loudspeaker, the room and the brain.
Toole has used of course real products to try to understand what is important, what to measure and so on.
Impact of direct sound, first reflection and diffuse field must be studied and understood. It si not so easy and Tool's book is a must read IMHO in that respect.
I am not believing that listening tests are weak, I am saying that the experience of listening is complex and the right set up of this experience is difficult if the objective is finding and understanding improvments.
His pages on carefull listening to the influence of amplitude spectral linear distortion in anechoic and room environment is a very interesting example. One observation is that voice and more femal voice is a forgiving program for amplitude response variations (resonnances) of the loudspeake because the energy is not always enough to fully excite these resonnances.
After having read this book ( and I need to reread it) I am even more convinced that you have to remain humble if you try any definitive judgment in audio
JPV
john curl said:
Yes, so few people remember, when listening to audio gear (as after all they are listening to the gear, not real music) exactly what a real transient sounds like. The trick lies in correctly interpreting what you've heard and correlating that back to a fix in the given design, if at all possible.
Andy C: I see you've spent a moment or two on the Stereophile forum with that tagline of yours.
john curl said:
And the fact that you can walk down the street while making aural sense out of all the sounds around you makes any direct and linear linear and textbook interpretation of what 'distortion' is (with relevance to how the ear/brain works) practically irrelevant.
Some of you guys keep slipping back into your old habits. PMA, by his own admission, has seen that this is not the thing to do,and has seemingly been rewarded for this 'sea change' in his thinking.
If the answer isn't in your engineering books then it's time to move beyond them, and do some discovering of your own.
Warning: preconceived notions will have to be dropped first.
You can't do it by reading all the known answers in other subjects/textbooks as you have to remember thousands of guys have done the same before in the same pursuit....and all have reached no satisfactory conclusion by going that way.
So, obviously, the answer lies elsewhere.
It's simple, actually. It's called 'striking out on your own'.
Another important area of passive component selection is how we make the volume control. Do we buy a commercial pot? Or do we make our own? The CTC Blowtorch used the TKD volume pot, usually 10K in value, but I elected for 25K. Why 10K? Why 25K? Why not 100K?
These volume pots became SO expensive that Michael Percy (our usual supplier) refused to order any more. There are even more expensive solutions, and well worth it to some.
These volume pots became SO expensive that Michael Percy (our usual supplier) refused to order any more. There are even more expensive solutions, and well worth it to some.
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