Well, your policy statement is peachy but you really like to play cat and mouse games. Personally, I find it tedious. But you owe me nothing and I expect nothing, life's too short etc. 🙂
Re: Re: Re: Re: Re: VAS fighting
Hi Syn08,
I am acutely aware of the problem with the Slone circuit, and may have been one of the first to point it out. As I suggested to Glen, look more closely at the circuit I designed and posted. There is a method to the madness and it works. It is a modest, simple, DC-friendly way of slightly crippling the VAS.
BTW, it is a simulation trap sometimes for those who have simulated the complementary architecture always with the same value for the twin Miller capacitors.
Cheers,
Bob
Cheers,
Bob
syn08 said:
Hi Syn08,
I am acutely aware of the problem with the Slone circuit, and may have been one of the first to point it out. As I suggested to Glen, look more closely at the circuit I designed and posted. There is a method to the madness and it works. It is a modest, simple, DC-friendly way of slightly crippling the VAS.
BTW, it is a simulation trap sometimes for those who have simulated the complementary architecture always with the same value for the twin Miller capacitors.
Cheers,
Bob
Cheers,
Bob
Hi Glen,
Now, you answered to my statement,
-Chris
Clearly I was responding to a comment you made about an EF buffered Vas. Was I unclear on that? I think you are deflecting attention from your error.
You don't say? Hell, I can't believe it! You stated an obvious fact as though I had assumed something really stupid was true. Keep focused on what is actually said Glen. Respond to that and you will appear to be far more intelligent, rather than skilled in debating through deflection. 🙄
Didn't you post this...
If you look at your post, 16839, I believe you will find you are mistaken. Do I get an apology?
Now, you answered to my statement,
which referred to this idea,
With
May I ask how you measured the difference? Your comment suggests that you did investigate the subject. Notice that I am being polite and responding to what you have actually posted.
-Chris
Hi John,
If I may try to clarify a couple things, let me know if you disagree please. The why would be nice also.
I will agree with you that measuring well is no guarantee of a good sounding product. I will also agree that some products that may measure less well may sound very good. However, there have been too many examples of products that don't measure well that also completely fail in subjective appreciation. Wouldn't you agree with that?
The only way to stay on track while designing an audio product is to allow your test equipment to help guide the design, just as a listening test also will help guide that same design. We have two tools to use, and it would be stupid not to use them both - yes? Knowing what to listen for is similar to knowing what to measure for. They both go hand in hand. This is the art part. Changing things so that "it" sounds better is fine, as long as you don't make the design perform less well. It's easy to imagine a positive change when in fact you make a negative impact. A few more days listening may illuminate that, or not. However, test equipment will show you if things are getting worse or not. There are times when you can not measure a change. That's the nature of our world. Also, how you interpret the readings affects how you perceive whether the design is improving or not.
Example. Measuring an amp, we make a change and notice the THD meter shows an increase in distortion. The THD meter is not showing us what we need to know. Not the whole story anyway. For more information we turn to a spectrum analyzer. What we see is that our 2nd harmonic increased a little, but everything above the 3rd decreased. The THD meter is one that is limited to 30 KHz -3dB and did not "see" the higher orders of THD. This is the reason the indicated reading increased while the product may sound much better.
It is painfully obvious that your average EE out of university is probably not going to be able to design good sounding amplifiers. It should also be plain to see that any design facility without the proper test equipment may not either, unless the skilled engineers have the experience to know when the instruments "lie" and why. They can then make the proper choices. I think that this may be partially your message, and one I can truly accept.
So, I quote you again.
-Chris
If I may try to clarify a couple things, let me know if you disagree please. The why would be nice also.
Absolutely! No arguments at all.
Again, I completely agree with you. So far, no problems. I am questioning why test equipment is being brought up and I'm somewhat worried where you might be going with this.
All right. I am having trouble seeing how this relates to your earlier statements. I mean, I agree. It's obvious, but there are other factors affecting the collection of "mid-fi" out there. Are you trying to link the act of using test equipment as part of the design process as being responsible for a mid-fi product? Do all products that may have good measurements fail in subjective appreciation? I guess this is where you and I really must depart from agreeing with each other if this is your meaning.
I will agree with you that measuring well is no guarantee of a good sounding product. I will also agree that some products that may measure less well may sound very good. However, there have been too many examples of products that don't measure well that also completely fail in subjective appreciation. Wouldn't you agree with that?
The only way to stay on track while designing an audio product is to allow your test equipment to help guide the design, just as a listening test also will help guide that same design. We have two tools to use, and it would be stupid not to use them both - yes? Knowing what to listen for is similar to knowing what to measure for. They both go hand in hand. This is the art part. Changing things so that "it" sounds better is fine, as long as you don't make the design perform less well. It's easy to imagine a positive change when in fact you make a negative impact. A few more days listening may illuminate that, or not. However, test equipment will show you if things are getting worse or not. There are times when you can not measure a change. That's the nature of our world. Also, how you interpret the readings affects how you perceive whether the design is improving or not.
Example. Measuring an amp, we make a change and notice the THD meter shows an increase in distortion. The THD meter is not showing us what we need to know. Not the whole story anyway. For more information we turn to a spectrum analyzer. What we see is that our 2nd harmonic increased a little, but everything above the 3rd decreased. The THD meter is one that is limited to 30 KHz -3dB and did not "see" the higher orders of THD. This is the reason the indicated reading increased while the product may sound much better.
It is painfully obvious that your average EE out of university is probably not going to be able to design good sounding amplifiers. It should also be plain to see that any design facility without the proper test equipment may not either, unless the skilled engineers have the experience to know when the instruments "lie" and why. They can then make the proper choices. I think that this may be partially your message, and one I can truly accept.
So, I quote you again.
However, the design of equipment to accurately reproduce an audio performance is rational, the enjoyment of it is subjective! That is not to say that there isn't a subjective component to the design, because there is.
-Chris
anatech said:
Obviously, I'm not John. However, John stated at least few times in this thread that he DOES measure his design prototypes and end prducts.
So, measurements are definitely a clue, albeit, not the whole story. (Like 7th harmonics VALUE and PROPORTION which aren’t shown in THD figures)?
Hi Joshua,
I am aware of this, but I just am trying to present a clear picture of where John stands. A summation if you will, given his last post here.
I'd very much like to know how close our viewpoints are. I don't think my view is unreasonable, but hey! I'm just me and easily wrong.
-Chris
I am aware of this, but I just am trying to present a clear picture of where John stands. A summation if you will, given his last post here.
I'd very much like to know how close our viewpoints are. I don't think my view is unreasonable, but hey! I'm just me and easily wrong.
-Chris
anatech: mountains out of molehills
The guy, JC, said, if I might paraphrase, that audio has lots of rational/objective tools but they are applied to, or are to serve, a subjective experience.
That should be an easy thing to agree with and not worth paragraphs of interrogative bumpf.
All he's saying is that it has to sound good or the enterprise with all its technical application is .... midfy?
BTW that Stereophile article and its addendum is quite good. It has some indications of what objective criteria might actually serve as a predictor of the good subjective experience.
The guy, JC, said, if I might paraphrase, that audio has lots of rational/objective tools but they are applied to, or are to serve, a subjective experience.
That should be an easy thing to agree with and not worth paragraphs of interrogative bumpf.
All he's saying is that it has to sound good or the enterprise with all its technical application is .... midfy?
BTW that Stereophile article and its addendum is quite good. It has some indications of what objective criteria might actually serve as a predictor of the good subjective experience.
"Mid -fi" .. What an interesting terminology.
Surely , this must be a subjective definition
as cost could not be the deciding factor.
The $7100 genesis stealth would be hi-fi ?
I am sure the suckers that bought it would
tell their friends it was. It sounds good , just
as good as the $300 JVC "super a" I had for
several years.. but that was made in japan
and did not cost several grand.(mid-fi)
For the extra $6800 the "hi-fi" does keep its
smooth class A sound ALL the way to max,
but at a hefty pricetag 😱 . As far as sound
goes, the simple DX amp is "neck to neck"
with the $7K one 😕 with only 9 devices
run by a trafo extracted from a "mid - fi " unit. 😱
With all the diatribes about differing topologies
and component choices, while being (semi) important,
do not seem to hold true at the last "stage"..
the living room. As steve dunlop said , just more
fuel to the "fire" as they jerk off in front of their
simulators.
OS
Surely , this must be a subjective definition
as cost could not be the deciding factor.
The $7100 genesis stealth would be hi-fi ?
I am sure the suckers that bought it would
tell their friends it was. It sounds good , just
as good as the $300 JVC "super a" I had for
several years.. but that was made in japan
and did not cost several grand.(mid-fi)
For the extra $6800 the "hi-fi" does keep its
smooth class A sound ALL the way to max,
but at a hefty pricetag 😱 . As far as sound
goes, the simple DX amp is "neck to neck"
with the $7K one 😕 with only 9 devices
run by a trafo extracted from a "mid - fi " unit. 😱
With all the diatribes about differing topologies
and component choices, while being (semi) important,
do not seem to hold true at the last "stage"..
the living room. As steve dunlop said , just more
fuel to the "fire" as they jerk off in front of their
simulators.
OS
The Mc2300 is mid-fi, and the Mc3500 is HI END. Why?
The Levinson ML-2 is HI END, and the Levinson ML-3 is mid fi. Why?
The Levinson ML-2 is HI END, and the Levinson ML-3 is mid fi. Why?
350watts from a tube amp is indeed impressive, as is .0XX THD.
(HIGH END)
An externally hosted image should be here but it was not working when we last tested it.
While the 2300 is a low-fi (what a amateurish design) crude
attempt at a amplifier.
http://www.berners.ch/McIntosh/Downloads/MC2300_own.pdf
These seem to be two eggs from the same bird. the 2...
An externally hosted image should be here but it was not working when we last tested it.
is a work of art (mid-fi/hifi?) 😕 neater wiring ?
the 3 just seems to be a monster with loads of headroom
(like the genesis). For hi-fi you get dual mono (2 x 1.2kva)
and the "big brother" amp as compared to the 2..
An externally hosted image should be here but it was not working when we last tested it.
OS
You have to measure them, in this case. You could listen to them, as well. The outside is not the inside.
Hi Frank,
<sigh>
Of course. I have learned that to get the answer to a question around here some times, you had to frame the question properly. My intent was simply to hear from John himself.
However, you were able to negate the entire effort. I have not yet heard from John himself. Just a lot of back and forth comments without his rationale in one statement. An attempt to really have John define what he actually believes, and to see where we depart.
Gee, I didn't expect the question to be so difficult to answer that others felt John wasn't able to.
-Chris
<sigh>
Of course. I have learned that to get the answer to a question around here some times, you had to frame the question properly. My intent was simply to hear from John himself.
However, you were able to negate the entire effort. I have not yet heard from John himself. Just a lot of back and forth comments without his rationale in one statement. An attempt to really have John define what he actually believes, and to see where we depart.
Why did you say that, and what did you mean, exactly?
I think you can see exactly where I stand on this, and that I thought John was saying a similar thing. But I have seen enough half answers to simply want something more defined. In fact, didn't I state that I wanted John to reply? Instead, I had two other people post on what John thinks. So, do you know exactly what John thinks? I'm guessing that you do or you would not have felt the need to reply to a question directed to John.
Gee, I didn't expect the question to be so difficult to answer that others felt John wasn't able to.
-Chris
Chris, I regret that you are not getting complete input from me. However, you have shown me that you do not like my style of communication and you often take it personally, and this is not a good thing, as you are a moderator, and I don't wish to get on your bad side.
Looking back at the question, I am surprised, because I have maybe $50,000 in audio test equipment (at least when it was first purchased), and I measure to below -120dB on a regular basis. SY has seen this equipment in action.
However, measurements are not everything, BUT they can be 'everything' for a mid-fi design.
A successful design has to sound good as well as measure OK.
I think that in future, we will have better measuring equipment that will track more closely what and how the ear really hears. Thd and SMPTE IM will be obsolete, then.
However, measurements are not everything, BUT they can be 'everything' for a mid-fi design.
A successful design has to sound good as well as measure OK.
I think that in future, we will have better measuring equipment that will track more closely what and how the ear really hears. Thd and SMPTE IM will be obsolete, then.
Hi John,
I do not take your posting personally at all. You have no worries about getting on my "bad side" either. Besides, as a moderator I can not get away with what many other members do.
I post in these forums as a member only. When I have to go to work, I'll use the
symbol to make it perfectly clear I'm on official business. We've talked a reasonable amount back and forth over a few years. If anything, you should see that I am genuinely interested in what you are doing and what you are thinking.
The only thing I don't like is a half answer, or an answer that addresses something other than what was asked. If you were to say, "Hey, that's my secret", that's cool.
Now, very often you make comments such as
The concepts are simple, I suspect that if we were to be forced to work together on a project, we'd probably see eye to eye and get along fine. It's your responses to some of the posts I have made over time that I wonder about. It's almost as if you like to debate, even if you agree at times.
Anyway, no one has any fear of "getting on my bad side". You'd have to really work at it for one. For two, I'd probably feel sorry for anyone working that hard for a negative reaction.
So John, one simple question. If you refer to my post # 16904 (the long rambling one), what there do you disagree with, if anything?
-Chris
I do not take your posting personally at all. You have no worries about getting on my "bad side" either. Besides, as a moderator I can not get away with what many other members do.
I post in these forums as a member only. When I have to go to work, I'll use the
symbol to make it perfectly clear I'm on official business. We've talked a reasonable amount back and forth over a few years. If anything, you should see that I am genuinely interested in what you are doing and what you are thinking.The only thing I don't like is a half answer, or an answer that addresses something other than what was asked. If you were to say, "Hey, that's my secret", that's cool.
Now, very often you make comments such as
Then go on about people measuring things, or saying how important the subjective experience is. You often act as if you are besieged, and you sometimes are. What I have posted more than once is that a balance of measurements and listening is what I think you are getting at. You most often treat each topic in separate posts as if it's one or the other.
The concepts are simple, I suspect that if we were to be forced to work together on a project, we'd probably see eye to eye and get along fine. It's your responses to some of the posts I have made over time that I wonder about. It's almost as if you like to debate, even if you agree at times.
Anyway, no one has any fear of "getting on my bad side". You'd have to really work at it for one. For two, I'd probably feel sorry for anyone working that hard for a negative reaction.
So John, one simple question. If you refer to my post # 16904 (the long rambling one), what there do you disagree with, if anything?
-Chris
?? how would they do that in the future ? Class D?
I read that the typical "D" has .01 to even .1 % IM- far
from perfect. by sampling the servo loop and correction
through a MP (microprocessor controlled PWM feedback).
Much lower than analog, but still no elimination. 🙁
OS
Re: Re: Re: Re: Re: VAS fighting
Bob, I understand exactly how the circuit works and the different values of emitter degeneration resistors are to account for the differences in Vbe between the NPN and PNP transistors.
This is one way to avoid the Slone problem, however you are missing the point. The large gain of the LTP's makes the circuit excessively sensitive to an input offset imbalance between the LTP's.
Do the experiment I showed here in post 16874 to see for your self just how small an imbalance is required to throw the VAS bias out:
http://www.diyaudio.com/forums/showthread.php?postid=1793473#post1793473
BTW, you are not the only one:
http://www.diyaudio.com/forums/showthread.php?postid=1654719#post1654719
Cheers,
Glen
Bob Cordell said:
Bob, I understand exactly how the circuit works and the different values of emitter degeneration resistors are to account for the differences in Vbe between the NPN and PNP transistors.
This is one way to avoid the Slone problem, however you are missing the point. The large gain of the LTP's makes the circuit excessively sensitive to an input offset imbalance between the LTP's.
Do the experiment I showed here in post 16874 to see for your self just how small an imbalance is required to throw the VAS bias out:
http://www.diyaudio.com/forums/showthread.php?postid=1793473#post1793473
BTW, you are not the only one:
http://www.diyaudio.com/forums/showthread.php?postid=1654719#post1654719
Cheers,
Glen
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