This approach is one way to avoid total feedback designs. It could be fairly good, IF the output stage is designed properly. Actual distortion values at working levels could be more than adequate in a real system, with a quality output stage.
A partial example of this kind of design was incorporated in the JC-3 power amp that was originally designed in 1974. Schematics of this design are on this website. However, the JC-3 design was FIXED at 20dB feedback in the output stage, but this could have been changed, and was made variable in an experimental model.
Today, we usually use total feedback or no global feedback. I am of the opinion that the no global feedback solution has some advantage in listening, over measurement only.
A partial example of this kind of design was incorporated in the JC-3 power amp that was originally designed in 1974. Schematics of this design are on this website. However, the JC-3 design was FIXED at 20dB feedback in the output stage, but this could have been changed, and was made variable in an experimental model.
Today, we usually use total feedback or no global feedback. I am of the opinion that the no global feedback solution has some advantage in listening, over measurement only.
The Effects of Psychology on Evaluation
When discussing things like the effect of negative feedback on the sound of amplifiers, and subjective listening comparisons, we all know that we must not overlook psychological influences like the placebo effect and the effect of expectations.
Here is a link to a very interesting news story having to do with psychological effects on wine tasting.
Raising prices enhances wine sales - Yahoo! News
http://news.yahoo.com/s/ap/20080114/ap_on_bi_ge/costs_more_tastes_better
This doesn't mean that subjective differences don't exist, but it is a cautionary observation in regard to un-blinded listening tests that are not disciplined or controlled.
Cheers,
Bob
When discussing things like the effect of negative feedback on the sound of amplifiers, and subjective listening comparisons, we all know that we must not overlook psychological influences like the placebo effect and the effect of expectations.
Here is a link to a very interesting news story having to do with psychological effects on wine tasting.
Raising prices enhances wine sales - Yahoo! News
http://news.yahoo.com/s/ap/20080114/ap_on_bi_ge/costs_more_tastes_better
This doesn't mean that subjective differences don't exist, but it is a cautionary observation in regard to un-blinded listening tests that are not disciplined or controlled.
Cheers,
Bob
Re: The Effects of Psychology on Evaluation
Hi Bob,
Differences do exist and normal people hear them. The problem is more in having a neutral environment to evaluate them in and the experience to observe and accurately describe the observations.
I attended an audio club amplifier comparison this last weekend. At the end when we had gone back to the amp that subjectively sounded the most like music (locked in with the rest of the system) and were just listening for fun, I asked and they played my CD copy of Allison Krause Live "New Favorite", I noted the sound lacked alot compared to what I'm used to (which, after all was why I wanted to get a reference point). But it did sound very interesting and our host pulled out the 3 disc vinyl copy of it, and a CD/vinyl comparison was done.
The vinyl version just opened up and was enjoyed by all. At the end one participant noted, basically, that was a prime example of vinyl's superiority over the CD.
My feeling was that the vinyl part of this system brought the performance into the range of what I hear with the CD on my Wadia.
The point being is that alot of observations put forth as the gospel truth that are not based in reality, yet spread to become the psychological influences, the placebo effect and the effect of expectations you speak of.
The only way to test and compare one approach to another is to build, test and listen in an apples to apples format. Anything else is just beating one another with simulation results (doesn't hurt much and means about the same.)
I know, nevermind.
Oh yeah, the amp was the Cary 500.
Bob Cordell said:
Hi Bob,
Differences do exist and normal people hear them. The problem is more in having a neutral environment to evaluate them in and the experience to observe and accurately describe the observations.
I attended an audio club amplifier comparison this last weekend. At the end when we had gone back to the amp that subjectively sounded the most like music (locked in with the rest of the system) and were just listening for fun, I asked and they played my CD copy of Allison Krause Live "New Favorite", I noted the sound lacked alot compared to what I'm used to (which, after all was why I wanted to get a reference point). But it did sound very interesting and our host pulled out the 3 disc vinyl copy of it, and a CD/vinyl comparison was done.
The vinyl version just opened up and was enjoyed by all. At the end one participant noted, basically, that was a prime example of vinyl's superiority over the CD.
My feeling was that the vinyl part of this system brought the performance into the range of what I hear with the CD on my Wadia.
The point being is that alot of observations put forth as the gospel truth that are not based in reality, yet spread to become the psychological influences, the placebo effect and the effect of expectations you speak of.
The only way to test and compare one approach to another is to build, test and listen in an apples to apples format. Anything else is just beating one another with simulation results (doesn't hurt much and means about the same.)
I know, nevermind.
Oh yeah, the amp was the Cary 500.
Re: Re: The Effects of Psychology on Evaluation
Hi Mike,
That Allison Krause Live cut is one of my favorites.
Why vinyl sounds better to some people has always fascinated me. Tom Holman and I discussed that in a conversation at the last AES convention. We speculated that it has to do with differences in the mastering process, some of which involve the various measures that must be taken to control cutter head acceleration, velocity and displacement. These measures do not necessarily result in an objectively more faithful transport of the signal, but in differences that may end up sounding better.
In other words, it is not necessarily due to objective inferiority of the CD medium by comparison. Interestingly, Michael Fremer of Stereophile has often demonstrated the vinyl sound by dubbing LPs onto CD.
I have also often suspected that in some cases SACD sounded better than CD because it was mastered differently (for a different target audience). Of course, not all SACDs are mastered differently than their CD counterparts.
Too many CDs have been mastered for playback in boom boxes and automobiles.
Cheers,
Bob
MikeBettinger said:
Hi Mike,
That Allison Krause Live cut is one of my favorites.
Why vinyl sounds better to some people has always fascinated me. Tom Holman and I discussed that in a conversation at the last AES convention. We speculated that it has to do with differences in the mastering process, some of which involve the various measures that must be taken to control cutter head acceleration, velocity and displacement. These measures do not necessarily result in an objectively more faithful transport of the signal, but in differences that may end up sounding better.
In other words, it is not necessarily due to objective inferiority of the CD medium by comparison. Interestingly, Michael Fremer of Stereophile has often demonstrated the vinyl sound by dubbing LPs onto CD.
I have also often suspected that in some cases SACD sounded better than CD because it was mastered differently (for a different target audience). Of course, not all SACDs are mastered differently than their CD counterparts.
Too many CDs have been mastered for playback in boom boxes and automobiles.
Cheers,
Bob
Re: Re: Re: The Effects of Psychology on Evaluation
My personal experiences has been, at several occasions, that LPs transferred to CDs can sound pretty much indistinguisable from the LP. I agree that differences between LP and CD are more related to the mastering process than to any inherent issues with the CD technology. Your comment about the SACD points in the same direction.
Jan Didden
Bob Cordell said:
My personal experiences has been, at several occasions, that LPs transferred to CDs can sound pretty much indistinguisable from the LP. I agree that differences between LP and CD are more related to the mastering process than to any inherent issues with the CD technology. Your comment about the SACD points in the same direction.
Jan Didden
Pricing....pricing ..... says it all ..................Hmmmm!
I keep repeating this often. A local TV manufacturer sold their TV at the lowest price in the matrket and stocks started piling up. So they called in a Marketing expert . He said raise the prices and re-introduce the set. So they priced it as the most expensive TV in that cetegory ( no change to internals ) and re-introduced it as a new model.
They couldn't make enough to meet the demand !
Humans will never change ......no matter how well informed they are.
Edit:
I just noticed that several posts appeared while I was typing my post. I even forgot why I posted this.Response to something that I saw earlier. Whew.......I'm getting old .........must type faster !!!
I keep repeating this often. A local TV manufacturer sold their TV at the lowest price in the matrket and stocks started piling up. So they called in a Marketing expert . He said raise the prices and re-introduce the set. So they priced it as the most expensive TV in that cetegory ( no change to internals ) and re-introduced it as a new model.
They couldn't make enough to meet the demand !
Humans will never change ......no matter how well informed they are.
Edit:
I just noticed that several posts appeared while I was typing my post. I even forgot why I posted this.Response to something that I saw earlier. Whew.......I'm getting old .........must type faster !!!
Re: Re: Re: The Effects of Psychology on Evaluation
Hi Bob,
My observation as to the negative bias towards the CD when a direct comparison was made with an LP seems to tie into the discussion on feedback because, without a direct comparison with as many variables as possible controlled, any conclusions drawn are speculation, for both measurements and listening tests results.
I don't believe the real sonic differences we hear today are inherent to either CD or vinyl technology. Think back a few years and you would find that today’s level of performance for both vinyl and redbook CD was thought to be impossible, based on the percieved limitations of the base technologies. What was this viewpoint based on?
Is the current response to global (actually most all) feedback based on a similar body of incomplete experimentation and work arounds; i.e. using minimal amounts of feedback to improve a designs musicality when it might be possible obtain comparable results while still using global feedback and addressing other issues in a design?
Mr. Hansen gets documented good results with his very well researched approach that avoids global feedback, as do others. Has it been definitively demonstrated or proven that the same or better sonic results might not be possible using global feedback? Of course not. It just hasn't been done and appeared on the market.
Mike.
Bob Cordell said:
Hi Bob,
My observation as to the negative bias towards the CD when a direct comparison was made with an LP seems to tie into the discussion on feedback because, without a direct comparison with as many variables as possible controlled, any conclusions drawn are speculation, for both measurements and listening tests results.
I don't believe the real sonic differences we hear today are inherent to either CD or vinyl technology. Think back a few years and you would find that today’s level of performance for both vinyl and redbook CD was thought to be impossible, based on the percieved limitations of the base technologies. What was this viewpoint based on?
Is the current response to global (actually most all) feedback based on a similar body of incomplete experimentation and work arounds; i.e. using minimal amounts of feedback to improve a designs musicality when it might be possible obtain comparable results while still using global feedback and addressing other issues in a design?
Mr. Hansen gets documented good results with his very well researched approach that avoids global feedback, as do others. Has it been definitively demonstrated or proven that the same or better sonic results might not be possible using global feedback? Of course not. It just hasn't been done and appeared on the market.
Mike.
Re: Re: Re: Re: Re: The Effects of Psychology on Evaluation
What do you consider to be the most technically correct, musically accurate amp/preamp available right now? One that with a bit of money and effort I can audition.
Can I live with it without losing interest in listening to music?
G.Kleinschmidt said:
What do you consider to be the most technically correct, musically accurate amp/preamp available right now? One that with a bit of money and effort I can audition.
Can I live with it without losing interest in listening to music?
Global NFB or not?
This thread goes so fast that I may be repeating - in that case apologies.
Depending (very much!) on the design - so in general: Even with better consistency in the characteristics of modern transistors, if the necessary measures are not taken with enough local NFB, there may be such a variation in worst case global gain/phase characteristics that it is well nigh impossible to get consistent/stable results with global NFB without trimming. This is a strong point in favour of local NFB, with or without extra global NFB.
This thread goes so fast that I may be repeating - in that case apologies.
Depending (very much!) on the design - so in general: Even with better consistency in the characteristics of modern transistors, if the necessary measures are not taken with enough local NFB, there may be such a variation in worst case global gain/phase characteristics that it is well nigh impossible to get consistent/stable results with global NFB without trimming. This is a strong point in favour of local NFB, with or without extra global NFB.
Re: Re: Re: Re: The Effects of Psychology on Evaluation
Negative feedback got an undeserved bad rap a long time ago, and among some people it has unfortunately stuck. Maybe this is what you are drawing the analogy to in regard to CD's.
There are plenty of NFB amps out there that have gotten great reviews. This is not to take anything away from the good performance that the MX-R has achieved. The overall body of reviews does not suggest NFB doesn't sound as good. Even among the Ayre amplifiers, the MX-R is really the first to garner super reviews. Call it coincidence or not, the objective performance of the MX-R is far, far superior to that of the earlier Ayre no-NFB amps. It is not easy to achieve that level of performance without NFB, and I'm sure Charles worked very hard to get there. My hat goes off to him for that.
Cheers,
Bob
MikeBettinger said:
Negative feedback got an undeserved bad rap a long time ago, and among some people it has unfortunately stuck. Maybe this is what you are drawing the analogy to in regard to CD's.
There are plenty of NFB amps out there that have gotten great reviews. This is not to take anything away from the good performance that the MX-R has achieved. The overall body of reviews does not suggest NFB doesn't sound as good. Even among the Ayre amplifiers, the MX-R is really the first to garner super reviews. Call it coincidence or not, the objective performance of the MX-R is far, far superior to that of the earlier Ayre no-NFB amps. It is not easy to achieve that level of performance without NFB, and I'm sure Charles worked very hard to get there. My hat goes off to him for that.
Cheers,
Bob
Re: Re: Re: Re: Re: The Effects of Psychology on Evaluation
That's pretty much it. Yet I've listened to many top rated amps and can hear what is missing that the zero FB crowd loves and misses..
This was supposed to open up discussion as to what are the possibilities, yet I should know better by now.
I was going to say more but this is the opposite of preaching to the choir. I have a different background and set of experiences.
I'll go finish my latest project. It had relevence here but they shut the thread down due to a ******* match.
Bob Cordell said:
That's pretty much it. Yet I've listened to many top rated amps and can hear what is missing that the zero FB crowd loves and misses..
This was supposed to open up discussion as to what are the possibilities, yet I should know better by now.
I was going to say more but this is the opposite of preaching to the choir. I have a different background and set of experiences.
I'll go finish my latest project. It had relevence here but they shut the thread down due to a ******* match.
Re: Re: Re: Re: Re: Re: The Effects of Psychology on Evaluation
Hi Mike,
Never give up Mike. I hope it wasn't anything I said that is pushing you away. I didn't think I was disagreeing with you, and would like to better understand your point and where you are coming from. This is definitely the place to discuss the pros and cons of NFB.
Whatever it is that the zero FB cowd loves and misses, we should try to better understand IT. The IT may or may not have to due with absolute faithfulness to the origibal signal. For example, If one were to build a zero-FB amp with extremely low distortion and extremely high DF, would it sould more like an NFB amplifier or like a typical no-FB amplifier in reasonably controlled tests (i.e., the listener doesn't know which uses NFB and which does not)?
Cheers,
Bob
MikeBettinger said:
Hi Mike,
Never give up Mike. I hope it wasn't anything I said that is pushing you away. I didn't think I was disagreeing with you, and would like to better understand your point and where you are coming from. This is definitely the place to discuss the pros and cons of NFB.
Whatever it is that the zero FB cowd loves and misses, we should try to better understand IT. The IT may or may not have to due with absolute faithfulness to the origibal signal. For example, If one were to build a zero-FB amp with extremely low distortion and extremely high DF, would it sould more like an NFB amplifier or like a typical no-FB amplifier in reasonably controlled tests (i.e., the listener doesn't know which uses NFB and which does not)?
Cheers,
Bob