"Some Amplifiers Do Sound Different"
"Some Amplifiers Do Sound Different" is the title of an article in the 3/1982 issue of "The Audio Amateur" magazine. The authors were the ABX people, David Carlstrom, Arny Krueger and Larry Greenhill. The amplifiers were a Audio Research D-120 (120Watt)and a CM Labs CM914a (150Watt). This was in the pre-CD era. On a Dave Grusin track they scored 15/15 correct and on a Eagles track they got 19/21 correct.
"Some Amplifiers Do Sound Different" is the title of an article in the 3/1982 issue of "The Audio Amateur" magazine. The authors were the ABX people, David Carlstrom, Arny Krueger and Larry Greenhill. The amplifiers were a Audio Research D-120 (120Watt)and a CM Labs CM914a (150Watt). This was in the pre-CD era. On a Dave Grusin track they scored 15/15 correct and on a Eagles track they got 19/21 correct.
Re: Re: "Some Amplifiers Do Sound Different"
Oh let me guess. The load or test protocol caused easily measurable performance variations well within the bounds of audible differences acknowledged by the AES, IEEE, blah blah blah. Quit being disingenuous, presuming of course you are aware what the question is. If not, my bad.
G.Kleinschmidt said:
Oh let me guess. The load or test protocol caused easily measurable performance variations well within the bounds of audible differences acknowledged by the AES, IEEE, blah blah blah. Quit being disingenuous, presuming of course you are aware what the question is. If not, my bad.
Re: Re: Re: "Some Amplifiers Do Sound Different"
Ermmm, regardless of what the load and test protocols were, we apparently have a list of amplifiers that do sound different by the subjective opinion of the “ABX people”.
According to some around here “ABX people” would never admit to such a thing.
rdf said:
Ermmm, regardless of what the load and test protocols were, we apparently have a list of amplifiers that do sound different by the subjective opinion of the “ABX people”.
According to some around here “ABX people” would never admit to such a thing.
AA 3/82
I've cited that paper (albeit not as specifically, so thanks) several times in the parallel discussion.
rdf, on the contrary, I do indeed use sonics as one of the performance metrics. Not the only one to be sure, but I know the design and measurement attributes that will give me an amp that *I* will enjoy using and be true to the signal I feed it.
I've cited that paper (albeit not as specifically, so thanks) several times in the parallel discussion.
rdf, on the contrary, I do indeed use sonics as one of the performance metrics. Not the only one to be sure, but I know the design and measurement attributes that will give me an amp that *I* will enjoy using and be true to the signal I feed it.
Re: AA 3/82
My understanding has always been that achieving that performance metric was entirely a function of meeting a goal set out by the current state of the psychoacoustic sciences with no 'surprises'. Less than say, 0.03% distortion of any sort across the band at non-clip levels, system noise well below room ambient at max gain, +- 0.05 dB freq response to the speaker terminals would meet them (adjust to taste.) That automatically disqualifies any requirement for excessive parts selection (teflon over polyprop caps for example), chassis techniques, layouts or exotic topologies (Allen Wright's dislike of miss piggie), as long as the choices remain the right side of pathological. Short form: we already know by means of the current published literature every criterion for effectively 'true' reproduction in the electronic realm and have access to the instrumentation required to achieve it. Tubes are an enjoyable rather than necessary means to that end for you.
Not that it's a bad thing.
SY said:
My understanding has always been that achieving that performance metric was entirely a function of meeting a goal set out by the current state of the psychoacoustic sciences with no 'surprises'. Less than say, 0.03% distortion of any sort across the band at non-clip levels, system noise well below room ambient at max gain, +- 0.05 dB freq response to the speaker terminals would meet them (adjust to taste.) That automatically disqualifies any requirement for excessive parts selection (teflon over polyprop caps for example), chassis techniques, layouts or exotic topologies (Allen Wright's dislike of miss piggie), as long as the choices remain the right side of pathological. Short form: we already know by means of the current published literature every criterion for effectively 'true' reproduction in the electronic realm and have access to the instrumentation required to achieve it. Tubes are an enjoyable rather than necessary means to that end for you.
Not that it's a bad thing.
I have placed a noise filter in line on this thread... 
Ummm... SY that poor AA article is hopelessly out of date, and the amps mentioned are rather horrid by today's standards, I am sure you will agree... no matter.
I guess what I am looking for is for someone to step up with some finding(s) and say that they've got two or more amps that sound different, and what they are...
Otoh, maybe someone wants to say something about two or more amps that sound the same?? And quite frankly, I don't care if it is driving a particular speaker or not - as far as I am concerned it is sufficient for now to just tell us what the speaker is/was...
Let's keep this simple, no need to engage in an argument about this.
_-_-bear
Ummm... SY that poor AA article is hopelessly out of date, and the amps mentioned are rather horrid by today's standards, I am sure you will agree... no matter.
I guess what I am looking for is for someone to step up with some finding(s) and say that they've got two or more amps that sound different, and what they are...
Otoh, maybe someone wants to say something about two or more amps that sound the same?? And quite frankly, I don't care if it is driving a particular speaker or not - as far as I am concerned it is sufficient for now to just tell us what the speaker is/was...
Let's keep this simple, no need to engage in an argument about this.
_-_-bear
True, in the sense that I can enjoy great music through any old amp. But false in the implication that I attribute my long-term satisfaction with components in my listening room to merely hitting the numbers. But you also know that my focus is on overload recovery, absence of blocking, and unconditional stability, all of which are easy to measure and aren't reflected in the usual numbers game.
Oh, and I'm sorry, bear, for skipping past your other question. The two amps that I used on my speakers that sounded alike (again, in the sense of me not likely to be able to distinguish them in a conventional ABX test) were a modified Adcom GFA555 and a Bryston (can't remember the model, it's a real little guy, pretty old, I use it for speaker testing). I guarantee you I could tell them apart blind on John Curl's speakers.
At the time of the comparison, the speakers I was using were NHT 3.3. John uses WATTs.
At the time of the comparison, the speakers I was using were NHT 3.3. John uses WATTs.
Blocking is an overload recovery phenomenon. One classic example is the strangulation of a cathode biased output stage after overload while the cathode bypass cap discharges. RF oscillation can cause the same sort of overbias in other sorts of stages, and that may be what you're most familiar with.
Amplifiers often sound different because of the way they interact with speakers. Damping and the feedback configuration influence how the amplifier interacts with the speaker. With tube amps this should be obvious. But there are differences in solid state amps too.
Of course back emf can be fed back into the feedback loop. How the amplifier reacts to this back emf depend on many factors; including "damping factor", and whether the feedback network returns to a differential input or the emitter of the input stage. The emmiter feedback is more like a current amplifier in a sense and will provide different back emf effects than a ltp would (for better or for worse). An there are two stage solid state amplifiers out there (like the Nakamichi Stasis amplifiers which are quite well behaved), which remove back emf from the feedback network altogether and circumvent the whole issue.
So should it be any surprise that amplifiers sound different? I only touched on a couple of points that can potentially affect the "sound" of an amplifier.
If you want to demonstrate a measurable difference between two amplifiers, perform a null test with them.
Of course back emf can be fed back into the feedback loop. How the amplifier reacts to this back emf depend on many factors; including "damping factor", and whether the feedback network returns to a differential input or the emitter of the input stage. The emmiter feedback is more like a current amplifier in a sense and will provide different back emf effects than a ltp would (for better or for worse). An there are two stage solid state amplifiers out there (like the Nakamichi Stasis amplifiers which are quite well behaved), which remove back emf from the feedback network altogether and circumvent the whole issue.
So should it be any surprise that amplifiers sound different? I only touched on a couple of points that can potentially affect the "sound" of an amplifier.
If you want to demonstrate a measurable difference between two amplifiers, perform a null test with them.
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