Well I worked out who he was talking about and I think in this case it is correct not to name names even in the face of some playground level goading. But that's just me.
There are VFA with low distortion at 10s to 100s of MHz. This isn’t 1980 or 1990 even.
Any proof to this outstanding statement? Or everybody has to take your word for it?
http://www.ti.com/lit/ds/symlink/opa1656.pdf
The new OPA1656 VFA has 0.000029%(–131 dB) THD @1KHz and 0.000035% (–129 dB) THD at 20 kHz. And, horror of all horrors, it is a CMOS device, so I'm pretty confident each and every serious audiophile ears will be insulted by these levels of THD, and the 2.9nV/rtHz noise.
Not having myself any vested interest in the audio industry, sometimes, after reading such a data sheet, I'm really wondering what the hell are we doing here. Marsh Audio could think otherwise, of course.
Patiently disregarding enormous volumes of bullsh1t while watching to see if a gem suddenly appears. Occasionally it does.
It's actually CMOS, there's a thread on it started by johnc124 who had a hand in its creation. I guess the only hint would be the 1/f corner.
The 1kHz noise corner is not impressive, but the Ib spec would seem to indicate JFET unless there are other junctions hanging off the inputs. Quite amazing to see several pages of RIAA pre-amp applications in 2019, a couple of these would double the price of one of those Walmart TT's. I've become quite attached to my open-loop, Muntzed, Cordell pre-amp.
I guess there's something making 10pA Ib.
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Build and compare the two topologies of the same amp and make your own opinion by yourself. (that I did). Nothing to "believe" and nobody ask-you to do-it.
This endless request of a "proof" is both boring and useless (unless you can provide a proof of the contrary), in absence of complete and definitive studies of auditory threshold of all parameters we can measure (distortion, bandwidth, slew rate etc) when nobody can, as far as I know, provide a satisfactory explanation at this time of something a lot of people seems to feel in the same way.
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That is a cop out, "complete and definitive studies" are not required for "proof", nothing can be proved to such a degree, evidence is all that is required.
John said loudspeaker distortion is less noticeable than distortion in the electrical chain, you agreed, can you show any evidence that that's correct?
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I guess these are the reverse biased diodes protecting all the CMOS I/O from curiously touching audiophile hands.
It is your right to not provide any evidence, as much as it is my right to disregard whatever I believe is an unsubstantiated claim.
Would you have an answer for yourself?
Yes. I'm preparing for retirement, when time will be my most disposable resource.
Wait, SYN08. I can provide evidences (differences in measurements between voltage/current feedback topologies of the same amp).
Nobody can explain why some can report a difference in listening impressions and prefer one or an other, as the differences are supposed to be far from our supposed listening range (20-20 000 Hz etc.). I would like to add those differences are subtitle enough to not need any fighting ;-)
Are-you kidding ? Don't you enjoy your speakers ? Would you accept and suffer an amplifier with such levels of distortion? (~ -30dB under listening level)
Thats a nutty reply. How many of those are what is being sold to audio consumers !
We are dealing here with what we have available and typically HiFi amplifier use. Aren't we?
Plenty of distortion graphs on new consumer electronics which still shows the behaviour which causes trouble with DAC/CD but not so with TT.
-RNM
That's an interesting reply.
Thats a nutty reply. How many of those are what is being sold to audio consumers !
They are open market parts available to any audio manufacturer.
May-be it is because they produce lot more H2 harmonic than higher ones, or/and because their distortion levels are not at all linear with frequencies ?
I don't follow-you on your feedback point: they *use* feedback of the amps (damping factor) to dump their resonances.
We have a lot to learn about the way our brains process what we hear. By example, what a difference between a direct listening of a speaker, and the recording of the same signal with a good mike from the same listening point.
If i was courageous enough, i should make measurement on a speaker of the curve of directivity of a frequency and the harmonics distortions it produces.
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Here is Bill Johnson's (of Audio Research) take on whether the loudspeaker is the limiting factor.
"William Z. Johnson: Back in my youth I built several amplifiers just to build them. The first one that
I built commercially was in 1949. I was working for a music company in those days, after coming back
from service in the Army right after World War II. I was approached by a then-audiophile who had a
Klipschorn speaker and a Williamson-type amplifier. He wanted better electronics. He had caught on
to the fact that the secret of good sound was not in the loudspeaker as much as in whether the
electronics were transparent."
Read more at William Z. Johnson of Audio Research: High Definition | Stereophile.com
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i underline this sentence:
"I'm sure you've become aware that the measurement techniques we use today really don't necessarily tell you about the sound quality. Obviously, if it measures badly, it isn't going to sound good. But the simple fact that it measures well doesn't assure that it will sound good."
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