Sound Quality Vs. Measurements

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#3,202
Hi,

SoNic_real_one said:
I always judge a DAC bandwidth and dynamic by the cymbals and trumpets.
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I always judge a DAC's Bandwidth and dynamic range with an AP2, not sure how you would use cymbals or trumpets to measure frequency response or dynamic range.

I use recordings of cymbals and other items for listening evaluation of "realism". I have not yet found any "measurement" or sets of measurements that helps me to judge this without listening.

Ciao T
 
#3,208
FrankWW said:
Yes, maybe there is something going on.

This paper has some interesting spectral graphs. (I didn't post any cuz they're distinctly marked copy write):

There's life above 20 kilohertz! A survey of musical instrument spectra to 102.4 kHz

Boyk is interested in the harmonic spectra above 20 kHz but looking at below that range is interesting.


I think there's plenty going on under 20 kHz to give a system some grief. Given the energy maybe even under 1kHz.
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Most interesting paper, I'd not seen that.

"Professor F. Brock Fuller jangling his own ring of keys."

I love it.
 
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#3,210
bcarso said:
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A profound statement! I agree! 😀😀😀

Kidding aside, what am I worried about? I've belonged to the widebandwidth school from my beginnings. You know, the freaks who think that if the electronics don't hit at least 200 kHz at full power, under any conditions, they're no good.

As for the speakers, Audax' data sheet showed a peak at around 25 kHz, like 20 kHz -1 dB, 22 kHz 0 dB, 25 kHz +1 dB, and decaying quickly after that. That's all I can do, except perhaps rig up some elcronic compensation, but I honestly feel that would do more harm than help.
 
#3,211
#3,214
After a week of struggling, it is now rock solid, BW of over 80K, symmetrical. So here is the final config for the DH-120.
DH120-final.png
 
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#3,215
scott wurcer said:
JB and my old aquaintance Jerry Sussman of MIT are both very interested in this >100kHz stuff. Jerry is a brilliant guy and consumate scientist so I can not dismiss this lightly.
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When Sussman teamed up with Boyk I think it enriched JB's perspective immensely. That paper they did on feedback (of even the simplest local sort) affecting the IM distortion products, even though the models of tubes, bipolars, and FETs were idealized, actually got Jim to say something almost positive about bipolar transistors! 😀 (People may recall JB's T-shirt, emblazoned with "Digital finishes what the transistor began")

I passed that paper to a friend who was strongly influenced as a Caltech undergrad when taking JB's class. Oddly, he said something to the effect "Well, it's about IM distortion". He wasn't that interested, which astonished me, and I entertained suspicions that Boyk had fallen from grace by countenancing something besides hollow-state devices.

It reminded me a bit of another friend from high school days, very bright guy, who had two heroes: Bertrand Russell and B. F. Skinner. When there was some Russell-Skinner contretemps, he decided Skinner was the "harder-headed" one and sided with him, something I thought was a terrible mistake. But this was high school. Someone said they'd run into him a bit later walking the streets of Chicago, barefoot and holding a flower.

Brad
 
#3,218
Yes, that is how I am leaving it, unless extended listening says I did something wrong. I did not put the degeneration in the input CM and really did not see a need to speed anything up by bypassing the spreader.

There is no limit where one could go with FET inputs, doubling the outputs, newer transistors, metal film resistors, splitting the power rails with a cap multiplier or pi filter, DC servo, whatever. It's a 35 year old amp with no protection, power control, mute, or modern niceties. The physical config is a royal pain to work on. Best to leave it be and get a newer amp to play with. I learned a lot and that was the goal.

Of course, I still have no clue what parameters make my wife prefer the Rotel to the Hafler or Parasound. I believe it is something aggravating the tweeter deficiencies, so I want to get back to better tweeters. Better speakers may change our views of the amps completely. The B&K ST-140 failed her tests, and it is still recognized as one of the easiest amps to listen to out there. (for only money) I have a lot to digest.
 
#3,220
bcarso said:
Bertrand Russell and B. F. Skinner. When there was some Russell-Skinner contretemps, he decided Skinner was the "harder-headed" one and sided with him, something I thought was a terrible mistake. But this was high school. Someone said they'd run into him a bit later walking the streets of Chicago, barefoot and holding a flower.

Brad
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Chomsky was greatly raised in my esteem by taking on Skinner. BTW my wife and I went to an open house next door to the Skinner residence many years ago, there goes the neighborhood.
 
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