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Musings on Future Measurements

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Solderdude:
Even though FFT has a purpose I think it doesn't say that much except for constant signals.
Why not 40Hz + 60 Hz to test for bass distortion ?

Agree with D North on most of his 'questions' .

I would suggest to use OTHER types of test signals.
Like real music under real loads, or tests that can show 'dynamics' or 'linearity' in an easy way or think of other artificial signals.

If you test for dynamics for instance then.... how much dynamics do you want tested ?
For instance if you measure with about 100dB peak SPL (and regard that as 0dB) why would you need to measure below -70dB and call it relevant as it is inaudible?
Even at 120dB ... why would one call -90dB from 120dB relevant ?
The dynamic range of hearing may well be 100dB but NOT at the same moment for SURE.

Can someone explain the correlation between 'known' measurements and sonic qualities/attributes and defend those ?
Can you take 'brain issues' (See Anax's PRaT remark for instance) and correlate that to measurements ?
Can you take mood, tiredness and time of day into consideration when evaluating static signals ?
Can you take cognitive (brain) aspects of different people in consideration when evaluating technical signals ?
Does one NEED to do that ?
Can you correlate with the standard set of measurements ?
Do squarewaves or Dirac pulses say ANYTHING at all about sonic attributes (in amps and DACs) as they don't exist in music at all.
Can we agree on audibility thresholds and get them to hold up in a court of audiophiles ?

What's the point of using -3dB / -6dB other than for obvious power/voltage/current levels that are obvious ?
What's the point to -10dB or -20dB for FR in a headphone or not mentioning it at all ?

What's a representative load ?
A resistor would be fine for mimicking orthos and very few dynamics.
What capacitance and inductance do you guys use (I test everything with 1 and 10nF in parallel to the load for instance as well as resistive only)
A headphone is always connected to a cord, how is your dummy load connected ?
Should we use inductors or even complex (LCR) loads to mimic an 'average ?' headphone and standardise this of sorts ?

You know what I don't like about standards ?
You can design something to work well during known tests but slum it on other specs and get out on top measurement wise ?

The question for me is WHAT aspects do we want to measure and what type of signals do you need.
Not a question of what 'current' methods should we use and what uniform settings .... though that may very well be a contributing part of a measurement set.

Marvey:

--- Quote from: Solderdude on July 30, 2015, 07:47:56 AM ---<<<stream of consciousness>>>

--- End quote ---

We have to start somewhere. Simple is a good place to start.

Solderdude:
Ah too bad ...
I was hoping for more though  facepalm.
As the measurement suite is now, the only thing that can be 'proven' is that the O2 is better than Magni, Vali and Studio in all 'electrical' departments that have been measured in the other thread.
One can also prove the Studio performs better in the bass area than a lot of other all tube transformer coupled amps.
Speculation doesn't cut it in the world of measurements...  8)

Where is the adventure in sticking to the 'old' ?  :)p2

How to show in measurements that what cannot be shown in current measurements.
Sonic superiority like Studio > Vali > Magni > O2 as has been established subjectively ?

Surely there MUST be some proof somewhere ?  :-Z
I mean after all.... stereo is just 2 voltages varying in amplitude over time or is there more to it ?  :)p7

just teasing a bit ....
Following this with  popcorn

Anaxilus:
No one has ever complained about the O2 having bad bass. People complain about it's Helen Keller level of resolution, lack of micro dynamics and tonally compressed and slightly foggy signature. Hell, you can hear that compared to an Ember. You helped to design that thing, you tell us.

OJneg:
I myself am fine with the fact that the Studio or any vacuum tube amp will never measure as well as a modern opamp design or any solid-state amp that uses plenty of negative feedback. Perhaps because I understand the mechanism behind the non-linearity in those amps and how the others "get rid" of it. As others have mentioned, the moderately higher THD won't keep me up at night when I consider the whole system and chain from a macro perspective.

It still doesn't explain the difference in sonics but fortunately we have this other great tool called the auris aurea to determine that for us.

The standard measurement suite as it is gives us a good idea of what's going on from a circuit design view and is still worth running through for any and all amps that can be measured in such a way. But if we want to a get a better gauge of "sonic superiority", best to look at amps with topology and component selection in mind. IMO and IME that is the best indicator of perceived sound quality we have at the moment.

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