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Test measurents and their overall value.

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Posted on May 15, 2016 at 14:57:12
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 I'm one that always believed that measuring the basic fundamentals of a piece of audio gear such as purity of the 1khz and a 10khz sq wave,total power,total distortion,feedback,dampening,total frequency response and bandwidth at 1 watt and full power,at least gives a starting point of how well the amp or preamp will function for basic listening.
The problem is,we cannot measure every element under dynamic conditions as it relates to the human ear and psyche.This is why we can measure two amplifiers that spec almost identical in every way,yet they can sound quite a bit different once we hook them up and listen for a while.
We are learning new things every day and there is equipment that can test a lot more than the typical test bench however,I still don't believe it can measure everything we can hear as it relates to each individual.

"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

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RE: Test measurents and their overall value., posted on May 15, 2016 at 17:24:46
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 I am coming to the same conclusion.

"...,I still don't believe it can measure everything we can hear as it relates to each individual."

Or even one individual on a different day. Or the same day but when that individual is in a different mood.....

I've been watching "Brain Games" a lot. We are all easily fooled. Our minds play tricks on us and we can't stop it from happening no matter what.

Here's one example (not from Brain Games).






That being said, I still don't think that is an excuse, or a license to build something that is technically wrong on purpose.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Test measurents and their overall value., posted on May 15, 2016 at 18:44:24
Triode_Kingdom
Audiophile

Posts: 10047
Location: Central Texas
Joined: September 24, 2006
 I'm not sure about this assumption. There are certain things we don't routinely measure, such as transient distortion. If it were easier to include all the various tests that we suspect are important, but which prove impractical or too expensive to implement, the story might be different. I personally believe that an arbitrary waveform generator in conjunction with an ultra-fast A/D could ferret out some of these unfathomable differences. In fact, I think a system capable of comparing input to output in this way would render specs like THD and frequency response all but obsolete.




 

RE: Test measurents and their overall value., posted on May 15, 2016 at 18:52:59
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 "In fact, I think a system capable of comparing input to output in this way would render specs like THD and frequency response all but obsolete."

Comparing the electrical input from the source to the feed from a microphone placed at the listening position?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

There are certain things we don't routinely measure, such as transient distortion., posted on May 15, 2016 at 19:44:03
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 I agree and that is a very important dynamic condition.Surprisingly we don't measure IM distortion or slew rate much anymore and I think both have a place where they can be useful being an amp or preamp doesn't just play one frequency at a time.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Test measurents and their overall value., posted on May 15, 2016 at 20:34:59
hahax@verizon.net
Audiophile

Posts: 4309
Location: New Jersey
Joined: March 22, 2006
 avid Berning once demoed an amp with variable feedback, the Audionics BA-150 designed by David for me. As the feedback got lower all the standard distortions got higher of course. But the amp sounded better, more alive and dynamic. When I asked them if they thought any measurement correlated with good reproduction expecting no answer they both replied simply linearity. If 1 volt in gives 2 out, then 5 in should give 10 out. The better the linearity the better the reproduction.

 

RE: There are certain things we don't routinely measure, such as transient distortion., posted on May 16, 2016 at 00:43:39
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 Which is more important, current or voltage slew rate? Is this a tube vs. SS issue? And where (at what point(s)) do you measure each?

And one final question is there such a thing as the slew rate of impedance?

 

RE: Test measurents and their overall value., posted on May 16, 2016 at 06:29:22
lovetube
Dealer

Posts: 3008
Location: Melbourne Australia
Joined: June 8, 2003
 measuring is the only tool that tell us where we at . our ears are the best tools for the final .

 

RE: There are certain things we don't routinely measure, such as transient distortion., posted on May 16, 2016 at 08:20:14
Triode_Kingdom
Audiophile

Posts: 10047
Location: Central Texas
Joined: September 24, 2006
 "is there such a thing as the slew rate of impedance?"

Technically speaking, no. Impedance is a RMS function. Slew rate is based on measurements of instantaneous values.

 

RE: Test measurents and their overall value., posted on May 16, 2016 at 08:21:53
Triode_Kingdom
Audiophile

Posts: 10047
Location: Central Texas
Joined: September 24, 2006
 I was referring only to the amplification equipment itself. Results that include the transducers are important too, but that's a step past all this.

 

RE: There are certain things we don't routinely measure, such as transient distortion., posted on May 16, 2016 at 21:53:20
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Slew rate is based on measurements of instantaneous values.

To me it's one of the more important things because it's basically giving you a number of how quick an amp or preamp can respond to dramatic change in signal.You want the amp to be able to sound consistent going from extreme lows to extreme highs without sounding like your listening to two separate amplifiers that are mismatched.

"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Play different amps. , posted on May 17, 2016 at 14:56:43
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 If you use a lot of different amps your ears won't become accustomed to just a particular quality. I like to use a lot of different types Single ended, push pull, single ended triode, sorry no SS. I think their own particular sound qualities help to keep ones auditory sensors more aware of each amps sonic fingerprints and thus allow it to discern more nuances? I guess when i no longer hear any differences would be the time to sell all my gear. regards, Dak

 

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