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Audibility of speaker nonlinear distortion - test
Audibility of speaker nonlinear distortion - test
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Old 13th November 2017, 03:14 PM   #11
PMA is offline PMA  Europe
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For the 1kHz test, try to play with volume. The generator file volume to be lowered until the limit of ear intrinsic distortion, must sound clean. Go to the limit until the ear starts to distort and remain just below. Then, the 1kHz recorded through speaker will have audible harmonics and 1kHz from generator will remain clean.

Sines are the only possibility for the test. The key is to remove "room sound", that means reverberations and room noise. It is possible with sine, but not possible with music or transients. If I did not remove the room noise from the files, one would immediately hear it as echoes and reverberations.
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Old 13th November 2017, 03:23 PM   #12
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Quote:
Originally Posted by Pano View Post
Well you have to start the tests somewhere, right?

Thanks Pavel - I'll have a listen later today. And I'll have a couple of requests, if you don't mind.
Hi Pano, your requests will be appreciated
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Old 13th November 2017, 04:09 PM   #13
TNT is offline TNT  Sweden
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Quote:
Originally Posted by PMA View Post
For the 1kHz test, try to play with volume. The generator file volume to be lowered until the limit of ear intrinsic distortion, must sound clean. Go to the limit until the ear starts to distort and remain just below. Then, the 1kHz recorded through speaker will have audible harmonics and 1kHz from generator will remain clean.

Sines are the only possibility for the test. The key is to remove "room sound", that means reverberations and room noise. It is possible with sine, but not possible with music or transients. If I did not remove the room noise from the files, one would immediately hear it as echoes and reverberations.
I fully agree on the aspects you mention. Unfortunately, it still does not make sine a good test signal as I see it.

Also, maybe better to compare 2 transducers, one with low distorsion and one with higher?

Manipulating one of the signals i.e. removing noise etc. I believe is an uncontrolled activity which might have effect on the object itself and thus the result of comparison might not be what we think. It's hard. But needs to be made as correct as possible or will fail to give an interpretable result.

There was different Fs used (48 and 44). For Mac users we need to change system setting in order to not get resampling by the OS (for most apps). Better beware.

But I'm all for it. Have never done any ABX until now really. I'm using a pair of Philips Fidelio L2 connected to a Macbook Pro Mid 2012.

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Old 13th November 2017, 04:28 PM   #14
turk 182 is offline turk 182  Canada
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until i can sort out foobar and file problems i can't do the test.
i've always reasoned that most speakers and amps have a sonic signature that is the culmination of both linear and non linear distortion, if this was not so then there would be no way we could distinguish any differences what so ever, but since the early days of audio this has always been a bone of contention.
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Old 13th November 2017, 04:41 PM   #15
turk 182 is offline turk 182  Canada
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Originally Posted by TNT View Post
Isn't sine a really bad signal for listening tests?

My guess is that you will not find insufficiencies in the DUT by using sine in listening tests.

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that would depend on what your testing for. it's the quickest way i know of for detecting the presence of distortion products. any new or spurious frequencies will be detected easily even by ear.
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Old 13th November 2017, 04:55 PM   #16
PMA is offline PMA  Europe
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Originally Posted by TNT View Post
Also, maybe better to compare 2 transducers, one with low distorsion and one with higher?

Manipulating one of the signals i.e. removing noise etc. I believe is an uncontrolled activity which might have effect on the object itself and thus the result of comparison might not be what we think. It's hard. But needs to be made as correct as possible or will fail to give an interpretable result.

There was different Fs used (48 and 44). For Mac users we need to change system setting in order to not get resampling by the OS (for most apps). Better beware.
//
There has to be one reference and this reference is always the pure clean signal.

Removal of the ambient noise is the only chance, as you will never get 2 runs with same ambient noise. As Scott Wurcer likes to say, there are never 2 same runs from the one vinyl record. This test, with speaker in the room, is even worse for repeatability of the ambient noise. The noise removal does not change harmonic content, as you can see from plots with and without ambient noise - attached.

The 2kHz recording is 2 years old and is in 44.1, you are right. But it should not matter, because 2kHz reference is also 44.1. The necessary condition is that the reference and recording must be at same Fs and bit depth.
Attached Images
File Type: png speaker_dist_2k.PNG (113.8 KB, 191 views)
File Type: png speaker_dist_2k_extracted.PNG (116.7 KB, 184 views)

Last edited by PMA; 13th November 2017 at 04:59 PM.
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Old 13th November 2017, 04:56 PM   #17
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Quote:
Originally Posted by turk 182 View Post
i've always reasoned that most speakers and amps have a sonic signature that is the culmination of both linear and non linear distortion, .
Well said.
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Old 13th November 2017, 05:27 PM   #18
Mooly is offline Mooly  United Kingdom
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Audibility of speaker nonlinear distortion - test
Quote:
Originally Posted by PMA View Post
For the 1kHz test, try to play with volume. The generator file volume to be lowered until the limit of ear intrinsic distortion, must sound clean. Go to the limit until the ear starts to distort and remain just below. Then, the 1kHz recorded through speaker will have audible harmonics and 1kHz from generator will remain clean.
I found both the 1 and 2 kHz files are 100% distinguishable using just a volume level of '2' while the 11 + 12 kHz file needs a level of '4' to be 100% reliably differentiated. By way of comparison your Bach file was played at levels in the 60's and Marcel's files in the 40's.
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Old 13th November 2017, 07:34 PM   #19
TNT is offline TNT  Sweden
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For me, using same levels, the IM was really easy. Strange - but indicates that it might not be so surpsrising that we "fight" over what sounds good or bad

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Old 13th November 2017, 08:11 PM   #20
th33nd is offline th33nd
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Greetings from Sicily!
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