Can you tell original file from tube amp record? - test

Which file is the original and which do you prefer

  • Apricot is the original file

    Votes: 7 46.7%

  • Avocado is the original file

    Votes: 5 33.3%

  • I prefer Apricot by listening

    Votes: 7 46.7%

  • I prefer Avocado by listening

    Votes: 7 46.7%
  • Total voters
    15
  • Poll closed .
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PMA

PMA

Member
Joined 2002
pmacura.cz/audiopage.html
Paid Member
#1
I have a new test, and now it is an original file vs. the file that was recorded through hybrid tube-SS amplifier. So,

one of the files is an original, original rip
the other file was recorded, playing the original file, through the chain: D/A – hybrid tube SS power amplifier loaded with real speakers – A/D

The levels of the two files was not digitally manipulated, the levels were only equalized by the analog potentiometer.

Please listen to the files and tell me which one is the original file and also which one you prefer sonically. It would be nice if you also could add a foobar ABX protocol, but it is not a necessary condition, I am not forcing you to do it, just asking if possible.

The link to the test files is
Dropbox - tubepower.zip

0dBFS in the recorded file is about 6Vrms and the maximum sample amplitude is about -0.3dB, just FYI what was the recording level.

The hybrid tube-SS amplifier has its own thread
Class A hybrid tube-SS openloop power amplifier

The poll expires on December 4

------------------------------------------------------------------

Amp schematics has been now linked. Output impedance is 0.23 ohm, so damping factor is 17x for 4ohm and 34x for 8ohm load.

http://pmacura.cz/HYBRID_PMA.pdf
----------------------------------------------------------------------
Disclosure:
Apricot is the file that was recorded through the open-loop hybrid tube-SS power amplifier, with transistor class A unity gain output stage.

Avocado is the original CD rip.

=================

December 15, new test files
Dropbox - fasteners.zip
(Beethoven violin concerto)
 
Last edited:
#2
Using ABX23 / Lacinato 2.37 on Mac and I could quite fast identify a preference while playing the version sighted. I prefer Apricot and I think that Avocade is the "tobes" 🙂

My very quick run ended like:

Completed trials: 15
Number correct: 8 (53.333336%)
Confidence that your results are better than chance: 0.5

Last played: A

Individual test results [choice/actual] from among 2 possible files:
Test #1 [ A / B ]
Test #2 [ A / B ]
Test #3 [ A / A ]
Test #4 [ B / A ]
Test #5 [ A / A ]
Test #6 [ A / B ]
Test #7 [ A / B ]
Test #8 [ A / B ]
Test #9 [ B / A ]
Test #10 [ B / B ]
Test #11 [ B / B ]
Test #12 [ A / A ]
Test #13 [ B / B ]
Test #14 [ B / B ]
Test #15 [ A / A ]

But I felt I got the hang of it better at the end and this seem to have been the case.

I belive in ABX. I think it will serve a result that could guide me. The difference between the files where not in my opinion great and I could live with both SQ in some sense but still, I didn't care for the soft/muddy base in Avocado.

//
 
#11
Thanks again for your kind words, George.

This is the test setup used for recording of the "tube amp file" that is compared to the original rip in this test. The amp is loaded by my regular speakers.
 

Attachments

  • IMG_1449-1.JPG
    IMG_1449-1.JPG
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#12
I would like to participate once my flu clears up. In the mean time, since the tube mu stage is inverting, could you clarify whether both files are of the same phase or one is inverted? If both files are of the same phase, could you describe where you put the second inverting stage. Thank you.
 
#13
Hello indra1, thank you for your question. Both files have the same phase (and are time aligned, except for small time shift in microseconds in the amp channel). A/D input is balanced, so I made the phase inversion for the amp recording just by swapping +IN and -IN wires at the input XLR connector.
 
#14
TNT said:
Using ABX23 / Lacinato 2.37 on Mac and I could quite fast identify a preference while playing the version sighted. I prefer Apricot and I think that Avocade is the "tobes" 🙂

My very quick run ended like:

Completed trials: 15
Number correct: 8 (53.333336%)
Confidence that your results are better than chance: 0.5

Last played: A

Individual test results [choice/actual] from among 2 possible files:
Test #1 [ A / B ]
Test #2 [ A / B ]
Test #3 [ A / A ]
Test #4 [ B / A ]
Test #5 [ A / A ]
Test #6 [ A / B ]
Test #7 [ A / B ]
Test #8 [ A / B ]
Test #9 [ B / A ]
Test #10 [ B / B ]
Test #11 [ B / B ]
Test #12 [ A / A ]
Test #13 [ B / B ]
Test #14 [ B / B ]
Test #15 [ A / A ]

But I felt I got the hang of it better at the end and this seem to have been the case.

I belive in ABX. I think it will serve a result that could guide me. The difference between the files where not in my opinion great and I could live with both SQ in some sense but still, I didn't care for the soft/muddy base in Avocado.

//
Click to expand...

TNT, are we understanding this the same way? 8 correct out of 15 is not better than chance, and would mean that you can't hear a difference.

Jan
 
#15
This is my result in "brief" listening, just one test of one (no more trials). I will try again 🙂

Code: 
foo_abx 2.0.2 report
foobar2000 v1.3.7
2018-11-21 09:14:55

File A: apricot.wav
SHA1: 366faaef08134ef83262c95ee8a5ccbdeedb7395
File B: avocado.wav
SHA1: b404fd5526030ace6f56bead6dd1f780cab0a533

Output:
WASAPI (event) : OUT (DUO-CAPTURE EX), 24-bit
Crossfading: NO

09:14:55 : Test started.
09:16:13 : 00/01
09:16:26 : 00/02
09:16:38 : 01/03
09:16:48 : 02/04
09:16:59 : 02/05
09:17:08 : 02/06
09:17:19 : 02/07
09:17:27 : 03/08
09:17:39 : 03/09
09:17:51 : 04/10
09:18:01 : 05/11
09:18:12 : 05/12
09:18:22 : 06/13
09:18:58 : 07/14
09:19:07 : 08/15
09:19:16 : 09/16
09:19:16 : Test finished.

 ---------- 
Total: 9/16
Probability that you were guessing: 40.2%

 -- signature -- 
2221ad1a5108d55c51f22159f1a36313ab4808f2

So, same as TNT, my score was 8/15 before I hit 9/16 😀
 
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#16
indra1 said:
I would like to participate once my flu clears up. In the mean time, since the tube mu stage is inverting, could you clarify whether both files are of the same phase or one is inverted? If both files are of the same phase, could you describe where you put the second inverting stage. Thank you.
Click to expand...

Hi Indrawan
The content of the two files is of the same polarity (I've checked it)

George
 
#18
jan.didden said:
TNT, are we understanding this the same way? 8 correct out of 15 is not better than chance, and would mean that you can't hear a difference.

Jan
Click to expand...

Thats how it turned out - yes.

I think I could do better - maybe I will try. Apparently I just couldn't "wing it".. But I did want to succeed - who wouldn't like to claim "golden ear" 😉

//
 
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#19
I am getting better 😉

Code: 
foo_abx 2.0.2 report
foobar2000 v1.3.7
2018-11-21 14:00:10

File A: apricot.wav
SHA1: 366faaef08134ef83262c95ee8a5ccbdeedb7395
File B: avocado.wav
SHA1: b404fd5526030ace6f56bead6dd1f780cab0a533

Output:
WASAPI (event) : OUT (DUO-CAPTURE EX), 24-bit
Crossfading: NO

14:00:10 : Test started.
14:02:02 : 01/01
14:02:16 : 01/02
14:02:26 : 02/03
14:02:36 : 03/04
14:02:45 : 04/05
14:02:53 : 04/06
14:03:05 : 05/07
14:03:19 : 05/08
14:03:31 : 06/09
14:03:43 : 06/10
14:03:52 : 07/11
14:04:01 : 08/12
14:04:14 : 09/13
14:04:27 : 10/14
14:04:45 : 10/15
14:04:55 : 11/16
14:04:55 : Test finished.

 ---------- 
Total: 11/16
Probability that you were guessing: 10.5%

 -- signature -- 
319534ee2037ab2caae98e66f0ed5721db5b9f10

Yes it is the bass sound that seems to make a difference.
 
#20
I think it might be interesting to show what is this hybrid power amplifier bringing into the recording chain:

- frequency response, there is a -2dB decrease at 20kHz
- distortion vs. amplitude from 1mV to 5.5V (fits to rec level) at 1kHz is shown
- distortion vs. frequency is shown, which is pretty flat
- output impedance is 0.23 ohm, not very low but not very high
- SNR for the FS recording level is -90dB(A)
 

Attachments

  • hybrid_pma_freqresp2.png
    hybrid_pma_freqresp2.png
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  • hybrid_pma_thdamp.png
    hybrid_pma_thdamp.png
    47.9 KB · Views: 312
  • hybrid_pma_thdfreq.png
    hybrid_pma_thdfreq.png
    32.7 KB · Views: 309
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