After a short rest, I have a new listening test. Now, the original file is tested against the file that was played and recorded through the real tube preamplifier and of course there was a DAC/ADC path to record the file. The link to test files is
https://www.dropbox.com/s/1nji8wcczathq3b/Quintet_tubetest.zip?dl=0
If you would like to participate in the test, please download the test file (you do not need to have a dropbox account. Click somewhere outside log-in window and then click to download the quintet_test.zip file. Do no try to play the files directly from dropbox, it is impossible.)
In case you want to participate, I would ask you to make an ABX test in Foobar 2000
http://www.foobar2000.org/components/view/foo_abx
and then to post the full protocol of the test, which we are able to verify.
Test description
The output of the DAC was amplified by the tube preamp to some 11Vrms at full scale. Then it was divided by a stepped attenuator to the same amplitude as was the DAC output. This attenuated signal was connected to ADC input. The original file and the recorded file were time aligned as the last step.
Distortion of the tube preamp close to full scale of the ADC
Photo of the test setup
However, as the test file peak amplitude is about -8dBFS, the distortion near peaks is lower than at FS, and is about 1%
THD and THD+N at -8.7dBFS, which is close to peaks in the music sample
The tube preamp used is the SRPP+ by Glassware and it was described here earlier
https://www.audiosciencereview.com/...ube-preamp-kit-review-and-measurements.15883/
Again, have fun listening the samples!
https://www.dropbox.com/s/1nji8wcczathq3b/Quintet_tubetest.zip?dl=0
If you would like to participate in the test, please download the test file (you do not need to have a dropbox account. Click somewhere outside log-in window and then click to download the quintet_test.zip file. Do no try to play the files directly from dropbox, it is impossible.)
In case you want to participate, I would ask you to make an ABX test in Foobar 2000
http://www.foobar2000.org/components/view/foo_abx
and then to post the full protocol of the test, which we are able to verify.
Test description
The output of the DAC was amplified by the tube preamp to some 11Vrms at full scale. Then it was divided by a stepped attenuator to the same amplitude as was the DAC output. This attenuated signal was connected to ADC input. The original file and the recorded file were time aligned as the last step.
Distortion of the tube preamp close to full scale of the ADC
Photo of the test setup
However, as the test file peak amplitude is about -8dBFS, the distortion near peaks is lower than at FS, and is about 1%
THD and THD+N at -8.7dBFS, which is close to peaks in the music sample
The tube preamp used is the SRPP+ by Glassware and it was described here earlier
https://www.audiosciencereview.com/...ube-preamp-kit-review-and-measurements.15883/
Again, have fun listening the samples!
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