A few weeks ago I compared the measurements of my Stax SRM-007t differential tube amplifier against the SRM-313 solid state amp. Results showed that the tube amplifier showed significantly more distortion as levels increased compared to solid state:
Objection was raised that the 100 kilo ohm input impedance of my audio analyzer was to low for the tube amp and hence stressed it more. I bought the parts to build a higher impedance load but by then I had also purchased my new GRAS 45C headphone measurement system. So I thought we cut to the chase and measure what the headphone itself produces when driven by the two different amps. Such acoustic measurements are tricky though as they are subject to noise so accuracy is not high at low amplitude. So I measured from medium to high output level. The volume control was set to 7 on both amps and I ran a sweep driving two channels but showing one. Here are the results:
The two follow each other within margin of error but then distortion takes off in the tube amp(SRM-007t) while it stays level in stolid state (SR-303). Other than low resolution of the acoustic measurements, the results correlate well with our electronics measurement.
Note that the distortion could have been increasing earlier in the tube amp but masked by the headphone distortion.
Conclusions
There is no question that the tube energizer has lower power capability before its distortion rises. To the extent you listen softly then you won't notice it. In my use I do and have been frustrated for a lot time about the tube amp becoming distorted before I run out of satisfaction with the volume.
And oh, this is evidence that electronic distortion can be worse than our transducers (speakers and headphones). Always get electronics that are far better than your transducers to avoid this. Definitely don't skimp on power capability.
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As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Objection was raised that the 100 kilo ohm input impedance of my audio analyzer was to low for the tube amp and hence stressed it more. I bought the parts to build a higher impedance load but by then I had also purchased my new GRAS 45C headphone measurement system. So I thought we cut to the chase and measure what the headphone itself produces when driven by the two different amps. Such acoustic measurements are tricky though as they are subject to noise so accuracy is not high at low amplitude. So I measured from medium to high output level. The volume control was set to 7 on both amps and I ran a sweep driving two channels but showing one. Here are the results:
The two follow each other within margin of error but then distortion takes off in the tube amp(SRM-007t) while it stays level in stolid state (SR-303). Other than low resolution of the acoustic measurements, the results correlate well with our electronics measurement.
Note that the distortion could have been increasing earlier in the tube amp but masked by the headphone distortion.
Conclusions
There is no question that the tube energizer has lower power capability before its distortion rises. To the extent you listen softly then you won't notice it. In my use I do and have been frustrated for a lot time about the tube amp becoming distorted before I run out of satisfaction with the volume.
And oh, this is evidence that electronic distortion can be worse than our transducers (speakers and headphones). Always get electronics that are far better than your transducers to avoid this. Definitely don't skimp on power capability.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/