Dynaco-Doctor Forum

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Original Message

7199 Subs

Posted by Joe Curcio on July 5, 2011 at 16:04:32:
I don't want to pour cold water on this but they're all terrible. I recently did comparison of st-70 driver stages mostly looking a THD+N, IMD, noise and linearity over the output voltage range. By a wide margin the 7199 and the 6AN8 were superior to 6GH8 and 6U8 when used in the stock st-70 driver circuit. The 6GH8 samples I tried (5 samples) all showed very high THD+N and IMD (by a factor of 4 to 10 times worse) compared to the 7199's or 6AN8's.

Listening tests also confirmed the poor measured test scores with muted mids and rough (un-musical) high frequencies. Bass was pretty much the same.

When I get some time I will publish the test results.

Bottom line - opt for 7199's or use an all triode replacement module (which measures best BTW).