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Re: Tube for Jolida

Posted by DevoX on November 8, 2002 at 18:07:46:
If you've seen any of my other JoLida posts, I have a JoLida 502A (the so-called big-brother to the 302A). In fact, the 302 and 502 are identical inside other than four resistors that allow biasing for different tubes. I found this out because I wanted to modify my amp to accept either EL34's or 6550's. The 502 uses 6550's, the 302 uses EL34's.
If you're handy with a soldering iron, you can replace these four resistors quite easily. It takes about 30 minutes.
At this point, your 302 can become a 502. This will allow you to run a variety of 6550's, KT88's, or -- as I recently have experienced -- the mighty KT90. The 6550's will provide more bass impact in this amp. I don't have experience with the KT88's, but some people really like them. Just this last week I tried the KT90's and fell head over heels for them in the 502 in my particular setup.
If you're not wanting to modify and are just looking for a bassy EL34, I am sure someone in here can offer some advice. As for signal tubes, I have not done a lot of rolling so I can't really comment. I run EI ECC83's (same as 12AX7) and Sylvania Gold Brand 6201 (same as 12AT7).
-- Robert