Retubing my 2:90

[vitod]

Do all the tubes HAVE to be matched or it's just hype?

Thanks

[mr_fender]

For all 8 tubes, no. For individual push pull pairs, I'd say yes. Push pull amps require matched pairs of tubes for the best tone. Basically, the positive half of the signal uses one tube while the negative half uses the other. If the two tubes are not matched, you'll get crossover distortion and it will not sound its best. The 2:90's power tube layout is a little confusing. The pairs are arranged like this looking from the back of the amp:

----------------
- V1 V3 V5 V7
V2 V4 V6 V8
----------------

Tubes V1 through V4 are for channel A, and tubes V5 through V8 are for channel B. The matched pairs are oriented vertically and angled to the right, so V1 and V2 are matched, V3 and V4 are matched, V5 and V6 are matched, and V7 and V8 are matched.

Some say that for the most balanced stereo image the tube pairs for Channels A and B should be matched as well, but I'm not sure anyone would really notice with a fixed bias amp that has a "ballpark" bias setting anyway. Since all Boogie tubes are selected to be within a specific bias range, you shouldn't see any drastic differences from one matched pair to another.

[vitod]

Thank you so much for that thorough explanation! Now to get the tubes!

[vitod]

Put in a fresh set of JJ retube.