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Mesa 400 tube recommendations

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georgestrings:
I have a Mesa 400 on it's way to me, and am considering tube options - it already has 6l6s in it, but I'm pretty sure I want to put kt88s in it, instead... The preamp tubes will probably be left alone, unless there's an issue with them...

Any thoughts???


   - georgestrings

rahock:
PBG and others much more technical than I will surely reply, but swapping 6L6s for KT88s is a sometimes you win, sometimes you lose thing. Some amps handle it just fine, sometimes you put a lot of stress on your transformer. I would see how it sounds as is for a while.
Rick

georgestrings:

--- Quote from: rahock on December 16, 2014, 05:01:58 AM ---PBG and others much more technical than I will surely reply, but swapping 6L6s for KT88s is a sometimes you win, sometimes you lose thing. Some amps handle it just fine, sometimes you put a lot of stress on your transformer. I would see how it sounds as is for a while.
Rick

--- End quote ---

Yeah, I'm definitely looking forward to PBG's thoughts on the matter... My research (so far) says that the Mesa 400 was originally designed to run 6550s, and that the use of 6l6s in them was due to the lack of a reliable source for 6550s *at the time* - which resulted in a slight downgrade in power, and different musical characteristics... I also haven't discounted going with 6550s, FWIW...

Thanks for your input,


   - georgestrings

amptech:
I'll just chime in here until PBG posts..

Just curious, what kind of upgrade are you after, soundwise?

I have not used a mesa 400 since 1993, and I did not experiment with tube swapping during the time i played it.

Usually, when people upgrade to 6550 or KT88's, it's usually because they want more clean headroom.
If they just want a somewhat different sound, they might experiment with different manufacturer of the same tube.

In many cases, they end up spending a lot of money (KT's are expensive - at least here in Europe) for not quite the
most impressing results. More often than not, a 'stock' amp sounds best with the tubes it was designed for, if it is serviced/set up/biased correctly. I see many cases where owners have worn out 2-3 different sets of output tubes, with the original driver tube still in. So the ouput stage may not work properly with any output tubes.

That said, there is no reason not to experiment, but I'd check that the power supply and output trannies can handle the tube, and of course check that there is enough negative supply available, and that you will not exceed the total current draw the unit was designed for.

Perhaps not the answers you want, but I'm sure someone here have tried this and can post something on how it sounds :)

gearHed289:
Is it a 400, or a 400+? The original 400 ran (6) 6550, while the "+" ran (12) 6L6.

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