Gear Discussion Forums > Bass Amps & Effects
Mesa 400 tube recommendations
georgestrings:
--- Quote from: amptech on December 16, 2014, 07:25:22 AM ---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 :)
--- End quote ---
I'm definitely looking for more clean headroom, which a change from 6l6s to 6550 or kt88s will provide, according to all accounts I've read thus far... Also, AFAIK the 400 WAS originally designed to run 6550s - so I doubt that'll be a problem... I also know of several people that are running kt88s in their 400s with excellent results - but I believe they had bias pots installed...
At any rate, I appreciate your contribution..
- georgestrings
georgestrings:
--- Quote from: gearHed289 on December 16, 2014, 08:57:02 AM ---Is it a 400, or a 400+? The original 400 ran (6) 6550, while the "+" ran (12) 6L6.
--- End quote ---
It's a 400, not a 400+... and as you say, the 400 originally ran 6550 power tubes...
- georgestrings
rahock:
For a bit more clean headroom with 6L6s you could try a set of JJ Teslas or whatever they are called now. I have done side by side comparisons between JJs , old Motorolas and Winged Cs. The clean headroom winner was definitely the JJ Tesla. Warm low end break up was a tie between the other two. If I was retubing a guitar amp I would probably go with the Winged C or old Motorola(if you could find them). For a bass, JJs would be my choice.
Rick
georgestrings:
--- Quote from: rahock on December 18, 2014, 05:06:16 AM ---For a bit more clean headroom with 6L6s you could try a set of JJ Teslas or whatever they are called now. I have done side by side comparisons between JJs , old Motorolas and Winged Cs. The clean headroom winner was definitely the JJ Tesla. Warm low end break up was a tie between the other two. If I was retubing a guitar amp I would probably go with the Winged C or old Motorola(if you could find them). For a bass, JJs would be my choice.
Rick
--- End quote ---
Thanks for weighing in...
- georgestrings
amptech:
And while you're at it, ask your supplier for a strong set! When shopping matched sextets or octets of tubes, there are not always much to choose from. But if your supplier/shop is kind, let them pick a strong set for you. Either brand (and I point to the WC/JJ comparsion here) can have early or late breakup. Yes, there are differences between tubes, but a working tube can be weak or strong. A/B tests (in my ears/opinion) of tubes/breakup is only ever valuable if they are equally strong (within reason). That said, even as a WC endorsee, I say thumbs up for JJ too - good and reliable for the most part!
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