MIXING TUBE BRANDS

[doobchec]

Good day to 'ya,
I need to replace my power tubes- in my Mk IV-B combo- and was wondering if any harm would occur if I mixed a quad of JJ 6L6's with my Mesa "brand" 12AX7 preamps. I can't think of any reason why not to experiment, but I don't want to thrash my amp either! The manual doesn't mention mixing power AND preamp tubes. Peace...

 

[crane]

Absolutely no problem if you put a matched quartet, selected for Mesa's bias.
The only one can happens if you don't like the sound. :mrgreen:

 

[doobchec]

OK, good. But I'm not clear on Mesa's tube bias. I have understood that Mesa has certain "stadards" when selecting tubes. So how do I know if the tubes I want to purchace online (or in the store for that matter) are "selected for Mesa'a bias?" Are their standards really that much higher than other major tube retailers/manufactuerers? Thanks for the clarification.

 

[Old BF Shred]

Ah, the $64,000,000 question! :shock:

It comes up a lot.
Since Mesa's bias voltage is not adjustable (unless the amp is modded), you need to get tubes that fit into their "ideal range". They base this on the nominal "perfect world" specification that all tubes, in theory at least, should hold to.

Unfortunately, that's easier said than done as tubes, nowadays especially, can vary quite a bit (this does not necessarily mean the tubes aren't good, contrary to what Mesa seems to infer in order to sell you theirs).

As a reference, the Groove Tube ratings of 4, 5 or 6 (out of 1-10) are known to fit the Mesa spec (this was told to me by Mesa, BTW).
And most reputable suppliers of tubes will know which ones to send you for your Mesa amp.

Let them know the model of your amp and they should be able to get you the right ones. If you already have the tubes, check back with where you got them or measure the idle current (or have a tech do it if you are unsure how to). Where the current should be is a spec that Mesa should be willing to provide....give them a call, or your local tech will know.

Good luck!

ps...for most amps in general, 6L6 should draw 25ma to 30 ma, safely....

 

[stokes]

OK, good. But I'm not clear on Mesa's tube bias. I have understood that Mesa has certain "stadards" when selecting tubes. So how do I know if the tubes I want to purchace online (or in the store for that matter) are "selected for Mesa'a bias?" Are their standards really that much higher than other major tube retailers/manufactuerers? Thanks for the clarification.

Its not a matter of their standards being higher,it is a matter of them setting the bias at a specific point and then selecting tubes that will be "safe" with the given plate voltage and control grid bias voltage.It was a good scheme for them when they first introduced the idea,you had to buy tubes from them,making you a customer for life.But,tube dealers went and measured the specs in a Boogie and now almost any supplier will match tubes to your amp.I can tell you that Mesa's are biased so cold that it is hard to find tubes that wont run "safe",but "safe" isnt always optimal.

 

[dodger916]

Remember that running anything but Mesa tubes will void the warranty.

 

[stokes]

Only if you tell them you used some other tubes.

 

[Old BF Shred]

Remember that running anything but Mesa tubes will void the warranty.

Not quite exactly...... :?
Groove tubes rated 4, 5 or 6 are approved for use in Mesa. This is per conversation with the folks at Mesa.

And only if it is determined that the non-Mesa tubes caused a problem (of course, Mesa makes this determination and their assessement is final).

This generally will not apply to preamp tubes (unless, again, they actually caused a problem, i.e. shorted internally which is very, very rare).

Using non-Mesa tubes, alone, does not automatically void the warranty, but the user does assume more of the risk involved. With Mesa tubes, virtually every possible scenario is still covered by the warranty (abuse excepted, of course).

Still, one should be very careful in choosing output tubes so as to avoid problems, but many suppliers are getting savvier as to what works reliably in a Mesa.


Good luck!

 

[dodger916]

Remember that running anything but Mesa tubes will void the warranty.

Not quite exactly...... :?
Groove tubes rated 4, 5 or 6 are approved for use in Mesa. This is per conversation with the folks at Mesa.

And only if it is determined that the non-Mesa tubes caused a problem (of course, Mesa makes this determination and their assessement is final).

This generally will not apply to preamp tubes (unless, again, they actually caused a problem, i.e. shorted internally which is very, very rare).

Using non-Mesa tubes, alone, does not automatically void the warranty, but the user does assume more of the risk involved. With Mesa tubes, virtually every possible scenario is still covered by the warranty (abuse excepted, of course).

I used to think so too, until a board member pointed out the warranty language. Per my Mark IV warranty: "This warranty becomes void if any tubes other than genuine Mesa tubes are used". So Mesa has the right to void the warranty if they know you ran tubes other than Mesa. Anyone know if they changed the language in the new warranties?

I think the Groove Tubes reference is great help. If you blow a tube and need a replacement set, you'll know what GT tubes will run within the Mesa spec. GT tubes are more available than Mesa tubes.

Still, one should be very careful in choosing output tubes so as to avoid problems, but many suppliers are getting savvier as to what works reliably in a Mesa.

This is true. Reputable tube suppliers (e.g., Doug's) will know which tubes to send you if you specify your Mesa amp.

 

[stokes]

I have always been under the impression that GT's were okay by Mesa,after all Smith and Pittman are reportedly good friends.