Integrated Quad on Mesa 2:90?

[trouble311]

Does anyone know if you can do this? An integrated quad being 4x6L6 power tubes and 4xEL-34 power tubes instead of the standard 8x6L6s.

I know on the Rectifiers you can replace the four "inner" tubes with EL-34s and get a really good sound, but wasn't sure if you could do the same on the 2:90. Has anyone done this, or know if it is possible?

[bduersch]

I don't think the 2:90's support this... I'm pretty sure they'll only run with 6L6's. Then again, I thought that when you switched from 6L6's to EL34's in the Rectifiers, that you had to switch ALL the tubes.

What I do know... many of the Mark amps that support simul-class (Mark III, Mark IV) can be run with a pair of 6L6's and a pair of EL34's. Haven't tried it in my Mark IV yet, but next time I retube it I'm planning on ordering a pair of EL34's so I can try it out.

--B

[leadfootdriver]

Originally Posted by trouble311

Does anyone know if you can do this? An integrated quad being 4x6L6 power tubes and 4xEL-34 power tubes instead of the standard 8x6L6s.

I know on the Rectifiers you can replace the four "inner" tubes with EL-34s and get a really good sound, but wasn't sure if you could do the same on the 2:90. Has anyone done this, or know if it is possible?

Just put the EL's in the outer tube sockets of each channel. So if you're looking at the amp from the back, it be like this:

EL 6l6 6l6 EL
EL 6l6 6l6 EL

It will be fine. And it will do what is expected, and inheirit the characteristics of the EL34. You'll loose a little bass, and gain some looser feeling midrange.

[bduersch]

Actually, if you've got any doubt, why not call Mesa? Now that I think of it, I've called them twice in the past with relatively simple questions about my Triaxis and Mark IV, and they were very helpful & friendly.

In the mean time, I was digging through my tube box and found some leftover EL34's from my old (& long gone) Crate Blue Voodoo, so I'm going to try the EL34's in the outer sockets later today.

--B

[trouble311]

Brent,
Cool beans. A bit after I posted this, Paul Secondino replied to my question by saying his 2:90 is tubed that way and that he prefers that sound. Since I prefer a more "even" sound, I think I will too, so I am going to try it, too. So if you do try those in the outer sockets, let me know what you think of the sound!

Abe

[bduersch]

Well, I tried, but I guess it wasn't meant to be...

First, I tried it with a pair of Groove Tubes EL34's, and accidentally broke off the tab off of one of 'em.

Then I moved on to an old pair of Sovtek EL34's, but one of 'em was blown and make some majorly hideous noises.

So I guess I won't find out until I get around to ordering my new tubes.

--B

[trouble311]

Brent....hehehe...magic 8-ball says "Brent should use 6L6s. Only."

[leadfootdriver]

I tried it too. But I prefer the focused sound of ALL 6L6's. Plus I like the big bass that you get with 6L6's. Midrange ain't everything. But we all have preferances.

[failsafe306]

The only way you can use EL34's with the 6L6's is if they're all matched to have the same current draw. You can't just throw in any set of EL34's, you'll end up frying something. Call Bob at eurotubes.com and order a matched set of whatever you want to use.

[Paul Secondino]

In this particular amp, the main goal will be to get a good matched pair of EL34's because you always want a good matched set any way.

But you wont fry the amp.The reason is that the EL34 tubes draw less current than 6l6 tubes do.That is why we all perceive 6l6 tubes as having more headroom.

The 4 outer sockets on the mesa 290 amp and the Mesa 295 and other simulclass amps (mark2,mark3) are wired for class A operation.So those sockets should run a little hotter.

So if those hotter class A sockets can handle a 6l6, then they can certainly handle a EL34 which is going to draw less current than the 6l6 that was in there.

I got the idea to do this from a gear guru from France named Bruno. And I simply called Bob and asked his opinion as well and he thought it sounded totally feasible.

If you have any matched pair of EL34's , you can throw them in the amp. But you will generally want a very hot pair of EL34's to keep the bias up.

The end result for me is less low end but tighter low end and more articulate low end.Also the midrange is alot more flattering to my ears and the amp will sound a little naturally brighter than stock all of which was what I wanted out of it.

FOr some guys , the stock configuration of eight 6l6 tubes will be better and that is cool as well. I only recommend using an integrated quad if you are looking to change the sound characteristics of the amp like I wanted to do.