Have a 50/50, but what tubes to use?

[mikezippo]

I have a 50 / 50, had it for well over ten years. I had always bought the 6L6 str 420's for it, as in the manual. I bought a few sets in 1999, but the last quad has finally run it's life.

Now I'm looking and see that Mesa doesn't even list the str 420s anymore. Can I just throw in a matched quad of any 6L6GCs in there?

I've used 5881s at times, and those were fine by me. Can I just throw a matched quad of those in without worrying?

If I buy two matched pairs, like pair XX and pair YY, do I put them in XYXY, XXYY, or XYYX, as they would be positioned looking at the back?

I've been looking up and down for replacements and came across some russian "equivalents" 6P3S-E. Whenever I see these, they are called replacements for 6L6GC and 6L6GT. Will these work? Will 6L6GTs work as replacements?

For what it's worth, I use a Mesa Formula Pre as a preamp, and my guitars are varying Stratocasters and an old Steinberger with active pickups. I can't really say I play any one style, but stuff from jazz and blues to metal, hard rock, and I love the heavy sounds of doom, too. 2x12s and 4x12s are my cabinets.

Yeah, it's a lot to ask for a first ever post, but I am thoroughly confused over the whole topic, and the music stores where I live don't even have tubes! I get a lot of trouble about shipping to my country, Lithuania, and it would be just as easy for me to drive to store in Berlin as it would to go wait outside the SED plant in St. Petersburg.

Thanks in advance, for any help, as well as humor.

 

[Snoopy551]

Check on eurotubes

https://ssl.eurotubes.com/cart/index.php?page=view_products&category_id=6&sub_category_id=57

 

[crane]

Mesa amps have fixed bias, so you have to use tubes with a selected grade, like Mesa's.
But if you want to use any 6L6GC quartet you can have your amp moded for an adjustable bias like I've done in this topic :

http://forum.grailtone.com/viewtopic.php?f=5&t=32130

For the other tubes I'm not sure, you have to check their datasheets (especially heater current (must be ~ the same as 6L6GC) and max. plate voltage (must support at least 450V)).

I don't recommend you to use 2 duets since they probably won't be of the same grade and your 2 channel will be unbalanced.

 

[t0aj15]

I agree with the Eurotubes suggestion, just talk to Bob & he'll set you up. See his website, but call him to order:
http://www.eurotubes.com/

BTW the answer to you second question is XYYX.

 

[crane]

BTW the answer to you second question is XYYX.

Aren't tubes supposed to be appaired in a push-pull ? channels are arranged like AABB in the 50/50.

 

[t0aj15]

BTW the answer to you second question is XYYX.

Aren't tubes supposed to be appaired in a push-pull ? channels are arranged like AABB in the 50/50.

In the 50/50 because it's stereo they are AABB but the Mark IV is four tubes in MONO and are configured ABBA.

 

[mikezippo]

I checked out eurotubes, but unfortunately, they aren't based in euroland, and the shipping would cost me a days' wage here. But in the future, I will probably get an E34L set from them. When I visit the US again, that is.

I actually called a Mesa dealer in Germany, and the guy said I could use the Mesa 440s, or even the Mesa 5881s... he also mentioned it was all they had in stock. I thought he was just trying to shine me on, and sell some tubes. So I emailed Mesa. They told me the guy was giving me the correct advice, and that either of those tubes would work.

Before the Mesa people emailed me, I asked my father in law to help me out, specifically where I could get tubes here. As it ended up, he works at a former soviet electronics barn. He was able to bring me a list of the tubes that would work. He even knew a "tv repairman" type who had a cellar of tubes.

Between the two of them, I'll definitely be able to get what I need, and matched, too. The price for a matched quad, or two duets, will come out to be half a kilo or rosin core lead solder.

Without saying, I gave my father in law my only unbroken 420 and told him to get four of those, and four 5881s that will fit the bill.

Thanks for pointing me towards the eurotubes site, I wasn't aware of some of the possibilities.

So, for a few more weeks, my Formula Pre will continue to be the "world's most expensive fuzz box."

 

[petejt]

Mesa/Boogie STR440s should work fine. I have them in my MarkIV and they sound fantastic.

STR440 is the Mesa/Boogie-tested Ruby Tubes 6L6, probably one of the best of the Chinese poweramp valves.

Otherwise you could use the STR450 which is the Mesa/Boogie-tested Svetlana Electron Devices 6L6.

 

[crane]

According to Mesa's tube reference guide the STR450 is an EL34 tube, so don't put that tube in your 50/50 !
STR440 should be fine, or else do the bias mod to put any quartet in it.

 

[Snoopy551]

HI Crane

Write to Eurotube, you will have an answer very quickly.
http://www.eurotubes.com/

 

[crane]

HI Crane

Write to Eurotube, you will have an answer very quickly.
http://www.eurotubes.com/

Don't need an answer thanks :mrgreen: