Anyone mix 6L6s and 5881s...or am I nuts?

[dodger916]

I was wondering how 5881s would sound in the outers with 6L6s in the inner sockets...or vice versa. Or will I blow myself up? Either in Mark II or Mark IV.
(Also posted in Tubes)

 

[av8or3]

While it's said that the "modern" 5881's are safe to use in place of 6l6's (Groove Tubes relabels Sovtec 5881's and calls them 6L6WGB ???? ) I WOULD NEVER DO IT IN A MILLION YEARS.
I have personally repaired 2 amps ,one Music Man and one Fender Twin that suffered damage when one of these 6L6WGB's (5881's) shorted and burned resistors before blowing the fuse.
If it says 6L6GC that's what it means. In Mesa Simul-Class amps the outer sockets ,only, can accommmodate 6L6GC's (or a tube of the same family with a higher rating, and can take the stress of class A) or el34's.
check out this website, it kind of boils it down. (Is good tube info)

http://www.vacuumtubes.com/6l6.html
Jim

 

[SonicProvocateur]

Im using Mesa/Boogie 5881-6L6's in my Mark III. I am reasonably pleased. They don't have the same woody cleans im used to as with the Electro-Harmonix 6L6GCs I normally run, but the gain is more managable and more closely resembles 1994-1998 Dream Theater rather than the ultra modern gain I normally have dialed in. Id say these tubes are like a 7.8/10 on gain. 9.0/10 cleans. They do NOT like to break up. The do handle voltage well though. My Mark III does need a slight re-bias though...and I do kinda want to switch back to the EH's. Id rate the EH's at like 9.5/10 and 9.8/10. They are probably the most perfect 6L6 ive ever used for metal or jazz.

 

[SonicProvocateur]

And yes, it is the STR-425 which has the correct plate voltage that is specifically designed to replace 6L6GC's.

 

[av8or3]

Interesting!
Why does Mesa or did Mesa have a 5881, called an STR-425, spec'd for use in place of a 6L6?
Am I missing something?

I can see that Mesa certainly feels differently and they've obviously designed their amps so that it's not a problem. However I still would never do it. I guess I would err on the side of safety if I had a choice. The two amps I repaired were older amps as well and maybe were not engineered to deal with whatever the difference is. The Music Man failed twice the same month, the same way both times before I sold the guy some GE NOS 6L6GC's to replace the GT 6L6WGB's (5881's) he had been using in the amp. He's still rocking with that little RD 112-Fifty a year later, happy as a clam.
Jim

 

[dodger916]

Interesting!
Why does Mesa or did Mesa have a 5881, called an STR-425, spec'd for use in place of a 6L6?
Am I missing something?

Thanks, George. I was just about to go looking for that chart!

 

[dodger916]

Im using Mesa/Boogie 5881-6L6's in my Mark III. I am reasonably pleased. They don't have the same woody cleans im used to as with the Electro-Harmonix 6L6GCs I normally run, but the gain is more managable and more closely resembles 1994-1998 Dream Theater rather than the ultra modern gain I normally have dialed in. Id say these tubes are like a 7.8/10 on gain. 9.0/10 cleans. They do NOT like to break up. The do handle voltage well though. My Mark III does need a slight re-bias though...and I do kinda want to switch back to the EH's. Id rate the EH's at like 9.5/10 and 9.8/10. They are probably the most perfect 6L6 ive ever used for metal or jazz.

That might work for me as I don't play high gain stuff. What color codes are you running, and which slots are running the 5881s? Have you tried swapping slots?

 

[SonicProvocateur]

That might work for me as I don't play high gain stuff. What color codes are you running, and which slots are running the 5881s? Have you tried swapping slots?

They are yellows. Mine is a 60 watt, so it is in both slots.

 

[Sauron]

So guys, what's the difference between 6L6 and 6L6GC and which ones should I put into my Mark IV?

Thanks

 

[SonicProvocateur]

6L6 is the variant name. 6L6GC has glass envelopes, and is, by all accounts, the most popular (and best version, IMHO) you can put in your amp. There are also other, more military or radio related variants of the 6L6, like the 6L6WGC, 6L6WGB (5881), and 6L6WXT+, but all have such different plate characteristics and most Mesa's are fixed bias so you DO run the risk of damaging your components by not following Mesa's guidelines or using their tubes, plus, some of those old tubes is a mixed bag of tone unless that's what you're SPECIFICALLY looking for...

Bottom line...stick to the 6L6GC...they sound the best.

 

[SonicProvocateur]

And to those curious:

Just slightly shorter than a regular 6L6, with a metal base. Still Mesa labeled. I wouldn't trust another company's 5881's though if you were dead set on getting them though, these are designed specifically for Mesa amps.

 

[Boogiebabies]

For some time the only 6L6 you could buy from Mesa was the STR-430 which was a Sovtek 5881 WXT.
The basic difference from the STR-425 was a taller base. Both the 425 and 430 are a 30W tube and are safe to run
in Simul's, 60's and 60/100's, The difference between NOS 6L6WB's or Tung Sol's is they were a true 25 watt tube.
With these, the plate voltage is not a huge concern nor is the IIC+ bias. The real issue would be what power transformer you have.
For a 105 you may not get the lifespan with up to 493V, but with a 100, X100 or X101 you will have a much lower plate voltage around 440V
much like the MK IV.

 

[dodger916]

For some time the only 6L6 you could buy from Mesa was the STR-430 which was a Sovtek 5881 WXT.
The basic difference from the STR-425 was a taller base. Both the 425 and 430 are a 30W tube and are safe to run
in Simul's, 60's and 60/100's, The difference between NOS 6L6WB's or Tung Sol's is they were a true 25 watt tube.
With these, the plate voltage is not a huge concern nor is the IIC+ bias. The real issue would be what power transformer you have.
For a 105 you may not get the lifespan with up to 493V, but with a 100, X100 or X101 you will have a much lower plate voltage around 440V
much like the MK IV.

Thanks, Ed. You can see you got me thinking about 5881s! What do you think about mixing with "regular" 6L6s in the outer (or innner) slots? Are they too similar to make any real difference?

 

[Boogiebabies]

Yes, they are basically the same horse with a different color.
It's the tubes design and sonic differences that make the decision in the end.

 

[Restless Rocks]

I played full time (5-6 nights a week) from 1985 till 1997 with a stock Mark III using what ever off the shelf Boogie or Sovtec 5881's I could get my hands on. Mostly Sovtecs because the Boogies were very hard to find without ordering direct and when you're on the road all the time you sometimes have to settle for whatever the "local" music shop happens to have. That amp to this day still has the factory fuse in it. I really liked the rolled off highs of the 5881 for a serious singing fusion lead sound without the fizz. Now that I'm playing a lot more diverse styles, including country I have been very happy with STR-440's. I still have a box full of Boogie branded 12AX7's from the 80's that are some of the best sounding tubes in my collection, which contains about every vintage tube you could think of.

 

[Boogiebabies]

Agreed. I have a box of old Mesa labeled Chinese that sound excellent, but the best are the Mesa
labeled Ei's from the mid 80's. What a smooth tube with good gain.

 

[frets70]

I've been using GT-6L6-CHP in the outer sockets for about 5 gigs and like them better than my STR 450 EL 34s

 

[igfraso]

I am using a pair of Mesa's STR-425 in the inner sockets of my Mark II-A (together with a pair of 6L6 in the outer sockets).
Other than sounding a little bit dark (maybe even a little bit too dark), I have never had problems with them.

 

[Fronzil]

says right in the manual, you can replace all 4 6l6s with 4 5881s, or run them on the outer sockets (class A) with 6l6s in the middle 2

 

[dodger916]

Well I have a pair of 5881s on the way from Petaluma. I'll let y'all know what I think. Thanks.