simulclass and 4 6L6s?

[Stonge]

can you use 4 6L6s in a mark and use the simulclass setting? This is probably a really stupid question. But I rarely use 6L6s in any of the marshalls and have had only the mix of the 2 since I have owned the amp (not the same tubes of course).

 

[Paul Secondino]

you can use 4 6l6's in a mark in simulclass mode no problem.That's normal. As with any amp though, you do need to keep an eye on your bias setting. mark amps are biased very cold and you'd have to find an extraordinarily hot pair of 6l6's to over heat in a the amp.

 

[Stonge]

I have a simulclass C+ and isn't mesa a fixed bias system?

 

[Elpelotero]

yes, mesa's are fixed bias. What this really means is that they set the bias of the amp really cold and then they have a range of tube current draws they suggest for you to follow. Their recommendations all fall around their suggested bias. Once you get a tube that falls outside of this range, you are placing yourself at risk unless you know how to measure bias and tube current draw. The tube may blow up/wear out fast and you may damage the internals of the amp.

When you place 6l6's in simulclass, the outside pair will run very hot because these positions are intended for el34 tubes. It doesn't mean anything bad will happen...simply that those tubes are going hot and they will wear faster and or blow up if they are weak.

All of this is related to the power transformer. A big power transformer such as the one found on a C+ will eat up weak tubes like nothing. Something like a mark3 or 4 has a smaller transformer and does not assassinate the tubes nearly as much.

4 6l6's in a simulclass Mesa will have a big fat bottom. mixing el34's in there will give it a tighter and smoother tone.

 

[stokes]

"Fixed bias",contrary to its name can be adjusted.When using Mesa's tubes the tubes are selected to match the amps current draw,rather than adjusting the amp to match the tubes current draw.If you contact Mesa they will tell you what grades to use in the outer or EL34 positions to approximate a match with the sockets that use the 6L6's.But the whole idea of "simul-class" is to have a mix of 2 different sets of power tubes,so you may not want the 2 sets to match exactly,in which case they will recommend tubes that are "safe" to sub for the EL34's.As Elpelo pointed out,6L6's in the outer sockets will be hotter,so it is best to be sure the grade you use wont be too hot,if the tubes fry,they could take other things with them.

 

[Paul Secondino]

I can say that in my mark 3 amps, I never found stock 6l6's that would run too hot. Even in the outer class A sockets. Mesa biased these amps so cold that I believe you'll have a hard time finding a tube that can run too hot.

I had a good set of SED 6l6's in one Mark 3 and all they would draw in the class A sockets was 22-23 mA . that's pretty cold actually.

 

[JOEY B.]

Read this thread, starting with the last post on page 1.

http://forum.grailtone.com/viewtopic.php?t=16487

 

[Racerboy44]

Oh, and by the way. All the Simul_Clas Marks' I have owned have all sounded awesome with all 4 tubes being 6L6's. It just sounds huge with big bottom end and very smooth midrange. Sound is subjective and some on here like the sound of 34's in the outside sockets. They sound good that way also but to my ears not nearly as menacing. I have never had a 6L6 go bad in the outside sockets. Plug them in and crank it up!!

 

[Stonge]

thank you guys I appreciate it. I have always been an EL34 guy. I don't know what it is. Even though I use mesa there is still a large part of me that roots for marshall. And their EL34 sections...well I will just have to try the 6L6 quad to know fully.

 

[dodger916]

But the whole idea of "simul-class" is to have a mix of 2 different sets of power tubes,so you may not want the 2 sets to match exactly,in which case they will recommend tubes that are "safe" to sub for the EL34's.

I thought the advantage of simul-class was to blend the all-out power of Class A with the smothness of A/B, thus getting the advantages of both simultaneously. Being able to select tubes adds tone palette versatility. My ears prefer 6L6's (or 6V6's) over the El34's, and Simul-class over Class A....but again, that's just me.

 

[dodger916]

thank you guys I appreciate it. I have always been an EL34 guy. I don't know what it is. Even though I use mesa there is still a large part of me that roots for marshall. And their EL34 sections...well I will just have to try the 6L6 quad to know fully.

In that case, have you tried running EL34's in the outer sockets in Class A mode?

 

[Paul Secondino]

But the whole idea of "simul-class" is to have a mix of 2 different sets of power tubes,so you may not want the 2 sets to match exactly,in which case they will recommend tubes that are "safe" to sub for the EL34's.

I thought the advantage of simul-class was to blend the all-out power of Class A with the smothness of A/B, thus getting the advantages of both simultaneously. Being able to select tubes adds tone palette versatility. My ears prefer 6L6's (or 6V6's) over the El34's, and Simul-class over Class A....but again, that's just me.

Yes, Simulclass refers to two different electrical operating classes at the same time. EL34's aren't exactly a different class of Vacuum tube compared to 6l6's because they are both Octal (8 pin design)