How to tell if Mark III amp is Simul Class?

[winterland]

I am going to look at a used Mark III blue stripe long body head with reverb and EQ and the owner doesn't see a sticker that says Simul Class anywhere. Has the full power/half power switch on front and 4 power tubes. 2-6L6's and 2-EL34's.

Is the sticker the only way to tell?

Thanks

 

[devilrob1979]

As far as I know what you're seeing is a 100/60 head. The simulclass have a switch that says simul-class/class-a.

 

[trem]

Most Mark IIIs are simulclass. Simulclass Mark III comes with a certain output transformer, which IIRC has 562003 code stamped on it. If it is a indeed a simulclass, the half power switch on the front is actually a class A/simulclass switch. That OT code is a sure-fire way to tell. Look it up.

And btw, if the previous owner installed the EL34 on the outside slots and nothing bad has happened, it may very well be a simul. Again, look up for the code to be sure.

~trem

 

[MrMarkIII]

I've seen quite a few long heads with the Full/Half power switch that were indeed Simul. Most did have the sticker on the rear of the chassis. Confusing, but I guess Mesa was just using the front plates they had. The (still alive) EL-34s are a dead giveaway, 'tho.
By the way, wouldn't "Half-Power" turn off the OUTSIDE pair, while SimulClass turns off the inner pair? Inquiring minds want to know...

 

[trem]

By the way, wouldn't "Half-Power" turn off the OUTSIDE pair, while SimulClass turns off the inner pair? Inquiring minds want to know...

If it's a simul, the "half power" (which is actually class A) turns off the INSIDE pair, and the "full power" (which is actually simulclass) turns the whole thing on, with different bias settings between the inside and outside pairs.

If it's a 60/100 then I think it's triode/pentode switch (half power = triode, full power = pentode), with all 4 tubes on all the time. I could be wrong though on this one.

With a Mark IV, you have all those options, :wink: and then some.

~trem

 

[winterland]

Ok so I went and tried out the Mark III and it has the Simil Class sticker after all. Maybe the sales guy has bad eyes?

The amp is in good shape and had no problems. I would say an 8 out of 10.

I tried to talk them down but wouldn't budge. $799

If anyone is interested it is at a Musicgoround in Burnsville Minnesota.

I was dealing on a Tremoverb combo from a private seller at the same time and am getting it today.

You guys are great.

Thanks Todd