iic+ Simul-class question-- Can you pull the outside tubes?

[texwest]

Curious if you can make a simulclass mark amp a straight 60 watter by pulling the outside class A tubes? Has anyone done this? Does it sound good?

 

[zodiac272]

i wouldn't run it without all the tube sockets full of good tubes... your outer pair are class A and you should have a switch to toggle full power and class A... which with 6CA7's or EL-34's is about 15 watts on the C+

make sure it's a simul before sticking EL-34's or 6cA7's in the outer sockets... I'm assuming you don't have the 300 series coliseum C+ that has 6 output tubes. If you do have 6 output tubes, the simul class pair are the middle pair

have any pics?

scott

 

[MrMarkIII]

Gee, it doesn't seem to be covered in the manual.
I'm sure it's OK... No problem...
Go ahead and do it and report your findings.

 

[rocknroll9225]

Gee, it doesn't seem to be covered in the manual.
I'm sure it's OK... No problem...
Go ahead and do it and report your findings.

I don't know, if I were him I wouldn't do anything potentially dangerous to a simulclass IIC+ without knowing ahead of time exactly what would happen. Those OT's are flat out irreplaceable.
You're right, it probably wouldn't do any harm, but I'd either wait for someone with 100% certainty to respond or call and ask mesa.

 

[MrMarkIII]

Gee, it doesn't seem to be covered in the manual.
I'm sure it's OK... No problem...
Go ahead and do it and report your findings.

I don't know, if I were him I wouldn't do anything potentially dangerous to a simulclass IIC+ without knowing ahead of time exactly what would happen. Those OT's are flat out irreplaceable.
You're right, it probably wouldn't do any harm, but I'd either wait for someone with 100% certainty to respond or call and ask mesa.

Buck, buck! .....Bacawww!

 

[texwest]

thanks for all the replies. I'm looking at buying a simul-class amp and am wondering if you can take it down to sixty. It just seems to me it would be like pulling two tubes on any hundred watt amp. The simulclass is just a different voltage and bias on the outer and inner tubes. If you can switch out the inner tubes and stop sending them voltage, why couldn't you do it to the outer tubes also? I'm going to be calling mesa in the next few days and I'll ask that question.

 

[rocknroll9225]

Gee, it doesn't seem to be covered in the manual.
I'm sure it's OK... No problem...
Go ahead and do it and report your findings.

I don't know, if I were him I wouldn't do anything potentially dangerous to a simulclass IIC+ without knowing ahead of time exactly what would happen. Those OT's are flat out irreplaceable.
You're right, it probably wouldn't do any harm, but I'd either wait for someone with 100% certainty to respond or call and ask mesa.

Buck, buck! .....Bacawww!

There's a fine line between courage and stupidity

But I think you're right, texwest. On a dual rectifier, you can take out one of the pairs without harming anything, so unless there's something different about class A, it should be fine. I'd still check first, though.

 

[gts]

thanks for all the replies. I'm looking at buying a simul-class amp and am wondering if you can take it down to sixty. It just seems to me it would be like pulling two tubes on any hundred watt amp. The simulclass is just a different voltage and bias on the outer and inner tubes. If you can switch out the inner tubes and stop sending them voltage, why couldn't you do it to the outer tubes also? I'm going to be calling mesa in the next few days and I'll ask that question.

Your better off looking for and buying a 60 watt C+ than doing what you are proposing.
You could afford the 60 watter and then some if you sell the Simul.
If you modify a Simul C+ the way you are proposing it'll be worth way less.

 

[texwest]

well I ended up buying a 60/100 instead so its academic now. I shortly talked to Mike Bendanelli today but he was rather anxious to get off the phone so I wasn't able to ask this question. It would still be interesting to know the answer.

 

[Whoopysnorp]

The simul-class amps are a pretty unconventional design. I would guess there could be some nasty repercussions to this. Plus, 60 watts compared to 75 watts is going to be maybe a tiny bit quieter, but not enough to make a difference. I don't think it's worth the risk.