Finally re-tubed the Coll IIC+

[Fear]

I just got done replacing all the 6L6 tubes and 12ax7s with new Mesa tubes. I just got a little confused when I took it apart. Instead of 5 12ax7s, I found 3 12ax7s, a 12AT7 (it got a 12AX7) and one 6FQ7 (huh?). I can't find a Mesa-version of the last one, so I'll let it ride a while longer. It was born a Colliseum Mark IIC with a fan but no reverb or EQ. It was became a plus later on (verified with Mesa tech support). Just don't know why it's short a 12AX7, has the 6FQ7 and WTF is the 1/4" jack in the middle of the tubes? The chassis was drilled for an extra 12AX7, but no evidence of the holes ever being used.

 

[JOEY B.]

The extra hole is for a 12AX7 (if the amp had reverb). The 1/4 inch jack is a Preamp out/Power amp in junction. Put a 12AT7 back in the phase inverter position, for best results. The knob on the back is the "limit" control, which has to do with the 6FQ7 and 12AT7 tubes.

 

[zodiac272]

+1 on putting a 12at7 back in.

mesa doesn't offer a 6FQ7. I don't anyone makes them anymore. I would just get a pair of whatever brand you like. The 6FQ7 which is the same as the 6CG7 last forever, pretty much. it's like a 4 watt tube that only sees 1/2 watt, so they rarely burn out.

your chassis is fine. when they are manufactured, they punch all the holes for the fully loaded version every time, so mesa only needs to order one chassis per size


scott

 

[Supersonico]

I run a 12AT7 PI in all my Boogies, including my Coli IIC+

Juan

 

[Fear]

I think EH and JJ both make both tubes. I'm gonna dig around Nashville, I'm sure someone stocks them. Thanks for the input.

 

[JOEY B.]

I think EH and JJ both make both tubes. I'm gonna dig around Nashville, I'm sure someone stocks them. Thanks for the input.

http://www.vacuumtubesinc.com/Products/VacuumTubes/NewTubes6AH6to6MN8.aspx

$10.50 for a new 6FQ7/6CG7 at this store.

 

[Fear]

I'm confused now. After putting in 6 fresh 6L6s and all the 12AX7s Mesa tubes, it sounds sweet. But I only get sound with the knob on the back in the zero position. It worked before the tube swap, the little I played it with just 4 6L6 Wing-Cs in it.

 

[gts]

I'm confused now. After putting in 6 fresh 6L6s and all the 12AX7s Mesa tubes, it sounds sweet. But I only get sound with the knob on the back in the zero position. It worked before the tube swap, the little I played it with just 4 6L6 Wing-Cs in it.

Put the old 6FQ7 back in.
That thing should still be good.
Like Scott said it sees next to nothing and should still be just fine.
The original 6FQ7 is still in my IIC Coli and it's a 28 year old tube!

 

[JOEY B.]

I'm confused now. After putting in 6 fresh 6L6s and all the 12AX7s Mesa tubes, it sounds sweet. But I only get sound with the knob on the back in the zero position. It worked before the tube swap, the little I played it with just 4 6L6 Wing-Cs in it.

If you are near Nashville, you are only about 2 hours away from another Coliseum owner and myself. I will have some well-deserved time off work next week and would be glad to help you if you could make the drive to North Alabama. I don't think that your amp has a serious problem, but I would get it looked at ASAP. 8)