Mesa 20/20 power amp

[sinfish]

Hi Guys,

I just picked up a Mesa 20/20. Are there any 20/20 owners here? I was told they can overheat pretty easy. Is there any truth to this statement?

Danke

 

[Ancient Alien]

Yes, it is very very true.
They also tend to burn tubes at a high rate, as does the Marshall 20/20.
This is also the reason Steve Fryette never built a single space EL84 amp.
There is no way to build a single space power amp without overheating issues due to the horizontal position of the tubes.
I would suggest that you mount a small computer fan in your rack blowing across the tubes.

 

[talltxguy]

Hmm, I never had a problem with my 20/20 overheating. I ran it with warmer tubes than Mesa's stock tubes as well - Eurotubes JJ84's. I did run it hard too. Had it for around a year.

End up selling it and getting a bigger power amp that could give me more thump and a little more nastiness. The 20/20 was pretty smooth - a bit more smooth than what I prefer.

Never had a problem with tubes burning at a high rate. Then again, I never messed with putting an adjustable bias on my 20/20.

Hope this helps.

 

[racerevlon]

I have a Marshall EL84 20/20 and I've never had it overheat, even after hours of playing--although, I always leave 1U above or below for ventilation. YMMV.

Cheers,

 

[HughJasol]

I use a Mesa 20/20 (I actually own two of them) and have had no problems with overheating. I'm not running any fans, but then again I don't drive it too hard either. I'm running Mesa EL84s, although JJs are supposed to be an acceptable drop-in replacement according to Mesa from what I understand (I've installed JJ ECC83S preamp tubes though). It's in the bottom space of my rack, and I don't leave an open space above it either - although the 20/20 is twice as deep as anything mounted above it in the rack, so the heat buildup in the top cover gets to dissipate pretty freely.

My latest 20/20 is brand new, so I haven't done anything to it, but on the 20/20 in my gigging rack I performed the "deep mod". I ordered push/pull pots directly from Mesa (it's a relatively new part number), and wired each channel's VOLUME pot to pull for the deep mod (I would have preferred to use the PRESENCE knobs instead, but alas the transformers get in the way), so I can enable/disable the deep mod on each channel individually.

 

[sinfish]

I am very interested in the "deep Mod" Where can I find more info on this?

 

[Audioholic]

I think any power amp will get rediculously hot very quick, specially if its racked up with other gear. Best to leave some space around it, and as suggested, maybe get a small clip on fan just to move some air around back there. I did that with a RT 2/50. You could fry an egg on the back of it if you wanted to.

 

[HughJasol]

I am very interested in the "deep Mod" Where can I find more info on this?

This thread should give you everything you need, including several different ideas on how to implement the deep mod (fixed, toggle switch[es], push/pull pot, etc. http://forum.grailtone.com/viewtopic.php?f=5&t=31723&hilit=tubes+mesa.

Also, here's some part numbers that may help you:

• Push/Pull Pots (I forgot the specs 596151 $8.90 ea.
• Chrome Knobs (note that the chrome plating prevented the set screws from fully tightening on HALF of the six knobs I ordered 408110 $4.80 ea.
• Replacement Fan: 783115 $29.25

 

[sinfish]

I am very interested in the "deep Mod" Where can I find more info on this?

This thread should give you everything you need, including several different ideas on how to implement the deep mod (fixed, toggle switch[es], push/pull pot, etc. http://forum.grailtone.com/viewtopic.php?f=5&t=31723&hilit=tubes+mesa.

Also, here's some part numbers that may help you:

• Push/Pull Pots (I forgot the specs 596151 $8.90 ea.
• Chrome Knobs (note that the chrome plating prevented the set screws from fully tightening on HALF of the six knobs I ordered 408110 $4.80 ea.
• Replacement Fan: 783115 $29.25

THANKS!!!!!

 

[threadkiller]

I have read about some problems with the mesa 20/20 but it's always "I knew a guy who...." Actual owners seem to love them. I run my Fryette in class A/B mode and it doesn't get too hot and the only difference I can hear is that the fan runs faster, i.e. makes a little noise, in class A mode.