Let's Get Technical > Troubleshooting Problems

MP2 Volume drop

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Shredzilla:
Hi!

I've got a volume problem with my ADA MP2. When I start playing everything is fine but after two to three hours there's a sudden volume drop. I tried different poweramps - same result.
Anyone got an idea? Are there any known heat problems? Compared to my other rack gear the MP2 seems to get very hot.

Thanks for your help!

MarshallJMP:
I would first try out a fresh pair of tubes.

And yes the mp-2 generates alot of heat,if you rack it,make sure you have enough cooling above and below the mp-2.

Shredzilla:
OK. I' ll try some new tubes. Which do you recommend? I guess the current tubes are the original ones from 1994:)


Regarding the heat problems I maybe have to buy a new rack case with more space left to prevent overheating.

rnolan:
There are lots of tube possibilities and choice is very subjective.  Basically you need a pair of low noise 12AX7 tubes. My personal preference for the MP2 are the New Sensor Mullard reissues, I've had some for a while now and love them.  MJMP likes Ruby tested JJs. Here's a link to Dougs Tubes with plenty to pick from.  The TUNG-SOL reissues would also be good (I've heard good things about them). (http://www.dougstubes.com/preamp-tubes/12ax7-ecc83-7025.html).
I mount my MP2 at the top of the rack as this gives some space above the unit.  I rack the effects under it as they don't get too hot (or leave a space under it if you can).
The original tubes were Chinese 12AX7s, typically no brand on them, just some red writing saying 12AX7.  And they will be way past their best if the unit has been well used.

Dante:
When you take the old tubes out, hang on to them just in case. You never know.

I tried a bunch of variations in my MP-2. I ended up putting some Sovteks in there (12ax7w?). They were the only tubes I could get crunchy enough while still being able to clean up a bit by picking softer. (I think I'm the only guy on the Depot that tries to tone down his gain - ha ha)

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