Acoustic 370 volume problem

[A_Librarian]

Got an acoustic 370 and an acoustic 106 (4 ohm 2x15). I have to dime the bass AND the acoustic volumes to get to the same level my band plays. We are NOT loud. I'm thinking somethings wrong but don't know where to start. I know the 370 is a loud amp and under normal conditions I shouldn't have to turn the volume past 2.

Is the problem the 370? Or could it be the cab? Where do I begin troubleshooting?

[throbbinnut]

It could be either one, but I recently repaired an old 370 where the inductor at the output stage had broken off the board, so it was putting out very little power.

Make sure the 2 15s are in phase - use a 9V battery (preferably kinda dead, but it really doesn't matter) and touch it to the speaker cable plugged into the cab. Both speakers should jump in the same direction, either out or in.

Also, if you have a multimeter, you could check the resistance of the cab. It should read about 3 ohms for a 4 ohm impedance cab.

If all that checks out, get the amp serviced.

Chris

[A_Librarian]

Thanks Chris. Looks like it was a cord. Everything is sounding mighty fine now.

[A_Librarian]

I take it back. The 370 has gotten super quiet again. Tested using different cords and cabs. When I turn the volume up it gets a little louder but mostly just distorts. Used a different head w/ the same cabs and cords and was much louder.

[garmenteros]

I've had the same issue. I haven't been able to fix it and it comes and goes. In me case it seems to be that something is loose inside. When I've been at my techs he reattaches one of the wires to one of the big steel cans inside, one of the capacitors and that seems to do it. I play 3-4 gigs and it comes back, and goes away in 5 minutes after I turn it off/on but creeps out again randomly 3 4 weeks later and goes away. I've fixed this issue twice the same way.

[wideload]

Gosh, I sure hope this happens to whoever stole my 370 back in '96!

[garmenteros]

Originally Posted by wideload

Gosh, I sure hope this happens to whoever stole my 370 back in '96!

i doubt it. This is a rare issue. These things are bulletproof.

[A_Librarian]

Thanks for the info. I'll give it a shot and see what happens.

[craig.p]

The 370 was a great head that used great components, but even the best electrolytic capacitors eventually dry out and change characteristics, and even the best heads get bumped around over their decades of use in the field. A 370 head is worth a complete refurb by someone who knows what he's doing, including replacing every electrolytic and checking every solder joint for integrity. Then it's good to go for another 20 years.

[A_Librarian]

Guess I need to find a good tech in PA. Thanks for the tip.

[craig.p]

Not sure where you are in PA, but if it's roughly southeast, give Progressive Studios a call and see who they recommend. Better yet, go to their "people" page and contact Jay Kirssin directly if you can.