Music Man HD-130

[musicman1]

bought an hd-130 pre 1975 amp a few days ago online. got it home, plugged my bass into it, and with the volume turned up at gigging sound level, it seemed to fart on the low notes. I do play a music man 2007 limited edition stingray, and it does have active pick ups. thought that could be the problem, but when i plugged my jazz or p-bass into it it does the same thing..

Any help would do.. thanks!

 

[BeauZooka]

On my HD150 I have the master cranked all the way up and the pre up to taste.

If that doesn't help then it may be your tubes. Can you see what brand/model they are?

 

[BeauZooka]

Also is this the one with the 1 pre-amp tube right?

http://www.musicmanamps.com/ has a great forum with some very technically inclined folks to help out with the old school MM's.

 

[ihixulu]

It's a 130W tube amp. It will fart on the low notes at gig volumes unless you mate it with a very loud cab that allows you to turn down. What cab are you using?

 

[musicman1]

it has 4 EL34 groove tubes.. I play it through a peavey 410 TXF cab.. I'll try it on my svt 810 when I go set up later on.. It doesn't have a pre amp tube, it's solid state.

 

[BeauZooka]

Prior to '79 or '80 all of the Music Man amps had single 12ax7 for a phase inverter. If it does not have the 12ax7 then it is probably not from 1975 (unless it was modded).
Do the Groove Tubes state the country of manufacture on them? Some EL34's are not able to handle the high plate voltages that Music Man amps use.