A couple of MusicMan 65 questions

[radioegg]

I can get hold of a MusicMan 65 reverb head on a long term loan, but it has a couple of issues: The tremolo doesn't work right (noisy), and also the tremolo channel sounds very thin and with less output compared to the normal channel (but normal ch sounds GREAT!). The guy who owns it thinks it might be the the 12ax7 phase inverter that causes this. Is this likely, wouldn't this affect the normal channel too? What else could be the problem?

Also there are EL34 power tubes in it. The original tubes are 6ca7. What's the difference here? I want to use the MM for Fenderish clean sounds, it's good with the EL34, but could I get more of the Fender-sounds out of it with 6ca7's? And could I even use 6L6's in it?

Thanks for any information and advice!

Tor

[miamimart]

http://www.musicmanamps.com/

[Peteyvee]

http://www.marshallforum.com/workben...7-vs-el34.html

[Winnie Thomas]

Originally Posted by radioegg

I can get hold of a MusicMan 65 reverb head on a long term loan, but it has a couple of issues: The tremolo doesn't work right (noisy), and also the tremolo channel sounds very thin and with less output compared to the normal channel (but normal ch sounds GREAT!). The guy who owns it thinks it might be the the 12ax7 phase inverter that causes this. Is this likely, wouldn't this affect the normal channel too? What else could be the problem?

Also there are EL34 power tubes in it. The original tubes are 6ca7. What's the difference here? I want to use the MM for Fenderish clean sounds, it's good with the EL34, but could I get more of the Fender-sounds out of it with 6ca7's? And could I even use 6L6's in it?

Thanks for any information and advice!

Tor

EL34 and 6CA7 are essentially the same tube with a different ID. EL34 is the Brit nomenclature, 6CA7 the US one.

The tremelo and reverb on the amp are SS, the 12AX7 is merely the Phase inverter. You are correct in saying that both channels would be affected if the 12AX7 was bad.

That amp is one of the unsung heroes of the past, enjoy it. A good tech could probably fing the source of the problem easily. There's REALLY HIGH VOLTAGE (700+Volts)in those MM amps so don't screw around with it.

Winnie

[teefus]

really great amps. i had one in the late 80's/early 90's and it was one of the best sounding amps for recording. for gain i used a vintage big box rat and it was perfect. i'd love to find one of the 50 watt combos for a good deal.

[jay42]

Offhand, it sounds like a cold solder joint. That's a marvelous amp, btw, and easy to repair...well worth cleaning up. I'm not a good reference point, but there might be better new output tubes for it, like JJ KT77s...anything that meets the EL-34 spec is good, but you're looking for better headroom. NOS 6CA7s would be pricey.

[wilto]

I have a HD 212 130. inside the cab, the sticker says 6ca7/12ax7 tubes. I put a matched quad of ruby Tubes EL34B's, and a good quality 12ax7. This thing is one sweet sounding amp. Oh and don't forget to rebias, this is important, 700+ volts will find any weak points in there. Enjoy!