Music Master Bass Amp Mafia

[Sidney Vicious]

I got turned on to these by Robbie D of the TDPRI and catnine over on the FDP. Hearing two cool cats singing the praises of such a funky stepchild of a Fender amp got my attention. When I learned how relatively affordable they were/are I really got interested. 12 inches of tube tone for cheap? I'm in.

I have gone through a few of these over the years but recently settled on this early 6AQ5 one:



Bone stock except for the tubes - three RCA's - and, at the moment, a Weber Sig Alnico. Truth be told, for at home play the stock speaker in this thing sounded great for my low-fi hacking. I may end up going back to it.

I have also decided to leave the tone circuit alone on this one - although I will install an in-line fuse soon to protect the trannys.

Step up and show me yours!

[edgetone]

Nice one, Vicious. Poor man's Deluxe....I love mine.

This one's got the 6v6's. Changed the input to a more standard "Fender" arrangement, i.e. 68K and 1Meg resistors and shorted that .047uF cap out of circuit. Sounded really good with a RI Jensen P12Q but wound up with the C12N due to the fact I noodle with a bass on it occasionally. The alnico couldn't take it, the N does fine. I've since added a 1/4" socket/plug connection for the speaker. Made it easier to hook to diferent speaker cabs and such.

Dan

[Sidney Vicious]

edgetone:

That thing is CLEAN! Thanks for posting.

[edgetone]

She'd been around the block a time or two when I met her....

[ravindave_3600]

Had one - but good such a good offer on it (well over then-current value) I had to sell! Highly recommended little amp.

[Sidney Vicious]

Here is a good legible copy of the MMB amp schematic:

[pchilson]

Here is an original schematic for a '74 6AQ5 version MMB
Kinda wish I still had mine...

[Sidney Vicious]

[QUOTE=pchilson;2130503]Here is an original schematic for a '74 6AQ5 version MMB
Kinda wish I still had mine...

Thanks for that - I had not previously seen a schematic specifically referencing the 6AQ5 version.

[varakeef]

Here's mine lurking in the right upper corner... it's a modded version with EL84's (or 34's... how to remember that?)

[Sidney Vicious]

Nice rig, varakeef. The 6AQ5 model, right?

Aside from the feet and tone knob, any other modifications?

[varakeef]

Originally Posted by Sidney Vicious

Nice rig, varakeef. The 6AQ5 model, right?

Aside from the feet and tone knob, any other modifications?

I think it is 6AQ5, 1974 I guess.

It's modded to use different tubes (EL34/84?) since the ones they normally would use were hard to find here when the mod was excecuted (in the early nineties). They probably still are.

I have no idea what the mod exactly is, I just know what tubes to stick in there.

[Sidney Vicious]

I believe the 6BQ5 is "close" to the el84 and so that is likely the tube it was modded to accept. '74 sounds right. Cool amp.

[pchilson]

Originally Posted by varakeef

It's modded to use different tubes (EL34/84?)

These are very different tubes. I would guess they modded to the EL84.

Originally Posted by varakeef

I just know what tubes to stick in there.

Only one type would fit the socket.

[endzone]

Here's mine. Yeah, I'm in the happy camp with MMB's. They are little tone monsters. I picked up an old '65 Jensen P12R for this one and it really stepped it up. This thing will really grind with a P-90. I found this amp at an old obscure flea market about a year ago for $40.

[varakeef]

Originally Posted by pchilson

These are very different tubes. I would guess they modded to the EL84. Only one type would fit the socket.

Yep... and I have a tube chart glued on the back of the amp where the right type is printed on. So I know but I just can't remember that kind of info by heart. The flaws of human brain.

[pchilson]

I hear ya! Use it or lose it...

[doggy1972]

Heres mine






The pictures are a bit limited I'm afraid. Sounds good with all my guitars. Its all stock except for the tubes. 12AT7 for home use 12AY7 for louder situations

[Sidney Vicious]

Sweet rig, doggy - I'll have to give that tube swap a try - I think I have a 12at7 around here someplace.

[doggy1972]

Thanks Sid. I love this little amp. On the lookout for another 1. I know some ppl will say that the 12at7 is a power tube and shouldnt be used for the pre but, it just sounds the best out of the 12ay5, 5751 Ive tried in there.
A question to those in the know- Are those square CTS speakers Alnico or ceramic?
Just a little curious

Ian

[Sidney Vicious]

Originally Posted by doggy1972

Thanks Sid. I love this little amp. On the lookout for another 1. I know some ppl will say that the 12at7 is a power tube and shouldnt be used for the pre but, it just sounds the best out of the 12ay5, 5751 Ive tried in there.
A question to those in the know- Are those square CTS speakers Alnico or ceramic?Just a little curious

Ian

The square magnet on your amp is ceramic - as I believe was stock on all the MMB amps - although some - Oxfords I believe - have a round ceramic magnet.