Music Man amp fans?

[G Mac]

How about Music Man amps? I started a thread on the Epiphone Lounge regarding this topic but, thought I'd post it here as well in case there are some Gibson folks who don't use the Epi fora.

I have an RD112 50 that is a killer of an amp and used to have an HD212 150(which was also a brute) when I was a kid. In my opinion, these amps are at the pinnacle of tone, power, craftsmanship and longevity.Share the Love and Play On!

[Guest Farnsbarns]

Pippy has a Music Man amp. Couldn't tell you the model. Given the size of it I would assume a 1x12. It's a combo and it's a good amp. Played though it a few times and really liked it. I would say it was te first in a series of events which led to my going down the Fender amp route.

[pippy]

Yes, I do, although it's a 2x12.

 

Glad I was instrumental (pun) in steering you down the Righteous Path, Brother Farns...

 

Pip.

[L5Larry]

I posted some of my Music Man info in the other thread, but here's a pic I dug up of the 212-130, 210-130 and 210-65 I owned. I did later add a 65-Reverb head to the "stack".

 

Sold off the 210-130 combo and the 65 Reverb head, but I'd never sell the 212-130 or 210-65. The 212 was my main gigging amp for about 15 years, and now the 210 has been my "go-to" amp for the last 15 years for any and all non-jazz type engagements.

 

 

After having a bad experience with a constipated Silver-Face Fender, I got interested in MM amps right after they came out. A friend of mine (eventually married his sister, hah) worked at a local music store that had just picked up the "new" Music Man line of amps. I walked in the store one day and he couldn't get me plugged into a Music man 212 fast enough. The 212-130 was being marketed as THE alternative to the Fender Twin Reverb. I had sworn off Fender amps and had been playing through a Sunn Model T half stack for a few years, and I found the MM to be a really interesting combo as a "Twin" option.

 

A few years later I bought a Corvette and had no backseat or trunk to haul the Sunn half-stack around in anymore, so a combo amp became a necessity. Found a used MM 212-130 for sale, and after a test-fit it to see if it would fit behind the seats of the Corvette (a perfect fit), I became a Music Man amp fan/player for life.

[G Mac]

Well, L5Larry... that is one beautiful family of amps! I too got my current MM after an ordeal with a Fender Hot Rod Deville. I guess we should thank Fender for their lousy customer service(at least in my case)! I must say that I'm slightly envious of your bevy of beastly beauties! Thanks for sharing!

Hey, pippy... what model is your 212?

And Farnsbarns... perhaps you should seek out an MM and do a side by side with your favorite Fender. You may become enchanted by(in my opinion) Leo's fine later works...

Peace to all!

[pippy]

Nice trio, Larry!..............

 

Mine is a 1977 (12AX7 Phase Inverter model) "212 Sixty Five".

It's the one pictured with the R0 in post #4 over in your MM thread in the Epi Lounge.

 

I noticed that you mentioned you swapped the caps out. I've read reports discussing how different valves (tubes) can give the amps a different 'character'. I'd be interested to hear what the cap-swap delivered.

 

Mine is still stock (EL34s apart). I've been meaning to replace the rather tired-looking speaker-cloth for a few years now but have never gotten around to actually doing anything about it.

 

Pip.

[Dub-T-123]

Nice trio, Larry!..............

 

Mine is a 1977 (12AX7 Phase Inverter model) "212 Sixty Five".

It's the one pictured with the R0 in post #4 over in your MM thread in the Epi Lounge.

 

I noticed that you mentioned you swapped the caps out. I've read reports discussing how different valves (tubes) can give the amps a different 'character'. I'd be interested to hear what the cap-swap delivered.

 

Mine is still stock (EL34s apart). I've been meaning to replace the rather tired-looking speaker-cloth for a few years now but have never gotten around to actually doing anything about it.

 

Pip.

People replace the electrolytic caps in old amps as part of regular maintenance. These caps are mainly used to filter the power supply, and go bad over time causing noise issues. Replacing the caps is about curing noise issues more than changing the tone (unless we're talking about a different modification)

 

From what I understand the Music Man amps still come up for sale cheap because many of them had solid state preamps, vibrato, and reverb

[pippy]

Ah. Thanks for that, Dub...............

 

Yes, the MM's had a solid-state per-amp section with a valve power-amp.

For obvious reasons they don't have the same 'classic' status as a Twin, of course, and they never will but, hey, I still like mine just fine..............................

 

As far as the reverb tank goes from what I've read the MM amps used the very same Accutronics 4-spring reverb tank as Leo used in his Twin Reverb.

No idea about the tremolo circuitry workings, though.

 

If Farns and I manage to sort out another session in the rehearsal rooms we'll have to write up our respective reports.

 

Pip.

[Dub-T-123]

Ah. Thanks for that, Dub...............

 

Yes, the MM's had a solid-state per-amp section with a valve power-amp.

For obvious reasons they don't have the same 'classic' status as a Twin, of course, and they never will but, hey, I still like mine just fine..............................

 

As far as the reverb tank goes from what I've read the MM amps used the very same Accutronics 4-spring reverb tank as Leo used in his Twin Reverb.

No idea about the tremolo circuitry workings, though.

 

If Farns and I manage to sort out another session in the rehearsal rooms we'll have to write up our respective reports.

 

Pip.

I don't doubt that they sound great

 

The reverb tank needs to be driven by an amplifier stage to work properly. In the Twin, this is done with a tube, in MM amps it seems to be solid state.

 

The vibrato in the twin has a tube LFO for example, while the MM would be solid state

[pippy]

The reverb tank needs to be driven by an amplifier stage to work properly. In the Twin, this is done with a tube, in MM amps it seems to be solid state.

 

The vibrato in the twin has a tube LFO for example, while the MM would be solid state

Yes...............I knew that.

 

 

Can you tell I'm not exactly an expert on electronics, circuitry and amp design?.................lol!

 

Thanks again!

 

 

Pip.

[Dub-T-123]

Yes...............I knew that.

 

 

Can you tell I'm not exactly an expert on electronics, circuitry and amp design?.................lol!

 

Thanks again!

 

 

Pip.

I wouldn't call myself an expert either but we definitely have some experts here that could give us a more informed/detailed explanation.

[Guest Farnsbarns]

I wouldn't call myself an expert either but we definitely have some experts here that could give us a more informed/detailed explanation.

 

I have a reverb circuit I nearly always use which drives the send and return to and from the tank with a 12ax7 (ecc83). Half of the tube driving send and half driving the return.

 

The return signal is very week so many use 1 and a half valves with one using both sides to drive the return and half a valve (using shared with a gain stage) driving the send. Also reduces the risk of an oscillation.

[pippy]

...we definitely have some experts here that could give us a more informed/detailed explanation...

I have a reverb circuit I nearly always use which drives the send and return to and from the tank with a 12ax7...

This is where my ignorance is a bit of a bugger. I've (almost) no idea what actually does what in the back of my MM.

As I mentioned earlier my "212 Sixty Five" is the '74-'77 version which has the 12AX7 phase inverter. What - precisely - does this do?

 

According to one source on the web;

"Originally, this design had a 12AX7 phase splitter (the circuit that derives the 180 degree phase shift and drives the output tube pairs in push-pull)..."

 

...yet according to another source;

"In the first few years of production, they used a 12AX7 tube for the pre-amp stage. Shortly after, they switched to a solid-state pre-amp. Many are fooled by the sight of a 12AX7 tube in all Music Man amps. That is the rectifier tube for the reverb, not the pre-amp."

 

What does all this mean? Who is right? Are they saying the same thing? In the early circuits is the 12AX7 used to drive both the pre-amp and the reverb?

I've always been led to believe that the essence of the MM gear was the hybrid SS/valve pre/power design yet the second source appears to claim that the early amps used the 12AX7 for the pre-amp.

 

I'm confused.....

 

 

Pip.

[Guest Farnsbarns]

Without researching it I suspect both are correct. There may well have been a few early examples with valve pre amps. In your amp a 12ax7 (ecc83 for Europe really) drives an "upside down" version of the wave form into one of the power valves. There are 2 power valves in this instance one receiving the upside down wave form and one receiving a right way up wave form. Both feed into opposite wound coils (opposite wound resulting, therefore, in re-alinged phase) in the output transformer. One reason for this is that it cancels out even order harmonics (great for hifi, arguably not so good for a guitar amp but ho hum, loads of excellent push/pull guitar amps out there).

 

There is also very likely (as in your quote) a valve driving the reverb return, possibly send as well. Why anyone would refer to that as a rectifier I don't know, that's just wrong, unless there is a separate ac-dc retifier for the reverb. Hmm, interesting.

 

That research I didn't do might prove interesting, if I do it.

[Dub-T-123]

The phase inverter is part of the preamp really. Not sure how the reverb is driven without looking at a schematic, but I would think it is solid state

[Guest Farnsbarns]

The phase inverter is part of the preamp really. Not sure how the reverb is driven without looking at a schematic, but I would think it is solid state

 

Yes, so the preamp provides both an upside down and a right way up wave form, one to each power valve.

[pippy]

...Hmm, interesting.

That research I didn't do might prove interesting, if I do it.

If we manage to meet up for a few beers on Thursday night you can confuse me in even more detail!...........

 

The phase inverter is part of the preamp really. Not sure how the reverb is driven without looking at a schematic, but I would think it is solid state.

I'll try to find the schematics. I've seen them quite a few times and have gazed admiringly at all the funny squiggles and shapes therein.

From what you say above it would seem that if the phase inverter used a valve/tube - the 12AX7 - does it follow that at the early production amps' preamp circuitry was valve-based?

 

Pardon my slowness...

 

Pip.

 

EDIT : Here you go.

The 212 65 is model number 2475-65.

 

http://www.thetubestore.com/lib/thetubestore/schematics/MusicMan/Musicman-2475-65-2275-65-Schematic.pdf

[Dub-T-123]

Just checked out the schem and the reverb is driven by op amps while the LFO is created with a BJT (transistor)

 

http://www.thetubestore.com/lib/thetubestore/schematics/MusicMan/Musicman-2475-65-2275-65-Schematic.pdf

[Dub-T-123]

If we manage to meet up for a few beers on Thursday night you can confuse me in even more detail!...........

 

 

I'll try to find the schematics. I've seen them quite a few times and have gazed admiringly at all the funny squiggles and shapes therein.

From what you say above it would seem that if the phase inverter used a valve/tube - the 12AX7 - does it follow that at the early production amps' preamp circuitry was valve-based?

 

Pardon my slowness...

 

Pip.

 

EDIT : Here you go.

The 212 65 is model number 2475-65.

 

http://www.thetubestore.com/lib/thetubestore/schematics/MusicMan/Musicman-2475-65-2275-65-Schematic.pdf

I must have been typing when you posted.

 

Actually this looks like the schem for the later version. I've gotta go back to work now but "at a glance" I'm not seeing the 12AX7 in this schem or any that I can find online.

 

What tubes do you have in your amp Pip? If it's one 12AX7, and four 6CA7 then I think it's safe to say that the 12AX7 is only acting as the phase inverter

[G Mac]

Hey, everybody! Thanks for your posts! If anyone is interested, the best website that I have found regarding these amps is www.pacair.com/mmamps3/ That address goes to their welcome page. This site is a treasure trove of info and knowledgeable folks who are willing to help! They have it all; from schematics to model/chassis #'s to owner's manuals and more! I must confess that I am an electronics know-nothing but, I still find the dicussion interesting in the same way that I find heiroglyphics fascinating...

As far as replacing the caps goes; I would agree that the sound quality didn't change too much but, it did have some effect to my ears. I found that the gain channel had gotten "mushy" and between the recap and putting JJ brand tubes in it(two 6L6's and a 12AX7), it came back to its former glory. Fortunately, all the solid state components were still solid!

And "Hey, pippy!". I should have remembered your post on the Epiphone Lounge; it's just that I was so stunned by the beauty of your Les Paul!

Peace to all!

[Guest Farnsbarns]

Caps in the power supply will have no effect on sound (unless they're shot causing motorboating or humming). Caps in the tone stack will make a difference if you're changing values or, again, replacing shot ones.

[G Mac]

Hey, Farnsbarns! All the caps in my amp were no longer holding a charge so my repair guy changed them all. I think it was thirteen in all. Again, I am electronically challenged so, I don't really know anything beyond what my tech told me. It sounds like you have a great deal of knowledge about such things and I certainly appreciate your input. I think that most of the tonal restoration was due to the JJ tubes. It wasn't 'til I put them in that the original sparkle returned. Hoping all's well across the pond!