Question New Music Man Amps questions.

[Spudmurphy]

In his blog, BP said that "the guitar amps are faithful reproductions the bass amps are super current".

As there were quite a few different models of the guitar amp built in the 70's/80's,some with solid state preamp, and some with a 12AX7 tube and 6CA7 or 6l6GC power amp tubes delivering 50/65/75/100/130/150 watts rms.

At this time, are we able to know the guitar amps that are going to be re manufactured please ?

Cheers.

 

[Johnny Alien]

I know for a fact that I don't have that info but they are most famous for the solid state pre design so I just assumed that is how they were going to go.

 

[Warg Master]

I'd vote tubes

 

[TNT]

only if you "promise" not to tell anyone!!

 

[Johnny Alien]

I think there was only ever one all tube MM amp. In the one's with the one 12AX7 that was a phase inverter tube and the preamp was solid state. Those were on the script models I believe and likely the ones that are reissued although the tube PI did not affect the preamp tone at all. There are those that say it did and if you swap tubes it would make a tonal difference but in my experience that was not the case.

 

[John C]

I think there was only ever one all tube MM amp. In the one's with the one 12AX7 that was a phase inverter tube and the preamp was solid state. Those were on the script models I believe and likely the ones that are reissued although the tube PI did not affect the preamp tone at all. There are those that say it did and if you swap tubes it would make a tonal difference but in my experience that was not the case.

Those were the very early MM amps, but I think you're forgetting about the 1980s RD50 models. I had one of them and it certainly had a 12AX7 as a preamp on the gain (or "Limiter" as the called it) channel. It was kind of like having one of those BK Butler/Chandler Tube Driver pedals (a pedal with a 12AX7 tube in it from that same era) in the front end, but it didn't sound as nice as the Tube Driver pedal. That amp really sounded better to me with an OD pedal in front of the clean channel than it did on the gain channel.

 

[Spudmurphy]

Yup the RD 50 is the amp I got. You oughta hear them with the Ed Goforth mods - D**ble to a T

 

[Johnny Alien]

Those were the very early MM amps, but I think you're forgetting about the 1980s RD50 models. I had one of them and it certainly had a 12AX7 as a preamp on the gain (or "Limiter" as the called it) channel. It was kind of like having one of those BK Butler/Chandler Tube Driver pedals (a pedal with a 12AX7 tube in it from that same era) in the front end, but it didn't sound as nice as the Tube Driver pedal. That amp really sounded better to me with an OD pedal in front of the clean channel than it did on the gain channel.

I did forget the RD50 but that isn't "exactly" a preamp tube either. The 12ax7 is basically split and half acts as the phase inverter and the other half acts as a final gain stage. The preamp is still pretty much solid stage except for the gain.

 

[DrKev]

To the best of my knowledge, a phase inverter requires both sides of a 12AX7 (because there must be two outputs, one driving each tube). Perhaps both sides can operate in "distortion mode" at the same time (I have no idea 'cause I'm definitely no expert) but we can't get two signals out of half of the tube.

 

[Spudmurphy]

I'll get to the bottom of this and get an answer from a music man amp guru.
Watch this space.

 

[FUCHSAUDIO]

In the case of Dr Key, a two section tube like a 12AX7 can be a voltage amp, followed by what's often called a "Concertina" phase splitter, which is a stage that takes a single ended signal from the first half of the tube, and produces two equal but opposite phased signals to drive a pair of power tubes push pull. Wow, long sentance... The Music Man amps used this with the tube driver, before they designed the IC/Transistor driver in the later amps. Fender used this in the Princeton's and a few other models, but it was nothing innovative nor unusual and was used in audio and guitar amps by many companies. It's different from the Schmidt style diff-amp driver in traditional Fenders and overloads differently for sure.

As far as the RD-50's, they used the 12AX7 at a fairly low plate voltage as an overdrive stage or sometimes called a limiter stage. The majority of the RD-50 preamp circuits were solid state, but the second channel used that 12AX7 to produce a warm compressed tube overdrive. They can sound pretty decent when dialed up right, and some people have come up with mods for those amps to improve them like Ed Goforth.

My company also mods Music Man amps quite extensively: Fuchs Audio Technology

Hope this clarifies any questions on this subject....

 

[GHWelles]

I have a Marshall JMD-1 and that is a digital modeling preamp with a tube phase inverter and tube power section. Sounds great. I would think a solid state preamp might be even more authentic sounding than a digital pre, and the tube power amp section is really the key.

 

[DrKev]

Concertinas, eh? Ya learn something new everyday! Thanks for your response, Andy.

Indeed, a super easy google search brings up the 1980 version of the schematic where the 12AX7 is in the preamp gain circuit and the PI is solid state.

 

[Spudmurphy]

In the case of Dr Key, a two section tube like a 12AX7 can be a voltage amp, followed by what's often called a "Concertina" phase splitter, which is a stage that takes a single ended signal from the first half of the tube, and produces two equal but opposite phased signals to drive a pair of power tubes push pull. Wow, long sentance... The Music Man amps used this with the tube driver, before they designed the IC/Transistor driver in the later amps. Fender used this in the Princeton's and a few other models, but it was nothing innovative nor unusual and was used in audio and guitar amps by many companies. It's different from the Schmidt style diff-amp driver in traditional Fenders and overloads differently for sure.

As far as the RD-50's, they used the 12AX7 at a fairly low plate voltage as an overdrive stage or sometimes called a limiter stage. The majority of the RD-50 preamp circuits were solid state, but the second channel used that 12AX7 to produce a warm compressed tube overdrive. They can sound pretty decent when dialed up right, and some people have come up with mods for those amps to improve them like Ed Goforth.

My company also mods Music Man amps quite extensively: Fuchs Audio Technology

Hope this clarifies any questions on this subject....

Thanks very much for the reply. Andy Fuchs posts on the Musicman Amp Forum and over there I asked for somebody to clear this up.
He's a great guy who makes and mods amps. he's answered my queries in the past and once came back to me many weeks later after finding something in his workshop which he initially thought he didn't have.His work on Musicman amps is legendary, and you can follow his work on facebook where he posts threads on his musicman amp work - great player too! Nice that he tipped his hat to Ed Goforth - another MM amp guru.
Thanks again.