Music Man Power Supply [was Re: #102 died yesterday :( how,why]

[rootz]

Schematic! Really, all links in that thread are dead, so have to guess what you mean exactly. Might it be what's in the schematic below? Centre tap as supply for screens, pi and preamp tubes. Mostly standard precision ps. Either way, it strays (a lot) from the topic here. Balancing resistors in a ps and those in a heater supply are very different things to begin with.

[talbany]

Hi Rootz, I remember reading somewhere that some high voltage amps (using music man HD130 PT, which had something like 700v on plates) were using not only balancing resistors for the power amp tubes but additional ones for the preamp tubes, and I was wondering why and how to do it. Those amps also had a second choke for the preamp heaters. Unfortunately this is as much information as I have...but wanted to undestand how to wire something as such...just as curiosity..

Are you referring to how Dumble implemented the MM powers into his ODS's or how Music Man's HD amps were done?

Tony

[Bombacaototal]

Hi Tony, I was referring to the Alligator Pentode amp with the MM HD130 PT. But I think I deviated a bit from the original topic...

Thanks Rootz, yes I started to deviate a bit, sorry...

[rootz]

No problem! Deviating is kind off my thing. So it was also a note to myself.

[talbany]

Hi Tony, I was referring to the Alligator Pentode amp with the MM HD130 PT. But I think I deviated a bit from the original topic...

Thanks Rootz, yes I started to deviate a bit, sorry...

First I don't know that the exact details of the Ry Cooder amp that has been disclosed and verified with detailed pics (or a trusted source?) but does make some sense in an SSS.. 2nd. The MM 200-130 PT has 2 X 6.3V supplies (coming off the same winding). In the ODS Dumble uses one for the filaments and 1 for the relays through a voltage doubler. According to Electron (who has been in the amp) says there was a separate filament transformer to supplement the load ( makes sense). If this is the case and the extra transformer he used did not have a CT then he more than likely ran the preamp tubes off that transformer and this is the reason for the extra false CT resistors being on the preamp sockets.. As far as the extra choke?.Dumble usually runs the screens (1/2 Voltage)off the doubler from the main filter caps (Splits them) then sends that through a choke off a separate branch from the preamp supply.Now a 2nd choke could be added to the preamp section coming off the HV side after a large 10w dropper (usually between a 30 or 35K) power resistor. He doesn't add an extra choke on his ODS's so this would be something a bit different but makes sense in an SSS type topology /w Reverb.
Here is the Cooder SSS in action
https://www.youtube.com/watch?v=ftRMqJaAFyI

Does this answer your question?

Tony

[pompeiisneaks]

Very interesting read and learning. For my last amp, which uses the 40-18042 classic tone PT I didn't use the balancing resistors on the heaters because the PT already has a central ground. Would it be advisable to use the 100R (1/2W) regardless of the PT having that central ground? I think I will add it to my amp...

that's a good question and I'd be interested in people views on this too. I've always used the CT if it's there.



M

As I understand it, you need to remove the center tap if you're using balancing resistors for the virtual center tap.
I also have hears the same thing on several fb threads that the 100R resistors act like a OT protector.

[sluckey]

It's only a problem if the power tubes have the plate pin adjacent to a filament pin.

[Bombacaototal]

Hi Tony, I was referring to the Alligator Pentode amp with the MM HD130 PT. But I think I deviated a bit from the original topic...

Thanks Rootz, yes I started to deviate a bit, sorry...

First I don't know that the exact details of the Ry Cooder amp that has been disclosed and verified with detailed pics (or a trusted source?) but does make some sense in an SSS.. 2nd. The MM 200-130 PT has 2 X 6.3V supplies (coming off the same winding). In the ODS Dumble uses one for the filaments and 1 for the relays through a voltage doubler. According to Electron (who has been in the amp) says there was a separate filament transformer to supplement the load ( makes sense). If this is the case and the extra transformer he used did not have a CT then he more than likely ran the preamp tubes off that transformer and this is the reason for the extra false CT resistors being on the preamp sockets.. As far as the extra choke?.Dumble usually runs the screens (1/2 Voltage)off the doubler from the main filter caps (Splits them) then sends that through a choke off a separate branch from the preamp supply.Now a 2nd choke could be added to the preamp section coming off the HV side after a large 10w dropper (usually between a 30 or 35K) power resistor. He doesn't add an extra choke on his ODS's so this would be something a bit different but makes sense in an SSS type topology /w Reverb.
Here is the Cooder SSS in action
https://www.youtube.com/watch?v=ftRMqJaAFyI

Does this answer your question?

Tony

Hi Tony, yes that is very interesting and does answer my question. The extra transformer could then either be an extra choke (very clear explanation on how to do it) or an extra filament transformer. If the latter then he would have the power tubes using the PT heaters and the preamp tubes using this extra transformer.

I don’t think this amp has ever been verified beyond Aarons attempt and the info from that thread.

But I have always been intrigued by those MM amps. What is the reasoning for running an amp at such high voltages? So far I’ve only done fende style 320-0-320 transformers. Am I missing anything? Maybe I will try a MM on the next opportunity

By the way, I am almost sure that song was recorded with the Borderline. The tremolo does sound like the LFO from that amp that I tried to build. The Alligator has a simple AB763 tremolo which sounds a bit different to my ears.

[talbany]

Hi Tony, I was referring to the Alligator Pentode amp with the MM HD130 PT. But I think I deviated a bit from the original topic...

Thanks Rootz, yes I started to deviate a bit, sorry...

First I don't know that the exact details of the Ry Cooder amp that has been disclosed and verified with detailed pics (or a trusted source?) but does make some sense in an SSS.. 2nd. The MM 200-130 PT has 2 X 6.3V supplies (coming off the same winding). In the ODS Dumble uses one for the filaments and 1 for the relays through a voltage doubler. According to Electron (who has been in the amp) says there was a separate filament transformer to supplement the load ( makes sense). If this is the case and the extra transformer he used did not have a CT then he more than likely ran the preamp tubes off that transformer and this is the reason for the extra false CT resistors being on the preamp sockets.. As far as the extra choke?.Dumble usually runs the screens (1/2 Voltage)off the doubler from the main filter caps (Splits them) then sends that through a choke off a separate branch from the preamp supply.Now a 2nd choke could be added to the preamp section coming off the HV side after a large 10w dropper (usually between a 30 or 35K) power resistor. He doesn't add an extra choke on his ODS's so this would be something a bit different but makes sense in an SSS type topology /w Reverb.
Here is the Cooder SSS in action
https://www.youtube.com/watch?v=ftRMqJaAFyI

Does this answer your question?

Tony

Hi Tony, yes that is very interesting and does answer my question. The extra transformer could then either be an extra choke (very clear explanation on how to do it) or an extra filament transformer. If the latter then he would have the power tubes using the PT heaters and the preamp tubes using this extra transformer.

I don’t think this amp has ever been verified beyond Aarons attempt and the info from that thread.

But I have always been intrigued by those MM amps. What is the reasoning for running an amp at such high voltages? So far I’ve only done fende style 320-0-320 transformers. Am I missing anything? Maybe I will try a MM on the next opportunity

By the way, I am almost sure that song was recorded with the Borderline. The tremolo does sound like the LFO from that amp that I tried to build. The Alligator has a simple AB763 tremolo which sounds a bit different to my ears.

Good I am glad I answered it.
It's a bit hard to explain the effect's of the added voltage on the plates provide. I'll just give you my take
The best way to describe it would be like adding a supercharger to an engine. The amp is more touch sensitive and has (for lack of a better word) a bigger sound and really pushes the mids out front. The sound is also clear and the lows are a bit tighter.Now with the amp down low and at livingroom levels it's not as noticeable so I am mainly talking gig volumes with the 34's pushed. The HD series Music Man amps were known to have similar qualities right? Loud amps with a big clean sound and real touch sensitive bright articulate and with plenty of mids!. Now I wouldn't say this is like playing a Music Man amp it just adds some of those qualities to the output section. More like an ODS seasoned with some Music Man Mojo
One other thing I'll add is OP tubes really matter in this amp! Last week a friend of mine came over and brought a Quad of Telefunken 34's and we loaded it up. The difference was rather stunning. So there is that. BTW. I almost cried when I had to pull those tubes out they were really nice

You may be right about it being a Boarderline? especially with how the tremolo sounds. All I can say is an SSS has a very distinct sound and that clip has that SSS sound all over it So we will just have to agree to disagree on that. Maybe I'll double check that one with Max

There it is! If those are some qualities you like in an amp then I would recommend it if not then stick with the 320.

Tony

[rootz]

Hi Tony, is this how the MM amps were done by HAD? This is essentially how a HD130 is done I think. Doubler, with the screens tapped from the doubler. 800V to the plates, 400V to the screens/preamp. All from a single 300VAC secondary winding. Lower it to 230-250VAC and this way you'd have a hefty setup for a couple of 6550A's with 12BH7 driver in class AB2 for a SSS from hell. Oh well, I'm diverting. Again

[Bombacaototal]

First I don't know that the exact details of the Ry Cooder amp that has been disclosed and verified with detailed pics (or a trusted source?) but does make some sense in an SSS.. 2nd. The MM 200-130 PT has 2 X 6.3V supplies (coming off the same winding). In the ODS Dumble uses one for the filaments and 1 for the relays through a voltage doubler. According to Electron (who has been in the amp) says there was a separate filament transformer to supplement the load ( makes sense). If this is the case and the extra transformer he used did not have a CT then he more than likely ran the preamp tubes off that transformer and this is the reason for the extra false CT resistors being on the preamp sockets.. As far as the extra choke?.Dumble usually runs the screens (1/2 Voltage)off the doubler from the main filter caps (Splits them) then sends that through a choke off a separate branch from the preamp supply.Now a 2nd choke could be added to the preamp section coming off the HV side after a large 10w dropper (usually between a 30 or 35K) power resistor. He doesn't add an extra choke on his ODS's so this would be something a bit different but makes sense in an SSS type topology /w Reverb.
Here is the Cooder SSS in action
https://www.youtube.com/watch?v=ftRMqJaAFyI

Does this answer your question?

Tony

Hi Tony, yes that is very interesting and does answer my question. The extra transformer could then either be an extra choke (very clear explanation on how to do it) or an extra filament transformer. If the latter then he would have the power tubes using the PT heaters and the preamp tubes using this extra transformer.

I don’t think this amp has ever been verified beyond Aarons attempt and the info from that thread.

But I have always been intrigued by those MM amps. What is the reasoning for running an amp at such high voltages? So far I’ve only done fende style 320-0-320 transformers. Am I missing anything? Maybe I will try a MM on the next opportunity

By the way, I am almost sure that song was recorded with the Borderline. The tremolo does sound like the LFO from that amp that I tried to build. The Alligator has a simple AB763 tremolo which sounds a bit different to my ears.

Good I am glad I answered it.
It's a bit hard to explain the effect's of the added voltage on the plates provide. I'll just give you my take
The best way to describe it would be like adding a supercharger to an engine. The amp is more touch sensitive and has (for lack of a better word) a bigger sound and really pushes the mids out front. The sound is also clear and the lows are a bit tighter.Now with the amp down low and at livingroom levels it's not as noticeable so I am mainly talking gig volumes with the 34's pushed. The HD series Music Man amps were known to have similar qualities right? Loud amps with a big clean sound and real touch sensitive bright articulate and with plenty of mids!. Now I wouldn't say this is like playing a Music Man amp it just adds some of those qualities to the output section. More like an ODS seasoned with some Music Man Mojo
One other thing I'll add is OP tubes really matter in this amp! Last week a friend of mine came over and brought a Quad of Telefunken 34's and we loaded it up. The difference was rather stunning. So there is that. BTW. I almost cried when I had to pull those tubes out they were really nice

You may be right about it being a Boarderline? especially with how the tremolo sounds. All I can say is an SSS has a very distinct sound and that clip has that SSS sound all over it So we will just have to agree to disagree on that. Maybe I'll double check that one with Max

There it is! If those are some qualities you like in an amp then I would recommend it if not then stick with the 320.

Tony

Great description Tony! Yes that is a tempting description for me to want to try this in the future for sure! Maybe on my next build, whatever that one may be

On the amp from Feeling Bad Blues hopefully Max will chime in!

[martin manning]

Rootz, Musicman amps had ca. 700V on the anodes, 350V on the screens via a voltage doubler. That requires 250VAC from the PT. Evidently HAD wanted more than 350V for the PI, so a large dropping resistor from the plate node was used to get, I'd guess, the 400V+ seen at the PI node in other ODS amps. From there, it'd be business as usual. The bias supply would have come from the low voltage winding on the PT that formerly powered the Musicman's solid state preamp.

[talbany]

On the amp from Feeling Bad Blues hopefully Max will chime in!

Max already mentions this in one of his older posts. I believe he owned the amp at one time. He referrs to it as the "Pentode" amp due to it's EF-86 front end.

"To get an idea, how the cleansounds of this amps are with tremolo and a bit of reverb listen to Ry Cooders "Crossroads" track 8, "Feelin' Bad Blues". This kind of "acoustic" sound I could easily get with the Pentode amp using a maple neck strat with usual strat single coils, jazz on, bright switch on, deep switch on (? not sure, maybe off) volume around 4 or 5, treble 9, middle 7, bass around 7 (not sure, maybe around 4), presence around 7, bit of reverb, slow tremolo."


https://ampgarage.com/forum/viewtopic.p ... ues#p69682

Tony

[talbany]

Hi Tony, is this how the MM amps were done by HAD? This is essentially how a HD130 is done I think. Doubler, with the screens tapped from the doubler. 800V to the plates, 400V to the screens/preamp. All from a single 300VAC secondary winding. Lower it to 230-250VAC and this way you'd have a hefty setup for a couple of 6550A's with 12BH7 driver in class AB2 for a SSS from hell. Oh well, I'm diverting. Again

Rootz
Here is a schematic of how Dumble configured his MM supplies in his ODS's. (Precision Power supply) As far as the voltages go Martin is correct. 700V B+ 350 scr /35V (pre amp)AC =50Vdc bias supply / 6.3V Fil /6.3V Rly

Super100_MMPSU (1).jpg

Tony

[Bombacaototal]

On the amp from Feeling Bad Blues hopefully Max will chime in!

Max already mentions this in one of his older posts. I believe he owned the amp at one time. He referrs to it as the "Pentode" amp due to it's EF-86 front end.

"To get an idea, how the cleansounds of this amps are with tremolo and a bit of reverb listen to Ry Cooders "Crossroads" track 8, "Feelin' Bad Blues". This kind of "acoustic" sound I could easily get with the Pentode amp using a maple neck strat with usual strat single coils, jazz on, bright switch on, deep switch on (? not sure, maybe off) volume around 4 or 5, treble 9, middle 7, bass around 7 (not sure, maybe around 4), presence around 7, bit of reverb, slow tremolo."


https://ampgarage.com/forum/viewtopic.p ... ues#p69682

Tony

Interesting Tony, thanks for sharing. To my ears it really doesn’t sound like an AB763 tremolo, but Max knows his stuff, so I believe it...