Master vol / power scaling for Plexi clone?

[jzucker]

Just picked up a rockytop JTM 45 clone and am looking for advice on the "best" MV circuit as well as possibly adding power scaling.

Thoughts?

[nickt]

IME the "best" MV is none at all - no experience with power scaling but believe it sounds better than MV and is pretty simple on a cathode biased amp. (not sure what a 45 is - suspect fixed bias).

Dana is about to start selling a board that varies supply voltage and bias voltage simultaneously controlled with a single knob - a VVR (variable voltage regulator) - there's a thread on the TrainWreck forum which points back to a thread on 18Watt on the VVR (it also talks about MV's).

cheers

[CaseyJones]

Just picked up a rockytop JTM 45 clone and am looking for advice on the "best" MV circuit as well as possibly adding power scaling.

Thoughts?

Hey Jack... I think you should throw down on a Soultone, it has the powerscaling built right in. You're the last person I'd trust with a soldering iron.

[jzucker]

IME the "best" MV is none at all - no experience with power scaling but believe it sounds better than MV and is pretty simple on a cathode biased amp. (not sure what a 45 is - suspect fixed bias).

Dana is about to start selling a board that varies supply voltage and bias voltage simultaneously controlled with a single knob - a VVR (variable voltage regulator) - there's a thread on the TrainWreck forum which points back to a thread on 18Watt on the VVR (it also talks about MV's).

cheers

Thanks. excuse my ignorance but who is dana?

Also, I'm not looking for overdrive at low volumes with the master. The master would be for just taking the edge off a really loud amp and getting some working range with the vol control. Of course, the scaling is a different matter. That *would* be for getting OD out of the amp at lower volumes. I realize that I might not need both...

[jzucker]

IME the "best" MV is none at all - no experience with power scaling but believe it sounds better than MV and is pretty simple on a cathode biased amp. (not sure what a 45 is - suspect fixed bias).

Dana is about to start selling a board that varies supply voltage and bias voltage simultaneously controlled with a single knob - a VVR (variable voltage regulator) - there's a thread on the TrainWreck forum which points back to a thread on 18Watt on the VVR (it also talks about MV's).

cheers

Yes, the 45 is a lower gain version of a plexi and fixed bias.

Thanks. excuse my ignorance but who is dana?

Also, I'm not looking for overdrive at low volumes with the master. The master would be for just taking the edge off a really loud amp and getting some working range with the vol control. Of course, the scaling is a different matter. That *would* be for getting OD out of the amp at lower volumes. I realize that I might not need both...

[jzucker]

Just picked up a rockytop JTM 45 clone and am looking for advice on the "best" MV circuit as well as possibly adding power scaling.

Thoughts?

You're the last person I'd trust with a soldering iron.

what's that supposed to mean?!?

[gearhead]

Dana = UR12 = Major Icon on this site.

MV - Do a search as per NickTs suggestion; pretty interesting read. Do be aware that the search function here defaults to OR (as in "VVR MV" would yield threads with one or the other). Need to put the word "and" in to narrow things down.

The short answer is probably PPIMV.

BTW, how much does your JTM-45 weigh?

[gearhead]

Just picked up a rockytop JTM 45 clone and am looking for advice on the "best" MV circuit as well as possibly adding power scaling.

Thoughts?

You're the last person I'd trust with a soldering iron.

what's that supposed to mean?!?

I think it's clear what he means. The real question is why he means it. Were you Lab class partners back in the day?

[jzucker]

You're the last person I'd trust with a soldering iron.

what's that supposed to mean?!?

I think it's clear what he means. The real question is why he means it. Were you Lab class partners back in the day?

i have no idea who he is and since i've never worked in a lab (other than a software one) it's highly unlikely...

I guess he's the last person I should be taking seriously...

[jaysg]

Jack goes back to the early Ampage days. Street cred geek style...

[jzucker]

Dana = UR12 = Major Icon on this site.

MV - Do a search as per NickTs suggestion; pretty interesting read. Do be aware that the search function here defaults to OR (as in "VVR MV" would yield threads with one or the other). Need to put the word "and" in to narrow things down.

The short answer is probably PPIMV.

BTW, how much does your JTM-45 weigh?

Ok, I looked it up. His board scales the whole amp. i wouldn't want to scale the preamp section. That would rob the character from the marshall circuit.

The jtm weighs around 35lbs.

[fusionbear]

I prefer to do the Fischer Type II PPIMV mod. It really helps with a JTM build. You only need to back of the volume a little to take the edge off with this mod.

[UR12]

Ok, I looked it up. His board scales the whole amp. i wouldn't want to scale the preamp section. That would rob the character from the marshall circuit.

The jtm weighs around 35lbs.

Just to set the record straight and head off some confusion, my board will do any part of the amp or the whole amp. Personally I perfer regulating the whole amp and using one knob to do everything but there are others who like the extra knob. The board will also work on fixed bias OR cathode biased amps. Even if you do the whole amp the VVR will rob the amp of nothing. On the contrary, the whole idea is to KEEP all of the character of the amp only at a lower vol.

[jzucker]

I prefer to do the Fischer Type II PPIMV mod. It really helps with a JTM build. You only need to back of the volume a little to take the edge off with this mod.

Is that the one with the dual 100k or the dual 1M? You have schematics/layouts?

[jzucker]

Ok, I looked it up. His board scales the whole amp. i wouldn't want to scale the preamp section. That would rob the character from the marshall circuit.

The jtm weighs around 35lbs.

Just to set the record straight and head off some confusion, my board will do any part of the amp or the whole amp. Personally I perfer regulating the whole amp and using one knob to do everything but there are others who like the extra knob. The board will also work on fixed bias OR cathode biased amps. Even if you do the whole amp the VVR will rob the amp of nothing. On the contrary, the whole idea is to KEEP all of the character of the amp only at a lower vol.

Sounds great. When/where will this be available? Thanks for the help.