New project: JCM 800 -> tone/volume -> Bandmaster PI+PA

[johnnyl]

Hi everybody, I´ve got a new project in the works

My favourite amp is the Marshall JCM 800 (& its infinite variants), but the first amp I´ve built was a "Lite" version of the Marshall 18 watt, and I really liked both its tone & simplicity... So, I´ve been thinking about mixing the two, and therefore basicly build a tone/volume JCM 800, for quite some time now. In the meantime I´ve got a (blackface) Bandmaster OT floating around and, since I like to mix things up and experiment a little bit, I´ve decided to use it for this project and feed the JCM 800 pre with tone/volume tonestack into an AB763 Bandmaster PI+PA+PSU.

One thing I´ve always wondered about though (since I´m not exactly an engineer ): does it make sense to keep the cathode follower at the end of the preamp (see the first of the two schems below), even though the tone/volume controls are more of a frequency cut than a "real" tone stack? Or should I just feed the JCM 800´s first two gain stages directly into the Lite pre (see the second schematic)?

[Haze13]

You can't just get rid of a cathode follower, since it's some thing that icreases current of the gain staiges. I don't say that it won't work, it will, but not as good as you wish. There is a pedal made by soldano - GTO supercharger. It's a 4 gain stages REAL tube overdrive. Some tried to run it before PI and Power Amp, and the result was bad (tonewise).
To make it work, you need to change ather things in the design. Look at the Blackheart BH15 schematics, it's may be an answer to your quastion.
Use Google for better resolution...

[rollyerown]

You CAN dump the CF. I've done it. But you lose a big part of the marshall tone. It becomes less middy, more fender like. If you like the JCM tone thats the last thing you wanna do.

[johnnyl]

Well, that wouldn´t be a big concern, since I like to "explore" new directions and already have a couple JCM-style amps...

I actually already tranformed the CF in an additional gain stage in a JCM 800-ish build before, and I liked the results (and especially the added gain! ) - I was more wondering if it would make any sense to KEEP the CF even if it won´t have a "regular" tone stack, but just a tone cut control...

[Ferrari-Dude]

The Marshall Silver Jubilee series of amps has a plate-driven EQ stack.

2550 and 2555 models.

I think they sound a little darker than the JCM800 style of amps but there is no denying they've got lots of gain. Add to that, the diodes in the preamp for clipping and you've got crunch to spare.

Check out SDM's page for schematics.

http://home.comcast.net/~mamp17/Jubilee%20Layouts.html" onclick="window.open(this.href);return false;