Marshall madness...1/2 to 1 watt poweramp for a rack preamp?

[HappyTelecaster]

Hello!

After years of collecting weirdo analog stompboxes that are supposed to nail the Marshall sounds I have finally come to the conclusion that there`s no way around the real thing to get that sound and, what`s even more important, the sensible dynamic reactions of a real tube Marshall. So I bought a Marshall 9001 stereo tube preamp. It was in the mail yesterday and I have spent the whole last night in front of my computer with my Tele on my lap, playing guitar instead of searching the holy grail on the internet. I have found mine now - should have done this years earlier but back then I had some prejudice against 80s rack guitar equipment, thinking that there must have been sonical reasons for most of the greats moving away from using racks.
Well, now I must say that it is complete nonsense - this old Marshall unit is by far the best tube preamp I have ever played through and I`d love to fire a tiny tube poweramp with it to get that power tube saturation for the open sound. I only need a tiny poweramp because I want to do some recording with it. Is there anything like this available somewhere?


Greetings,

HappyTelecaster

[eugenedunn]

Hey Happy,

This little guy already has a preamp, so it may not be your thing. You can sub in a very low gain preamp tube and get a less colored amplification of your preamp signal though.

http://www.emerysound.com/Microbaby.html

[Slow Reflexes]

ZVex Nano?


Killer Ant?

[eugenedunn]

Unfortunately, both of those have preamp sections too. Same difference as the Emery Microbaby, but cheaper.

[11 Gauge]

Grab a Valve Junior or similar and have it modified into a slave power amp. Very simple. Just tap into the circuit where C2 is, taking care to connect to the end that goes to R5 and R15 on the PCB.


Or, you could run your input into R6's place (and make it switchable, if need be), and then you could use the VJr's volume to adjust the power amp level. You'd also get the benefit of an additional preamp gain stage. This might be a nice plus, or it might be too much.

Or, you could use the VJr's entire preamp and plug into the existing input, but tweak some components to make the amp much more of a power amp:

- Switch R8 and R9 to ~4.7K. This will reduce the VJr's preamp gain immensely.

- Remove C3 and C4 altogether. DON'T jumper their connections. This will also reduce gain, and give the amp a flatter frequency response.

- Switch R7 to anywhere from 47K - 150K. The lower the value, the less overdrive you'll get from the VJr's preamp section (this is what we're aiming for).

- Replace R10 with a 1K resistor, 3 watt or better. This will keep the power tube from overdriving as soon, and will also extend the life of the tube.

[marshman]

Well, I'm not sure where you'd be able to get it made, but every fender tube reverb is built around a little 1-ish watt SE output transformer and 12AT7 tube, maybe there's a way to make that work for you. I think the AX84 website has some details about such a rig.