Cameron Aldrich mod questions.

drburns73

drburns73

Member
Hey there.
I recently bought a 100 watt JMP with an Aldrich mod. It sounds amazing. I was wondering if any of you out there with some knowledge of Mark's work could help me figure out the layout a little better. I have an idea of what the controls do from playing the amp, but I'm looking for more of a technical explanation of what they are.
1) There is a second gain control in place of the top input jack. How does this work in relation to the first gain control?
2) There are two knobs on the back: one is a depth and the other seems to be a presence that dials in more definition as the depth gets higher. Is this correct?
3) The amp seems quiet for a 100 watt JMP. Is this something Mark would do to keep the amp a bit more controllable, or should I have the power section looked at? It's currently running 6CA7's.
Thanks for your help!!
-Mike
 
All of his mods are a little different so it's kind of hard to tell what's on the back. Mine has a Voicing control, which appears to control the amount of negative feedback to go from vintage to modern response, and a Punch control, which appears to be sort of like a Resonance control (bass boost). The front though always seems to be pretty standard: bass, mid, treble, presence, volume, gain, and gain trim. The gain knob affects one gain stage and the gain trim affects another. The gain trim seems to add saturation and not a lot more distortion so on mine, it affects the feel and distortion character more than anything. If it seems quiet, try turning up the resonance control (maybe depth on yours?). My amp seems to get WAY louder as Punch is turned up. Mine's loud as hell anyway with the Punch knob set at 50%. I never have issues being heard with the master at 10 o'clock.
 
Is there a large cap along the back of the chassis in between V2 and the PI tube with a rectifier diode screwed through the chasis?
 
richard pretty much spelled it out. knobs on back are probably depth n voicing. the other gain on front cound be trim or pussy control and adjust the amount of signal in the voltage divider to ground making the gain wild or taming it.
 
Thanks for the info, guys.
I've been using the amp regularly so I haven't cracked it open as of yet, but here's a gut shot that I got from the previous owner. It's pretty gooped up, although it kinda looks like someone has made a de-gooping attempt.
 

Attachments

  • cameronguts.pdf
    774 KB · Views: 368
Thats a waste of effort to try and degoup one of Marks amps. If there is a large cap in between the pretubes like I said that is why it is quieter. DC heater conversion on the first 2 pretubes(4 gain stages) I think that might be the amp that has it. It was not degooped when I had it if it is.
 
You must log in or register to reply here.
Back
Top