Hammond H-122 mod

[baddog]

hello everyone

im planning on eliminating the bass channel and keeping the reverb . Any thoughts on how to mod it for guitar use?

thanks
baddog

[luthierwnc]

I can't get them to blow-up. Are they the Foldback schemo? sh

[baddog]

I opened it up with Adobe Reader 7.0 and didnt have a problem. I had to right click and then hit open . It wont open if i double click on it. Im not very computer savy so soory for the mixup.

baddog

[luthierwnc]

Savvier than me ... worked like a charm.

You have enough going on in that amp electronically that you can do whatever you want -- within the limitations of power and voltage. The trouble with stereo amps is that you have to split the signal sooner than the phase inverter so it is harder to be sure you are getting it even from both channels. You could have two completely different amps in the same box.

I'd start with what you want it to be and go from there. Gibson had a couple stereo amps like the 79RVT that might be a good place to start.

sh

[baddog]

hi

I think im going to try and make my own switching for the reverb and delay and put the guitar signal at the begining of the reverb and apply it to both channels. I got the amp for nothing so what do i have to lose.

keith

[luthierwnc]

You may as well. Keep in mind, you had better use a fairly clean circuit. EL84's get crunchy fast. If you run the reverb (or any time-delay) FX in the front end, it is going to distort through the gain stages. If this is going to be beastly, I'd be inclined to loop it near the PI. sh

[baddog]

When you say loop it through the PI do you mean phase inverter. How would i tie the input and output into the phase inverter. Could you draw something simple up and post it. Im pretty sure in now what you mean but i want to be sure.

Thanks
keith

[luthierwnc]

When I am in an amp mood I have mostly hung around the ampgarage. In the Dumble section you can find several active and passive loops and/or reverbs. Generally, they are right before the inverter with a resistor on the dry side between the send and return to equalize the load.

With as much electronic space as you have, you might seriously look at an active loop paralleled with the reverb so you can run other stuff in there too. Attached are a couple schematics I borrowed from Gary Johnson. They are publicly on his site but I still like to give credit where it is due -- expecially since he is a good guy.

Have a look and I'll keep an eye on this thread.