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turning a hammond tone cabinet into a giant reverb. help!
Old 5th June 2017
Gear Maniac

Yup. Well, best of luck! I think this has the potential to be a cool toy, but it'll take a bigger brain than mine! I'll start a new thread and hope to lure some "experts" in! Best of luck, and let me know if you ever get yours up and running!
Old 9th February 2020
Getting back around to this.

Im almost certain this amp can is just a preamp. I ran it into a tube preamp and got much better sound. I think it's also looking for guitar level on the input.

I did have a ratshack barrel transformer to go from guitar to the mic cable i wired into the can, i might try and remove that and see what i get. The sound was much more acceptable, but pretty dark. Absolutely no reverb either. I unplugged the reverb from the can even to verify no verb.

The weird bit is, the output transformer measures 16ohm, but two 8ohm speakers in series gave me nothing on the output. (Edit: Tracing wires in this can is actually kinda hard for what little is in it. That transformer goes from one unused feature to another in my case.)

Still a lot of mystery!

Last edited by sameal; 10th February 2020 at 02:01 PM..
Old 10th February 2020
I believe this unit is a hammond DXR-20. I found some photo's of one that looks a lot like the one i have. And it is being used as a preamp.

But no schematics!
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Old 10th February 2020
Confirmed! Same tube configuration.
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Old 4 weeks ago
Alright! I AM getting reverb from my original connections. I put an amp at the back end and plug straight in on the guitar to the preamp can.

It's just really soft, but i can hear the springs.

Hey! Looks like somebody did the homework for me!

Last edited by sameal; 4 weeks ago at 08:24 PM..
Old 4 weeks ago

Now, you need to add a gain stage in the front end.....


Old 4 weeks ago
Originally Posted by tINY View Post

Now, you need to add a gain stage in the front end.....


I think it needs to be a BIG gain stage too from what im reading.
Old 4 weeks ago

A 12AX7 can get you at least 30dB.....


Old 3 weeks ago
I used two roberts preamps in the test. I know those have plenty o'gain.

Turns out that my rochelle salt is caput. It had enough left to give weak signal making it seem like a problem in the preamp. I put a piezo element in the spring like a stuck frisbee and behold! Glorious and rediculous amounts of reverb.

So now im replacing the salt crystal pickup with a piezo, maybe reintroducing the original preamp, and playing with additional piezos in different places
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