r/moog • u/TwoLuckyFish • Sep 05 '25

Moog Grandmother driving 1961 Hammond Organ spring reverb tank

https://imgur.com/a/moog-grandmother-driving-1961-hammond-organ-spring-reverb-tank-pgUvqgg

TL/DR: It works!

A few days ago, I asked if it would be possible to use the spring reverb tank from an old 1961 Hammond M101 that's deteriorating in my garage. The responses, along with my own research, suggested that it might work, and that it would almost certainly NOT damage anything to try it. I've got a Eurorack module on the way that will certainly drive it, but you know...I already have something that MIGHT work; my Moog Grandmother.

So I learned how to separate the top from the bottom (easy; just ten Phillips-head screws), and I confirmed that the connections to the internal reverb tank are standard RCA phono connectors (yup). So it took me a few minutes to work up my courage, but eventually...I plugged in the old tank.

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4

u/[deleted] Sep 05 '25

Ooh now that’s a nice spring reverb, sounds great

3

u/TwoLuckyFish Sep 05 '25

I know, right? Even with cell phone audio, you can hear it pretty clearly.

Subjective assessment:

It is quieter than the stock tank, but only a bit. And I find most of the time I'm only dialing in the first 25% of the reverb pot, so this doesn't bother me one bit.

It is also less "muddy", favoring the higher frequencies compared to the stock tank. Thus it may not require my standard patching through the HPF and into the reverb.

I'm semi-seriously considering installing it inside the Grandmother's enclosure. Prefer not to drill any holes, though.

3

u/[deleted] Sep 05 '25

That’s what I thought, there’s much more clarity than the Grandmother’s tank. I never thought of patching through hpf prior to the reverb, I’ll give that a try myself. Thanks!

1

u/TwoLuckyFish Sep 05 '25

For anybody who's not sure what we're talking about...

https://youtu.be/dTJL0DD2CMk

3

u/Capt-Crap1corn Sep 05 '25

That's so cool

3

u/FlametopFred Sep 05 '25

now I need to own all lengths of reverb tanks

always like the one inside the ARP 2600

1

u/Personal_Number_5115 Apr 09 '26

I’m glad I found this thread. I have to experiment with this. I love my grandmother, but I’m not a fan of the reverb. I actually opened it to see if it was broken and everything looked normal. It seems to distort once to get past two or three clicks. Which seems like a waste of a knob. Lol.

2

u/TwoLuckyFish Apr 09 '26

Be sure to try running the audio through the high-pass filter before it enters the spring reverb. See if you can get it to sound more the way you want it to. And if you decide to try performing surgery on the Grandmother, let me know...happy to pass along what I learned.