Volume Control on PR-40?

[jbjorge]

Hi folks,

I have a Leslie 122, Leslie 715, and a direct out feeding a keyboard amp hooked up to my Hammond B3. Sounds great, but I decided to purchase a Hammond PR-40 Tone Cabinet to add to my rig. I realize I can adjust the level of the two Leslie's and the keyboard amp to get everything balanced out, but it would be nice to also be able to adjust the volume level of the PR-40. Any thoughts or suggestions would be greatly appreciated!

Thanks,

Johnny B.

[MihevicB3]

There is not an overall volume control like on the Leslie. However, there is a bass volume adjust on the back of the amplifier. I believe it has about 4 settings of room size. Also, if you don't need the PR-40 necklace reverb, turning it off on the bass and treble will increase the volume. Next I would balance the Leslie volume to how it sounds best to you with the PR-40. If you turn the Leslie volume to max, it will overpower the PR-40. Mostly, the PR-40 will add a bottom end with more bass than the Leslie.

Hope this helps,
John M.

[jbjorge]

Thanks John. I understand that I can balance all the cabinets using the volume controls on the two Leslie's and the keyboard amp. I'm wondering how hard it is to build a simple circuit to control the level of the balanced out from the organ's preamp to just the PR-40. I did some research and this looks a lot harder than I thought. I think I'll try doing it your way. Seems much simpler.

[David Anderson]

You could install a volume control on a PR-40 rather like the one on a 122. You'd need a pair of resistors so that you didn't short out the whole balanced line signal and a potentiometer of reasonably high enough value that it didn't significantly drop the signal at full volume control setting.

You could even build it in an inline box.

[jbjorge]

Thanks David,

I'll check out the schematic for a 122 amp and see if I can sort it out! Your suggestion makes perfect sense. I started doing some research and wound up looking at some information on a balanced audio attenuator. At that point I decided I was way over my head.

Johnny B.

[David Anderson]

Leslie 31A amps had no volume controls, but they were added with other minor changes to the 31H, so you can dig up those schematics and compare.

[jbjorge]

Thanks David, That's absolutely brilliant! I've noticed that you are so helpful on this forum. Can't begin to tell you how much I appreciate it!