Effet, Jon Lord, DEEP PURPLE

Below is Roger Glover's response to someone on alt.music.deep-purple who had questions about the mystery box on Jon's Hammond in the pre-reunion days:

Subject: Re: Effect device on Jon Lords Hammond C-3
From: (BAsec5)
Date: 10 Jun 1995 13:27:38 -0400

>This is something that's been puzzling me for a long time.
>Since cirka 1972, Lord has had some sort of effect box on
>top of his C-3. This box produces the strange noice that f.
>instance can be heard on the intro to Lazy on Made in Japan
>or the intro to You Fool No-one on both California Jam and
>Live in London.

>My question is: What precisely is this? Any ideas who make
>them, what they're called etc.

The device you're referring to is a ring modulator. His one was made by Gibson (NOT the guitar company, we think) and is no longer available, certainly not a a 'stand alone' device. It was an ugly, square box secured (nailed probably!) to the left side of his C3 so that his left hand could control what he played with his right. The effect of ring modulation is quite strange; - what one puts into it is transformed by a process that I couldn't explain (harmonic distortion I think, maybe someone more technically oriented could help?), but the resulting noise bears no resemblance to the original signal, and can be 'modulated' by a variable that the player has control of. One of the best examples of this is on the middle section of Woman From Tokyo. I remember well the session, I tried to get Jon to do the 'sweeps' very slowly and it worked well. That was one complete take. He still has his 'somewhere' but it is not an active part of his rig at the moment. These days, ring modulation can be found as a programme on many good sound effects modulators, or synthesizers, on the market, although the way Jon uses it - the 'old fashioned - way, is far superior because it is more controllable.
And yes, you're right, he played it on the live tracks you mentioned.