Add Rate Control to EHX Memory Man Deluxe LFO

[Mr. Lime]

Hi

I currently have a MMD clone on my bench and thinking of adding a rate control as it can be found on several other delays/choruses.

Howard Davis seems to offer such a modification.

DELUXE MEMORY MAN "LESLIE" EMULATION UPGRADE - not just a simple mod but a whole new range of effects, plus an expanded range of the effects the Deluxe Memory Man already delivers.

Who does not love that lush, liquid, rotating speaker effect? It is a complex combination of phase and amplitude modulation, hard to produce without mechanically rotating speakers. With this new upgrade you can now get it from your Deluxe Memory Man. You can set it for whatever rotational speed you want, and vary it from very subtle to so heavy it sounds like a rich tremolo. You can blend it with dry signal if you wish, and you can enhance it with feedback to get some indescribable, unique psychedelic and surf effects.

As it comes from the factory, the Deluxe Memory Man has only two modulation speeds - very slow for producing the chorus effect, and one faster speed for vibrato. This new "Leslie" modification upgrades the modulation oscillator with an added MODULATION RATE control pot. In addition it changes the chorus/vibrato switch to be chorus/vibrato at one setting, and the new LESLIE ROTARY EFFECT at the other.

Nothing is lost. Your Deluxe Memory Man will still be able to do everything it now does, and it will sound the same. What is ADDED is the ability to vary the modulation rate of the chorus and vibrato effects, and the amazing new Leslie rotating speaker emulation.

R51 (910k ) could be easily replaced with a 1M pot for the modulation speed and I guess the Vibrato/Chorus switch could be omitted when it's done.
I found a calculation of a Ce-2 LFO.
Is there something else to consider for this mod, especially concerning delay or chorus times?








Thanks!

[ElectricDruid]

There *is* one other thing to consider:

The rate control on the CE-2LFO you show reduces the amplitude of the LFO output as the rate increases. For chorus, this is actually quite useful as the amount of pitch variation will increase if the rate is increased without lowering the amplitude, giving the famous "seasick" effect.

Changing R51 to 1M variable will change the rate, but won't change the amplitude.

Try it both ways maybe?

HTH,
Tom

[Mr. Lime]

Thanks for the quick reply, Tom!

You're probably right. I've seen a lot of LFOs with the rate pot grounded or at least a 2u2 cap grounded after the schmitt trigger. As I would like to improve especially the chorus on the MMD I may have to try it.
The Magnus Modulus Chorus/Delay has separate controls for speed and "smooth" but to me it seems not very practical.
Is there anything else I could do to enhance the chorus effect of the MMD?
Sure it's no CE-2 with the pre- and post filtering but it's analog at least..

Not sure if waveform switch instead of the vibrato/chorus switch would be worth the work. I think I have seen an easy method somewhere and a pedal demo with square waves wasn't too bad at all.
After all I would like to keep the changes simple but effective.

Anything else to recommand?