Clock phase control?

Is there a module for that?

I want to control the phase of surge “rotary speaker”

thanks in advance

will try that

analyzing clock signal via oscilloscope,I understand that it’s not possible

(But maybe modulating the clock source🤔)

the feature should be in the surge module

Not sure if an LFO would help, but BOG 4FO has phase cv inputs for the 4 phase shifted outputs.

And Shapemaster has a CV input that basically moves it’s “playhead” forward with rising cv value, so saw shaped ramp makes it phase driven. Nearly anything you need, a sequence, modulation, clock, pitch cv, audio oscillations, can be coaxed from it.

1 Like

Shapemaster is a beast

Don’t really understand what you mean,I’m a novice

But I certainly will later

Novice here too, but it’s coming quicker everyday.


despite what the posts above say, I don’t think you can run a separate LFO into Surge Rotary to override the internal one. but if you can, then, like they say, there are plenty of choices.

1 Like

You can’t but you can hook up a ppq or bpm clock source and temposync the clock to that. If you use bpm it will respond to tempo changes every block.

1 Like

Huh…what does that mean? The only mention of the term phase for the Rotary speaker is in:

  • Rotary Speaker: A rotary speaker model, including two horns and an overdrive phase

Which for me means there is phase refers to a specific process in time. Not phase as in phase of a periodic signal.

In a Rotary speaker you do get phase shifts due to the rotating speaker/horn, varying the angle/direction and distance of the emitted sound (from the perspective of a listener at a fixed location). So…control over phase would be control over the rotation? Which you have in Rotary.

So, not sure what you want to achieve. If you want phase control over input ofroutput signals (including clock pulses), you could put a precision delay in the path.

E.g. Sckitam Waveguide Delay (that you can even you for audiorate phase mod synthesis on any signal).

I took it to mean that @Undersound wanted direct control of the internal LFO as opposed to just the rate. There’s actually two LFOs inside the circuit so I’m not sure how that would work easily but a good approximation of that could be realized by tempo syncing and adjustable tempo.

of course if you want the lfo to be non-smooth or discontinuous you can’t do that with temposync

and theres a lot more inside the circuit than just the lfos like feedback and filter

1 Like


I want to control the starting angle of the speaker :+1:‍‍

Not sure what that means or what the use case or goal or expectations might be.

For those who care…

Some general info on Rotary speakers. The most famous are the so called Leslie Rotary Speakers. As known for their use in combination with the uber famous Hammond Tonewheel Organs.

In a physical Leslie Rotary Speaker you will find:

  • a fixed speaker blowing down onto a rotating deflector (deflecting to horizontal).
  • to horizontally mounted opposite facing horns, rotating on a single shared vertical axis.

The rotation speed can be adjustable but rotation is continuous. No immediate start (or stop). No control over angles (other then rotation speed). The direction of the sound follows the rotation, causing all sorts of effects like phaseshift/canceling, different reflection patterns/angles etc which is the charm of the design. Also fun to overdrive the amp for added effect (non-linear distortion).

1 Like

So a new module should be made…“rotary sound”…for no name interfering with the classical effect

The acceleration curve and the starting angle should be controlled simply…

If I recall correctly (hey, it was 45 years ago), one of the horns was a dummy, just for balance when spinning.

What I’m less sure of is that I believe the horns could be rotated at a different RPM than the drum, and in a different direction.

It was fun to watch them with the upper and lower louvres removed. When you saw them spinning up faster you knew that something like an epic solo was about to happen. :metal:

1 Like


This guy is crazy (in a positive meaner)

1 Like

I always thought the horns are rotors could go at different speeds, but I’m not sure.

The rotating speaker effect is (at some level) some special filters driven by some LFOs. It seems totally reasonable to me that someone would want control over the CV to this thing, possibly by using their own LFO. Why not? Isn’t that kind of in the spirit of modular? Even if some some mechanical speaker for decades ago doesn’t have that feature?

1 Like

It’s been 30 years since I last lugged a leslie speaker around with a band, and now i have all that on my laptop, which is good because I know my back couldn’t take it any more. But yeah they had two horns and two rates is right. In the surge effect that @Undersound is talking about here it expresses itself as a horn rate and a rotor rate which is percentage of the horn. You can see the full circuit there. Starting phase isn’t really the key concern rather it filters between the two modulating signals and does a variety of gain normalization for different drive models.

1 Like

Yeah that’s basically exactly what it is.

You could make the same thing out of modules from scratch if you wanted and get all the control you needed. The point of the surge Rotary speaker is to be inspired by a leslie with a small number of front panel controls, so i think it is something different than what the op wants.