Moog Music Forum

hello forum people

I have a mf ring mod that I'm using as a tremolo (amp mod) on a vocal line,
with the internal osc acting in LO mode (LFO).
I'd like to achieve a rythmical tremolo/gapper effect in sync with my MIDI clock master.
I have a midi to cv converter and what I'm trying to do is:
- I make a step sequencer midi track in cubase to send an 8th trigger to the MCV. so the MCV sends 8th gate signals to the ring mod.
- I plug the MCV gate out into the FREQ input of the ring mod (with 0 as initial position), but what I hear is not the same effect I hear when I set the FREQ knob manually...

I tried with s-trig, 10v and 5v gate signals.

any hint to achieve a regular 8th tremolo with the above mentioned gear?

thanks a lot!

ed

rodion wrote:hello forum people

I have a mf ring mod that I'm using as a tremolo (amp mod) on a vocal line,
with the internal osc acting in LO mode (LFO).
I'd like to achieve a rythmical tremolo/gapper effect in sync with my MIDI clock master.
I have a midi to cv converter and what I'm trying to do is:
- I make a step sequencer midi track in cubase to send an 8th trigger to the MCV. so the MCV sends 8th gate signals to the ring mod.
- I plug the MCV gate out into the FREQ input of the ring mod (with 0 as initial position), but what I hear is not the same effect I hear when I set the FREQ knob manually...

I tried with s-trig, 10v and 5v gate signals.

any hint to achieve a regular 8th tremolo with the above mentioned gear?

thanks a lot!

ed

I think you'll need to do a little experimentation/calibration. What the ring mod needs to see is a fixed voltage (not a gate signal) that corresponds to the correct knob setting of the Frequency knob.

It gets a bit technical . . .

Lets say that the song is 120 bpm. That means that each quarter note is every 1/2 second and that every eighth note is every 1/4 second. In Hz, eighth notes are 4 Hz for that bpm. You need to find the correct voltage level that corresponds to 4 Hz on your ring mod.

The ring mod's Frequency knob scales from 0.6 Hz to 80 Hz. If I remember correctly, that 0.6 Hz is when the voltage of the control signal is 0 V. 80 Hz would be when it is 5 V (though it might be a bit higher . . . 5.7 V or something like that).

Further complicating things is that I don't think the Frequency knob is linear, I think it is exponential.

So, assuming that the knob scales from 0 Hz to 5 Hz, I get that the knob frequency of the ring mod corresponds to this function:

0.6 e^(0.97857 * Voltage)

http://www.wolframalpha.com/input/?i=ex ... C+80%29%7D


So, for eighth notes at 120 bpm, you'd want to set the knob to the solution of this equation:

4 = 0.6*e^(0.97857*V)

http://www.wolframalpha.com/input/?i=4% ... 97857+x%29

If I did that right, then the setting should be about 1.94 Volts.

Remember that I assumed that the knob goes from 0 to 5 Volts, if that isn't correct, then things won't work right.

In general, you'd find the frequency of eighth notes and solve this equation:

frequency = 0.6*e^(0.97857*V)

Eek!

Also, I think this is a great example of where software would be preferable to hardware. It would be easy to sync with the track's tempo and would be easily repeatable.

And if you're using the ring mod, don't forget that the Mix knob affects the way the tremolo sounds. Mix on 10 is quite different than mix on 4.

For completeness:

If the knob does go from 0 to 5.7 Volts, then you'd want to solve this equation:

Frequency = 0.6 e^(0.858395 x)

http://www.wolframalpha.com/input/?i=ex ... C+80%29%7D

So, for 4 Hz you'd want 2.21 Volts.

Bryan

ouch, things really gets quite complicated!
I think I'd better trust my ears and let my finger find the right knob position.

in the meanwhile I found an alternative solution using my voyager OS and the VX-351:
I send the lfo tri out of the voyager to the carrier in of the ring mod,
bypassing the internal ring mod osc.
not exactly the same waveshape of the internal ring mod osc, but it quite does the tremolo job. then I send the 8th midi gate sequence through the MCV to the lfo sync in of the voyager, so that the voyager triangular lfo cycle begins every 8th of the song. then I adjust the LFO speed to nearly match the 8th cycle (interesting variations of the waveshape possible here).
et voilà, midi synced tremolo!!

rodion wrote:ouch, things really gets quite complicated!
I think I'd better trust my ears and let my finger find the right knob position.

I definitely agree on that!

in the meanwhile I found an alternative solution using my voyager OS and the VX-351:
I send the lfo tri out of the voyager to the carrier in of the ring mod,
bypassing the internal ring mod osc.
not exactly the same waveshape of the internal ring mod osc, but it quite does the tremolo job. then I send the 8th midi gate sequence through the MCV to the lfo sync in of the voyager, so that the voyager triangular lfo cycle begins every 8th of the song. then I adjust the LFO speed to nearly match the 8th cycle (interesting variations of the waveshape possible here).
et voilà, midi synced tremolo!!

Good solution.

rodion wrote:ouch, things really gets quite complicated!
I think I'd better trust my ears and let my finger find the right knob position.

in the meanwhile I found an alternative solution using my voyager OS and the VX-351:
I send the lfo tri out of the voyager to the carrier in of the ring mod,
bypassing the internal ring mod osc.
not exactly the same waveshape of the internal ring mod osc, but it quite does the tremolo job. then I send the 8th midi gate sequence through the MCV to the lfo sync in of the voyager, so that the voyager triangular lfo cycle begins every 8th of the song. then I adjust the LFO speed to nearly match the 8th cycle (interesting variations of the waveshape possible here).
et voilà, midi synced tremolo!!

I made a thread about this with the MP201 a while back and am using a similar technique; using any of the MP's waveforms into the Carrier In to MIDI sync- as you noted its a little different than the internal lfo, but does the trick nicely. The squarewave has a significant volume drop though the other lfo's are fine, and I think the squarewave just needs to be adjusted, though I haven't experimented with it. Anyway, good to see you worked it out

DontBelievetheHype wrote:I made a thread about this with the MP201 a while back and am using a similar technique; using any of the MP's waveforms into the Carrier In to MIDI sync- as you noted its a little different than the internal lfo, but does the trick nicely. The squarewave has a significant volume drop though the other lfo's are fine, and I think the squarewave just needs to be adjusted, though I haven't experimented with it. Anyway, good to see you worked it out

Smart!

Now I'm wondering if you could send a gate signal to the "Carrier In" and have a squarewave tremolo that way. Hmm . . .

Bryan

Bryan T wrote:
Smart!

Now I'm wondering if you could send a gate signal to the "Carrier In" and have a squarewave tremolo that way. Hmm . . .

Bryan

Hmm, I took a quick look and for my setup its not ideal, at first glance anyway, as the options are to trigger the gate with either a footswitch, the treadle, or MIDI notes--- I would need to have the same LFO sync parameters to make it useful, ie Gate On/off ->Subdivision of choice->Sync to MIDI clock. The EG would still lack the ability to MIDI Sync to an external clock, other channels lfo, etc, in my setup where Im not controlling the MP201 with a MIDI controller, just syncing to external clock as using its CV outs.

For other applications it would be as easy I think: Say in Ableton creating a MIDI pattern with repeating MIDI Notes, say 8th 'C4' notes, syncing the MP201 to Ableton's clock, and setting the Gate to be triggered by 'C4'-- this would at least open the Gate, and then would you need a consecutive Off note tied to it as well correct? Or if using the Gate's new EG, creating a fast envelope (as square as you can get it) that could be triggered in a single MIDI note, though maybe not quite as square as an On-Off non-EG sequence? Am I on the right track? (this seems like a good time to plug a MIDI controller into the MP201 and experiment)