Moog Music Forum

Hi, I'm new to this world of modular stuff. I've got 4 mf's: 101,102,103,107.
I'm really into patching them up and getting crazy wacky sounds, but some of the sounds are pretty unpredictable. Sometimes I get a popping or ticking when the lfo peaks (still don't know the right lingo, i guess).
Any help? Is it a matter of attenuation?

Liquid Guy wrote:Sometimes I get a popping or ticking when the LFO peaks...

Hi Liquid Guy,

Is the LFO Shape Square, Saw, Ramp, or Random?

All four of those shapes have a flat, vertical (near instantaneous) transition in voltage, which can cause pops and ticking in some circumstances.

Yeah, I know the waveshapes and understand that the ticking originates from this spike in the wave. Of course it doesn't happen with a triangle wave.
Is there a way to prevent it? I tried patching the lfo thru an overdrive pedal so i can lower the volume (fake attenuator) , but got no lfo at all. Maybe a volume pedal? I'm a guitar player in case you haven't guessed yet...

Liquid Guy wrote:Yeah, I know the waveshapes and understand that the ticking originates from this spike in the wave. Of course it doesn't happen with a triangle wave.
Is there a way to prevent it? I tried patching the lfo thru an overdrive pedal so i can lower the volume (fake attenuator) , but got no lfo at all. Maybe a volume pedal? I'm a guitar player in case you haven't guessed yet...

My guess is that this will not work. Most guitar pedals are designed for processing sounds in the audio domain, and not in the low (non audible) frequencies as an LFO sends.

You probably don't want to hear this, but attenuation is featured on the CP 251, which incidentally is a great piece of gear.

You probably don't want to hear this, but attenuation is featured on the CP 251, which incidentally is a great piece of gear.

You're right, I dont want to hear this though I would definitely like to have one!
I'll look into building an attenuator, I build guitar pedals so I guess I can do it...

What you want is a lag processor or low pass filter to smooth the sharp transitions. It's very easy to make a passive LPF with just a resistor and a capacitor, they can even be built into 1/4" cables.

Liquid Guy wrote:Is it a matter of attenuation?

It really isn't about attenuation (or peaks either); it's far more about the rapid voltage change over time.

Sure, as you attenuate the LFO's amplitude closer and closer to near zero, it won't bug you as much, but it won't have very much of an effect either.
("Well, there's Spam, eggs, sausage, and Spam, that's not got much Spam in it.")

And, as suggested, you could run it through a Lag Processor (like the one on the CP-251). This will add a slope to the side with a vertical edge. But you're just making the LFO closer to the waveshapes that don't bother you.

One new suggestion: If you end up getting an MF-104M or MF-108M, they both have an extra LFO Waveshape (that you can only get to via MIDI) that's Random but without the steep edges.

_DemonDan_ wrote:

Liquid Guy wrote:Is it a matter of attenuation?

It really isn't about attenuation (or peaks either); it's far more about the rapid voltage change over time.

Sure, as you attenuate the LFO's amplitude closer and closer to near zero, it won't bug you as much, but it won't have very much of an effect either.
("Well, there's Spam, eggs, sausage, and Spam, that's not got much Spam in it.")

And, as suggested, you could run it through a Lag Processor (like the one on the CP-251). This will add a slope to the side with a vertical edge. But you're just making the LFO closer to the waveshapes that don't bother you.

One new suggestion: If you end up getting an MF-104M or MF-108M, they both have an extra LFO Waveshape (that you can only get to via MIDI) that's Random but without the steep edges.

Good points Dan! Remember that the CP-251 also generates the Smooth Random wave (not tap tempo tho). I sold mine a while back and miss it.