Moog Music Forum

I think a great addition to the MP-201 would be a simple lag processor. I was putting together a sound last night that used two discontinuous LFO signals. The end result was really cool, but it led to a lot of pops coming out of my speakers - probably not so good for them in the long run. I guess one option would be to get two CP-251's, but that seems like overkill for something that might be pretty easy to do in the code for the MP-201.

Pretty please?

Bryan

...used two discontinuous LFO signals...

If you don't mind me cutting in and asking; what do you mean by discontinuous?

I mean this line ------- is discontinuous, but how did you get the LFO to be discontinuous?

(I'm not trying to be smart here, I don't understand how you made it, and just using some visual stimuli for presentation )

Would the shape be like this: / \ / \ / \ / \ / \ / \ / \ / \ / \ / ? (like peak cut off?)

Or like this: / / / / / / (just swells?)

Or more like this: ~ ~ / , ^ ``` \ (some what random?)

He most likely means pulses.

Most of the LFO's are discontinuous. Square, Ramp, Saw, and S+H all jump from one value to another at some point in the waveform. Square jumps between the two values, ramp jumps between the highest and lowest, saw jumps between the lowest and highest, S+H jumps between each random value. Those jumps can cause audible pops depending on what they are controlling.

A lag processor can be used to smooth out those jumps.

Hope that makes sense,
Bryan

I fully understand the issue of the pops, and agree that a lag processor can be used to make a sudden change in CV value more gradual over time rather than a sudden pop causing change.

But what confused me was that I thought you were making an LFO discontinuous by adding a switch to turn the CV signal on and off at some rate, making a sound that could be described as (for example) a pitch changing Morse code. Just like thermionicjunky said, I thought you were making CV pulses. The rate of which was LFO controlled, while the second LFO controlled the pitch / effect.

LFO's, or any wave / oscillation are in fact continuous, and this is what had me confused.

Alien8 wrote:LFO's, or any wave / oscillation are in fact continuous, and this is what had me confused.

In a practical sense, maybe (though things do change quickly enough that I am getting pops). In an ideal sense, the square, saw, and ramp all have jump discontinuities.

Bryan

Square waves destroy speakers...I know from experience. That's about all I know in relevance to this topic.

Hi Bryan -

For fun you should try out the CV Smooth function in the utilities menu (see p.40/41). This switches in a global filter (for all four CV outputs). It might help - it's worth checking out.

Best of Luck
SD

SteveD wrote:Hi Bryan -

For fun you should try out the CV Smooth function in the utilities menu (see p.40/41). This switches in a global filter (for all four CV outputs). It might help - it's worth checking out.

Best of Luck
SD

I've tried it both ways and still get pops. The CV Smooth seems to have the most effect when LFO frequencies are in the audio range. It gets rid of ringing.

Bryan

I should point out that I do get the same pops when using other square wave sources, such as the Ring Mod or the CP-251.

Bryan[/i]

Bryan T wrote:I should point out that I do get the same pops when using other square wave sources, such as the Ring Mod or the CP-251.

Bryan[/i]

Sounds like it sounds like a squarwave...which pops...and destroys speakers.

Voltor07 wrote:Sounds like it sounds like a squarwave...which pops...and destroys speakers.

Right . . . and it can be made very useful with a lag processor. Hence the thread.

a lag processor would also be very nice to taking the edge off sample and hold and noise. yes please

f