Vca/Lfo problems

#1

Sorry. This is probably simple, but i cant figure it out.

Screen Shot 2016-04-28 at 21.46.26.png697x602 40.6 KB

In here i have a simple sine wave. The volume is modulated by the adsr or LFO. I can mix between the two.
If i have adsr turned all the way up, and lfo down i get a clean adsr curve. If i turn the adsr down and the lfo up ig get a clean tremolo effect. But what if i want to mix the two, and have the adsr curve modulate the volume of a tremolo'ed sine?
As it is now, if i turn both the adsr halfway up, i can always hear the tremolo effect, even though i have released the keys. What if i want the tremolo sound but i want it to shut off after i release the keys? How can this be done?

Thanks:)Test1.axp (3.0 KB)

#2

If you want the EG to control the volume of the tremolo-ed sine, I would put the LFO in series with the VCA (before or after) controlling another VCA module. At the moment they are in parallel, so if you mix them, the LFO still controls the VCA even if the EG is not triggered.

#3

Try using the LFO to 'scale' the ADSR output (A k-rate * object). You might want to shift the LFO into unipolar first though. Gabriel's suggestion is more elegant though. Think of it as a synth output VCA being followed by a guitar tremolo pedal.

#4

Thanks to both of you:) gabriel I already tried your solution but that gives me the opposite problem;
If I then turn down the tremolo I don't get any signal coming to the adsr and then no sound at all. Sorry I should have explained that I want to achieve this as well:)

I'm trying to make a simple synthesizer with a vca. The vca should have different modulation sources (noise, lfo, S/H, adsr) but I don't want any mod source heard if I don't press a key on the keyboard. So the adsr needs to be last in the chain somehow.

Sir, I'll try your solution. I haven't run it through my logic circuit yet(my brain that is;)
Thanks to both of you

#5

Oh, I see what you mean. In that case you need a dry/wet control hat mixes the original and tremolo signals, again in series with the EG?

#6

Sorry, could you explain it, or maybe show it in a patch? You can take my patch as a starting point.

I just want normal vca modulation source action, like on any normal substractive synth.

A vca with 2 or more modulation sources. But the audio signal shouldnt be audible unless i press a key. Then the adsr would open the vca, but before that the LFO/SH or whatever should be applied. But at the same time, if no modulation (LFO/SH) is applied before the adsr-vca, then the audio should pass through straight to the adsr-vca.

Thanks a million:)

#7

I'm afraid that what I described would behave like that too. You need to apply an offset to your tremolo mod input to avoid this, or crossfade between the tremolo output and the dry signal as gabriel suggested.
I've made a demo patch.

tremolo demo.axp (5.2 KB)

#8

I've made a version that only uses one VCA. I would consider this an improvement as it avoids unnecessary scaling of your audio and a k-rate * object is almost certainly cheaper than a VCA in terms of cycles.

tremolo demo 2.axp (5.5 KB)

#9

THANK YOU!!!!!!!!!!! Karma should be good to you today:)