Glitch problem in ADSR [synth - Plug-In]


Hi everyone,

I’am doing a synth plug-in in which I implemented 2 oscillators with different waveshapes, LFO, filters and ADSR.
Everything works great but not the ADSR: while I am playing and I change note, when the new note is starting I have an initial glitch. If I wait until the sound of the first note is finished I don’t have this issue…I neither have it when I am playing without the ADSR so I really don’t know how to solve this issue.
The ADSR is done by multiplying the samples with a linear envelope (practically using the basic formula y=mx+q of a line and calculating the angular coefficient “m” depending on the values of the ADSR parameters). I also tried to use all the values as “LinearSmoothedValue” but unluckily it didn’t solve the problem.
Anyone else had this problem or have any idea on how to solve this?


It could be any number of things… Just to check, is your synth polyphonic? If not, it will cut off each note as it starts a new.

You can output your ADSR values into the audio buffer alone, and inspect the samples afterwards to see any discontinuities (spectrum analysers can be a great help here).


Thanks for the reply!
Yes, the synt is polyphonic but even in monophonic case I have the same issue (if I play a note, even the same one, before it finishes it’s ADSR, I can hear a glitch when I start a new note). As I said, if I wait until the note is over (so the ADSR has finished) the glitch doesn’t show.
Your seems an interesting solution but I don’t think is a matter of the values of the ADSR: I tried to make it start from zero at every call and to clear the buffer before using the ADSR but I’m still having the problem.
Tomorrow I will try your suggestion (the spectrum analyser thing). Thanks for your time!


Record the waveform and look at the glitch … sometimes reveals a lot about the problem.

PS. I got a weird glitch once by neglecting to realise that the synth’s process function doesn’t always start at sample 1 when it gets a note…