popping sound bass / zero crossing

[guyman]

EDIT (TLDR: Seeking solution for noisy envelope popping w/o zero-crossing, interesting thoughts, but problem redundant... solved with schematic in the replies)

Hello all,

So I'm constructing a synth. Let's say you've got a real nice loud square wave playing in a bass octave. Whenever I release the note I get a terrible popping sound. I typically solve this problem by extending the release on the volume envelope a bit, however with this synth, and a few other wave forms in it, I am getting the pop even at long release times... I'd love a near instantaneous release. There is no visible DC, and I have a DC blocker filter at the end of my chain (it does this with or without this filter).

I started thinking what would be cool and perhaps solve my problem would be some sort of zero-cross envelope gatey thingamajig, so If it releases while wave form is off 0, it would fade out very very quickly - adding no perceptual release, but defeating the problem of the pop. The pop itself is simply the wave form letting go off zero, creating the equivalence of an impulse at the volume of the waves amplitude at non zero-crossing release...

After ranting about it, it seems simple - but why hasn't it been done/implemented into every ahdsr I have?? I think I shall tackle this when I get back to the lab.... unless someone else has already worked through this.

Hope I've been brainstormy enough for you.

Any one else ever tackle this problem? Want to chime in? help? Enlighten me with your 2-cents?

Cheers.

~That Guy

[guyman]

Maybe it's my filter section?? Should I DC block before my envelope?? Does that matter at all?

[guyman]

Is this like a specific envelope point triggered hysteresis?
a h d s r y are time constants, y being an additional super short r...

xa --> xh --> xd --> xs --> xr, if x>0 after r, (xy)..

xy bringing the signal to 0 with certainty

sorry for thinking out loud.. I'll be home to tinker soon... this is making me think about all sorts of cool/more complex envelopes... that trigger multiple times... maybe I've left earth...

[guyman]

oooh... or rather one release that extends according to the volume of the signal after the release is triggered, approaching 0 until it drops below point resolution, effectively - perceivably as long as the release set on the knob.
Quickly decaying to 0, exponentially extending to actual 0.

[guyman]

oooo K

After some digging around I was able to find a couple of ahdsr, and adsr by King Martin. They are exponential, and the release does not behave the same as the ahdsr I was previously using. I don't understand why/why not..
So I stitched their parts together to create what I needed, and extended the hold time...

I get a good clean envelope out of this.. It has the features I need it to. Check back for updates soon, I plan to add a delay and value displays after I get a drink....

Cheers.

~ That Guy

AHDSR exponential (bodyparts by Martin Vicanek)(frankensteined by That Guy).fsm

(13.66 KiB) Downloaded 742 times

[wlangfor@uoguelph.ca]

bass can also be treated with a hp and then the stereo width set to nearly mono. It fixes the prob almost every time.
I like to multiply the hp'd bass times 0.5 and I leave the bass at the begin at nearly mono, and add the other part after with no width alteration., gets rid of bass problems entirely.

Good luck.