Popping noise from 911 EG

[Rezin]

Hello all,

UPDATE: Power supply woes are solved for now- I'm now able to troubleshoot modules individually and as a whole system. (About time, since I've only got a few weeks to finish restoring this thing.)

I've been working with the envelope generators, and have been experiencing a popping noise upon attack and release. Does anyone know why this would be? It's rather noticeable, and I'd like to eliminate it if I can..

Video: https://youtu.be/PzVfJYhrBjw

Best,

~Rezin

[noddyspuncture]

You say you don't have a trigger converter... what would you need one for...?

Also, I see you have two EG's and two VCA's. Do you get the clicking on any and all combinations of them...?

Did you try process of elimination..?

It could be that just one of them is giving you the symptom - you need to make sure you're not "chasing your tail" there...!

[Rezin]

Thanks for suggestions- I was thinking of using a trigger converter to try and remove the 950 keyboard controller from the equation, which could very well (given its age) be related to the irregularity.

If my memory serves me, the popping noise is unrelated to which VCA is being used, though I will try and troubleshoot that more later on. One of the 911s has been giving me other issues as of late, I will see if I can investigate that some time soon.

Best,

~Rezin

[noddyspuncture]

I cannot see how your 950 keyboard could cause any "popping"... it just outputs S-trig and CV when a key is pressed..!
It will either output them or not - and a meter and a scope will confirm that for you.

Those keyboards - the 950 and 951 - are very well built and reliable. The only issue I have ever had is the little contact springs breaking on one of mine.

I think you need to look elsewhere.

Cheers,
Tom

[MC]

EGs don't make popping noises. VCAs will if they have too much control feedthrough with fast transients regardless of where the trigger comes from. There should be a calibration trimpot in the VCA to minimize this. Can't help from here, have never been under the hood of a moog modular.