Input grounding vs. oscillation...

[JisforJustin]

I came across this thread while searching for input grounding:

http://www.diystompboxes.com/smfforum/index.php?topic=75067.0

I am working on a high gain distortion using a 5534 input stage follwed by 3 stages of a CD4049. While bypassed I get a bit of oscillation bleedthrough. So I tried the input grounding shown in the thread (from generalguitargadgets.com), and while it does kill the oscillation I now get a bit of a hiccup when I engage the pedal. There is a moment before the effect kicks in now, which is no good. So, I was just wondering if anyone else has had this problem and what solution worked?

One thought I had , that I haven't tried yet, was to ground another point in the circuit (possibly between stages). Any thoughts?

Justin

[Paul Marossy]

One thought I had , that I haven't tried yet, was to ground another point in the circuit (possibly between stages). Any thoughts?

Never tried doing that, but it sounds like it might be a good compromise, depending on where exactly the hiccup is happening. Only one way to find out...

[R O Tiree]

The advantage of grounding the input cap is that the "jack" side of it should be at 0V. You'll have to choose your "between stages" point carefully, to ensure that it is also intended to be at 0V, otherwise there'll be an almighty great "BANG" through your amp, not a pop, as you engage.

Your hiccup sounds almost as if there's a large cap that is charging as you engage the circuit which is affecting some part of your biasing scheme, perhaps? Without access to your schematic, it's hard to say what's going on.

[Paul Marossy]

Doh! Yeah, that's true, I didn't think about the popping part of the equation. That could possibly end up being a pretty big pop when switching. It's better to find out why the lag is occurring and to to find a solution to the problem some other way.

[JisforJustin]

Wow, it was just a stupid mistake. I was connecting the input to the LED rather than ground. I used 2 resistors and a 10 uf cap for the LED which was causing the delay. Next time I guess I'll have to triple check my connections. 

[cpm]

if i remember well, the newer big muff (big box one) switches to ground after the 1st gain stage (where the gain pot is)

just a note...

[Paul Marossy]

Wow, it was just a stupid mistake. I was connecting the input to the LED rather than ground. I used 2 resistors and a 10 uf cap for the LED which was causing the delay. Next time I guess I'll have to triple check my connections. 

Huh, that had an interesting side effect.