Trouble with Anti-Stutter pedal [Please Help]

[effectsbay]

Hello All

I'm working on a anti-stutter pedal (basically opposite of a momentary kill). The pedal is dead until you click the momentary switch, which lets the signal pass. There is a 3PDT switch to send the signal to momentary switch and activate an LED.

Basic schematic here: http://beavisaudio.com/projects/StutterPedal/index.htm <= Version 2: The Anti-Stutter

So here's the problem I can't figure out. If you plug in a guitar to the pedal it works great. But if you plug in certain pedals, or pedals that increase gain, you hear signal (slightly) when it should be dead. The momentary switch I currently have.. is normal close which sends input signal to ground. So I really don't get why I'm hearing something at all. I'm guessing impedence possibly??

For example.. I plug in my guitar. Works perfectly. No bleed of signal. I plug in a MXR micro amp in front of it, turn the dial all the counter clockwise.. so should be unity. Then turn on the MXR.. I hear bleed. Add level.. the bleed gets louder. I was testing originally with a Boomerang Phrase sampler.. and I would get bleed on that?

Any ideas on what I can do?

Here is a quick schematic of what I have going on....



Thanks!
hank

[wavley]

Are you doing this as a general pedal or just with the intention of anti-killing the loop on your Boomerang?  I ask because I was tired of the hiss that the loop path of my boomerang made and I didn't want to roll the volume down every time I wasn't looping so I just added a stomp in the boomerang that grounded the volume control and I don't have any problems with bleed at all.

You've got some sort of crosstalk going on, but I don't really see why.  Maybe it's the switch, maybe it's your wiring layout.

[effectsbay]

Are you doing this as a general pedal or just with the intention of anti-killing the loop on your Boomerang?  I ask because I was tired of the hiss that the loop path of my boomerang made and I didn't want to roll the volume down every time I wasn't looping so I just added a stomp in the boomerang that grounded the volume control and I don't have any problems with bleed at all.

No.. this is a build for a friend of mine. I was just testing with the boomerang to feed it a infinite signal to test the stutter.

You've got some sort of crosstalk going on, but I don't really see why.  Maybe it's the switch, maybe it's your wiring layout.

Yeah.. I don't get it. I've already tried with different momentary switches. I haven't swapped out 3PDT switch yet, but if I pull the feed from the momentary switch, I obviously don't get the cross talk, which makes me feel it's the momentary switch, but like I said, I tried with two different types of momentary switches, and the bleed is the same.

The other thing I was thinking ... could be the ground, but running jumpers all over the place, I'm not seeing a problem or improvement.

Thanks!
hank

[induction]

Here's my idea:

If you consider the green and gray wires in your picture as very low value resistors (a few ohms each), then you have made a voltage divider instead of simply shunting to ground. With such a small resistance to ground in the voltage divider, an unbuffered signal will not be able to provide enough current to produce an appreciable voltage signal at the output, but a buffered signal will have much more current available. The input impedance of the next stage and the voltage divider will be in parallel, so most of that current will be dumped to ground, but there may be enough left to produce an audible signal at the output that is attenuated according to the voltage divider. Obviously, if you increase the voltage being input to the voltage divider, the output will also increase.

Try making the wire that comes from the input jack much longer than the combined length of the wire that connects the two switches and the wire from the momentary switch to ground. If that makes a difference, then this description may be what's going on.

Would you be able to keep the anti-stutter switch first in the chain? That would probably sort it.

[effectsbay]

Here's my idea:

If you consider the green and gray wires in your picture as very low value resistors (a few ohms each), then you have made a voltage divider instead of simply shunting to ground. With such a small resistance to ground in the voltage divider, an unbuffered signal will not be able to provide enough current to produce an appreciable voltage signal at the output, but a buffered signal will have much more current available. The input impedance of the next stage and the voltage divider will be in parallel, so most of that current will be dumped to ground, but there may be enough left to produce an audible signal at the output that is attenuated according to the voltage divider. Obviously, if you increase the voltage being input to the voltage divider, the output will also increase.

Yes.. that makes sense. I was thinking it might be impedance.. but that's all I know.. no solution.

Try making the wire that comes from the input jack much longer than the combined length of the wire that connects the two switches and the wire from the momentary switch to ground. If that makes a difference, then this description may be what's going on.

I'll try that in a few. If that is the case.. and that fixes the problem, what would be a cleaner solution? Add a resistor?

Would you be able to keep the anti-stutter switch first in the chain? That would probably sort it.

Unfortunately.. no. He wants to kick on the pedal first with TB switch.. then stutter.

Thanks!
hank

[effectsbay]

induction.. I did what you suggested. I cut the input lead from jack to 3PDT switch and added a long alligator clip.. tripling the length of that wire. The problem is exactly the same not better in any way.. not any worse.

Thanks!
hank

[GGBB]

The diagram isn't completely clear (to my eyes at least).

Assuming input=J3 and output=J2.

When engaged, it looks like you are tying both input and output tips together, connecting to the momentary, which is in turn tied to the input ring and 9V-ground, and then presumably via a mono input connector to the input sleeve, which then relies on what is connected to the other end of the cable (or possibly the chassis) to ground the signal.  I can't see why that wouldn't work, but since your problem is related to what is before this pedal, and your signal kill ground is affected by what is before this pedal, my suspicion is that they are related.  Try connecting the momentary ground wire directly to ground and not to the input ring.

[effectsbay]

The diagram isn't completely clear (to my eyes at least).

Assuming input=J3 and output=J2.

When engaged, it looks like you are tying both input and output tips together, connecting to the momentary, which is in turn tied to the input ring and 9V-ground, and then presumably via a mono input connector to the input sleeve, which then relies on what is connected to the other end of the cable (or possibly the chassis) to ground the signal.  I can't see why that wouldn't work, but since your problem is related to what is before this pedal, and your signal kill ground is affected by what is before this pedal, my suspicion is that they are related.  Try connecting the momentary ground wire directly to ground and not to the input ring.

You are correct.. input=J3 and output=J2

I did as you suggested, and ran the ground from momentary switch to ring of input. The ground was on the the sleeve (not ring) of the input (so battery won't drain for the LED when not connected). I also tried connecting right to the enclosure. Both resulted in the same behavior. No improvement. Not worse or better.

Thanks!
hank

[induction]

Just for grins, try a 1k resistor between the input jack and S1.

[effectsbay]

Just for grins, try a 1k resistor between the input jack and S1.

induction.. I did that.. and it cut the bleed by about 1/2! I don't think there was any signal lose between bypassed signal and the stutter signal. 10k next?

Thanks!
hank

[induction]

Yeah, give it a shot.

[effectsbay]

Yeah, give it a shot.

Ok.. 10k killed the bleed. Question.. will this lower the signal to the pedal? Meaning.. if I have this in the chain, will it drop the signal level with the 10k resistor at the input?

Thanks!
hank

[GGBB]

I did as you suggested, and ran the ground from momentary switch to ring of input. The ground was on the the sleeve (not ring) of the input (so battery won't drain for the LED when not connected).

Actually, I suggested connecting it to sleeve/ground instead of ring.  The diagram shows it connected to the ring which is where the 9V ground is and should be to prevent battery drain.  But you already had it on sleeve anyway, I think?  Not clear but don't mind me  .

[effectsbay]

Actually, I suggested connecting it to sleeve/ground instead of ring.  The diagram shows it connected to the ring which is where the 9V ground is and should be to prevent battery drain.  But you already had it on sleeve anyway, I think?  Not clear but don't mind me  .

I think the diagram shows it connecting to sleeve. The orange is the sleeve.

Thanks!
hank

[induction]

The resistor will effectively increase the output impedance of whatever comes before the stutter pedal, so you'll probably want to use the smallest value that kills the bleed. The resistor may not attenuate the signal, but it may change the tone a little, depending on the signal chain.

Also, I just noticed this:

Would you be able to keep the anti-stutter switch first in the chain? That would probably sort it.

Unfortunately.. no. He wants to kick on the pedal first with TB switch.. then stutter.

Thanks!
hank

What I meant here was, can you put the Micro-Amp after the stutter switch, instead of before it? If there are no buffers before the switch, then it's bad behavior is not a problem. It would be nice to be able to put it anywhere in the chain, but if your friend doesn't need that flexibility, you can get away with no resistors. Another option would be to buffer the input of the anti-stutter pedal, and use a 10k resistor. Then you get consistent results wherever you put it in the signal chain. Of course, if your friend wants true bypass, that won't work for him.

[GGBB]

The orange is the sleeve.

I'm sure that was your intention when you did the drawing (but then the 9V ground connection would be wrong), but if orange is sleeve, why doesn't the mono output have an orange connection?  Input has tip, ring, and sleeve; output has tip and sleeve; ring is the odd man out.  Input has blue, orange, and black; output has blue and black; orange is the odd man out.  Blue is tip/signal, black is sleeve/ground, orange is ring.

EDIT: Did I mention I wasn't clear about the drawing?