Problem: When using two pedals (which both work), signal cuts out momentarily

[D.C.]

NOTE: I fixed my problem. It was a silly mistake due to a bad connection; see my final post below.



Couldn't quite fit it all in the title, but I'm having a strange problem.

I've recently built a Ross Distortion (the "tan" version from TagboardEffects; vero; schematic) on a breadboard, as well as an Anderton boost circuit to amplify the mids a bit. (Here's how I added a buffer to the input of the EQ circuit.) By itself, this distortion+EQ combination works fine.

(Note: I made a couple minor substitutions on the Ross distortion. I didn't have a 50k pot, so I'm temporarily using a 100k pot on the output. Also, the op amp is a CHN4558C from Tayda, and I didn't have a 1uF capacitor (top-right on the vero), so I'm using two 2.2uF capacitors in series. Everything else should be as drawn.)

Some time ago, I also built an MXR Micro Amp (again, from TagboardEffects; vero; schematic), which I've long since boxed up. Again, it works great, by itself. Never had any issues pairing it with other circuits.

But when I bring the two together (Distortion -> EQ -> Micro Amp), I get trouble...

When I turn on the distortion+EQ, and then turn on the Micro Amp, my amp goes silent for about a second, and after that, everything works fine. When I turn off the Micro Amp, there's no problem.

When I turn on the Micro Amp, and then turn on the Ross+EQ, the amp goes silent for about a second, and then it works fine. When I turn off the Ross+EQ, the amp again goes silent for a second, and then is fine.

If it helps, I'm using an Ibanez Gio guitar, and a Peavey Studio Pro 40 amp.

Any thoughts on why this could be happening? I've never encountered anything like this, and I'm not even sure where to start on debugging this.

Also, if it helps, I just found a similar issue that looks like it could be related.

[PRR]

> goes silent for about a second, and then it works

Every time? Or just the first time in a while?

I suspect you have stray DC on an input or an output. When you switch, that DC throws the next stage out of its acceptable input range. Eventually (second?) the DC charge bleeds-down into the acceptable range. You need to find the leak and add a bleeder.

[D.C.]

> goes silent for about a second, and then it works

Every time? Or just the first time in a while?

The behavior that I described happens every single time. I just tried flipping each circuit on and off multiple times, and each time it happened as described.

It seems strange that there would be a consistent unwanted DC somewhere in the circuit. All of the schematics show capacitors on the inputs and outputs, which should remove any unwanted DC, right?

I do have a multimeter. How could I track down any possible unwanted DC voltages? Just measure DC voltage from the input to ground?

I feel like there's a hint in the fact that the problem does happen in these situations:

• Distortion+EQ on, Micro Amp off -> switch Micro Amp on
• Distortion+EQ off, Micro Amp on -> switch distortion+EQ on
• Distortion+EQ on, Micro Amp on -> switch distortion+EQ off

... yet the problem does not happen in the case when the distortion+EQ and Micro Amp are on, and I switch the Micro Amp off. In that case, the sound persists during and after the switching (but of course, without the volume boost).

[D.C.]

Whoops; I figured it out. Silly mistake.

Note that both circuits (the Ross distortion plus the Anderton EQ) are on a breadboard together.

At one point, I was comparing the Ross distortion with and without the Anderton EQ. In doing so, I was moving my effect output between the final output of the EQ, and the output of the op amp buffer. That was probably a bad idea, considering the op amp is biased to 4.5 V...

Now that I've moved the effect output to the output of the EQ, all is well. For a proper comparison (with and without EQ), I should have been tapping into my circuit before my op amp buffer, before adding the 4.5 V bias.

Thanks, PRR!

[PRR]

> All of the schematics show capacitors

Schematics are not actual builds.

I have been bitten MANY times when what was built was not what was drawn.

As you found.

Glad you got it sorted.