Dig Dug

[insomniac2295]

Here's a quick vid I did to capture that clicking sound. This is with the filter control turned all the way up:
http://www.facebook.com/v/2075833096776

and don't worry, that wasn't me playing. It was my girlfriend 

[JakeFuzz]

Damn all those lights are cool looking! I really want to make one of these now 

That clicking is a little too much to be poor isolation noise. That fishy pot 8 behavior is suspicious and could be the source of the issue, it sounds like you are only getting a click one time through the whole sequencer cycle too which would make sense if something was wrong with just one step. The LED for step 8 looks to be working though which means that the filter should be responding as well. My money is on a short on pot 8 somewhere, this could be causing a large current spike when the 8th step in the sequence triggers and the excess current draw from the digital side causes a pop in the analog circuit. When you set the 4-8-6 switch for just 4 or 6 steps do you still get a pop?

[insomniac2295]

Off the top of my head, I think that I still get a pop on the last beat of the sequence, no matter which setting it's on (4, 6, or .

You don't suppose that I might be getting this because I used high brightness LEDs?

[insomniac2295]

Ughhhhhh. so, whenever there is a pot in the sequence that is turned up all the way, or just about all the way, next to one that is lower in volume, it causes a "pop" in the sound. I have no idea why.

I reflowed the solder on pot 8 to see if I could get it to work and no luck. It still does nothing as far as controlling the volume for that part of the sequence.

[JakeFuzz]

Hmm that is weird about pot 8. Maybe the pot is bad? If you have a spare CD4017 pop that in and see if that helps. Temporarily disconnect LED 8 and see if that helps the pop. Also check that D1 D2 and D4 are facing the right directions and that all the 47K resistors on the pot connections are the right values (i've put in 4.7K sometimes and didn't find it till months later  ).

You could also try putting a capacitor across the LED part of the vactrol. Unfortunately at high speeds you wouldnt likely get any wah change because the cap discharge will be slow. This will just smooth out the transitions in the steps hopefully making that steep square edge a ramp (well actually an exponential decay function). I would try and get the step 8 to work before trying this one as it will reduce the quality of the wah effect.

[insomniac2295]

I've got some parts coming from Mouser, including a new 100kB Alpha pot. My custom enclosure for this is coming from Pedal Parts Plus, so I'm hoping to have everything working by the time it gets here. I'll report back any changes.

[insomniac2295]

I replaced pot 8 but it still doesn't do anything 

[insomniac2295]

Can anyone help? I checked all my resistors, diodes, ICs, everything. It's all the right values, polarity. I even swapped out the "bad" pot for one that I tested with a multimeter and found fully functional.
The pot is fine but for some reason it's not doing its job while in the circuit, but only at pot 8. How is it possible for the LED to come on and sound to pass through when the pot is all the way off and the circuit has to travel through it before going through the LED? I need help bad. I can't find any dead spots in the circuits with an audio probe, just a few spots where I hear ticking instead of clean signal.

Help?

[insomniac2295]

Anyone? Should there be this ticking in certain parts of the circuit when using the audio probe?

[LaceSensor]

I built the lite version per the schematic provided and the wah is not very deep effect at all. Sounds almost like tremolo, which itself is cool, but not near the zvex demos. I'm not disappointed just wonder what I can try to improve this. I used a vactrol vtl5c9 as recommended it the BOM.

I might try to take a video today to explain better.
Great project so far and fun to build. It all fits in a 125b but I haven't wired the ins outs and footswitches.

4 6 8 and random work great.

[LaceSensor]

Bump. Any input welcome.

[insomniac2295]

the wah is not very deep effect at all. Sounds almost like tremolo, which itself is cool, but not near the zvex demos. I'm not disappointed just wonder what I can try to improve this. I used a vactrol vtl5c9 as recommended it the BOM.

4 6 8 and random work great.

I've found the same to be true. The wah on mine is not prominent at all...

[JakeFuzz]

Ahh sorry, I haven't seen this one in a while.

For deeper wah effect I would look up a vactrol or an LDR with a larger resistance sweep for the same range of light input. I think vactrol lists the resistances as a function of led forward current which is a handy measure. Also I would look at the wah circuit and try to tweak some of the filter values to maybe change the bandpass width of the filter and the center frequency range. Should just e swapping out caps and resistors. I would try to do a manual sweep with just a pot instead of a vactrol and try to find if you need to optimize the control resistance to a certain value.

Anyone? Should there be this ticking in certain parts of the circuit when using the audio probe?

Yes, because half of the circuit is is essentially digital logic (the clock and sequencer) there is no audio signal passing through it. The clicks are just the pulses the oscillator is sending to tell the vactrol when you change the resistance value. As long as the clicks aren't coming through annoyingly strong in the audio signal at your amp then you are fine.

So is it still popping in the audio signal when it gets to pot 8? Does the LED for step 8 act normally? I guess it could be resetting the clock cycle before it gets to step 8 but that seems unlikely since the 8th step reset is hardwired on the PCB. If the LED for step 8 lights up I have no idea what could be wrong with it, past that point everything is hard mounted on the PCB and any defects past there would have bad effects on every other part of the circuit as well. Very strange issue you have here. Does the 4-8-6 switch and random functions work okay? When in 4 or 6 mode are there any weird issues with the operation?

[JakeFuzz]

And on another note, take a look near the bottom of this geofx page:

http://www.geofex.com/article_folders/wahpedl/wahped.htm#twintee

The wah type is called a twin-t. I would search around and see if you cant tweak the values to increase the depth of the wah effect.

[insomniac2295]

Yes, because half of the circuit is is essentially digital logic (the clock and sequencer) there is no audio signal passing through it. The clicks are just the pulses the oscillator is sending to tell the vactrol when you change the resistance value. As long as the clicks aren't coming through annoyingly strong in the audio signal at your amp then you are fine.

So is it still popping in the audio signal when it gets to pot 8? Does the LED for step 8 act normally? I guess it could be resetting the clock cycle before it gets to step 8 but that seems unlikely since the 8th step reset is hardwired on the PCB. If the LED for step 8 lights up I have no idea what could be wrong with it, past that point everything is hard mounted on the PCB and any defects past there would have bad effects on every other part of the circuit as well. Very strange issue you have here. Does the 4-8-6 switch and random functions work okay? When in 4 or 6 mode are there any weird issues with the operation?

Ahhh, that clicking thing makes much more sense now, thanks!
I'm not sure if it's still popping when it gets to pot 8. The LED for step 8 works normally in the sense that it lights up when it should. However, turning pot 8 down does not affect the sound coming through pot 8 nor does it decrease the brightness of pot 8.

The 4-8-6 switch works fine. No apparent issues there. I'm glad I'm not the only one who thinks I have a very bizarre problem! If I can get around to it, I may post a video to better demonstrate the problem.