Poison Apple Auto-Wah - With a Mod for Bass

BuddytheReow

Breadboard Baker
I picked up this board specifically for my bass. Envelope filters are a lot of fun and like Pokemon, I gotta catch em all. Or at least try em once.

Anywho, as a stock circuit this does pretty nicely on guitar and it kinda works on bass. Someone here, and I forget who, mentioned a simple mod to tune the envelope filter more to the bass frequencies. The mod I did was to increase C3 and C11 to somewhere around 47n. For me, I appreciate the Swiss Army Knife aspect of this and wanted to make it switchable for versatility. Adding a 22n OR 27n cap (they're both close enough) in parallel with C3 and C11 drops the filter frequencies and now this thing quacks like a duck when dialed in just right on bass.

As a standalone effect its pretty sweet, but IMO this shines when you put some dirt in front of it and dial down the sensitivity knob.

One control I'm kind of scratching my head on is the Resonance control. To me, its more of a tone control than anything else. It is on the more subtle side when used with bass.

Considering the mod I did, I wanted to keep everything else stock, including the LED placement. No issues whatsoever when populating, soldering, drilling or assembling. All in all a smooth build and a nice sounding circuit. I would highly recommend this circuit for anyone looking for something funky, something fun, or at least something different than dirt or phaser/flanger.

The enclosure is unfinished and I need some time to mull over the artwork and find a good opportunity for paint. Either way, it's boxed up and functional. I'll circle back here with the final product.

BuddytheReow

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Just in case you didn't see the recent update in the build docs, make sure D4 is oriented the same direction as D100.

Rather than try to desolder / flip it and risk damage you can just clip it out from the top of the board and leave it out.

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You’re right @Robert I followed the silkscreen. Looking at the schematic, what is the purpose of D4? Polarity protection for the voltage regulator? Either way I replaced it this evening.
 
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Looking at the schematic, what is the purpose of D4? Polarity protection for the voltage regulator?

Basically yes, but not the typical reverse polarity condition.

When power is disconnected from the circuit C10 may still hold a charge. In some (rare) cases this could damage the regulator since there is no longer a voltage on the input. The diode ensures that there is never a "reverse" voltage applied across the regulator greater than the forward voltage of the diode.

You wouldn't use this method to protect against reverse polarity applied to the circuit since that reverse voltage (and likely over-voltage) would flow right past the regulator through the diode and on to the rest of the circuit.

I personally have never seen a regulator damaged from the absence of this diode, and a majority of circuits don't include it, but theoretically it is possible. Some regulator datasheets will recommend the diode, although I can't find one that does at the moment.
 
I don't understand how you wired up the switch to add the 22n caps.
I checked the values I put in last night and they’re 27n. Both C3 and C11 are tied to ground per the schematic and board. Solder 1 end to the lead that is not tied to ground and the other lead goes to the switch. The other pole of the switch goes to ground. When the switch is activated these new caps run in parallel with the old caps to bring the total capacitance close to 47n.
 
I checked the values I put in last night and they’re 27n. Both C3 and C11 are tied to ground per the schematic and board. Solder 1 end to the lead that is not tied to ground and the other lead goes to the switch. The other pole of the switch goes to ground. When the switch is activated these new caps run in parallel with the old caps to bring the total capacitance close to 47n.
Of course! All clear now. Thank you
 
Swimming duck is positively ducky.


Weird, I thought I posted in this thread before... must've been another thread. My bass-friendly mod is to split the signal out of the instrument and use it as an input into the envelope detector portion of the circuit. Basically a side-chain situation, so the effect can be before/after dirt, modulation, whatever and have clean triggering. It'd be a...




Sitting duck:

71f3c1dda9a108257659c5d57d1e424f.jpg
 
Swimming duck is positively ducky.


Weird, I thought I posted in this thread before... must've been another thread. My bass-friendly mod is to split the signal out of the instrument and use it as an input into the envelope detector portion of the circuit. Basically a side-chain situation, so the effect can be before/after dirt, modulation, whatever and have clean triggering. It'd be a...




Sitting duck:

71f3c1dda9a108257659c5d57d1e424f.jpg

Any info on adding the side chain mod to the Poison Apple?
 
Any info on adding the side chain mod to the Poison Apple?
I gleebed it from the LG SnoWah Flake:

SNOWAH FLAKE SCHEMATIC.png

So build the PedalPCB 3-Channel Splitter and use one of its outputs to trigger the Poison Apple.
If that's too much, you could buiild a smaller splitter on perf or vero and include it in the same box as the Poison Apple — make sure it has a loop so you can put the wah after dirt.
 
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