“THE DEEP” – Double boost pedal for bass! 2N3904 build.

The Deep

Deeper & Deeper
(The Boys reference)

I was looking for simple-to-build effects and stumbled across the Electro-Harmonix Hog’s Foot / Mole. The entire LPB-1 line of pedals are the same basic BJT amplifier but with different capacitors to filter out high or low frequencies. Which got me thinking, why not build a stacked Mole which can also do away with the low pass to give the LPB-1. Or, play with the amount of high frequency attenuation.

I also came across this odd mod by moosapotamus, and I incorporated that too. He takes the voltage divider resistor tied to earth and disconnects it. Effectively changing the biasing style and bias. I tried to do some calculations for the new bias level but I came up with a negative Vce and gave up interpreting that myself.

LTspice simulation suggests the transistor is now biased such that it acts as a switch, switching between rail voltage and ground. IRL there’s no way the Vce can become negative with a single rail supply which means the transistor just saturates and switches on, which is probably what is happening here.

Moosapotamus describes this mod as giving the pedal a punchier compressed fuzzy tone.
Makes sense, the signal is now having the same amplitude throughout hence compressed. Square wave gives the fuzzy tone effect. As for punchier, I did a bode plot and cutting out the 47K does make the pedal more mid forward.

Either way, this simulation and my calculations are probably inaccurate but I did breadboard it up and found the sound to be agreeable at least.

Implementing too many modifiers for standard toggle switches. Finally a chance to use a DIP switch!

My takeaway: do not use standard wires with DIP switches; my enclosure ended up being 90% wires. A ribbon cable would have been neater. The DIP switch also took up a lot of space in the box and I ended up having to move the input jack to the front of the enclosure.

Fun fact, the DIP switch came out of an old circuit board from a very old Henkelman vacuum sealer.

The full list of all 4 (8) options are described in the build diagram. I initially wanted to use a 2 gang pot to save space but it didn’t make sense to limit volume adjustment by tying the two stages together that way.

I’ve been experimenting with nail polish finishes lately, feels good to have things done manually. Rather than relying on lasers, etching, decals, etc. Sometimes low tech is cool right?

All in all, I like the sounds this pedal can give me so far. I’ve never liked any of the fuzzes I’ve built so far. Double boosting the bass with this pedal gets it well into overdrive range and as a fuzz, it sounds much better for me. I usually have the switches set as 0,1,0,1,1,1,1,0.

This way the first stomp gets me a cleaner boost, and second goes into overdrive and cuts a lot of the higher frequencies.

Demo video coming soon:

Not the demo video. Placeholder.

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