# Clandestine Preamp Mod



## DSoda (Apr 22, 2022)

Hi everyone,

I'm new to pedalbuilding and I'm enjoying the hobby a lot. I bought myself a few PCBs from the site lately and I'm looking to modify the Clandestine Preamp a bit. Currently it runs one knob, one trimmer, and a toggle switch for the voicing. I'd like to change the toggle switch to a tone knob so I can get sounds in between the set tones.

Any idea how I can do this? Thanks in advance!


----------



## Big Monk (Apr 22, 2022)

DSoda said:


> Hi everyone,
> 
> I'm new to pedalbuilding and I'm enjoying the hobby a lot. I bought myself a few PCBs from the site lately and I'm looking to modify the Clandestine Preamp a bit. Currently it runs one knob, one trimmer, and a toggle switch for the voicing. I'd like to change the toggle switch to a tone knob so I can get sounds in between the set tones.
> 
> Any idea how I can do this? Thanks in advance!



It's a very subtle effect no matter how it's set. Having built the Aion Ares with some tweaks from the Clandestine, I can say the toggle provides just the right amount of change between set tones. 

You won't get any nuance or "in-bertweeners" with a tone control.


----------



## Feral Feline (Apr 22, 2022)

I don't doubt Big Monk's assessment one bit.

However, I think it's an interesting exercise that you may be able to learn from and implement in other builds down the road.

Take a look at how Joe Gore implements a simple "tone" control on the little-but-mighty Bazz Fuss:






How this could translate to the Clandestine might be something as simple as this:






You wouldn't even have to breadboard it, just experiment with the PCB-build before you box it by tacking in some wires to the Switch pads, keep the wiring numbers as per the switch with the pot's middle lug connected to the middle switch pad; you may find you prefer lug 3 connected to pad 1 and lug 1 connected to pad 3, but easy-peasy to swap the wires to reverse the rotation.

I'd start with B100k, but you can try anything between B5k and B500k and see what works best for you.


It'll be a fun experiment to learn from and, importantly, reversible for when you chuck that switch back in there instead of the pot. If you want to go crazy experimenting, you could socket C3 & C5 and play around with different sized caps, too, which may make having a tone-pot desirable after all.


Do it for science!


----------



## Big Monk (Apr 22, 2022)

Feral Feline said:


> I don't doubt Big Monk's assessment one bit.
> 
> However, I think it's an interesting exercise that you may be able to learn from and implement in other builds down the road.
> 
> ...



I’m definitely not trying to talk anyone out of experimenting!

It’s just that a Blend style control is not going to have enough range with the subtle changes in caps that are in the EP preamps. 

Personally, I found any of the “fat” settings in this circuit brought way too much gain. 

I use mine as a little bit of sparkle when playing in the cleaner range and to goose my El-Cap, so the “fat” settings sounded like trash to me. 

My Aion Ares doesnt have the “Fat” setting anymore. I cribbed the JFET source trimmer and the “Mid” setting from the Clandestine. 

By all means though, experiment. Lord knows I’ve had a flippin Fuzz Face on the breadboard for 5 months now so I’m not gonna stop ya! 

Just make sure you replace the “Mid” cap with something much larger than the “Bright” cap or else the Blend won’t do much. Also, keep in mind the Blend is not a clean transistion, i.e. you are not sweeping cleanly from one cap to the other across a range, which is why you need the large disparity in volume to begin with.


----------



## Feral Feline (Apr 22, 2022)

The "laugh"-like was for your first sentence, @Big Monk. 

You'd be the last person on earth to stop somebody else from seeking and tweaking tone!

Man, if only I had a completed build for every time I ignored sage & sound advice and tried to tinker only to get a circuit stinker...


----------



## Big Monk (Apr 22, 2022)

Feral Feline said:


> The "laugh"-like was for your first sentence, @Big Monk.
> 
> You'd be the last person on earth to stop somebody else from seeking and tweaking tone!
> 
> Man, if only I had a completed build for every time I ignored sage & sound advice and tried to tinker only to get a circuit stinker...



The true Echoplex style preamps are very subtle. The frequency switch does offer distinct tones but there is not a lot of boost on tap, as there wasn’t a lot in the originals either. At least the solid state versions. 

Folks with tube Echoplex units have commented that tube bias and amplification factor differences meant that sometimes you got a “hot” preamp bit the solid state units were pretty consistent. 

I really like my Ares/Clandestine hybrid for what it is. I think that tone switch gives a good amount, if subtle, of tonal flexibility.


----------



## DSoda (Apr 23, 2022)

Wow, thanks so much! 

I may still give the Joe Gore tone control a whirl just "for science" even if I now know it will be a subtle change. Luckily for me, I have 2 Clandestine PCBs.

I plan on doing a 2-in-1 with a silicon fuzz face. Let's see how it goes.


----------

