EQD Arrows input cap switch

[Supernaut_]

Hi guys!

I'm gonna build an EQD Arrows booster pedal and was thinking about implementing a simple input cap switch mod. I'm considering replacing C3 with a 100n cap, and wiring up a switch to change between a 4n7 and a 100n cap for C2. This should give the option of a flat frequency boost along with the Arrows signature mid/treble boost, right?

Are there any reasons why this wouldn't work or sit well with the Arrows? Or would it be better to include the C3 in the switch so I can switch between the original 4n7/10n and the modded 100n/100n cap pairs?

Schematic below:
http://effectslayouts.com/wp-content/uploads/2018/07/Lawn-Darts-schematic.pdf

Cheers!

[11-90-an]

Everything stated will work... 

There shouldn't be any problems... simple in/out cap changes (in this circuit) shouldn't cause much harm..

[Supernaut_]

Thanks for your reply 11-90-an, that's what I figured as well. I also figured that there's probably no extra benefit from making C3 switchable. A 100n output cap compared to a 10n output cap shouldn't change the sound when the stock 4n7 input cap is active, right?

[MikeA]

I just tried it in LTSpice, here's the effect of your cap changes on the approximate low-end rolloff (-3dB point).  Response is flat above that in the audio band, and none of these changes affect the output level or waveform:

Stock caps: 157 Hz
C2 = 100n: 140 Hz
C3 = 100n: 57 Hz
C2 and C3 = 100n: 15 Hz

So yes, changing both caps has a bigger effect than changing one. 

[Supernaut_]

Thanks MikeA! Very useful information, looks like I'd better make both caps switchable. C3 brings a much bigger change than I would've expected, suppose I've got to take a look at that LTSpice software for future reference.

[MikeA]

You can also calculate the individual filters (resistor/capacitor pairs.)  They may have a different result when you put several of them in sequence, a sim like LTSpice will show you that.