Transparent Boost Pedal

Few years back, I struggled getting a good tone. Whenever I plugged in my guitar's multi-effects (Zoom G2.1NU with Stack Amp/Cab simulation always turned on) into the front of a tube amplifer, I get bad tone most of the time (sometimes very sharp, sometimes I can't cut to the mix). Truthfully, whenever we rent a studio, we have very limited time and we would like to maximize the time by playing with our band rather than setting up/tweaking. To avoid the tube's preamp coloration, I tried to plug my multi-effects into an FX return of a tube amplifier. It sounded very good but it produced a very low volume. With this, I decided to create my own booster with the following criteria:

• Powered by 9VDC
• Fixed Gain (20dB)
• Should be as transparent as possible and no tone shaping (therefore, no tone control)
• Simple, only one knob
• Use a good audio op-amp (OPA2134)

With the following criteria, I did the following circuit in LTSpice.

And here is the actual circuit.

 

As you can see from the picture, I reused the silent rehearsal PCB I did on my previous entry on this blog. I can design another PCB, but since I would like to cut some cost, this PCB will do for a prototype. Plus, I also did the 3D printed mini-stand for this (look for the green line at the bottom) :)

This is not really a pedal because this is an always on circuit, and it is ok because this booster was designed to be very transparent and straight to FX return of an amplifier's effects loop and will always be turned on all the time. This is very ideal for someone like me who heavily uses cab/amp simulations.