Converting stomp box booster to onboard; can I simplify power filtering?

[Maverick6Strings]

Hello everyone,

I'm working on building the Aion Photon Booster as a built in preamp into a guitar instead of a stomp box.  https://aionfx.com/project/photon-booster-line-driver/

In their docs they mention that they added some additional power filtering to the original design.  Since an onboard version would only be running off a battery (and assuming battery power is "cleaner"), then the addition power filtering should be redundant and could be removed from the circuit to save space / simplify layout / etc.  Looking at the schematic (attached below) it seems like I should be able to take out C9 and C11, possibly C10? 

Also in my limited understanding R15, R14 and R9 make up a voltage divider. Shouldn't it be possible to eliminate R9 by adjusting the values of the other two resistors (assuming C10 were removed) to get the same voltage at the base of Q3?

Any guidance would be much appreciated...

-- Maverick

[GGBB]

Welcome to the forum.

C9 is also a power reservoir - not just a smoothing cap.

R9 is not connected to the voltage divider. R4 is. R4 can be jumpered if R14 and R15 are replaced with 1M.

[r080]

Welcome to the forum! Are you using the board from Aion? If so, you might not get much more space by removing those parts. Aion's site has schematics of the originals, so you can see what extra filtering was added. If you are worried about size, it could work to reduce the cap values.

GGBB makes a good point about R14 and R15. This particular circuit is sometimes called low noise biasing. You can simplify it, but you will probably get more Johnson noise from the larger resistors.

I had a production Pickup Booster years ago. It could definitely get noisy, but I don't know how much of that was power filtering vs just the low CMRR of the discrete opamp.

[r080]

Definitely take a look at the schematics from the tracing:
https://aionfx.com/news/tracing-journal-seymour-duncan-pickup-booster/

You should be able to build the power supply filtering of the original onto that board and save a little vertical space. Apparently, the original had just a single 100n filter cap due to a trace for a larger cap not connected properly on the board. They must have decided it was enough.