Aion Fx Halo V1 Mod question

[gm76]

Hi I am slowly getting back into DIY pedals after a long absence, was never strong at schematics. I have an V1 Aion FX Halo built to stock Violet Ram's Head specs (https://aionfx.com/app/files/docs/halo_legacy_documentation_v1.pdf) - am interested in removing q4 to mod it to Jumbo Tone Bender specs. I see a Q4 bypass feature in the newest version (https://aionfx.com/app/files/docs/halo_documentation.pdf), but since I already have the old version populated, was wondering if I could do this relatively simply. In addition to removing Q4, C13 and R20-23, do I have to place a jumper between C12 and the volume pot and/or place jumpers for the components I remove? My transistors are socketed and there was no sound when I just pulled Q4.

[iainpunk]

the C13 capacitor it currently connected to the collector of q4, if you move it over to the emitter, the transistor acts like a buffer, which practically does nothing to the sound.

cheers, Iain

[gm76]

Thanks.  Since Q4 is socketed, can this be achieved by just flipping the orientation of the transistor?  I tried this & the result was less output (but loud enough when turning up the volume),  more compressed.  I figured this connects C13 to the Q4 emitter like you suggested, but was not sure if changing the connector's orientation matter. 

[willienillie]

No, you just turned Q4 into a much lower-gain amplifier.  Iain's suggestion was quite a good idea, wish I had thought of it myself!  Should be quite easy to try.

[gm76]

Thanks for both of your  feedback, will try this. Sorry my questions are naive - would the easiest way for me to make this mod on the PCB be to desolder the C13 lead that connects to the Q4 collector, then jumper that lead to the Q4 emitter?  Since  my transistor is socketed, would it be reasonable to solder the jumper  to the emitter lead above where it sockets?

[willienillie]

It's hard for me to guess what physical situation you're faced with, since I'm not looking at your board.  Usually after a component has been installed on a PCB, the leads are cut, and are then too short to reach anywhere else.  I would probably remove C13, get a new cap with full length leads, and tack it on to the back of the PCB, between Q4's emitter and Volume pot lug 3.  Just a quick temporary rigging to see if you like the sound.  Then if you decide you want to keep that, reinstall C13, but cut the PCB trace that connects to the Q4 collector, and add a little jumper on the back of the board between C13 and Q4e.

Or if you already know you want to do this mod, just leave C13 in place and skip ahead to the trace cutting.  Even then, you can go back to the original circuit by replacing the cut trace with a jumper.  Hope that makes sense.

[gm76]

Finally got to try this- got the temporary 100n cap on the back between the Q4 emitter and the volume pot and it sounds great, thanks for the advice!