The original Sunn Beta Lead and Bass amps have two identical channels that can be run in parallel. I've never played these amps but built both lead and bass versions of the Aion FX Beta Preamp - a single channel pedal adaptation of the Sunn Beta's preamp section. I loved the sounds I was getting with these so much, I decided to build a two channel version.
I wanted to be able to select each channel independently as well as run them in parallel. For that to work I had to cut the traces that connect the in to the out jacks when bypassed. Otherwise the clean bypassed signal of the inactive channel would be mixed in with the active channel's output.
I put some lacquer over the cuts later to prevent accidental shorts when soldering in the footswitches. It works as intended but obviously no signal is passed when both channels are in bypass. It's possible to do a true-bypass version with only two footswitches but one of them would have to be a 4PDT and it would require some additional wiring. I decided against doing it that way since I'm using this pedal as an always-on preamp anyway.
To avoid some nasty oscillations at the upper end of the treble pot sweep I added a 15K resistor in series with the wiper. This resistor exists in the original amps as well but has been omitted from the Aion FX version for some reason.
Not my cleanest build in terms of soldering and drilling but it works and the sloppy drilling is hidden by washers anyway so who cares
I used shielded wire for the ins and outs. That turned out to be quite the pain in the ass since I had to connect the wires from both boards to each jack.
There's a series 27K resistor and 2.2uF cap on the output of each channel in the original amp before they're summed but not on the Aion FX board. I wired those between the main and daughter board. I don't think they're necessary or affect the tone in any meaningful way but included them anyway.
Overall I'm pretty stoked with how this turned out. It looks and sounds killer and the parallel channels allow for some unique tones. I will do a full demo video some time in the near future.
I'm planning to do another version at some point with the master volume control of the original amp. I have the vero layout for the master volume drawn up already but have not finalized the enclosure design yet.
Bonus shot with black knobs:
By the way, I found these knobs which I think would look awesome for the level and drive pots but they're kind of pricey, especially after shipping: https://de.rs-online.com/web/p/potentiometer-knopfe/2596935 Anyone got a cheaper source for these, please let me know!
I wanted to be able to select each channel independently as well as run them in parallel. For that to work I had to cut the traces that connect the in to the out jacks when bypassed. Otherwise the clean bypassed signal of the inactive channel would be mixed in with the active channel's output.
I put some lacquer over the cuts later to prevent accidental shorts when soldering in the footswitches. It works as intended but obviously no signal is passed when both channels are in bypass. It's possible to do a true-bypass version with only two footswitches but one of them would have to be a 4PDT and it would require some additional wiring. I decided against doing it that way since I'm using this pedal as an always-on preamp anyway.
To avoid some nasty oscillations at the upper end of the treble pot sweep I added a 15K resistor in series with the wiper. This resistor exists in the original amps as well but has been omitted from the Aion FX version for some reason.
Not my cleanest build in terms of soldering and drilling but it works and the sloppy drilling is hidden by washers anyway so who cares
I used shielded wire for the ins and outs. That turned out to be quite the pain in the ass since I had to connect the wires from both boards to each jack.There's a series 27K resistor and 2.2uF cap on the output of each channel in the original amp before they're summed but not on the Aion FX board. I wired those between the main and daughter board. I don't think they're necessary or affect the tone in any meaningful way but included them anyway.
Overall I'm pretty stoked with how this turned out. It looks and sounds killer and the parallel channels allow for some unique tones. I will do a full demo video some time in the near future.
I'm planning to do another version at some point with the master volume control of the original amp. I have the vero layout for the master volume drawn up already but have not finalized the enclosure design yet.
Bonus shot with black knobs:
By the way, I found these knobs which I think would look awesome for the level and drive pots but they're kind of pricey, especially after shipping: https://de.rs-online.com/web/p/potentiometer-knopfe/2596935 Anyone got a cheaper source for these, please let me know!
