Sushi Box FX Particle Accelerator Bass-Pot not responsive (+other issues)

[Löten]

Hello!
I did not find a general "Welcome new posters"-thread, so I'll just start directly here (if there is one, sorry, I'll post there of course!).

Nathan from Sushi Box directed me to the forum, as I'm having troubles with my build of the Particle Accelerator. I did read all the threads on the build, but it seems I ran into something new

I think I got something wrong with the build, or maybe a component is not functioning properly, as the Bass-knob has no effect on the sound whatsoever (I measured the resistance of the potentiometer in 0 and 100 % position, the resistance changed from 0 to roughly 190 kOhm, so it should work basically). The capacitator in front of the potentiometer is charged. The connections of the potentiometer to the next parts of the circuit are conductive. The ground is also conductive.
There is absolutely no effect. No boost, nothing.
Also the Gain is not as effective as I would have thought, there is quite a lot of volume difference between 0 and 100 %, but not much compression or actual "overdriviness" (but maybe this is just how it is supposed to be, this is my first experience with a preamp from Fender/Alembic).
The rest is fine I think, footswitch, volume etc. The tube filiaments are glowing, and the signal is quite free from interference (with a Bass VI with single coils). I measured the voltage at R8/R9 , which is 250V (as in the instructions), therefore I assume that the high-voltage supply is working as intended.
Maybe you have an idea where I could check, maybe could you help me out the voltage values which should be measurable on the pins of the tube, ?

Thank you very much! If there are languange problems, please let me know, as I'm not a native speaker
Best regards, Ben

 

[Bricksnbeatles]

Hi, Ben!
I don’t have any experience with this circuit or what it should sound like, so I’ll leave the help to someone who has built this before, but I just wanted to say welcome to the forum! Good luck with the troubleshooting— once it’s sorted, I’m sure it’ll sound incredible. Been thinking about building one of these for my Bass Vi setup too!

 

[kweefthief]

I'm not sure how to fix the bass issue but the gain is probably working correctly. This circuit does not produce a lot of overdrive. If you want to get more gain out of it, I'd suggest keeping the volume low and hitting it with a boost It reacts well to boosts and breaks up nicely!

 

[Löten]

Hi!
So, I found the culprit. It was indeed me, I did not realize the different values of the Middle and Gain potentiometers, I needed to swap them. Now everything works and it sounds like a Fender
I can only recommend the build, as it is quite nicely documented and a lot of fun to build!
Best regards, Ben

 

[pbrommer]

Hello!
I did not find a general "Welcome new posters"-thread, so I'll just start directly here (if there is one, sorry, I'll post there of course!).

Nathan from Sushi Box directed me to the forum, as I'm having troubles with my build of the Particle Accelerator. I did read all the threads on the build, but it seems I ran into something new

I think I got something wrong with the build, or maybe a component is not functioning properly, as the Bass-knob has no effect on the sound whatsoever (I measured the resistance of the potentiometer in 0 and 100 % position, the resistance changed from 0 to roughly 190 kOhm, so it should work basically). The capacitator in front of the potentiometer is charged. The connections of the potentiometer to the next parts of the circuit are conductive. The ground is also conductive.
There is absolutely no effect. No boost, nothing.
Also the Gain is not as effective as I would have thought, there is quite a lot of volume difference between 0 and 100 %, but not much compression or actual "overdriviness" (but maybe this is just how it is supposed to be, this is my first experience with a preamp from Fender/Alembic).

Maybe you have an idea where I could check, maybe could you help me out the voltage values which should be measurable on the pins of the tube, ?

Welcome. Let's see what we can figure out.

We know that you have good voltage from the smps -- 250v. Good start so far.

What will help is if you can SAFELY measure the pins of the tube. I'm not sure on the layout which is which, but we should see this:

Pins 1 and 6: tube plates, probably around 200v
Pins 2 and 7: not much voltage on the tube grids
Pins 3 and 8: tube cathodes should have about 1.2-1.7V
Pins 4 and 5: filaments for heating, I think 6.3V

Fender preamps are not going to have much gain, and the bass changes will happen but not be easy to detect.

If you check voltages, let us know, and if those are good, then we can figure out if the wiring is bad or something else. Good luck and hopefully we can find a solution.