PGA gain in supercollider

RafaeleAndrade

giuliomoro Thank you, Giulio! Could you just tell me if it's even possible to add 15 dB of gain on these inputs before I remove the whole PCB and all the wiring? I am afraid that I'm going into a rabbit hole and in the end, it's not even doable.

giuliomoro

yes it is, there's 42dB of gain available on channels 2-9

giuliomoro

before tearing apart the PCB, I recommend you remove your PCB, put on the input wing with the jacks and test the inputs there. You can even use the signals on the sockets with the wing on, if you prefer pins to jacks: they are already AC-coupled. If that fixes the issue then most likely what you are missing is the capacitors I described above.

What pickups are you using ? Is their output AC- or DC-coupled?

RafaeleAndrade

giuliomoro Okay, I will try it tomorrow! I am using the Nu Cyfi pickups , it behaves as an AC audio signal.

since I have 16 of it in total and bela can only receive 8 channels, I use a resistor of 1k to combine 2 pickup signals into one (as advised by the maker of the pickups), which works but unfortunately remove some loudness of it.

RafaeleAndrade

giuliomoro Hi Giulio, I tested this morning with 2 pickups at the channel 2 and I can confirm the problem was the capacitors. I could boost up to 40dB this time.

I will be busy finding a way to connect these 2 capacitors on my PCB Design, meantime. could you confirm if I should follow these steps to set this new gain at the startup of bela? Will these setting also be triggered if I update the code on the fly ?

Access bela:ssh root@bela.local
Create /root/.bela first with: sudo mkdir -p /root/.bela
Create a file with: nano /root/.bela/belaconfig
Write on the file: CL=-I2,10,3,10,4,10,5,10,6,10,7,10
for sc users: Use the adcLevel hack( s.options.adcLevel = 1) on sc patch. The gain of the first two channels can be set via pgaGainLeft/Right from the scd file.
reboot

giuliomoro

those steps should work yes; you won't need to reboot the board, just restart the program.

RafaeleAndrade

giuliomoro it worked! Mistery solved!

« Previous Page