Clarification requested : Ambika Mainboard with no Audio 100k , which pins to solder

Hi all, Im in the process of putting together my ambika and Im almost done the mainboard, I ordered a custom case from FCD that didnt have an audio potentiometer as it spoils the sleek look :slight_smile: Ill be using my mixer for volume control anyway

I just solder a piece of cut wire in the middle and right holes I realise thats what the instructions say but I want to double check if there is another method or just like in this photo of earlier on in the build?

No, it’s fine to do the same trick on the middle and right pads of the volume pot.

I find the signal to be quite “hot”, it does distort on my mixer set to minimum gain, so you may want to put a smallish resistor instead of just a cut of wire…

A resistor won’t have any effect - you need two resistors to form a voltage divider. Or simply change the resistor in the op-amp feedback loop to 4.7k.

Thanks Olivier! Im taking my time with this and hopefully it will be error free . 12 hours to make the mainboard!

Since we don’t have a voltage divider any more doesn’t the amplification decrease if we increase the resistance between the output of the summing opamp and the last opamp stage?

why do we not have a voltage divider anymore? instead of using a pot you can use 2 resistors in its place

@Lindeborg: yes, it would work in this particular case, but it’s a bad habit, because in other contexts this “replace the pot by a single resistor” trick won’t work.

Rosch: Because we have replaced it by a cut of wire. Yes, that is also an option.
Pichenettes: Agreed…

it’s still a divider, just all cranked up. but i understand now

Hmm Im thinking I may have to put the trim pot in there after all, this thing is LOUD

rosch: sort of, but the resistance to ground is far more than 100k so there is really no dividing going on :wink:
dude163: I’ve mounted my 100k pot on a flying lead in the back panel, works like a charm.

Thanks, Ill take a look at what I have left over, I did order the 100K trimpot so I at least have that!