Low volume on Auduino granular synth

Other Hardware Audio
1

Hi there,

I breadboarded an Auduino, adding AC coupling and a voltage divider to the output, because I'd like to safely play it through my guitar amp.

Breadboarded (with an Uno) it sounds great, but when I soldered it all up (with a nano) the output volume is really low. I'm pretty new to electronics - could low volume be due to a bad solder joint? How might I got about troubleshooting this issue? I have a multimeter, but no oscilloscope.

Thanks so much for your time!

Edit: I drew the pots wrong on my original diagram.

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2

Your circuit will burn out your pots. If you put them up to full then the tracks on the pots will burn out as you short out your power supply.

There is no danger connecting your Arduino directly to your guitar amp as long as it is AC coupled. You potential divider is cutting down the volume.

Also it might not be producing enough signal to drive it loud enough, you might have to use a preamp.

You also need a resistor with the led on pin 13, or you will burn that out as well.

3

Hi Mike, thanks for replying. Do the pots need a resistor to ground?

I breadboarded this exact circuit and it didn’t have lower volume, which is why I was wondering if it could be a soldering connection problem?

The LED does have a resistor. Thanks for catching that on my diagram!

4

If true, then your breadboard is faulty!

5

Two different breadboards. Do you think it’s possible that the pots burned out while I was testing it on the breadboard? Would that make it quieter? The pots all still affect the sound though…

Thanks for helping me get to the bottom of this!

Here’s a photo of the Uno breadboarded circuit:

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I also have a photo of the breadboarded circuit with the nano I used in the actual device, but I can only put one picture per post.

Neither prototype had the volume issue.

6

Here’s the other prototype:

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7

No.
You have shown them on your circuit with the wiper connected to ground and the other end of the pot to 5V.
However this isn’t how you have it in your photograph. You connect the wiper to an analogue input. I suspect this is what you want to do.

A schematic is nothing if it is not accurate. If we can’t trust the simple stuff how can we trust the stuff you are asking about?

9

Okay, sorry. I appreciate the correction! This is my first soldered project with pots.

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10

Thanks for the corrections.
Now we can concentrate on getting the output correct.
First off remove the 100K to ground resistor. This is acting as a low pass filter and is removing a lot of the high frequency from the output of your synth.
Then remove the 10K to ground, all this does is to cut down the volume of the output.
Try it like that first. The only effect of the series 1K is to increase the input impedance into your amplifier. This is normally something you don't want because this will increase the noise picked up from the digital switching circuits, so you could try removing that as well.

11

I see 1µF into 100k, so a 1.6Hz roll-off high-pass filter. No low-pass involved. Unless the diagram changed.

12

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