Auduino volume problems

Hello,

I’m working on an Auduino (Arduino-based synthesizer, info here: http://code.google.com/p/tinkerit/wiki/Auduino).
After connecting the wires correctly (nothing is soldered yet) I’ve noticed that the volume is rather low compared to videos I’ve seen on the internet.
I couldn’t find any solutions to the problem until I accidentally put my finger on the six ISCP pins while testing it. This increased the volume a lot. When I released my finger the volume goes down again.
My question is: What is causing the volume to go up? Is this supposed to happen? Is placing my finger on these pins in any way damaging it? Can I perhaps make use of this? I really do not think my Auduino should be operating at a volume so low that I can barely hear it at max volume, while I’m almost going deaf playing music at that level.

I’ve tried connecting the jack to a Fiio E07K amplifier (with headphones connected) and a large guitar amplifier. I’m using a Arduino Uno R3.


These are the pins I am talking about

This sort of thing can happen for various reasons. Most of them down to incorrect or incomplete wiring. Narow down the actual pin that is causing it. You might find it is the ground indicating that not all ground wiring is as you thought. You also could be injecting noise on a control input. What ever the cause it is a fault and should not happen.

Grumpy_Mike: This sort of thing can happen for various reasons. Most of them down to incorrect or incomplete wiring. Narow down the actual pin that is causing it. You might find it is the ground indicating that not all ground wiring is as you thought. You also could be injecting noise on a control input. What ever the cause it is a fault and should not happen.

Thanks for replying.

At first I thought it was indeed the grounding, but after wiring the D3 and GND directly to my jackplug correctly (without the socket) it didn't fix anything.

I want to add that the volume seems to decrease as the tones get lower when my finger isn't on the pins. When I do use the finger trick the volume is constant as I turn the potentiometer (connected to A4 which is a pentatonic ladder). I can hear every step it's on, from the individual grains repeating to the highest pitch (it's the repetition of grains after all). Without my finger on the pins the volume dies when I get below the midtones. I went and made a quick video to demonstrate the problem. It shows the difference between finger-on-pin and finger-off-pin, It can be viewed here:

http://www.youtube.com/watch?v=JHyPk1CB5q0

Oh, and the pin that is causing it is the middle left one (if you take the picture I posted earlier)

I notice that the output to your jack is wired across the left and right inputs and not between one input and ground. Is it any differant when you use the tip and lower barrell for your sound input?

Grumpy_Mike: I notice that the output to your jack is wired across the left and right inputs and not between one input and ground. Is it any differant when you use the tip and lower barrell for your sound input?

No difference. Same result as in the video. Guess the wire moved a little so it looked like it was touching the middle part. Could this perhaps have anything to do with the code? It's all default, but still...

Could this perhaps have anything to do with the code

No not in the slightest, it is a pure hardware problem.

Grumpy_Mike:

Could this perhaps have anything to do with the code

No not in the slightest, it is a pure hardware problem.

I've found out the ICSP pin that's causing it is named SCK. Am i grounding it through touching it? I'm a complete beginner when it comes to electronics. But even if, how would that influence the damn audio. I'm lost.

Argh, I've been trying to fix this for a week now. I'm thinking of just sending it back and getting a replacement. Every vieo or picture of other Auduinos so far have the exact same connections and wiring as I have yet work fine.

Update:

Wrecked the speaker out of a small toy finger drum machine and wired it to digital 3 and ground. It did not solve the problem, but putting my finger on the ICSP pins stopped having effect. So, it seems that it only has effect on the jack output.

I also tried wiring to pin 13 instead of 3. Volume issue solved (loud, ICSP trick doesn't work anymore) but now only one out of five potentiometers works... I know it's not a software problem but isn't there a way to change the digital 3 tot something else? I'm planning on making this arduino a permanent auduino (build a case for it as well) so having a faulty digital 3 output wouldn't really matter if I could just use one of the others.

It sounds like it is a simple mechanical problem with the wiring not making proper contact. Try and use proper header pins and solder the wires.

You can't change pin 3 because it is fixed to one of the internal timers, although I have not looked at the code so they might not be doing this.

Wiring a speaker direct to an output will draw too much current from the Arduino pin and damage it. You need either a seriese resistor of at least 100R or a transistor driver for it.