I'd like to build my own soundboard. Never attempted anything like this, but I'd like to make all the circuitry and stuff by hand. Has anyone had any experience with stuff like this? Am I in over my head?
>pic unrelated
What kind of sounds are you looking for? Simple beeps and sirens can be done with oscillator circuits using chips like the 555.
Almost any microcontroller can play WAV files because those are just a sequence of voltage levels you dump to a DAC to play the sound.
There are also some chips designed specifically for applications like yours. ISD1420 can record and play up to 256 different sounds so long as the total duration is less than 20 seconds. This was used in 90s toys like the yak-back and billy bass. SPO256 is an alaphone chip used for things like speak-and-spell and Steven Hawking.
>>919681
Mayhaps "soundboard" was ambiguous. I meant an audio mixer. 12 channels ideally with stereo XLR and 1/4' output.
>>919682
Do you mean a mixing board like pic related or a single-channel mixer? It's the same circuits either way. A mixing panel is just several single-channel mixer circuits combined so you get multiple outputs mixed differently. Potentiometers are arranged in a grid so the Y-axis is your different inputs and X-axis is pots controlling the different mixed outputs.
You want Stereo, so you'll need dual potentiometers. These are two separate potentiometers controlled by a single knob. You're working with audio so use audio (logarithmic) potentiometers. These will be labeled something like A100k where A means audio and 100k is the max resistance. I can go into more detail about h=why you use log pots with audio if you're interested.
You can build a simple audio mixer with nothing but potentiometers, but it's common to put op-amp buffers on the input and an op-amp amplifier on the input. Without the buffers a small amount of the mixed signal will show up on the inputs which can cause problems for some audio sources.
>>919687
Not OP but I'm looking to do sort of the same thing. I just want a 4 channel mixer with one output going to a battery powered speaker for "non venue performances".
I've found a couple instructables where it seems each input just has a resistor (can be subbed for a pot) and each input connects to one output. But it there's no pre amp or amp in any of these tutorials.
tl;dr
4x1 mixer for super diy/lo-fi performance. Output to speaker with amplifying circuit. Simple resistor circuits okay?
>>919776
A passive mixer will bring the volume levels down at the output so you'll have to compensate by turning the volume on your stereo up. This means you're also amplifying any noise on the wire between the mixer and stereo, and stereos don't always sound good when you turn the amplification too high even if there isn't much noise.
You can think of a passive mixer as a voltage divider. I've attached a picture for reference. Lets say all inputs are getting an audio signal ranging from +1.5v to -1.5v and at one point in time In1 is 1.5v and In2,3,4 are at 0v. Simplify the resistors on In2,3,4 as 1/(1/10k+1/10k+1/10k) = 3.33k, so now the output is In1 through a voltage divider formed by a 10k resistor and 3.33k resistor. The output is In1 * (3.33k / (10k+3.33k)) = 0.25*In1.
Decibels, human hearing, and volume knobs are all logarithmic, so the circuit will sound like it cuts the volume of inputs to 60% of their original volume, not 25%.
>>919801
Alright, I think I follow.
One quick dumb question though, if the resistors are potentiometers would reducing the resistance on the un used inputs lessen the reduction?
Do I have any alternatives that if powered could be done so by battery?
