First project nerves! - Help with a simple PiZero + PhatDAC = Mini Games Box


#1

I hope this makes sense! I’m trying to make a little box to hold our Pi0 Recalbox emulator with on-board sound driven by the PhatDAC and a mini-Amp. I’m using a Zero4U as USB Hub, but havent included that in my design ‘drawings’, just to try and keep things simple.

I’m not sure I have the right idea when it comes to the audio wiring.

My layout looks like this (ie. a messy mess)

http://imgur.com/zQBBQf0

With the real thing overlaid:

http://imgur.com/s1EeW8i

Just triple check my GPIO choices please (4 and 14 used to power the mini-Amp). I’m not sure what Ground I should use between the Pi and the DAC either:

http://imgur.com/xhtez3l

Now, when it comes to wiring one speaker from this mini-Amp: Do I wire the speaker to one side (R+ and R-) or split it between channels (R+ and L-)?

http://imgur.com/CUuoAab

And, is this the right way to wire the audio-out on the PhatDAC? Going from the DAC to the Mini-Amp, then to a single 3W speaker.

http://imgur.com/2PH3ihK

Going really low-budget and up-cycling some Amazon packaging! Hopefully, I’ll be able to add-on a power/reset button and status LED. The speaker is made of clear plastic and with the LED housed inside the box should give off some cool ambient lighting.

http://imgur.com/wHsdXVF

I want it to be as raw and basic as possible to show you can make things from what’s around you. I’ve used a built-in speaker instead of HDMI-Sound because the kids cheap monitors dont have built-in speakers and I don’t want them to miss out on glorious 8Bit chiptunes!

Any pointers or criticism will be gratefully received! All aboard!


#2

I can see several issues with your wiring:

  1. wiring the pHAT DAC to ground

it does not matter which ground pin you use on the Pi or DAC, but you need one (for example pin 6).

  1. wiring to the amp

I think liking the ‘G’ on your amp to one of the pHAT DAC’s larger output terminal may be required. Worst case scenario it can only help minimise noise/interferences.

  1. wiring to the speaker

I can’t answer for certain but it does not look right. I don’t think you could safely double wire the speaker to both terminals but unless you downmix the playback in software I don’t see how you’d get both left and right channels.

honestly, this is a bit beyond my realm of expertise (assuming I have any), but I’m wondering if using a stereo DAC and a stereo amp to feed a single speaker makes much sense. I guess if that is what you have at hand then it’s fair enough and could work, but it’s an odd BOM in my opinion.


#3

you could use something like the following, using a single terminal on your amp (left or right your choice). Note the resistors to dip the signal following merge of L and R from the DAC:

EDIT: this is the full project this pic was extracted from, if that’s any interest:


#4

Thank you! I didn’t think the audio was right but was sure I’d seen someone use the DAC into one speaker … turns out it was that project and I’d remembered it completely wrong.

AND I just remembered that I ordered two tiny speakers for this ages ago (Chinese parts tend to get ordered and forgotten before they arrive!) so I can use those and wire up the DAC & Amp properly :)

Turns out I can’t use the status LED as it’s code uses Pin 18, which is taken by the DAC. If I get everything working I may look into editing the code to change that to another pin.

Thanks again, this is fun.