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Question about pinouts on FX Mini Sound Board
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Question about pinouts on FX Mini Sound Board

by vader7071 on Wed Sep 11, 2019 11:45 am

I recently received my FX Mini Sound Board (https://www.adafruit.com/product/2342).

I have a few questions about this module.

1) I was reading the wring description on the product, and the pinout diagram shows a "Vol + -" pins. I don't have these. I also only have 7 GPIO pins where the pinouts show 10. Overall, I am just guessing that the board is designed to feed an amplifier and the amp is to have the volume control, is that correct? And due to the smaller size, only 7 pins were able to be made available?

2). On the output of the board, there is "CS GND R L GND". Now I know CS is not used for output (just giving a point of reference). But can I wire my Right channel to the "GND R" pins and then wire my left channel to the "L GND" pins or is the last GND the only point to connect for signal out?

I ask all these questions because here is my endgame.

I also purchased a 3.7W amp (https://www.adafruit.com/product/987). I want to use the pin connectors and go straight from the FX board to the Amp board (basically make the amp a "backpack" or "piggy back").

I believe this will work, the amp has "L+ L- R- R+" all together and the FX board has "GND R L GND" all together. So I'll be reversing L and R and running them 180 degrees out of phase of the original signal. But that won't matter.

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Re: Question about pinouts on FX Mini Sound Board

by adafruit_support_carter on Wed Sep 11, 2019 6:49 pm

The mini version of the board (PID 2342) does not have the volume pins broken out. That is on the standard size version:
https://www.adafruit.com/product/2133
It also only has 8 trigger lines (0 - 7).

The GND pins on the output are the same. You could maybe tie it together with the amp piggy back style, but it'd probably be best to do a simple wire crossover to route GNDs to L/R- and L/R to L/R+.

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Re: Question about pinouts on FX Mini Sound Board

by vader7071 on Thu Sep 12, 2019 8:48 am

Thank you.

I figured the volume was just because it was smaller. That answers that question.

As for the piggy back. So there really should be no reason I can't piggyback the amp? I plan to test wiring on a breadboard first using jumpers, but in final assembly, I am trying to keep everything as compact as possible.

vader7071
 
Posts: 74
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Re: Question about pinouts on FX Mini Sound Board

by adafruit_support_carter on Thu Sep 12, 2019 12:40 pm

For this particular configuration, you should be OK with that "reversed" wiring, since the MAX has differential inputs.

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Please be positive and constructive with your questions and comments.