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Topic: Proper Setup for the Adafruit WAV shield with stereo microphone and Amplifier (Read 1 time) previous topic - next topic

arbeers

I'm trying to create the "Wave Shield Voice Changer" according to the instructions from Adafruit.com site, using the following components, and I'm having trouble getting it to work properly

Parts:
-Arduino Uno R3 with separate 9-V power supply
-Adafruit Wave Shield kit: https://www.adafruit.com/product/94
-MAX98306 3.7W Class D Audio Amplifier
-MAX4466 Microphone breakout
- 3V power supply using 2X 1.5V AA batteries to the amplifier
-2X 4 ohm 3 W speakers wired to the amplifier pickups

I've wired the components up according to the instructions  ( Instructions ) , however I only hear sound from 1 of the speakers.

I'm not sure if this is a power issue or if I've wired it up incorrectly.

-The instructions on the Adafruit website suggest powering the amplifier separately, which I've done using the 3-V power supply.

-Also, I've used the green wires (in the picture) to attach the "L+" and "R+" headers to the "IN" header of the Wave Shield, and the yellow wires (in the picture) to attach the "L-" and "R-" headers to "OUT" on the Wave Shield.


Thank you, and please feel free to ask questions about the problem. I hope that my "situation" is clear.

arbeers


Grumpy_Mike

Quote
lso, I've used the green wires (in the picture) to attach the "L+" and "R+" headers to the "IN" header of the Wave Shield, and the yellow wires (in the picture) to attach the "L-" and "R-" headers to "OUT" on the Wave Shield.
I would have thought that one wire should be to the out header and the other to the ground. What is the IN header?

Sound out of only one speaker suggests an error in wiring up the amplifier inputs.

DVDdoug

Are you sure it's supposed to be a stereo effect?    Because with one microphone the input  is mono.

If you swap the inputs of the amplifier module that will tell you if the problem is the amplifier/speakers or something before that.

If swapping inputs makes the sound come out of the other speaker, it could be a hardware problem or a software problem.  And it depends on if the software is supposed to make a stereo effect from a mono input or if the mono analog signal is supposed to be "split" and routed to left & right somewhere.    


If the same speaker works when the inputs are reversed, try swapping the speakers to see if it's the speaker or the amp.

 
If you only have one good signal out of the wave shield you can connect both amplifier channels to the working output and you'll get sound out of both speakers.  (But, I don't know if that's the way it's supposed to work...     If the software is supposed to make different left & right channels it's not correct to drive both channels from the same signal.)


Grumpy_Mike

Quote
Are you sure it's supposed to be a stereo effect? 
No it is not, both left and right inputs for the audio amplifier are connected to the same audio output on the wave shield.

arbeers

Thanks all for the suggestions.

Mr. Mike - I think you are correct in that the inputs to the amplifier are incorrectly wired. I reviewed the Class D amplifier setup on the adafruit website, and it looks like that is the culprit.

To Doug - great suggestions about testing the speakers, that showed that they are still working.

I think the most illustrative solution to the problem is the following, which shows a picture of the proper wiring of these types of Class D audio amplifiers (this is a setup example of the adafruit TPA2012 2.1 W stereo audio amplifier, however I'm using the MAX98306 Class D from adafruit):

https://learn.adafruit.com/assets/13978

I think the "R-" and "L-" need to be wired to GND, and the in needs to go to L+ and R+. Will try this and see if it works correctly.

Grumpy_Mike

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think the "R-" and "L-" need to be wired to GND, and the in needs to go to L+ and R+. Will try this and see if it works correctly.
Yes that should work.

arbeers

Yes, it was a wiring problem - the R- and L- pins on the MAX98306 Amp needed to be changed.

I've gone ahead and attached two .gif files showing the "before" and "after" re-wirings of the amplifier, perf-board, and the Adafruit Wave shield.

 It has been a pleasure learning how to do this fix with your help, all. I hope that future arduino users find this thread useful. Thanks!

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