Muffled Audio with Audio+ V2 [resolved]

MikRED97 · July 10, 2022, 2:56am

I purchased a coupled of Audio+ V2 shields with the intention of getting them set up to as an alternative to Sonos for streaming audio from my plex media server in my house.

The problem I am facing now is that the audio works but sounds like a box is put in front of my speakers with how muffled they sound. The problem exists both with the test sound when first installing the driver for raspberry pi in addition to how I am playing the audio from my plex library, linked below. I have attached the Audio+ V2 up to my AV Receiver and a set of powered bookshelf speakers I have and changing between them appears to have no affect.

I have tried it with both my Raspberry Pi 3B and Pi 3B+ using Debian Bullseye Lite 64 Bit.

If anyone has any suggestions for a solution or has any context for what may be causing it would be greatly appreciated.

github.com

odinb/bash-plexamp-installer/blob/main/README.md

# PlexAmp-installer for Raspberry Pi with ARM64 HW.

For more information and hardware used, see here:<br /> https://github.com/odinb/bash-plexamp-installer/wiki

Currently installs/upgrades to: Plexamp Headless v4.2.2

## Burning the image.
Burn the OS-image to the Micro-SD card using Raspberry pi imager, etcher (or app of your choice).

This will currently only work with 64-bit capable Raspberry Pi and Pi OS that is 64-bit.
Images for Bullseye can be found here:
https://www.raspberrypi.com/software/operating-systems/#raspberry-pi-os-64-bit

### Enable SSH.
How to enable SSH:<br />
For security reasons, as of the November 2016 release, Raspbian OS has the SSH server disabled by default. You will have to enable it manually.
1. Mount your SD card on your computer.
2. Create or copy a file called ssh in /boot. 
On most Linux-distros, after re-mount of micro-SD-card, run: ```touch /media/$user/boot/ssh```.
On MacOS, after re-mount of micro-SD-card, run: ```touch /Volumes/boot/ssh```.

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Raspiaudio · July 10, 2022, 6:19pm

Hi !

So are you using our installation script ?
Your audio+ is compatible with the Hifi Berry DAC + described here so you can use any tutorial for plex using this board.

It’s very unlikely that your 2 boards are defective, also try another amp or an headset (volume will be low) to test the quality.

Let me know,

MikRED97 · July 11, 2022, 11:55pm

Yes I did use the installation script prior to following the instructions for Plexamp and did configure Plexamp to use the Hifi Berry DAC+ in that installation.

I have tried a plugging some headphones directly into the Audio+ V2 and a headphone amp and the same muffled (tinny) audio persists. I also uploaded a known good wav file to my pi and played it using aplay and it exhibited the same muffled (tinny) sound.

I feel as though it is likely something to do with the software but I can’t seem to find the culprit as I have a nearly clean install and the fact that the problem persists when using plexamp or playing a wav file through aplay.

Any further suggestions would be greatly appreciated.

MikRED97 · July 12, 2022, 2:11am

I have also tried installing Volumio and playing backing audio from there I am still get the muffled (tinny) output.

Raspiaudio · July 12, 2022, 8:07am

“tinny”? what do you mean
The Audio + have a line level output, so you need an amplified speaker to plug it to.

The level is not like as loud as an headphone

Raspiaudio · July 12, 2022, 10:42am

OK there is indeed a problem on the last batch of Audio V2, the filtering capacitor value is wrong.
So no worry we will fix it, send me your Amazon order number for a full refund.

A quick solution for you to unsolder (or destroy) C14 and C15 on the right and left side of the jack. You can of course keep the cards for free.

The stock will be fixed soon, so nobody could buy this batch, only a couple clients were supplied with this batch.

Thanks for helping us to detect the issue so quickly

MikRED97 · July 12, 2022, 10:49pm

Removing those Capacitors did indeed resolve the issue I was seeing.

Raspiaudio · July 13, 2022, 8:27am

For the few customers notified by email with this issue those are the 2 capacitors to remove.

philm · July 13, 2022, 7:55pm

The notice via Amazon said I could smash the capacitors. What is the best way to do that? Pliers? Cutters? Other tool?
Sorry, but I’m not fluent in hardware ECs but I would like to learn!

Raspiaudio · July 14, 2022, 8:06am

The cleanest way is to use a soldering iron at around 360 C put a bit of soldering to allow a good thermal conduction in the 2 pads of the capacitors and remove them.

If you do not have a soldering use a pair of cutting pliers to destroy them by cutting in the middle. Protect your eyes with glasses to avoid pieces of ceramic jumping in your eyes.

phamiltonsmith · July 15, 2022, 5:04pm

I too purchased a defective board and received the message to remove or “smash” C14 and C15…

Those capacitors are there for a reason. I assume they are filters…

Q: could you provide me w specs for the caps and I will try to replace them?

Tks
P

Raspiaudio · July 16, 2022, 6:17pm

Sure, in the original correct design C14 C15 are 50V 2.2nF ±5% 0805 package
I personnaly can’t hear the difference when C14 and C15 are not implemented versus when there is 2.2nF. It is here theoricaly here to filter any potential electromagnetic noise frome the power supply, but I never heard some on the Audio+, maybe because I have inclued on the Audio+ a separate power supply for the DAC generated from the RPi 5v.

But feel free to let me know if you hear a difference.

Thx

phamiltonsmith · July 18, 2022, 4:20pm

Thanks for the reply! Much appreciated! Thanks also for the refund!

I will try without c14/c15 caps. If I can hear any noise from the power supply, ill install them

P