VM114 and wiring to rasberry pi

Kits Audio Hi Fi Projects
1

Hi,

I bought some time ago a VM114 to connect to a raspberry pi.
For now, i only try to verify that my circuit is ok, so my power suplly is a ATX power supply boot with a trombone in 5v or 12v.

When the line in is connected to an ipad, the sound is ok.
When i unplug before connecting to the audio output of raspbery pi, power on, it’s very noisy and still noisy plugged in the raspberry. Someone told me it could be about the electromagnetic field of rpi. When connected to ipad, the rpi is startup too and the sound is ok.

I’m curious why the sound is ok connected to a ipad and noisy otherwise.
Thanks in advance.

2

Can you provide a link to a schematic and a picture of your hookup?

3

This is an advanced implementation to check if it’s a power supply could be the problem.

Even if i remove the capacitors, the diods and have two separated power supply, it’s the same
I heard the rpi boot as the ACT diode on rpi is flashing.

Soemone advise me to install a pre-ampli bewteen the rpi & ampli, but it’s worst. k2572.

4

First: Make sure the regulator does not oscillate by putting 100nF between GND and +5V as close to the regulator as possible.

5

A first video only power ne, with a simpler hookup
youtube.com/watch?v=2e3aYy4HdL8

An other video with music on and a overview of how how the hookup is
youtube.com/watch?v=L-0uDnUxzfc

An overview

The power supply are different, for the ampli it’s the 12v on ATX
For the rpi it’s 5v from an other outlet

6

We’d recommend to use shielded wiring from pi to amp input.
Most likey, there is a hum loop somewhere.
You might want to disconnect the gnd of the line out of the pi at the amp