Hello everyone,
I’m having trouble with the DAC output of my DFPlayer Mini and I’m a bit stuck.
The SPK1 and SPK2 outputs work perfectly: the audio is clean and stable when I connect a small speaker directly.
The DAC output also seems to work when I connect earphones directly to DAC_L / DAC_R — the audio plays and sounds fine.
However, when I try to use the DAC output with an external amplifier (line-level), I get a constant noise.
I am powering the DFPlayer with a 5V 3A power supply, and there's a 1000uf electrolytic capacitor and a 10nf ceramic one between the (+) and the GND; and the Arduino and DFPlayer share a common ground.
So far I’ve tried:
using a 470ohm resistor and a 10uf capacitor between the dacl-r to the audio output (tip and ring of a 3.5mm breakout module)
To avoid damaging the amplifier or the DFPlayer (and Because I've been pushing my deadline) I’m currently not using the DAC output and instead routing the sound from SPK1 / SPK2 to a speaker and I will make a box to fit the speaker with two directed microphones to get the show going. But I'd love to have a functional DAC working
Has anyone experienced something similar with the DFPlayer DAC?
Is the DAC output known to be noisy or unreliable for line-level amplification, or am I missing something obvious in terms of wiring, filtering, or power isolation?
Review the schematic of the DF Player. You will see there is NO GROUND associated with the speaker connection. Your amplifier input grounds one of the connections. So you are shorting 1/2 of the player output.
Find an amplifier that uses a balanced input or use an audio transformer that will change the type of connection from balanced to unbalanced.
Connect the 8 Ohm winding to the the Dfplayer, Connect the other side of the transformer to your amplifier input. Any similar transformer with similar connection will work.
I'm thinking of completely replacing the DFPlayer mini for an MP3 Trigger from Robertsonics, a friend that has it is going to sell it to me. Please let me know what you think
Groundloops are a common problem with unballanced (RCA) inputs to an amplifier.
The noise could come from the ground of a switching supply of a laptop/PC or switching supply for the DFPlayer, leaking back into the ground of the amplifier setup, completing the loop via the mains wiring.
If... it is a groundloop, then it must be broken
by putting the DFPlayer setup OR the amplifier setup on battery supply.
or by adding audio transformers in the line output.
I would first simply try an elecrolytic capacitor in series with each of the DAC outputs and your amp. Trial & error, but maybe 10 uF?
EDIT I tested an hour later. Although it 'works', the noise level was far too high. Supplies to the module and the amp were independent. Hardly less noise if battery used to power DFR, and Arduino removed (grounded IO2 to play successive tracks.)
