Now turn the amp board over and solder a small length of wire between the 2 points below (this is because the amp board is designed for balanced input, but the HiFiBerry outputs unbalanced only):-
Finally, wrap the amp board in insulation tape to secure the connections and insulate it from the metal case. Then mount the stereo headphone socket into the case. Reassemble the case and all is finished.
NOTE
These instructions will mean that you lose the ÂĽ inch signal outputs. Also. because I have not incorporated a potentiometer for volume control, be very careful when changing synth engines or patches as the volume level may be too high (this can be adjusted on most patches with the CH encoder).
I have bought two headphone amps and tried to install one. But If it is connected, no sound is produced on any output. I have seen that there is a pin labled CTRL. But on the circuit description this one seems not to be used.
Hi holger,
Have you tried connecting a different audio source to the headphone amp? Also, have you tested audio output from the dac card L and R. Mame sure L+ and R+ are connected together. Make sure signal from dac L and R and gnd are connected to amp L- and R- and gnd goes to either L+ or R+. Finally, check 5v and 0v to amp. Ive used 2 of these amps connected as described and they work ok.
Good luck
Chris
I’ve succesfully added a headphones output to one of my zynthians. @cdswift, I’have followed your instructions, but i’ve added an extra mini-jack to the case:
@C0d3man
Have you solved your problem?
I would like an amplifier in the hope to get rid of the noise when rotating the encoders.
But I don’t want to lose the cinch out.
Just adding another option for Headphones. Some lower cost boards like the Audio Injector use a chip for portable consumer products that includes a headphone driver. Headphone specs from the WM8731 data sheet include.
50mw for 16 ohm, 30mw for 32 ohm.
THD -65 db @ 10mw, -45 db @ 20mw (32 ohm)
Programmable +6dB to –73dB gain and mute, 0 db = 1 volt.
Looks like ear bud fidelity numbers.
I see zynthian block diagrams showing the Hifiberry card provides 3W headphone outputs.
Hi @jofemodo - I want to do the same mod to my kit Zynthian and I just got the headphone amp board listed earlier in this thread but when I opened my Zynthian case I saw that I have the Hifiberry DAC+ADC Stage which has a bunch of unmarked header pins. I reached out to hifiberry for a datasheet and they said that since this is an OEM product that they don’t have any documentation they could forward to a lowly plebeian such as myself. Do you have anything on tap I could work off of? Thanks!
The Stage’s 20-pin connector is identical to ZynADAC’s one and has this pin assignment:
This is from the wiki’s build tutorial
You also can take the audio output from the ZynAuCon module, using the contacts from the mini-jack footprint, or directly from the Stage. You can access the Stage full specification here:
