Bad sound quality with phatDAC


#1

Hi folks,

I recently ordered a wireless audio kit (Raspberry Pi Zero + phatDAC) to extend my multiroom audio setup.

However after assembling the unit I’m a little bit dissapointed about the audio quality.
The sound I’m getting out of the device sounds somewhat too bassy and by far not as clear as the sound from my other multiroom clients (Raspberry Pi 1A, Raspberry Pi 1B+ and Synology NAS, each of them equipped with a usb audio adapter). It sounds like listening to loud party music through a shut door.

The software I used for the test was
Test 1: the latest max2play HifiBerry image (m2p_rpi3_hifiberry_235_wps.img) with the squeezelite player from https://www.max2play.com/en/max2play-image/
Test 2: the latest raspbian jessie image (2016-11-25-raspbian-jessie-lite) with the phatDAC installed according to your tutorial (https://learn.pimoroni.com/tutorial/phat/raspberry-pi-phat-dac-install) and playing music from the network using the squeezelite player / playing local music using the mpg321-player.

I tried the 3,5mm and the RCA output.
I connected a JBL Charge 2 speaker, a Medion Life P69053 speaker and a LG mini stereo system.
I tried the PhatDAC on the Pi Zero and on the Pi 1B+.
I also tried several AC Adapters

Does anyone have an idea what is wrong here?
Is this a hardware problem, a software problem or is the DAC supposed to sound ike this?


pHAT DAC - Wireless Audio Kit - Sound
#2

Hi There - Me Too ! - I have a Phat Dac that i bought yesterday with no HIGH Frequencies (or very little) and a distinct BASS boost. My first separate DAC.

I don’t know whats going off with this DAC - the local audio sounds better much better as it has a “full” freq range.

The PhatDac sounds muffled and all “bass” - its def got an issue. If i play same track through my macbook or my other audio gear it sounds fine and normal - but played through the Phat sounds muffled and woolly.

So…dont know what to do really is it faulty ? - is it software settings ? - i was playing a 44khz 16bit mp3 file using the OXM player but youtube also sounds woolly too ?

Does anyone know what this could be ?


#3

FIXED IT ! - Read On :-

OK This is what’s wrong, i used my testing kit (scope multimeter capacitance testers etc)

The team in sheffield have fitted 2 x 2.2nF Caps across the output of the analogue of the Chip to GND.

These in conjunction with the 470K resistors inline with the Analogue outputs unfortunately provide a very effective “LOW PASS FILTER” - (remember this from college guys) around 8-9khz cut so…

I just removed them with the Iron - tiny little surface mount caps about 2mm across - follow the tracks to the 3.5mm socket you will see them as they are the first pair you come across before the tiny 470k surface resistors. Pretty sure the PIM team just copied the Mfg’s example diagram on the chips data sheet when they made the PCB up - makes sense nice and quick way to start. - though TBH its not really the best way to get a decent sounding setup.

BINGO - crystal clear audio now - perfect sounding and now the full spectrum tested unto and above 24khz !

Have fun !


#4

Also see our official response, basically confirming @avaproductions findings: pHAT DAC - Wireless Audio Kit - Sound