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Headphone driver card

A project log for DSP Field Mixer Recorder

USBmidi, bluetooth app controll 8 chan portable DSP mixer.balanced audio IO,phantom power,flexible routing,ISO recording. networked Timecode

ben biles 03/16/2017 at 06:460 Comments

So after the success of the PreAmp card , I was thinking , great , easy !!! never think that :)

I soldered the componants onto the card, channel one working , nothing on channel 2.

I checked the gerber files as there seamed to be no trace from pins 3 & 4 to the 2nd 1632 OPAMP and

this is what I had.

pins 3 & 4 should go to U2 opamp. the more I looked at the layout the more channel2 seam totally messed up! R10 should be an input

resistor to the 2nd opamp and not parraleled with R20 ! I thought maybe I can run a few bodge wires but more problems croped up !

Althought , channel 1 does work.

Another problem with this design I had already realised before the board arrived was that U4 OP134 used to correct the bias from the DAC ( 2.5v ) was pointless. OPA1632 Vcom pin left floating allows the OPAMP to center around the +/- rails ! So why did I include the bias buffer when I did'nt need it and I'm not planning on running the headphone amp on single supply rail.

All right !!! enough problems , I'm going to label this one a FAIL and toss it in the bin ! shame because it looked nice !

the scarey thing is that the DRC passed in circuit maker and did not detect any unrouted pins.. mmm

I'm not going to blame my tools here though.. I think its just me getting clever and rushing out a design and not checking

over the board enough before making it !!

At least I can test the one channel while I'm waiting for the next card !

I made this card at seedstudio fusion like the preamp card. no problems at all with there work !!! all the mistakes were mine !

on a side note , has anyone used seeedstudio for 3d printing ? https://www.seeedstudio.com/fusion-3d-printing.html

I'm thinking of eventually making a box although a long way off.. no idea if 3d printing is the way to do it ?

also thought about making a stencil here https://www.seeedstudio.com/stencil.html for the next DSP board , its 10cm x 10cm and really is hard work to manually place paste with the injection needle I have... can anyone recomend it ? or is it more for if your making lots of boards ?

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