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 ?