Hi there,

I just finished to build my BIII, but it seems that I have a problem.
When I turn the power on, The Mute LED is glowing and the LOCK LED is off.

My configuration is quite basic: I want to use the DAC in Stereo mode only with 4 SPDIF inputs.
No Sidecar. No Volume control for the moment.

For my test I use a DVD player with a Coax audio output. I already test it with other dacs without problems.


1) Input / MuX




I soldered 75Ohm resistor on each input as I use only SPDIF input.
They are connected between - and + as required. Not Ground.
I verified that the Mux is powered by 5.25V from DAC.


2) Dac Board


Voltage seems OK


Current seems OK



I don't know if I need the firmware chipset on as I don't want to use th volume control.
Everthing seems ok here


I soldered all jumpers 6 to 17 as required.

3) Switch 1

All switchs are off.

Quantizer setting 6-bits
Differential mode True
FIR Roll Mode Fast
DPLL bandwidth Default
DPLL bandwidth 128X multiplier OFF

I tried with 5/6/7 DPLL Bandwith On , but It didn't worked.

3) Switch 2


All switchs are off except 8

S/PDIF input selection D1
Normal/Dual mono selection Normal
Oversampling filter and reclocking Use
S/PDIF auto-detect Use
IIR Bandwidth Normal
Input remapping On

3) Switch Board


I don't know how the selection should work.

I guess:

MUX DAC Low Bit High Bit
A D1 0 0
B D2 0 1
C D3 1 0
D D4 1 1

Is that correct ? I'm confused because labels on my selector are not the same than on the Guide. (D1 instead of D4 etc...)



Do you have any idea of what could be wrong ?
Perhaps it's obvious but I can't see anything at all.

-> The ribbon cable is long (17cm)
-> There is no connection to the ground

Thanks a lot for your answer.

other pictures

Edited by user Thursday, January 5, 2012 3:09:41 PM(UTC)  | Reason: Not specified

- You've made the connector for the EXT_IO on the front of the selection switch, not on the rear. This will make mounting it much harder. Is there any reason why you did this? If you feel it's not connected like it should, you could disconnect the selection module and control the input with the DIP switches for now.
- Firmware is always required. If you don't use it, the board won't work as anticipated. Connect PB4 to 3.3V if you don't want volume control (it seems that you did this).
- You could try different switch settings, like S/PDIF auto-detect - Bypass.

Thanks Leon for your answer
For the selector it was just for test purpose
I think my problems are on tridents...

Edited by user Thursday, January 5, 2012 3:51:24 PM(UTC)  | Reason: Not specified

They appear to be in the correct positions. I thimk the probelm is more likely with the cable.

Sorry, I missed that post (was reading on my phone).



You can't measure R4 in circuit, as it is in parallel with other elements. I am sure the resistor values are correct. It only adjusts the shunt current, not the output voltage. The R3/R8 values you list indicate that the Tridents are in the correct positions (these set the output voltage).

Since the ribbon cable apparently checks out, the next suspect is solder joins. Can we get some close-up pics of the trident joins (top and under the B3 board)?

I don't see that you have installed R4 on any of the Tridents. That is the problem.

Edited by user Friday, January 6, 2012 3:10:44 PM(UTC)  | Reason: Not specified

No problem, enjoy! It is almost always something simple in the end.

You don't. Connect the safety earth to the chassis near the power inlet. Keep the DAC's ground isolated from the chassis.