NOT QUITE NEVER AGAIN, THE GROUP BUY DAC BUILD

[nige2000]

I can't see how having two Rs (one on each output) to GND changes anything. Though his output voltage might be measured differentially between the two, that wouldn't change the offset, which would be zero measured between the two output pins.

ahhh.. its because there mono, outputs are in parallel
dddac explains here
"The current outputs from the DAC are summed up on the Mainboard. In the Mono Mode, actually the two DACs inside the chip are already operating in parallel, so the outputs can be tied up together to sum up the currents. For the passive I/V conversion, which is done by the parallel of Ra // Rb, space is offered for these two resistors. By using two resistors, you can combine to different values. With one deck, 270 Ohm per current output is the nominal load. There are two current outputs parallel, so one 133 Ohm resistor is being used. The small table at top right shows the values when more than one DAC module is being used."

[Sligolad]

Draft CAD for aluminium Front plate below.
Inset SD Card in the back with slot for both the IR and LED with recess on the front for 3mm window.
Only one button in the assembly at the moment for reference only.
I dropped 3 switches on the left but these can be placed anywhere we like so jump in with suggestions on the group chat. These switches will be mounted in the 3D spacer behind which I assume will be at 15 degrees.
I have not added mounting screws yet but most of the machining is captured in the solid file.
Should have most of the CAD work done over the weekend once we decide best layout.

[Sligolad]

A good video to show just how powerful these Ultracaps can be when let loose and a good explanation on ESR.
https://www.youtube.com/watch?v=EoWMF3VkI6U

[nige2000]

the bigger the spark the better the job.

[Fran]

Handy video that

[nige2000]

thought id figure out why the s-caps took so long to charge (20 mins), turns out jkenny was right they are been thermally shutdown because of the max current draw is basically all it can get. the regs max is supposed to be 3amp. you will see in the video ive added an amp ps heatsink to the monitored reg and cap you will see discharging of the cap and recharging about 3 mins amazing what some heatsinking can do. and it still gets hot, and the bridge rectifier too. i think we should use amp heatsink plates for regs and rectifiers for this i hope I've enough spare, ill count what i have. if it gets too hot in case we can put in current limiting resistors.

[Sligolad]

Finally got restarted on the DAC build yesterday after the holiday break and oh boy were we rusty. could not remember where we were at last year!!
Anyway eventually got on track and managed to listen to the lasted version DAC with high quality resistors bot with and without buffer stages.
All were immediately in favor of going with the buffer stages as the sound was really sweet and tight so that was a slam dunk.
The DAC sounded amazing so much so that we struggled to pull ourselves away from just listening to lots of music.

For the front panel we are working out whether it is worth the expense of going with a machined aluminium and anodised panel at considerable expense, a machined polymer composite at an unknown price just yet or just printing front panels and hand finish with painted finish.
We have a good idea of the final layout now and Tony preped some Traffos so we could get one set in the case.
We dropped some of the boards on printed shelving just to get an idea of cable runs so we are close to final assembly work in the coming weeks.

Some pics of a possible final layout below:

[Sligolad]

Its been a while since we posted an update on the build so here goes.
I had the great pleasure to bring the first test build home with me 2 weeks ago and i have to say the sound performance has been a revelation.

Its easily the best DAC i have ever heard and i expect there will be more glowing reports in the coming months once we finish off all the final touches and get the rest of the units in everyone's hands.

For now I will post some pictures of the test DAC before final finishing.

[nige2000]

[jkeny]

Looks & sounds fantastic, Nige - when's the big reveal - interested in hearing it