[FallenAngel]

Hey guys,
 
I've recently discovered this DAC and it looks just too cool not to build.
http://soekris.com/products/audio-products/dam1021.html
 
Thoughts?
 
Has anyone built one?
 
I think I'll be building one soon and wanted to document the progress as well as get ideas from others.

 

[audiojun]

I remember seeing that website not too long ago (one month ago max) and they had the DAC pre-built for $650, I don't see it anymore. Looks like a difficult diy project good luck.
 
edit: found it!
 
http://www.soekris.dk/dac1101.html

 

[jcx]

ratio matching, tracking over temperature, aging is so much better with all the R integrated on a common substrate - and cheaper given the effort put into it by the big semi houses - just buy a good DAC chip for better performance in every spec
 
I've pointed it out before:

  the economics of things that can be done on chips is a little different - some chips are made on Billon US Dollar semiconductor fabrication lines, staffed by specialists with decades of inside experience just getting/keeping the whole process running repeatably
 
if the demand interests companies with the Fabs and design teams then often the only performance competition is from other big companies with the same investments in tooling and people
 
but once the chip is designed then they do grind them out "cheaply" in incremental cost compared to anything made by any other tech - so "the best" we know how to do technically in some electronic domains can be done at low cost too
 
 
I don't know what MSB is doing today but older product pcb photos, appeals to the discrete precision R ladder's expense was laughable to those who know the tech - today that really is "doing it wrong"
 
it is reasonable to believe that a pair of AD5791 per channel do outperform discrete tech even when spending 10s, up to 100x as much for the pile of parts
 

 

[FallenAngel]

Point taken, but come on, it just looks so cool

 

[b0bb]

  Hey guys,
 
I've recently discovered this DAC and it looks just too cool not to build.
http://soekris.com/products/audio-products/dam1021.html
 
Thoughts?
 
Has anyone built one?
 
I think I'll be building one soon and wanted to document the progress as well as get ideas from others.

I have a pair and planning to get another pair soon.
 
Here is an early picture, the raspberrypi turns the dac into a Squeezebox.
This is a Gen1 board with the 0.01% resistors in the R2R ladder.
 

 
Thermal drift and DC drift and offset issues on the DAC is not measurable on my 6.5 Digit HP Multimeter
 
The DAC is incredible value for its price point, total built up cost is about USD$500 including case and power supply.
 
One unique feature of this DAC is the ability to change the conversion filters, there about a half dozen good ones done by various people out there. If you have an interest in Sox+MATLAB this would be interesting.
 
Sound quality wise it comes within striking distance of my Schiit Yggy which uses R2R chip DACs.
 
Currenty building the Dual Mono Variant of this dac which used 2 modules.
 
Soekris recently added DSD conversion capability to the FPGA, it is a little bit better that the results I am getting compared to software conversion on the Squeezebox server.

 

[FallenAngel]

I won't be doing USB or network input, just simple spdif, add in a regulated power supply and volume control.

Will also do the vref mod with 16 small caps.

Considering building standalone or integrated into another amp.

Have you compared buffered to unbuffered out?

Boards arrive next week.

 

[b0bb]

Have you compared buffered to unbuffered out?
 

 
The buffered output isolates the R2R ladder from the downstream load with a small impact on sound quality.
 
Transients are smeared and the soundstage is reduced slightly.
 
If you plan to connect the DAC directly to an amp  without a volume pot, the unbuffered output is better, for everything else the buffered output gives a more consistent output.
 
The unbuffered output is sensitive to cable lengths >15ft, the sound starts to change on the unbuffered output for loads below 2kOhm

 

[FallenAngel]

Yeah, I wouldn't use a cable longer than 1m.

 

[FallenAngel]

 

[bimmer100]

Just some sneak peeks on my build so far. Two chassis design. Multiple o core transformers in bottom chassis with SE output and Balanced output amplifiers. About 4watt @110ohm approx for balanced outs.
And the DAC build is a dual soekris 28bit dam1021. True balanced setup. One board per channel for quad 28bit discrete r2r
And also psu's will be quad parallel lt3042. Or 8 per psu. Two rails total. 5 psu's. Diyinhk 768khx xmos xu216 USB module. Normunds pcbs. The chassis has cut out for screen kit with graphics I designed showing the boot up screen. Filters are selectable through the interface front panel buttons. And choosing source. Spdif digital rca, toslink with genuine torx 142L 25mbps, HDMI i2s, RCA out eizz rhodium plated tullerium copper, xlr 3pin out eizz gold plated copper, ackodac akr75 regulator , volume control 10K pot on power/amp chassis and headphone outs for 6.3mm and 4pin XLR.

How far am I along? Maybe 30-40%. I have 95% of the parts. And 80% of the stuff soldered/assembled. Still deciding on some components. And will need to have custom back plates made for input/outputs. Also custom modification for headphone outs and volume control. Otherwise it should be a cool project when finished. I'm building it for my wife and she is selling her nfb28 once I'm done. Quite the upgrade!!

 

[FallenAngel]

Great stuff so far, I'm very impressed!
 
I'm building another DAC with USB input through XMOS U8 and S/PDIF input.
 
One thing I'm implementing a little different is a "volume off" switch that turns off volume control if I have an amp that comes with a volume pot. I sometimes build amps without volume control - power amps of course, as well as some headphone amps that I simply don't need an extra volume pot in. Photos coming next week.
 
Please keep this thread up to date, I'm very much looking to seeing your build.