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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

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#1,641
For anyone who is interested, I've attached POS's 44.1 filter converted to .skr for upload to the DAC.

It's pretty interesting to compare the different filters. The ones I did are pretty basic but still sound reasonably good. POS's filter sounds great.

Anyway it might be time to start a Soekris R2R Filter Brewing thread 😉
 

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#1,645
soekris said:
If you insist to improve the onboard power supply, try replacing the 6 electrolytic capacitors with aluminum polymer types, 1000u 16V exist in same 10mm smd footprint and t.ex. digikey stock them at $2.20 each. Should be easy to replace.
Click to expand...

Hi Søren,

What capacitors are installed now ?

Just got the DAC in my hands yesterday, a very nice piece of engineering !

Regards,
Danny
 
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#1,648
Filter solution

Hi Soren,

Last year I started working with Professor Patrick Gaydecki (Patrick Gaydecki | The University of Manchester | School of Electrical and Electronic Engineering ) of Manchester University, we are working together in a commercial joint venture to develop a new breed of DSP controlled loudspeakers….Building on the Signal Wizard 3 technology, Signal Wizard Systems Home we are developing some rather special boards…..We may well have a very neat solution to all your filter ( and connectivity) issues!
Please email me if you would like to explore some ideas, derek@custominstallaudio.com

I will copy this on the other thread.
All the best
Derek.
 
#1,654
Dimdim said:
Would a manual change in input source also trigger a filter reload?
Click to expand...

Anything that make the LED blink will trigger a reload.

Also, AFAIK the filters are stored in flash memory. Should we be worried about "wearing out" the flash memory from too many erase / rewrite cycles?
Click to expand...

No, you only write when you download new files and the used flash type minimum have 100K erase/write cycles....
 
#1,656
Dear Paul!

Treat the USB to SPDIF as you would a CD Transport or similar. It is a SPDIF transmitter and it makes no difference if it has a trafo or not. All that matters is that the output jack is driven correctly, and you have to assume the designers have done this correctly. FWIW I'm using a Stello U3 USB -> SPDIF interface.

Soren's circuit is a SPDIF reciever, and is designed to correctly terminate the recieving end of the SPDIF line, and to correctly drive the LVDS inputs on the DAC board. The resistor and cap in the power and gnd filter the +1.2V, and block DC from the GND. The idea is to lift the gnu point of the Transformer output to +1.2V which is the common mode voltage the LVDS logic requires.

Basically you can safely build the circuit Søren provided "as is" and it will work correctly with a USB to SPDIF interface with no changes required.
Click to expand...

Thank you for the nice, civilized and detailed answers and your help!😉
Yes, I already understand this Spdif input. I will use PE-65612NL Pulse Transformer.
Greets:
Tyimo
 
#1,657
768k input SR

Søren,

is there any possibility to implement 705.6/768kHz input sample rates?
Maybe via special version of firmware/NOS mode?
It would take SQ one step further...

I think many of us are computer-oriented and will use software upsampling/filtering/sophisticated DSP, taking advantage of our i7s and gigabytes of RAM :^)

Thanks for your hard work!
 
#1,658
jaffar said:
Søren,

is there any possibility to implement 705.6/768kHz input sample rates?
Maybe via special version of firmware/NOS mode?
It would take SQ one step further...

I think many of us are computer-oriented and will use software upsampling/filtering/sophisticated DSP, taking advantage of our i7s and gigabytes of RAM :^)

Thanks for your hard work!
Click to expand...

Would require major reorganization in the FPGA if you want to keep the same number of IIR biquads for filtering.

And it would be a the point of diminishing returns, and afaik, no USB interface supports it yet....

So not in the short term.
 
#1,659
Soren,

Could you please post the full set of filters based on rePhase's settings?

Spzzzzkt,

I will try yours as soon as get a chance. really excited, thank you for the effort. btw, can you post the txt format as well so I can learn how to manipulate the file from your example? The rePhase one uses 1015 taps, seems a lot less on Soren's original filter for 44.1. should I just change the # of taps in rePhase to match that the original filter?

Fred
 
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