Soekris' DAC implementations
A thread to know how to implement : volume control, filter, casing, shielding, powersupply, etc for the discrete R2R DAC made by Soekris:
Feel free to ask and answer. Regards, Eldam
Original Vendor thread (DAM 1021) http://www.diyaudio.com/forums/vendors-bazaar/259488-reference-dac-module-discrete-r-2r-sign-magnitude-24-bit-384-khz.html
OEM (DAM 1121) Building thread: Building with the Soekris dam1121
Currently available files for dam1021 (updates): Soekris Engineering ApS, Downloads
For a quick drawing with connections and more detailed descriptions + tweaks, : The Soekris R-2R DAC: Technical Details | H i F i D U I N O
Diyaudio WIKI : Soekris R2R DAC - diyAudio (usefull links, more to come)
Parts: some usefull parts ref and inputs given by members (thank you) :
62020 - 2x7AC 5VA - http://www.digikey.com/product-detai...108-ND/3881389
62030 - 2x7AC 7VA - http://www.digikey.com/product-detai...059-ND/3881371
2x7AC 10VA 70040K Talema Group LLC | 1295-1040-ND | DigiKey
2x7AC 7VA - MCFM70/07 - MULTICOMP - TRANSFORMER, TOROIDAL, 2 X 7V, 7VA | element14 Australia
2x7AC 5VA - MCFM50/07 - MULTICOMP - TRANSFORMER, TOROIDAL, 2 X 7V, 5VA | element14 Australia
Netherlands : Toroidal transformers for 115V and 230V applications
France:transformateur torique 15va 2x7v
The links are to the Australian website but it's easy enough to change location using "Change Country" at the top right of the page. The 2x7AC 5VA is also available from a UK based seller on eBay (more than 10 in stock) MCFM50 07 Multicomp Mini Toroidal 5VA 2X 7V | eBay
US: AN-0107 - 10VA 7V Transformer - AnTek Products Corp good price !
For alternative DC feeding possibility, some informations below & elswhere in the original thread: some mention noticeable difference. A simple torroid is a good enough starting point.
Pulse transformers if input Spidf (SE) choosed (Soekris's input post 41): PE-65612NL Pulse Electronics Corporation | 553-1580-5-ND | DigiKey or better (?) S22083 Newava Technology Inc | 470-1003-ND | DigiKey ; DA101C - MURATA POWER SOLUTIONS - TRANSFORMER, 1:1, 0.01H - 0.0206H, DIL | element14 Australia. Notice here than the first PE would have the best inter-windding capacitance which is the interisting point for chosing it- Dac itself has a the best jitter rejection possible due to the fifo, so jitter perf of the others pulse transformer do not matter with this DAC, so quietest noise is prefered over the best jitter perf for the input pulse transformer! Abraxalito input : read the thread)
SPIDF (AES) : Audio Note or Tribute traffos (sorry no cheaper refs yet :) ! but here surely sota noise rejection... cobalt core, etc)
TOSLINK: Toshiba RX modules advised for good quality: TORX177 for 5V and TORX147 for 3.3V
Connection shematics for the SPIDF; http://www.diyaudio.com/forums/vendo...ml#post4202602
Volume control (if the pot way is choosed) : "Any mono linear one from 1K to 10K, preferable high quality conductive plastic to avoid noise" (so just one mono linear pot control the two chanels) http://www.diyaudio.com/forums/digit...ml#post4194108 : I.E. : 3851A-282-103BL - BOURNS - POT, COND PLASTIC, 10KOHM, 20%, 1W | element14 Australia or P231-QC20BR10K - BI TECHNOLOGIES / TT ELECTRONICS - POTENTIOMETRE POUR PANNEAU 10K | Farnell France
DIY H.Q connectors (to avoid shorts) J3 : 2-87456-1 - TE CONNECTIVITY / AMP - WIRE-BOARD CONNECTOR RECEPTICLE 26 POSITION, 2.54MM | element14 Australia ; J10 : 1-87499-7 - TE CONNECTIVITY / AMP - CRIMP HOUSING, 1 ROW, 10WAY | element14 Australia or :
Inputs & front panel switch board GB (for USB Amareno+ SPIDF): Input and switch boards for Soekris DAM1021 DAC
USB to Serie RS232 interface to update the DAC via a laptop: 1 Port RS232 USB to Serial Adapter - US-101 - Brainboxes - RS422/485 RS232 Serial Cards , Digitus USB auf Seriell DB9 Adapter schwarz: Amazon.de: Computer & Zubehör (PLL throughpass chip inside) / USB-to-Serial Converter - UC232A, ATEN USB Converters ;Trendnet - Convertisseur USB vers Série, TU-S9: Amazon.fr: Informatique etc ! (take care with the compatibility with W 7/8 when you buy one)
Debuging your USB to Serie interface DimDim member blog : R2R | Dimdim's Blog
Working Thread about the Digital filter improvementof the FGPA chip: http://www.diyaudio.com/forums/digit...ml#post4224106
Output-stage Thtread: http://www.diyaudio.com/forums/digit...ml#post4228899
Mother board control kit: http://www.diyaudio.com/forums/vendo...ml#post5071729
I have plan to use ssr03-super-regulator-power-supply. DC (+12/-12) out put .
I go with LM 317
Sort of pre voltage regulation to help PSSR for the embeded low noise LDO ?
Does just a shunt stabilizer could give better result than a super shunt with voltage regulation (as this function is managed with sota smt ldo into the pcb ?
Or just a snubber at the secondaries if AC is used instead DC as the design allow as well ?
I read somewhere than more than a standalone common self is good for filtering.
Some put a comon self before the primary but add one after the secondarie in a Pi filter as well, sometimes mixing it wit an another Pi with no comon filter !
Soekris is ok with the measurement, what can add a more complex PS before this DAC ?
Let it simple ?
May want to start with an R-core transformer instead of a toroid, for better line isolation/filtering.
They're hard to find in the 115v primary versions in the USA, but are available here:
I was going to just feed it AC, but now I'm wondering if adding a DC pre-regulator would be of any benefit.
Since the board will regulate anyway, I don't see a reason to use a fancy pre-regulator, seems like a 317 type should be fine, but I could be wrong.
I also started looking at remote controllable pots to handle volume control. Might buy a cheap ebay one.
will you put a snuber ?
You could unwind some secondary turns to get down to 7-8V.
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