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

I am seriously considering this product as my Birthday/Christmas gift. I do have a few questions that I hope someone can answer.

- Is it bad practice to regulate (such as with a Salas shunt) then have it regulated once again by the 1021?
- Is the Dam1021 truly balanced from input to output? I would guess no but when OpAmps are involved I do not know (I’m no engineer).
- Are there any changes in the DAM1121 design that makes it inherently superior?

Thanks
 
Basically a R-2R DAC board based on the dam1021, sitting directly on top of the RPi board, to fit the RaspTouch case or some of the other Audiophonics cases. Will be a little larger than a RPi, and have what's needed for easy interfacing, t.ex. using the RPi I2S signals and serial port. Output will be RCA single ended buffered by LT1815's, which are powerful enough to also drive high impedance headphones.

See Rasptouch – The ultimate Open Source Player



Routing signals from the RPi GPIO connector to another connector, to avoid soldering, two options:

1) Route power for the RPi 7" touch display.
2) Route power and RPi SPI signal for simpler displays.

Any more updates or a timeframe on availability for this?

Thanks!
 
- No. A clean feed can never hurt.
- Its natural output is single end but the OP-amp output creates a balanced one.
- Yes, the re-clocking of the output from the FPGA.

//
Thank you TNT. These following questions are not all necessarily for Soekris as I understand this is not his primary source of income, he does have a real engineering business to run. Just doing my due diligence before a purchase.

Regarding the re-clocking of the output from the FPGA
- In layman's terms what is the benefit of re-clocking of the output from the FPGA? Is re-clocking noticeable? Or is it merely perfectionist...similar to pursuing lower jitter (R2R's are less vulnerable) or <.05% resistors (arguable if it's noticeable)?
- Is this modification planned for any future versions of the DIY dam1021 line?

Power Supply
- Anyone have any measurements of the built in Power Supply? How does it compare to other external supplies? Most information I can find is either v1 or v2. The v3/v4 model is improved but how much?
- Perhaps another set of power input (J1) to bypass the power supply (if that’s possible). A built in supply is a very good idea. Still added flexibility is a plus.
- If two supplies are okay why did people ask for no supply in the 1121?
- I have attached screenshots which explains why I care. Measurements from Linear Audio (https://linearaudio.net/downloads) of all the top performing regulators.
Linear Audio - PSRR negative regulators.JPG Linear Audio - Positive regulator output noise.JPGLinear Audio - Zout positive regulators.JPG

Analogue output
- Just wanted to say I love the option on the dam1021 for buffered and unbuffered RCA and XLR jacks. The ability to run with chip buffers or DCB1 buffers offers great flexibility and satisfies my curiosity.
- Any plans to revert back to the LME49710/LME49724 buffers for more current? Honesty I don't think it matters much and the OPA1602 has lower Intermodulation distortion.

External display & digital remote control
-
Is there an easy well documented way to have an external display and remote?
- Dimdim's site has an Arduino control but that model is discontinued, using v0.99 firmware (compatible with newer firmware?), and the code might not be complete/buggy.
- I assume this is why a Rpi model is being made by Soekris. Will this be RCA only? XLR balanced outputs? Unbalanced option like the dam1021? Power Supply?
- Will there be code provided (similar to Dimdims Arduino code)? Or will the Rpi model only be easily mountable without soldering but still requiring code? If there is code can it be used with the dam1021 model?
 
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- Dimdim's site has an Arduino control but that model is discontinued, using v0.99 firmware (compatible with newer firmware?), and the code might not be complete/buggy.

I've been meaning to do a major re-write of my code to fully support the latest available firmware for a long time now, but my free time has been very limited. I do intend to get to it by the end of this year.

Regarding the discontinuation of the Arduino DUO, there is no cause for alarm. DUE clones and/or knockoffs will be available for many many years.

Also, if / when Arduino puts out a board that will succeed the DUE it is most likely that I will update my HW & SW to support it..
 
Dimdim: Why did you choose a Due over a more compact Arduino to start with? Limited resources or i/o's on the smaller boards? I like the compact arduino devices much, because they take less space from the audio-oriented parts. That is if it you don't need the bigger boards.
 
Hi,
I'm thinking of powering the Amanero with an external 3.3V psu and connecting it to dam. I have read that some people did that. Are there any benefits of it?

Yes, there are, but it also depends on quality of PSU you will use for this. Although Soekris has fifo and isolators, the overal sound quality still depands on quality of I2S signal. I found xmos xu216 to work the best here, better than amanero and xmos xu208.