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

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Z

zfe

Member
Joined 2014
Granite said:
... the question for me is whether this leaves the original 16 (or 24) intact.
Regards
Click to expand...

No, In general already the FIR filters will alter your bits even without attenuation.
For the NOS filter (one and the only filter coefficient 1), which would normally be expected to map the input unaltered to the output, at least at 0dB gain, does this not with the current firmware.
As a design decision of the newer firmware only filter coefficients smaller than 1 are possible. The idea behind that is that for most filters only such coefficients appear and you so have one bit more of filter accuracy.
Thus for the NOS filter a small overall attenuation of is needed (which is done by setting the multiplicator in the filter smaller than 1.
 
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TNT

TNT

Member
Joined 2003
Paid Member
I'm afraid that many of the things you write is based on an incorrect understanding on how it works. It's to much and to confused and to OT to really comment in detail here. I suppose you are free to start a thread yourself to discuss the matter in general.

//

Granite said:
Hi Guys,

the discussion about the neccessity of dithering is an interesting one, the only caveat for me is that this thread might not be the right one to continue the discussion. Havn't been around here for too long, so I do not know the etiquette. Is it possible that a moderator opens a new thread an moves the corresponding messages there?

For me concerning dithering these links were helpful:

Dithering Explained: What it is, When to Use It, and Why it’s Important

When should you use dither ? - Production Advice

When in doubt, dither - Production Advice

Dither or distort ? Listen and decide for yourself - Production Advice

Concerning the fact that DAC may increase the bit depth from 16 (or 24) bitsnto a higher level and then use digital volume control the question for me is whether this leaves the original 16 (or 24) intact. As far as I know when increasing bit depth is done by adding zeroes to the original code, when I reduce volume do I then only strip away the added zeroes and do not change the signal until I reach the original bit depth?
It is clear to me that with increasing bit depth I have more level in which to divide the signal (therefore higher resolution). If I reduce a 32 bit signal to 16 bits I will run into trouble because certain levels disappear and I need to put the signal in a level which does not correspond to its initial one introducing quantisation errors, which cause distortion (there you ate TNT it is so easy to give more distortion to the people). What I do not know what happens if I take a 16 bit signal, increase bit depth (to 32 for instance) and then reduce bit depth to sixteen again. Initially all samples are in 16 bit levels of course. Then they are put into 32 bit levels and then back into 16 bit levels. If I do not manipulate the signal (samples) they should (in my mind) still be in levels which exist in both bit depths and they should find there initial place meaning this would not introduce quantisation error. If I did manipulate the signal in the meantime levels which exist in the 32 bit world might be populated and when going back to 16 bits I will introduce quantisation error. What happens when I attenuate the signal I do not know.
The question is of interest to me because I upsample all my music to 32/96 kHz on the fly apply DRC via a filter and hand over the 32 bit signal to the DAC. Now in theory USB Receiverchips like Amanero, XMos and CMedia are able to handle 32 bits (but not all of them), still a lot of DAC manufacturers specify 24/384 as the capability of the USB input. That makes me womder whether they just truncate an incoming 32 bit signal, which if I am not mistaken also introduces errors or whether they convert the 32 bit incoming data to 24 bit internally by applying dither (then everything would be ok). Next question would be, if a DAC manufacturer specifies 32/384 does it mean the DAC handels 32 bit signals throughout the digital domain or does it only mean that the USB receiverchip is able to handle 32 bit data but the DAC still works with 24 bit data internally. Food for thought.

Regards
Click to expand...
 
M

marslove

Member
Joined 2012
ultimate dam1121

I was thinking if it's possible, and what would be needed to take this board to a top level performance of, for example, totaldac or msb.

Multiple LCRCRC+shunt regulated power sources, substituting the clocks with something like pulsar clocks, making use of iancanada's FIFO-> isolator->dual XO. Would have to be fully balanced too.

But have anyone tried stacking these boards? Like 4 boards per side? This would lower the already low output impedance and noise, and should enhance dynamics. And there would be no need for any output buffer.

Have anyone tried such a a cost-no-object attempt?
 
H

henrylarsen

Member
Joined 2011
1321 or 1021 what would you recommend for me?

soekris said:
The power supply in all our products are designed to be good.... The dac1321 has a little switcher that convert the +5V from either USB or an external switcher to the internal +- 7V, which then is filtered and regulated with a low noise low impedance discrete regulator.

If you don't need the headphone amp or the volume control then the dac1321 is a good choice.
Click to expand...

I am torn between building from the 1021 or buying the 1321 when it comes. I am a "light" diy'er, not with much time at the moment, but with an interest in being able to modify a bit if "easy" improvements emerge.

After having read for several weeks in the different tracks I have a few questions, some of them probably to Søren, and one to other DIY'ers:

1. is the 1321 built from the 005% or from the 001% resistors?
2. It is possible to take the "raw" output from j8, right?
3. There is a filter button on the 1321 - how does that work - is it rolling between different filters, or is it a pick of one filter? And other filters can be implemented with serial port as well, I assume?
4. Will it be possible to eventually draw on the I2S input from a Raspberry or should I give up such an idea if I go for the 1321?
5. If I go for the 1021, I would probably go for the 01 board. What is your current recommendations with the newest board for making it fly in the easiest way - I cannot resist thinking of using the MeanWell power supplys, I am aware of the discussion of linear/ switch supply, but it would be quite easy to try them out for the 1021, I think. And then an Amanero board or Xmos for USB input. The Murata pulse transformer for SPDIF eventually - what else? Maybe the AZ OLED light board for convenience?
 
zgtc

zgtc

Member
Joined 2016
power RPi from J2

Hi,

Is it possible to power a RPi2/3 from the "J2 Pin 6: PWR +5 volt / J2 Pin 7: GND" pins? Are those regulated somehow? (don't want to fry the pi).

Also, if the above are correct, is it possible to power the pi ONLY when the I2S source in J3 is being (manually) selected?

Thank you
 
J

janosch simon

Member
Joined 2017
Hey there i just ordert the dam1021 cant wait to install it into my streamer :)

as with the new firmware the dam1021 supports dsd does any of you found a native raspberry pi package that works? Direct DSD support on Volumio up to DSD512 * Volumio they say that only 2 usb dacs can decode it natively?

does the rpi 3 is2 bitstream to the dam1021? if so which package? :)

cheers and thx
janosch
 
S

soekris

Member
Joined 2009
soekris.dk
Paid Member
zgtc said:
Hi,

Is it possible to power a RPi2/3 from the "J2 Pin 6: PWR +5 volt / J2 Pin 7: GND" pins? Are those regulated somehow? (don't want to fry the pi).

Also, if the above are correct, is it possible to power the pi ONLY when the I2S source in J3 is being (manually) selected?

Thank you
Click to expand...

No, the J2 on the dam1021 is for test use, you can only draw small amounts of power.
 
S

soekris

Member
Joined 2009
soekris.dk
Paid Member
henrylarsen said:
I am torn between building from the 1021 or buying the 1321 when it comes. I am a "light" diy'er, not with much time at the moment, but with an interest in being able to modify a bit if "easy" improvements emerge.

After having read for several weeks in the different tracks I have a few questions, some of them probably to Søren, and one to other DIY'ers:

1. is the 1321 built from the 005% or from the 001% resistors?
2. It is possible to take the "raw" output from j8, right?
3. There is a filter button on the 1321 - how does that work - is it rolling between different filters, or is it a pick of one filter? And other filters can be implemented with serial port as well, I assume?
4. Will it be possible to eventually draw on the I2S input from a Raspberry or should I give up such an idea if I go for the 1321?
5. If I go for the 1021, I would probably go for the 01 board. What is your current recommendations with the newest board for making it fly in the easiest way - I cannot resist thinking of using the MeanWell power supplys, I am aware of the discussion of linear/ switch supply, but it would be quite easy to try them out for the 1021, I think. And then an Amanero board or Xmos for USB input. The Murata pulse transformer for SPDIF eventually - what else? Maybe the AZ OLED light board for convenience?
Click to expand...

1) The dac1321 use a mix of resistors, best ones are 0.02% precision.

2) J2 is the buffered outputs. Raw output is at TP1 & TP2, small holes at the end of the resistors strings.

3) Filter button is going though the four filters. And yes, the dac1321 use same software and filter file as the dam1021, so you could load other filters, the serial port is at J10, at digital level.
 
D

Dimdim

Member
Joined 2008
janosch simon said:
Hey there i just ordert the dam1021 cant wait to install it into my streamer :)

as with the new firmware the dam1021 supports dsd does any of you found a native raspberry pi package that works? Direct DSD support on Volumio up to DSD512 * Volumio they say that only 2 usb dacs can decode it natively?

does the rpi 3 is2 bitstream to the dam1021? if so which package? :)

cheers and thx
janosch
Click to expand...

To get DSD out of the RPi you need a USB dac, or in case of the DAM, a USB receiver in front of it. DSD out of its I2S pins is not supported.

It doesn't really matter whether you are doing DoP or "native DSD", in both cases the end result is the same, as long as you are satisfied with going up to DSD128.
 
iancanada

iancanada

Member
Joined 2009
twitter.com/iancanadaTT
Paid Member
janosch simon said:
Hey there i just ordert the dam1021 cant wait to install it into my streamer :)

as with the new firmware the dam1021 supports dsd does any of you found a native raspberry pi package that works? Direct DSD support on Volumio up to DSD512 * Volumio they say that only 2 usb dacs can decode it natively?

does the rpi 3 is2 bitstream to the dam1021? if so which package? :)

cheers and thx
janosch
Click to expand...

I like DSD too, so I designed this DoP to native DSD solution for RPi. It should be no problem working with DAM1021 that has DSD support. Just hope I get chance to try.


DopDecoderIsolator1 by Ian, on Flickr

Ian
 
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J

jacklee

Member
Joined 2009
Talking about DSD anyone did a direct comparison of PCM vs DSD over the 1021?

I did a quick test earlier using the same music from a disc with both PCM/CD and SACD layer. Guess what - PCM is much better to my ears.

I might be biased as I never find DSD sounding superior over PCM in general. Variations in recording quality trumps format differences by a long shot.
 
M

matt_garman

Member
Joined 2008
Paid Member
Dual-mono RPi Board

I have two dam1021 boards in balanced dual-mono config, using a Raspberry Pi as my I2S source. I'm currently using normundss input board to "glue" the RPi and two dam1021 boards. Everything works, except that there is no easy way to get independent serial control of the two dam1021 boards.

So I'm thinking of having a board similar to normundss', but simpler and purpose-built for my role. I haven't designed the board yet, but I whipped up a quick schematic. Does anyone see any obvious errors? The idea is as follows:
  • Three connectors: one 2x20 to mate with the RPi GPIO, and two 2x13 to mate with each of the Soekris dam1021 J3.
  • Two FTDI FT230x USB to UART ICs - these are known to work with the dam1021's isolated 3.3v TTL UART interface. They're also cheap and have a simple implementation. The board would have two USB headers to connect to the USB ports on the RPi.
  • The I2S lines from the RPi are paralleled to each dam1021.
  • I intend to put screw terminals on this board for RPi 5v power.
  • I'm using the 3.3v output from the FT230x chips for the dam1021's 3.3v - hopefully they can supply enough current. Is this a bad idea? Should I instead put a dedicated 3.3v reg to supply the dam1021's 3.3v?

Thanks!
 

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