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

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J

Juhleren

Member
Joined 2011
PKI said:
Hi all,

a couple of days ago I assembled a newly purchased 0.02% dam1021 dac on the AZ OLED motherboard. Let me tell you that I am more than pleased with AZ OLED kit.
I am listening to the dac and comparing it A/B to the schist gungnit multibit. Here are my first impressions:
dam1021 is really good sounding DAC and its sound is quite different from the schiit. I guess some might prefer either of them.
Strength of dam1021 as I see it. Pretty rich tone a lot ob body. Pretty wide soundstage and in combination with AZ OLED board and amanero flawless work with different interfaces and switching between sources and resolutions.
Weak points, again, as I see it. As a downside of the richness when music gets difficult and dense things are getting busy. Sound loses its resolution and gets a little bit compressed as a record with lower dynamic range. Tonal balance is a little bit not neutral (especially compare to schiit), looks like you use a tone control and boosted up top and bottom a bit, or like you padded mid range in your speaker XO if you know what I mean. A little bit laid back, not neutral. Where it looses to sth schiit is the top end, highs are a little bit not synthetic, but more forward and less neutral on dam1021. The sound stage is wider with the dam, but a little bit more forward, some might like it.

So saying this I imagine that there are might be improvements in terms of filtering and I would really appreciate if you guys pointed me as I am completely new to all these stuff and DAC filtering in general.

Another thing I think that different buffer might be an improvement, as switching raw/buffered change (obviously) things and there are some aspect in that I do like. I will try to drop in B1 or Salas version of the Buffer after RAW outputs of the DAC.

As I say it is my very first impression as I need to put it in any case so switching and A/B is a bit easier without being afraid to shorten something on freely laying boards.
Click to expand...

Thanks for sharing. The AZ OLED kit sounds very interesting! Do you know how it supplies the Soekris board? IME soekris needs a reguleted PS as I found the transformer alone to sound messy. You may also benefit from bypassing the output buffer and take the output directly after the resister ladder.
 
PKI

PKI

Member
Joined 2011
Paid Member
Thank you guys! AZ OLED main board has onboard TPS7A47 / TPS7A33 PSU, so I am feeding dam1021 with not with AC. Maybe you need Salas' shunt regulator will be better, but should not be that bad... As for filters, can you guys point me to those presumably better ones? How many filters you can have loaded?
 
J

Juhleren

Member
Joined 2011
PKI said:
Thank you guys! AZ OLED main board has onboard TPS7A47 / TPS7A33 PSU, so I am feeding dam1021 with not with AC. Maybe you need Salas' shunt regulator will be better, but should not be that bad... As for filters, can you guys point me to those presumably better ones? How many filters you can have loaded?
Click to expand...

I have no experience with the TPS regs, but suspect that the main supply caps could be the bottleneck (only judging from the pictures i gathered from another thread). I would probably look there before opting for better regs. After all, you have several on board regulators that affect perfomance and may suppress many of the advantages of a further improved reg earlier in the chain. If you want to really improve on the PS, I would suggest you to hack the dam board and give it your in +/- ref from the best possible reg you can procure.

That said, when I compare my dam dac with Ciunas and my Oppo 95's internal dac, I find the dam to be utterly precise and uncolored. The Oppo sounds 'thick' and veiled in comparison and clearly adds something that the dam doesn't. The Ciunas is wonderful in its own way with its dense and smooth top end, but has a midrange orientation that the dam escapes. I know from reputation that the gungnir multibit is an excellent dac but other reports comparing it to the dam consider the later closer to the Yggi with the former being a bit crude in comparison. My point is that your dam should at least be equal to your gungnir, otherwise something isn't entirely right :)

best
 
PKI

PKI

Member
Joined 2011
Paid Member
Thank you for the information, it is very useful!
What supply caps you are talking about on the DAC board or on the TPS psu? What would be the cleanest (least invasive to the board) way to bypass onboard PSU?

So we are talking about all these mods, what about dam1121 ohm board? Am I correct that that boards is identical to 1021 only without PSU and output buffers or something is missing in digital aspect? I am asking as I am not very experienced in all that clocking and receiving pard of the dacs.
Thank you!
 
J

Juhleren

Member
Joined 2011
I was referring to the supply caps on the TPS psu -which don't appear to be better than those on the dac board. My gut feeling is that the major reason why the dac benefits from a regulated DC ps is because its on-board supply caps aren't up rejecting AC ripple well enough. The TPS supply psu looks like is has room for some larger supply caps. Just find some decent ones that fit the board and have at least 25V, 2200uf and low ESR specs. I'm using super cheap reg boards from ebay with onboard supply caps. Don't go nuts. Just pick something reasonable :)

I haven't tried the oem board, but yes it looks like it is a simplified 'clean' version of the diy. Just look up some modding threads about the dam board and follow the instructions. Bypassing the opamp was very easy. Start with that :)
 
TNT

TNT

Member
Joined 2003
Paid Member
PKI said:
Thank you for the information, it is very useful!
What supply caps you are talking about on the DAC board or on the TPS psu? What would be the cleanest (least invasive to the board) way to bypass onboard PSU?

So we are talking about all these mods, what about dam1121 ohm board? Am I correct that that boards is identical to 1021 only without PSU and output buffers or something is missing in digital aspect? I am asking as I am not very experienced in all that clocking and receiving pard of the dacs.
Thank you!
Click to expand...

Not identical as on the 1121, the signal is re-clocked after the FPGA. Might be more but this is the important and desired one.

//
 
PKI

PKI

Member
Joined 2011
Paid Member
Juhleren said:
I was referring to the supply caps on the TPS psu -which don't appear to be better than those on the dac board. My gut feeling is that the major reason why the dac benefits from a regulated DC ps is because its on-board supply caps aren't up rejecting AC ripple well enough. The TPS supply psu looks like is has room for some larger supply caps. Just find some decent ones that fit the board and have at least 25V, 2200uf and low ESR specs. I'm using super cheap reg boards from ebay with onboard supply caps. Don't go nuts. Just pick something reasonable :)

I haven't tried the oem board, but yes it looks like it is a simplified 'clean' version of the diy. Just look up some modding threads about the dam board and follow the instructions. Bypassing the opamp was very easy. Start with that :)
Click to expand...

I have additional 3300uf per rail installed on the TPS psu, might increase that one :) Yes, I am using only RAW output as it is definitely better sounding for my taste. Will run it directly into Salas' new preamp.

TNT said:
Not identical as on the 1121, the signal is re-clocked after the FPGA. Might be more but this is the important and desired one.

//
Click to expand...
Ouch I see that I don't know anything on that matter haha :). Will need to do some reading and I will definitely look into that option.
 
S

stephengrenfell

Member
Joined 2012
Hello All,


I am interested to implement a dam1021-12 with either a BBB or RPi.


I don't really care if I use BBB or RPi - I just want to get the best sound from the DAC.


Are there any opinions on which is the best to use with the dam DAC ?.


I have tried to read some of this thread but it is very very long. I have seen some comments about clocking and jitter.


What would be the best way to exploit a dam with a BBB or RPi
- with an audio quality external clock source for the BBB / RPi
- I2S with DAC as master clock



I intend to use separate power supply rails for the BBB/RPi and the dam. Plus maybe try to improve the 3,3v regulator on the dam - I have seen some comments about this on the thread to improve soundstage.


I will also implement a USB - I2S as well. It seems the Amaero is being used the most. Has anyone used a galvanic isolator (like mentionned here http://www.6moons.com/audioreviews/ami2/amanero.pdf on page 4 with the ISO764FM) ?.


Any advice / guidance would be appreciated.


Thanks.
 
D

Dimdim

Member
Joined 2008
If I remember correctly, the DAM does not provide a functioning MCLK output so you cannot slave a BBB / RPi to it. There is a pin that is supposed to do that but I believe it's disabled when running the current DAM firmware.

While the DAM does reclock and buffer the incoming I2S signal, a USB to I2S interface is probably a better sounding solution. There have also been reports of external FIFO/buffer solutions improving things even more (even though in theory they shouldn't).

Don't worry about galvanic isolation. The DAM's on-board isolators will take care of that.
 
P

pawelp

Member
Joined 2006
Sorry for asking a rather fundamental question that most likely must have been asked before but I went through the first 15 pages, did not find it and gave up. Am I right in thinking that the real physical resolution of the DAC board is defined by the resistor tolerances and then it would be ca. like 12 -13 bits ? If so the quantization noise should be high and would not allow to achieve 127 dB of S/N.
Can you please explain what I am missing here or just point me to the page where I could find it ?
 
Last edited:
S

soekris

Member
Joined 2009
soekris.dk
Paid Member
pawelp said:
Sorry for asking a rather fundamental question that most likely must have been asked before but I went through the first 15 pages, did not find it and gave up. Am I right in thinking that the real physical resolution of the DAC board is defined by the resistor tolerances and then it would be ca. like 12 -13 bits ? If so the quantization noise should be high and would not allow to achieve 127 dB of S/N.
Can you please explain what I am missing here or just point me to the page where I could find it ?
Click to expand...

Actually it's in the name of this thread: "Sign Magnitude". Google it....
 
S

stephengrenfell

Member
Joined 2012
Dimdim said:
If I remember correctly, the DAM does not provide a functioning MCLK output so you cannot slave a BBB / RPi to it. There is a pin that is supposed to do that but I believe it's disabled when running the current DAM firmware.

While the DAM does reclock and buffer the incoming I2S signal, a USB to I2S interface is probably a better sounding solution. There have also been reports of external FIFO/buffer solutions improving things even more (even though in theory they shouldn't).

Don't worry about galvanic isolation. The DAM's on-board isolators will take care of that.
Click to expand...

Thanks for your reply Dimdim.

So if the Dam does not provide a functioning MCLK then it can only work with the Dam as I2S slave - hmm.... that's a shame as this is surely one of the key ways to reduce jitter and of course then means you are down to buffering the data between the clock domains.... and AFAIK the bigger the buffer the better.

When you say "a USB to I2S interface is probably a better sounding solution" is that what people have observed comparing with a BBB / RPi as I2S source. Using USB means you will also have the "jitter effects" caused by the irregular / bursty data packet delivery from the USB source (pc / mac / etc..).
 
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