The Soekris R-2R DAC: Technical Details

[hgpsemaj]

  Thank you for your kind offer.  I would be looking for a tube output board using the 6922.  That would only require a PS and input and output hookups.  I have found these but they use a different tube.  I wanted something like the tube output stage of the Lite DAC60.
 
This one is close - but I would like the 6922 tube vs the 6n3p-ev
http://www.ebay.com/itm/Tube-output-stage-for-cd-player-or-dac-upgrade-/190613962046?pt=LH_DefaultDomain_0&hash=item2c617a3d3e
 
This one looks like overkill:
http://www.ebay.com/itm/LITE-LS60-Assembled-Balanced-Tube-Preamplifier-Board-12AU7-6DJ8-6922-/181712540779?pt=LH_DefaultDomain_0&hash=item2a4ee9546b

 
Something like this?
 

 
http://www.diyhifisupply.com/opcart/index.php?route=news/article&news_id=120
 
Please advise.

 

[hgpsemaj]

It seem TaoBao offers a considerable amount of discount over Ebay on the following items:
 
http://item.taobao.com/item.htm?spm=a230r.1.14.19.KTL8hO&id=40796497747&ns=1&abbucket=14#detail
 
and,
 
http://item.taobao.com/item.htm?spm=a230r.1.14.12.KTL8hO&id=40881269639&ns=1&abbucket=14#detail

 

[rb2013]

   
Something like this?
 

 
http://www.diyhifisupply.com/opcart/index.php?route=news/article&news_id=120
 
Please advise.

Yes that looks very interesting.  But I don't understand how they can get 12dB of gain from a single 6n23p - there must be an opamp output with the tube acting as a buffer.  The design would be using one section of the dual triode for each channel.  Without a close up it's hard to see the opamps.

 

[rb2013]

  It seem TaoBao offers a considerable amount of discount over Ebay on the following items:
 
http://item.taobao.com/item.htm?spm=a230r.1.14.19.KTL8hO&id=40796497747&ns=1&abbucket=14#detail
 
and,
 
http://item.taobao.com/item.htm?spm=a230r.1.14.12.KTL8hO&id=40881269639&ns=1&abbucket=14#detail

Yes but my anti-virus blocks me fro buying on TaoBao -and shipping to the US is expensive (someone trying to buy a MXU8 was charged $40).

 

[hgpsemaj]

  Yes that looks very interesting.  But I don't understand how they can get 12dB of gain from a single 6n23p - there must be an opamp output with the tube acting as a buffer.  The design would be using one section of the dual triode for each channel.  Without a close up it's hard to see the opamps.

 
I will contact 'diyhifisupply.com' to confirm the details of this output board sometimes next monday.

 

[hgpsemaj]

 
Yes but my anti-virus blocks me fro buying on TaoBao -and shipping to the US is expensive (someone trying to buy a MXU8 was charged $40).

It must be a matter of territorialism. I got the similar phenomenon in here, I couldn't surf 'diyinhk.com' in Hong Kong and Shenzhen, China.
 
For your information, please note Melodious Audio/TaoBao offer their MX-U8 in three price levels as follows：
 
（i）   Standard Version: Ordinary Transformer; Pulse Output Transformer; Stick Pad Clock & Rubber Feet @ RMB680.
 
 (ii)      With-High Version:  Ordinary Transformer; Pulse Output Transformer; 1PPM Clock & Rubber Feet @ RMB780.
 
 (iii)     Ultimate Version: Talema Transformer; Murata DA101, 0.1PPM Clock & Aluminum Feet @ RMB1,080.

 

[rb2013]

  It must be a matter of territorialism. I got the similar phenomenon in here, I couldn't surf 'diyinhk.com' in Hong Kong and Shenzhen, China.
 
For your information, please note Melodious Audio/TaoBao offer their MX-U8 in three price levels as follows：
 
（i）   Standard Version: Ordinary Transformer; Pulse Output Transformer; Stick Pad Clock & Rubber Feet @ RMB680.
 
 (ii)      With-High Version:  Ordinary Transformer; Pulse Output Transformer; 1PPM Clock & Rubber Feet @ RMB780.
 
 (iii)     Ultimate Version: Talema Transformer; Murata DA101, 0.1PPM Clock & Aluminum Feet @ RMB1,080.

Glad to have gotten the iii!  I used Shenzhenaudio.com in HK.  Stacy is great to deal with (for me a good thing he speaks English as it makes communication easier).  And his price with shipping was very reasonable - although he said it would be going up.

 

[hgpsemaj]

Superceded.

 

[skeptic]

  Thank you for your kind offer.  I would be looking for a tube output board using the 6922.  That would only require a PS and input and output hookups.  I have found these but they use a different tube.  I wanted something like the tube output stage of the Lite DAC60.
 

 
Here's another option that I've seen mentioned on other forums - http://lampizator.eu/shop/viewitem.php?productid=262

 

[rb2013]

   
Here's another option that I've seen mentioned on other forums - http://lampizator.eu/shop/viewitem.php?productid=262

That's what I'm looking for!  Thanks!

 

[rb2013]

After doing much more research on TXCO and OXCO clocks - I think I'm gonna pass on this project.
 
The single clock on board just didn't cut it for me.
 

  CLOCK SECTION
The clock in the dam1021 DAC is the Si514. This the lower grade of programmable clocks from Silicon Labs (.8 psec RMS jitter) [link], and according to Soren, it is well matched to the system as a whole.  It is also used instead of the Si570 because of lower power consumption.

Why would you pick an inferior clock based on it's lower power consumption!  Just supply more power and put in a better clock.  Or at least give the use the option of a TXCO.
 
Would have preferred a TXCO solution using dual clocks (or even a single TXCO compatible like on my Lite DAC60 Mod project - which will soon be seriously upgraded to a Audio-GD Z71 board and an upgraded Crystek 957). 
 
Didn't even go with the better 570 - went with the 514.  These are all DSPLL's.

 The Si57x replaces multiple discrete fixed-frequency oscillators with a single device, minimizing system costs and simplifying design reuse while improving system reliability. Targeting high-performance timing applications, the Si57x provide outstanding frequency flexibility and jitter performance. For relaxed jitter and lower frequency applications, the Si598/599 and Si514 offer lower cost alternatives.

 

  Silicon Labs has leveraged its proven DSPLL^® technology to create user-programmable XOs and VCXOs that provide any-rate frequency synthesis. The Si570 any-rate programmable XO and the Si571 any-rate programmable VCXO generate any frequency from 10 MHz to 1.4 GHz and target low jitter applications requiring reconfigurable clock sources. The Si57x replaces multiple discrete fixed-frequency oscillators with a single device, minimizing system costs and simplifying design reuse while improving system reliability.
Targeting high-performance timing applications, the Si57x provide outstanding frequency flexibility and jitter performance. For relaxed jitter and lower frequency applications, the Si598/599 and Si514 offer lower cost alternatives.

Zoom

 
 
 

Featured Products

Device	Type	Phase Jitter (typ)	Frequency Range	Footprint	Performance
Si570	XO	0.3 ps RMS	10 - 1400 MHz	5x7 mm	Best
Si571	VCXO	0.5 ps RMS	10 – 1400 MHz	5x7 mm	Best
Si598	XO	0.5 ps RMS	10 – 810 MHz	5x7 mm	Better
Si599	VCXO	0.7 ps RMS	10 – 810 MHz	5x7 mm	Better
Si514	XO	0.8 ps RMS	0.1 – 250 MHz	5x7 mm, 3.2x5 mm	Good

Next...

 

[sunsun22]

Is it possible to connect directly from CDPro2's I2S output to Soekris R2R DAC?

 

[abartels]

Hello all,
 
 
Just found something interesting to read about the Soekris DAM.
 
Quote from: http://www.dimdim.gr/
 
 

Soekris R-2R: Sound impressions with Salas BiB PS & alpha20 line stage

Posted on March 29, 2015

2​

A couple of days ago I took my DAM and headed out to a good friend of mine to do some listening tests.

My DAM at the moment is powered by a Salas BiB at 12VDC. It has a DIYINHK XMOS based USB to I2S interface powered by a Salas Reflektor-D at 3.3VDC. The same power supply powers the isolated side of the DAM.

(note that this picture is a bit old. I have since swapped the transformer for the one shown in the next picture plus I have used an IEC with a built-in filter)

The first objective was to assess the importance of a good DC power supply instead of a plain transformer. In order to do that I took with me an extra 50VA toroidal with 2 x 7V windings.

My friend’s system consists of Magnepan speakers, a DIY fet-based preamp and DIY power amp (solid state, 60KG monster). It is widely regarded as a very revealing and non-forgiving system. Any change in any of its components (or a component withing the components) is clearly heard.

The DAM was connected to the preamp through its unbuffered outputs.

We gave the system some time to warm up (it was probably a couple of hours) and then sat down to listen. We started with the DAM as it was, with the Salas BiB. We then unplugged the Salas and hooked up the plain transformer.

The change was immediately obvious. The sound thinned, it became more harsh in the high end. It also lost resolution and detail. Going back to the BiB made all the good qualities come back.

Thus, I can definitely recommend a proper DC power supply for the DAM. I cannot say whether it was the Salas that did the work or that any DC power supply would do the same, but the improvement was definitely there. Note that I have the BoM for the Salas BiB I built in the Soekris’ page.

The second objective was to assess the difference that could be made by using a “proper” output stage after the unbuffered outputs.

So I built a pair of AMB alpha20 line amplifiers. I set their gain to 2 and powered them temporarily by the same Salas BiB that powers the Soekris.



Note that my DAM outputs roughly 1V RMS at its output @ 0db since I’m using a filter that includes attenuation at FIR2 (I can’t really remember which one it is though..). This meant that the alpha20 brought its output to a nice 2V RMS.

Going back and forth between using the alpha20 and just the unbuffered outputs, the conclusion was that the alpha20 removed a small amount of the “magic” of the DAM while not really helping in anything besides output volume. I was hoping that it would help improve the dynamics of the DAM – its Achilles’ heel IMHO. In my friend’s system the DAM sounds “flat” compared to his other sources (a heavily modified Sony 50ES cdp, a Buffalo 3 DAC, and an Aune S16). However, this “flatness” is not particularly obvious in other more forgiving systems.

So, my assessment of the DAM so far is as such: It has great detail, exceptional mid-range, proper bass, it is a little soft on the highs, but its main problem is the dynamics. It can sound a bit “flat”, with this “quality” either accentuated or minimized, depending on the rest on the system.

If there was a way to improve its dynamics, to make it more “aggressive”, it would be a stellar performer (with a proper DC power supply of course). As is, it is just great VFM.

 

[RudeWolf]

What digital filter did you use?

 

[abartels]

???? It was a QUOTE