Lite DAC60 - PCM1704 R2R tubed DAC Mod Project

PCM1704 DAC MOD PROJECT - LITE DAC60

 
My goal was to have a near state of the art true R2R DAC with no opamps with a true tube output stage.
 
I choose the Lite DAC60 to start with.  It has 2 PCM1704 DAC's one per channel, uses a real tube output stage (easy to find 6922), has lot's of room to work, is very well built, and is relatively inexpensive.
 
There has been much written about this DAC and how to modify it - so a good starting point.
 
But why the older style R2R DAC chip?  Well I value rich natural tone as a hallmark of great sound.  I love the richness of vinyl and have and had many high quality turntables and cartridges.  Vinyl also has this smoothness, lack of graininess that makes listening to it for hours very enjoyable.  So I wanted my digital to have the same (especially after digitalizing my LP collection at 32bit/176K sampling).  I found one DAC from APL that did it - but it was very, very expensive $20K+.  I needed something more affordable for my office system.  So my aim was to build a competitive DAC for less then $1500.
 
More on the R2R dacs and the more modern delta-sigma and multi-bit dac designs here:
 
http://www.mother-of-tone.com/conversion.htm
http://funwithaudio.blogspot.com/2012/01/today-in-electronics-everything-is-made.html
 
I did my modding in three stages.  I'll detail each stage - what it cost and what I did - and the sound improvement or lack of.
 
One note: There are dangerous, even lethal currents inside this unit.  If you are not an expert I would suggest Sonic Craft DIY can do the specified mods for you.
 
Links to Lite DAC60 mods:
 
http://www.audiocircle.com/index.php?topic=51316.0
 
 
Well the before and after pictures:
Before:

 
After:

 
 
What was the improvement in sound?  Well the stock unit is very, very good - especially when you upgrade the stock EH 6922 to some of the best vintage 6922's.  In this case I chose my favorite - the '75 6n23p silver shield single wire getter post Reflectors.
 
This change alone improved the sound immensely.  Greater detail, bigger sound stage, smoother presentation.
 
But this was just the beginning...
 
PS Final version:

 


 

Details, please...

Subscribed!  Cool stuff.

walfredo said:

  Details, please...

Click to expand...

Just finished it!  I moved the huge Mundorf Silver/Oil coupling caps to the side - wired with Mundorf Silver wire.  They were a little to close to the tubes for comfort.  They don't like high heat.  They are better secured now and isolated from vibration as well.
 
This DAC sounds amazing!  All the new caps have finally broken in.  Sweet, sweet, sweet sound.  Great detail - rock solid bass.  Deep and wide sound stage.  A very pure and natural tone.
 
It has exceeded my best expectations!
 
I will add details as to parts, cost and what I did to take this DAC to near sota levels.

The Final product:
 

 
Mundorf 2.7 uF Silver in Oil coupling caps re-mounted to the side, wired with Mundorf solid silver teflon coated wire..  Hammond choke PS filter.

 
Replaced the 2 generic 47uF PS caps with a dual 47 uF + 47 uF Mundorf Mlytic HV cap wired with .9999 solid copper wire. Mundorf Supreme 2.2 uF 600V replaced the white box 2.0 uF cap.  Elna Simlic II 470 uF/63V caps replaced the stock Elnas.  Rubyicon BXW 120uF/400V replaced the cheap horizontal PS 'lytic caps.

 
Replaced the Sanyo PS caps with Nichicon Fine Gold 2200uF/35V, standard Elnas replaced with Elna Simlic II 470uF/63V.


 

Upgraded pure copper Viper connectors and upgraded cyro'd fuse holder and silver HIFI fuse.
 

Very cool, great job - a good deal of work put into that.  Looks like coax and optical in?  What sort of sampling rates are supported?  (Understanding that it's definitely not the end-all approach it's now made out to be.)  Would love to hear if you have some modern-ish non-R2R DACs for direct comparison...details on sound differences!  Very interested to hear information on your time invested and overall budget.

shortcuttomonct said:

  Very cool, great job - a good deal of work put into that.  Looks like coax and optical in?  What sort of sampling rates are supported?  (Understanding that it's definitely not the end-all approach it's now made out to be.)  Would love to hear if you have some modern-ish non-R2R DACs for direct comparison...details on sound differences!  Very interested to hear information on your time invested and overall budget.

Click to expand...

I'm putting together the spreadsheet with all the parts and each of the three stages.  I'll put up a post with all that detailed.
 
I have and have had many non-R2R DACs.  In my main system I have the $6,000 APL modded 3910 - it uses 6 AKM DACs per channel, tubed output, Lundhal transformer coupling, superclock, etc... (a junior version of the awesome $25K APL - NWO 3.0).  Here is a review of the big brother, but similar design NWO on 6Moons. http://www.6moons.com/audioreviews/aplhifi/nwo30go.html
 
It uses the AKM 32bit 4397 6 per channel.  APL states they have found away to run these multi-bit DACs in a unique way.  It's my understanding he uses the 6bit R2R portion of each DAC chip in serial to form a 24bit R2R configuration.  Anyway this DAC is amazing and should be for the cost.
 
I've also had: Xindak DAC5, Audio Mirror Tubadour DAC, Lite DAC 68 and a Eastern Electric Mini Max DAC plus.
 
The last uses the 32bit multibit Sabre DACs.  I also have and had a very high end turntable/cart setup for comparison.

 
 
Now I have not done the head to between the Modded Lite DAC 60 and APL and hope to over the weekend.  But just from listening in my office system - which I've had all my DACs in at one time or another.  The Modded Lite DAC60 is something special.  An ease to the music that is so natural, unfatiguing, I can and do listen for hours (8hrs/day).  Excellent dynamics as well.  This is probably the richest most natural tone I have ever heard from digital!  And better then my analogue system at this point (Ortofon 2M Black, Dual, modded Jolida JD-9, etc..).
 
Of course I would love to try against a $7,000 Total DAC tubed DAC as a comparison.  The TotalDAC uses a custom built R2R DAC with individual resistors, and a tubed output stage.  So again no opamps in the curcuit. http://www.totaldac.com/D1-tube-eng.htm
 
More info on the latest multibit Delta Sigma DAC chips:
http://funwithaudio.blogspot.com/2012/01/today-in-electronics-everything-is-made.html
 
More good stuff on building a SOTA R2R DAC:
http://killerdac.com/forum/index.php?topic=932.20

Do you know if the stock Lite DAC-68 has better sound than the stock DAC-60 ? How about mod for DAC-68 is the same as DAC-60 ? Thanks.

lestuan said:

  Do you know if the stock Lite DAC-68 has better sound than the stock DAC-60 ? How about mod for DAC-68 is the same as DAC-60 ? Thanks.

Click to expand...

Yes you could mod the DAC-68.  But it does use the Delta Sigma AD1853 - vs the R2R PCM1704.  Used in many of the best DACs (Total DAC, Audio GD Ref, etc...) the R2R is considered to have better tone.  The DAC 60 is also cheaper
 
 
http://www.totaldac.com/principles.htm

rb2013 said:

  Yes you could mod the DAC-68.  But it does use the Delta Sigma AD1853 - vs the R2R PCM1704.  Used in many of the best DACs (Total DAC, Audio GD Ref, etc...) the R2R is considered to have better tone.  The DAC 60 is also cheaper
 
 
http://www.totaldac.com/principles.htm

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I just wish the DAC-60 had balance input and output as the DAC-68. Can we add these to the DAC-60 modded ?

lestuan said:

  I just wish the DAC-60 had balance input and output as the DAC-68. Can we add these to the DAC-60 modded ?

Click to expand...

No, since it's output is wired as single ended.
 
But I would suggest the excellent DA83 - it does not have tube output, which I prefer, but it uses the PCM1704, and offers balanced outputs.
 
http://mesgmy.ebay.com/ws/eBayISAPI.dll?ViewMyMessages&CurrentPage=MyeBayMyMessages&folderId=0&CurrentView=fromMemberQuestions&sentItemId=231396630948&ccSender=false

rb2013 said:

  No, since it's output is wired as single ended.
 
But I would suggest the excellent DA83 - it does not have tube output, which I prefer, but it uses the PCM1704, and offers balanced outputs.
 
http://mesgmy.ebay.com/ws/eBayISAPI.dll?ViewMyMessages&CurrentPage=MyeBayMyMessages&folderId=0&CurrentView=fromMemberQuestions&sentItemId=231396630948&ccSender=false

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Oh, great ! Now I start looking on that DAC. Heave you ever heard the DAC-83 ?

lestuan said:

  Oh, great ! Now I start looking on that DAC. Heave you ever heard the DAC-83 ?

Click to expand...

No, I really like tubed DACs for their rich tonal musicality - especially with the best tubes. 
 
But Darko gave it very high ratings
 
http://www.digitalaudioreview.net/2011/01/lite-dac-83-4-x-burr-brown-pcm1704uk/
 
PS edit: From his review 

There is an abundance of tonal richness and density that often eludes DACs of a delta-sigma bent. When done right, delta-sigma chipset implementations can offer tremendous dynamics and top-end detail. 

Click to expand...

Do you know if Sonic Craft DIY can do  all the mod with same parts and mod's step just as you done with your DAC-60 ?

lestuan said:

  Do you know if Sonic Craft DIY can do  all the mod with same parts and mod's step just as you done with your DAC-60 ?

Click to expand...

I did piece together the parts from different sources and supplied the very rare tubes myself (those make a huge difference).  But I'm sure they could acquire those same parts themselves and do it.
 
I could do the mods for you as well.
 
I'm putting together the parts list, and what was replaced with what in a monster post.  It's taking a little time to put it all together.
 
Here were some of the resources I used as part of my research.  So happy with the Mundorf Silver/Oil caps.
 
Great resource on the film coupling caps selection:
http://www.humblehomemadehifi.com/Cap.html
 
Great resource on the electrolytic cap selection:
http://tech.juaneda.com/en/articles/electrolyticcapacitors.html
 
Some discussions on modding the DAC60 - in the end I did not have an issue with congestion on complex passages - not with these Holy Grail tubes.  I believe the issue some folks were hearing was related to the tubes they were using not he IV resistor loading.  So I did order the parts but never did that change (it increases the stress and distortion from the tubes).  My modded 60 is very dynamic and keeps everything in order during loud, complex passages.  My long history of tube rolling the 6922 is many of them have congestion issues.  So using the right tubes is key.
http://www.audiocircle.com/index.php?topic=51316.40