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In Reply to: Re: DIY DAC posted by Thorsten on January 12, 2005 at 03:04:51:

Hi,
Here the most simple PCM56 DAC possible:
This is from here:
http://www.y-min.or.jp/~nob/Audio/DAC/DAC03.html
The Author first a version with a more complex arrangement to direct the correct signals to L/R but appears just like I did to have found the simplest arrangement the best.
The DAC uses the on-board Op-Amp's for I/V etc, I would probably change this to passive I/V. Here a "hacked up" schematic that shows how to use the passive I/V:
The PCM56 is fully charaterised to use 1K I/V resistors, which means my original TDA1543 I/V with "anti sinc" filter will drop right in, in place of the two resistors to ground shown in the schematic:
Output would then be 0.7V RMS, this can be just enough to drive a preamp/integrated. Otherwise an Analog stage with a little gain would be desirable, around 3 times would be good.
Sounds to me like a pair of 2A3's (or 45's or 71A's) would be an interesting twist, run with a suitable Anode load choke 50H+/20mA and with a 250V HT and a 2k2 Cathode resistor, capacitor coupling to output. Anyway, many ways of skinning that particular cat.
Also here an example of a matrix Board circuit to which a copper groundplane was added using self adheasive copper tape:
Ciao T

Follow Ups:

Will this PCM56 DAC outperform Yeo's ? - mamu 11:37:27 01/12/05 (6)
...or come close to a TDA1545 based design?
-Matthias
- Re: Will this PCM56 DAC outperform Yeo's ? - Thorsten 12:08:34 01/12/05 (5)
  Hi,
  > Will this PCM56 DAC outperform Yeo's ?
  > or come close to a TDA1545 based design?
  The PCM56 is IMHO a much better dac than the TDA1545 which in turn is a lot better than the TDA1543....
  Ciao T
  - Re: Will this PCM56 DAC outperform Yeo's ? - mamu 10:56:52 01/13/05 (4)
    Thanks T!
    Any idea where to get the PCM56?
    Tried several sources like rs-componets etc. but wasn't able to find it.
    Looks like that the CS8412 will get hard to find too (was easy last year over here in Germany, but now...).
    -Matthias
    - Re: Will this PCM56 DAC outperform Yeo's ? - Thorsten 13:14:39 01/13/05 (3)
      Hi,
      > Any idea where to get the PCM56?
      Try TI's website, they list plenty of sources with the PCM56, remember, it is a currently active and readily made product. You might even be able to get a pair of free samples (ever since TI took over BB they are a lot less tightfisted about samples I noticed recently).
      > Looks like that the CS8412 will get hard to find too
      Use a CS8414 on adapter. Actually, the CS8414 is chunky enough for hardwiring anyway and there are few enough connections to make....
      Ciao T
      - Re: Will this PCM56 DAC outperform Yeo's ? - fred76 02:04:51 01/14/05 (2)
        
        In Reply to: Re: Will this PCM56 DAC outperform Yeo's ? posted by Thorsten on January 13, 2005 at 13:14:39:
        
        Hi T,
        Our local RS-Comp has the PCM56P (I've yet to find a source for the Crystal Sem DIR).... Some questions though, did you try the schematic from the Japanese site or did you make your own design?Between the 5V to 12VDC supply, which specific V have you found "best" sounding (ie, sweet spot)? Thanks.
        fred
        
        Re: Will this PCM56 DAC outperform Yeo's ? - Thorsten 04:29:23 01/14/05 (1)
        
        In Reply to: Re: Will this PCM56 DAC outperform Yeo's ? posted by fred76 on January 14, 2005 at 02:04:51:
        
        Hi,
        > Some questions though, did you try the schematic from the Japanese
        > site or did you make your own design?
        I used my own, differences in powersuplies where applied, the core circuit happend to be identical, I even used a 74HC04 as it happened.
        > Between the 5V to 12VDC supply, which specific V have you
        > found "best" sounding (ie, sweet spot)? Thanks.
        I only used 5V.
        Ciao T
        
        Re: Will this PCM56 DAC outperform Yeo's ? - fred76 01:59:45 01/15/05 (0)
        
        In Reply to: Re: Will this PCM56 DAC outperform Yeo's ? posted by Thorsten on January 14, 2005 at 04:29:23:
        
        > > I used my own, differences in powersuplies where applied, the core > > circuit happend to be identical, I even used a 74HC04 as it > > happened.
        That's pretty cool...
        
        Thanks again T.
Re: PS... - fred76 11:15:33 01/12/05 (1)
Hi T,
Thanks for the copper tape tip.. The matrix boards available here already have a copper grounding plane on one side. I'll keep the PM56 Dac in mind.
A young buddy of mine is good at making pre-sensitized pcb's - but so far only single sided types for his discrete ss phonostage (his own design). We plan to launch it (locally) as soon as the bugs at the MC section get "solved" (pp or differential *?*). So far the paralleled chokes after the ic V regulator helped a lot, he is yet to try a power opamp as regulator with some trick V reference. BTW, the whole PSU board uses a matrix board with a copper groundplane.

Anyways, the designer of the rockna DAC prefers 1:1 upsampling for the incoming data - counter to the more purist approach of almost all "non-os dacs". I still have to ponder if I'm going for a module or complete diy from ground up using available schematics like Pedja's (I can only do this with a buddy's help of course)...
Do you have a good schematic for a tube outputstage for 1A out type dacs like the AD1856, preferably the Gomez type compund circuit? I have seen a dac kit being sold in the UK using four 12SN7's for Gomez output. I have some 6SN7's lying around I could try.
Thanks for the exhaustive thoughts on DACs.
Regards,
fred
- Re: PS... - Thorsten 12:14:40 01/12/05 (0)
  Hi,
  > Do you have a good schematic for
  > a tube outputstage for 1A out type dacs like
  > the AD1856,
  not specifically, simply adjust any one you like to suit.
  Ciao T
How about this? - NewbieBaby 11:01:20 01/12/05 (2)
Does Curcio's CD12V appear to be reasonably weld executed?
http://www.curcioaudio.com/cddacsch.gif
There is anecdotal reportage that it can be configured for 1X or 4X oversampling. The schematic is apparently the 4X configuration.
Thanks.
And a dumb question: From looking at a few schematics, I am wondering that if the digital signal is iput through one line, how is channel separation maintained?
- Re: How about this? - Thorsten 15:09:24 01/12/05 (1)
  Hi,
  > Does Curcio's CD12V appear to be
  > reasonably weld executed?
  Probably better than most.
  > From looking at a few schematics, I
  > am wondering that if the digital signal is iput
  > through one line, how is channel separation
  > maintained?
  The input is digital, its all numbers. As long as you know which, number belongs to which channel and at what time you can reconstruct what was encoded.
  Ciao T
  - Hooray - NewbieBaby 17:32:54 01/12/05 (0)
    This one's available for the building, for me, anyway.

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