View RSS Feed

Jud

Semi-Customized DAC

Rate this Entry
A very nice person has provided me some DAC innards, which will give me the opportunity to put together a semi-customized DAC that employs some thoughts I've picked up from various smart people along the way. Said nice person has requested that his/her identity and that of the innards remain confidential. Out of respect for that request, I'd ask anyone commenting as this project proceeds to please refrain from speculating on those points.

The thoughts I'd like to try to put into operation:

- Vibration control and (two) chassis from maple - see the discussion from Pierre Sprey of Mapleshade here: Maple Isolation Platform

- Internal cabling (if and where possible) with Omega Mikro ribbons - here's a photo from a Positive Feedback article on the Walker Proscenium turntable:

blogs/jud/attachments/5205-semi-customized-digital-analogue-converter-omega_mikro_cable_connector.jpg

- The minimum number of sample rate and format conversions necessary, and where they are necessary, done by means of software I can control, rather than a chip programmed by someone else. Thanks to PeterSt, Miska, Damien, and the iZotope developer for essentially opening a new world to me in this respect that I hadn't known existed. The parts I have will allow me to play my DSD files natively, so no need to convert to PCM (though Audirvana+ does a very nice job in this respect with my present DAC). For PCM material, I will be able to use software to convert the input to the same resolution at which the DAC chip performs D/A conversion, eliminating any need for internal upsampling.

Right now this is at the stage where some internal parts have arrived, and I'm awaiting the rest. Then after preliminary testing to make sure everything works, it will be time to get down to chassis design and fabrication, as well as ordering the Omega Mikro parts (ribbon and RCA connectors).

Watch this space....
Categories
Uncategorized

Comments

  1. The Computer Audiophile's Avatar
    Sounds really cool and really fun!
  2. junker's Avatar
    Sub'd!
  3. wgscott's Avatar
    Front Panel Express was a pleasure to deal with.
  4. Jud's Avatar
    Quote Originally Posted by wgscott
    Front Panel Express was a pleasure to deal with.
    Thanks for the suggestion, Bill. I'm going to be using wood for the two chassis, so I don't know whether they'd work with that. They do mention they work with non-ferrous materials, but all the examples are metal or plastic; wood may be a non-ferrous bridge too far. ;)

    Actually, it looks like another CA member may be working on the chassis for me. I'll have to see whether he'll allow me to give him credit publicly, or if he prefers to "keep his light under a bushel," as the saying goes.
  5. The Computer Audiophile's Avatar
    Quote Originally Posted by Jud
    Thanks for the suggestion, Bill. I'm going to be using wood for the two chassis, so I don't know whether they'd work with that. They do mention they work with non-ferrous materials, but all the examples are metal or plastic; wood may be a non-ferrous bridge too far.

    Actually, it looks like another CA member may be working on the chassis for me. I'll have to see whether he'll allow me to give him credit publicly, or if he prefers to "keep his light under a bushel," as the saying goes.
    How are you going to dissipate heat with a wood chassis? I love the idea.
  6. Jud's Avatar
    Not a lot of heat to dissipate; there are small heatsinks on individual parts where needed, and at the moment I'm conceiving of slots or holes in the appropriate locations in the tops, very possibly also the bottoms, of the chassis to get air flowing through to carry that small amount of heat away.
  7. wgscott's Avatar
    I have a wood chassis and front and back panels are Al from FrontPanelExp. The wood is an extra Peachtree shell they sold me, and this is for an amp (albeit class D). The vents they put in are more than adequate.

    At risk of hijack, let me again briefly lobby for a DIY sub-forum. (OK, I'm done.)
  8. Jud's Avatar
    Not just wood chassis, Bill, but no conductive/magnetic metal other than the circuitry and wiring.

    (Wouldn't mind a dedicated DIY sub-forum myself, but we'll have to leave that to Chris.)
  9. bdiament's Avatar
    Hi Jud,

    I do not believe a solid maple platform, coupled to the surface under it with hard cones/spikes, provides any isolation at all. As I see it, this is a *coupling* device (the diametric opposite of isolation).

    Test:
    1. Place component atop this platform.
    2. Shake shelf upon which platform sits.
    3. Note there is not even a delay between motion of the shelf and motion of the component atop said platform. The motion is one-to-one, with no delay. To me this says there is zero isolation and 100% coupling.

    My impression of that particular design is that it is simply adding mass --- basically a (vibration) energy reservoir.

    I would very much recommend trying some real isolation under the DAC. I have found many benefits and no drawbacks -- the properly isolated component is merely free to perform its best, which is more often than not, significantly better (in every sonic parameter I know how to describe) than it does without the isolation.

    Perhaps this article will be of interest.

    Best regards,
    Barry
    Soundkeeper Recordings
    Barry Diament Audio
  10. Jud's Avatar
    Hi, Barry. I agree the arrangement you've described is a coupling device. Good thing that's not the (entire) Mapleshade configuration.

    The component is indeed supposed to be coupled to the maple platform with spikes. But then the maple platform is isolated by cork-and-rubber-sandwich "isoblocks" of substantial thickness. So (I'm supposing) self-vibration is drained to the coupled platform, while the platform is isolated by the cork-and-rubber blocks so relatively little vibration is transmitted to the platform from the other direction.

    I don't know how the Isoblocks perform as isolators compared to the "roll your own" described in your linked article. I probably won't have the chance to find out, not especially wanting to hear what my wife thinks of the interior decoration aspects of half inflated inner tubes at the front of the family room.
  11. bdiament's Avatar
    Hi Jud,

    Inner tubes can be very easily hidden.
    (They're in the distance but see the rack that is visible to the right of the right speaker at the home page here. Do you see any inner tubes? There is one for each shelf.)

    Outside of that, I'll send it as a PM.

    Best regards,
    Barry
    Soundkeeper Recordings
    Barry Diament Audio