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TADAC dac + ht bypass + upgraded tubes

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  1. nathan_h
    For Sale
    Very conservatively rated as 8/10 cosmetically, it's a sonic "10".   I just got it tuned up by Paul Grzybek, Designer-Builder, Tube Audio Design.  Seeking $729 + shipping to a paypal verified address.
    General info: see paul's web site.  Here is a summary of the relevant stuff from his site:
    "Select 12AU7 tubes are included. [In this case, he upgraded to a pair of NEC tubes]. Tight contact gold ceramic sockets - install slowly to prevent bending a tube pin. Use 12AU7, 5814, 5963 tubes. Can leave on all the time without tube life worries. The unique Tube Audio Design analog tube circuit not only sounds out of this world, it is extremely easy on tubes. Perhaps a pair of U7's will last a lifetime in this circuit - time will tell. Make a tube removal tool out of 3/4" inner diameter clear plastic tubing (Ace Hardware sold by the foot).
    Large epoxy potted toroidal power transformer resides in the black box on top
    Separate DC voltage regulators for all digital & audio circuits
    Each Power Supply Electrolytic is Film Cap Bypassed
    Contains 5 op-amp: 2 between DAC output & tube circuit to convert to single ended and make the phase switch feature. 2 op-amps after the tubes to drive XLR jacks, 1 op-amp after tubes in the headphone circuit.
    One Invisa-Cap in each tube audio circuit (same caps used in the TAD-150 Signature preamp)
    Data input selector switch [on side] for Optical Toslink or Coaxial-RCA data selection
    2 Gold RCA jacks are 100% tube driven outputs
    True balanced gold XLR Outputs are hybrid tube/chip driven 
    RCA Output impedance is 400-Ohms, XLR Output 75-Ohms
    Tubes Light Up Blue when audio data is locked on the input
    96k max input data speed, Crystal 8414 feeds a Burr-Brown 1793 Advanced Segment Verification Jitter Free D/A chip - a combination that sounds best in this tube design.
    Connect digital SPDIF (CD Player data) single RCA or Optical Toslink to the TADAC
    Designed for PC digital audio (up to 96k). PC Windows & Mac computer USB to audio SPDIF data interface adapter needed (purchase separately).
    Tube/SS Headphone jack for amazing HF sound - does not automatically switch main back outputs off with HF plugged in to keep audio paths short and pure. Designed for regular light load headphones.
    Phase Switches: Useful to determine if a recording is properly phased - singing towards you-in phase, away from you-out of phase. Tip: Bass usually sounds stronger in phase, some recordings are phase balanced - in or out sounds about the same - older recordings tend to reveal phase changes more distinctly - some actually recorded out of phase, a sound board oops. Normal phase is with both switches down. Try one switch in phase, one switch out to create 1950's Orthophonic out of this world stereo sound.
    The TADAC has a unique Tubyness knob to adjust how harmonically balanced the music sounds."
    This is a slightly different model than on his web site.  On mine, the Tubyness knob is on top, and to keep the signal path pure, there is no analog line input and no remote control circuit.  Minimal analog and digital all the way!
    I bought this direct from Paul originally, and here is what he wrote at the time:"Hard to find 2007 TADAC tube D/A converter loaded with upgrades: Has The Tubyness Control on top, Master Volume Control in front (can use like a tube preamp, or not), Side Input Selector (Coax or Optical – 2007 TADACs only have digital inputs). Comes with a select pair of 1960's NEC brand 12AU7 long rib plate tubes. Has balanced XLR Outputs, RCA outputs and a Headphone Jack."
    ALSO included is a special outboard HT bypass that Paul built for me.  Custom design to allow insertion in a HT system to bypass the HT pre-amp for a more pure signal path.  Awesome little device!
    No sales overseas or to buyers without positive feedback, except in person. 
    I have Paul's original packaging for the TADAC, and will add the bypass in a separate box for safety.
  2. ctm
    What do you mean by "HT" (home theater)?  Also, how is the the outboard bypass connected to the TADAC (are the inputs on the side)?  Thanks.
  3. nathan_h
    Good question. Sometimes the jargon gets the best of me.
    Yes, "HT" means home theater, since usually people use the bypass box to skip putting two channel audio through their surround processor (note this won't apply if you use a receiver, you need to be using separates;  if you are using a receiver you can ignore the bypass box and plug the DAC straight into an analog input on your receiver).
    The wiring is dead simple:  There are two inputs on the bypass box (see the screen shot) and one output.
    Into one input, you put the FR and FL from the HT pre-pro.  Into the other input, you put the L and the R output from the DAC.
    Then, the output of the bypass box goes to your amp R and L inputs.  (Obviously this assumes you are using singled ended [ie, RCA] connections throughout.)
    It's kind of like a switch box without the switch.
    Paul G, the designer, has made some TADAC's with this bypass feature in the DAC itself, but the principle is similar with this outboard device.
  4. nathan_h
    I guess I should mention that I am local to the SF Bay Area, in case buying in person (save money!) is appealing.
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