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MDAC First Listen (part 00101100)

Discussion in 'audio' started by timola, Nov 25, 2015.

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  1. misterdog

    misterdog Not the canine kind

    I think you have been badly misinformed.

    "Outokumpu maintains a stainless steel melting facility in Sheffield which has potential operational capacity of 400,000 tonnes per annum. This is the UK’s only large scale stainless steel melt shop however."
  2. JohnW

    JohnW pfm member

    The Master FDAC serves as the "Input Device" and decodes and distributes the Data to the Slave FDAC's via the Slave / Master interface.

    For example, if a single Slave unit is connected then the Master enumerates over the USB interface as a 4 channel DAC (if used for surround channel applications = 4 Channels).
  3. torstoi

    torstoi pfm Member

    So, if I had an analogue Xover for a 3 way active speaker I would like to bypass and drive the 3 amps directly via the FDAC..

    what options would I have to select from the pre-order form ?
  4. JohnW

    JohnW pfm member

    For 6 audio Channels you would need one Master and Two Slave FDAC's.

    A word of caution is that initially the software will only support "Multi Channel" Audio as we rely on MiniDSP for the DSP Xover software - and they will only start to customise there software for the FDAC once the units are in production.

    Depending on Jarek / Dominiks workload (its more about priorities) we might be able to realise our own simple DSP XOver software.
  5. occamsrazor

    occamsrazor pfm Member

    Maybe this is a stupid question but.... If the FDAC can do crossover duties, can those be applied to the two analogue outputs? I'm wondering if you could do a simple crossover in the FDAC and send below-cutoff frequencies to output#1 and above-cutoff frequencies to output#2. Would be pretty useful for a 2.1 setup with output#1 going to subwoofer and output#2 going to power amp & main speakers.
  6. fusion5

    fusion5 on the dark side of hifi...

    No, there is only one output stage with two sets of connectors (RCA & XLR).
  7. occamsrazor

    occamsrazor pfm Member

    I must have misinterpreted John's last post, thanks for clarifying.
  8. JohnW

    JohnW pfm member

    The FDAC only has two audio channels per unit - although we could HPF the Main Analogue outputs - and send the LF channel to a subwoofer via the SPDIF outputs...

    You would need a Slave FDAC for two more audio Channels...
  9. occamsrazor

    occamsrazor pfm Member

    Cool. Could then, for example, you HPF the main outputs, and send the LF channel over SPDIF to an MDAC then to the sub? (He asks as an existing MDAC owner....)
  10. JohnW

    JohnW pfm member

    It would work BUT there would be a varying time delay between the FDAC and MDAC signal output. As the Wavelength is so long at LF it might be OK for subwoofer duties.

    We could compensate for the "fixed" group delay of the FDAC / MDAC signal conversation, but as there Audio clocks are not locked there would still be a varying signal phase shift between DACs... But strictly for LF sub woofer duties it should be OK.
  11. fusion5

    fusion5 on the dark side of hifi...

  12. Discovery

    Discovery pfm Member

    I couldn't resist the opportunity so bought the power supply and the RS lead.

    Initial tests have used the lead at its original length (but as it's over two metres there's plenty of scope to shorten it). My unit's output is 15.45v and, contrary to an earlier report, it is slightly louder, not quieter, at usual MDAC volume settings.

    Having had a few nights to allow for burn-in, bass is most noticeable, being tighter and slightly punchier. There's greater clarity across the rest of the spectrum. No negatives found so far, apart from the need for another case for H&S reasons.

    I'm now wondering whether this is the best £25 I've ever spent on my system or whether that accolade remains with my Pi 2... ;)
  13. davidjt

    davidjt pfm Member

    As I use 2 x REL subs, that would suit me down to the ground, and obviate the need for a third terminal. After everyone has their FDAC, obviously.
  14. fusion5

    fusion5 on the dark side of hifi...

    You did notice that I was talking about the VFET amp and not the FDAC, didn't you?
  15. JohnW

    JohnW pfm member

    As we are CNC'ing the VFET Chassis its not impossible to add Custom connectors - or maybe as you say have both options... the problem really is the rear panel labelling artwork rather then the custom connectors.
  16. JohnW

    JohnW pfm member

    Does the speakon have a "Ground" terminal? so 5 Conductors?
  17. Rune

    Rune pfm Member

    Does this also mean that it is not possible to get a loop-thorough XLR connector for bi-amping the VFETS?
  18. JohnW

    JohnW pfm member

    There will be XLR loop-though connectors fitted as standard.
  19. jirij

    jirij Virtual Member

    No, they come only in 2/4/8 pin versions, but I haven't actually seen a speaker cable with a shield or a dedicated cable for sharing the "ground". :(

    The 2pin is actually a "special case" of the 4pin connector (2pin plug -> 2pin socket, 2pin plug -> 4pin socket, 4pin plug only -> 4pin socket) and the 8pin just extends the 4pin on some series:


    As for safety, it relies heavily on non-conductive materials (mostly plastic) instead of grounding the shell, which makes sense, I guess. I would very much prefer to touch heavily isolated plastic than what are supposed to be unpowered banana plugs. :D
    As the contacts aren't directly exposed, pulling the plug out of a live speaker would be safe (as in - the human doesn't get injured, the equipment might).

    I had a chance of working with them few months back and it well suits the "tour" lifestyle of "plug & play", not sure about longevity, though. Maybe the enormous STX series is really built to last.

    Full range for browsing:
  20. JohnW

    JohnW pfm member


    Your up late :) its 3.30am about to hit the sack as they say...near completing the input / Transformer section of the ADC inputs :( :)

    Thanks for the info on the Speakon - I didn't recall seeing any Grounding connection on the 4 pole jacks... Shame...
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