Digital cable musings (part 2).

Discussion in 'Hi-Fi and General Audio' started by michaelab, Jan 20, 2004.

  1. michaelab

    michaelab desafinado

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    So, as you'll remember (or not :D ) I ditched the Monarchy upsampler between my transport (modded Teac T1) and DAC (Chord DAC64) as I felt it wasn't really adding anything and merely confusing things with not one but two digital cables in the equation.

    So, now my mate who's trying out the NAD S300 integrated (separate thread) brought it here for a couple of days before he has to return it. Cracking amp btw but that's not the point of this thread :) Anyway, at first he was having trouble getting a similar kind of sound to the one he had at his place where he has a Meridian 507 as a transport for Chord DAC64 (same as mine) and Dynaudio Crafft speakers which aren't that dissimilar to my Dynaudio 1.3MkIIs. The sound was somehow hard and bright :confused:

    Well, he decided to try switching out my Apogee Wyde-Eye digital (RCA) cable for an Ixos XHD308 optical (TOSLink) cable as he was using a cheapo optical cable aswell (as per the recommendation of Rob Watts, the designer of the DAC64). Well blow me down if the sound wasn't transformed! All the brightness and hardness was gone and what was left was a gorgeous full sound full of life :eek:

    I was surprised because before I'd tried using the optical cable from the transport to the upsampler (when I still had it) and it was a downgrade.

    To rule out the effect of the different amp we just switched back in my Arcam A22 and tried the same test, Ixos optical vs. Apogee RCA and there was no contest, the optical link was a clear winner and it's staying in my system.

    So, WM, if you've heard the DAC64 sounding bright, try an optical cable ;) Will Omiga Audio see the "light" :D and be making an optical cable too? :MILD: (of course, for DAC64 owners only as in other DACs the benefits of the optical link are less clear).

    In the last month I've gone from two digital cables totalling nearly £200 plus an upsampler that cost me £200 between my transport and DAC to an optical cable that cost me £25. A £375 saving and a big sonic improvement - I like it :cool:

    Michael.
     
    michaelab, Jan 20, 2004
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  2. michaelab

    timpy Snake Oil free!!!

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    I once spent a year designing optical cables, not the placcy tat that is used in these Toslink set-ups though, proper glass ones in both modes. It was fun, and there is much more to it (as with anything) than I expect most people realise.

    To be perfectly honest, the actual cables themselves are probably ok, the normal problems associated with the optical links lie in the toslink connectors themselves, and the quality of the transceivers and conversion in the units themselves.

    Glad it works for your DAC64. Optical can work well, particularly if the optical link is not an afterthought tacked on for convenience, or if the unit is expensive enough for it to be done properly anyway. If Chord have a good implementation (hardly unlikely) then some of it's benefits will be realised.

    We don't have any plans for an optical link though, but that's mostly because a) we've been concentrating in other areas and b) we haven't really identified a need.

    Glad also that the Teac is still doing the business, mine lives on a sink now, but I think I've killed a little of it's drive by doing that. Still it doesn't skip all over the place when my chair hits the desk anymore, which is a more important consideration, what with it happening quite a lot. :D

    Cheers
     
    timpy, Jan 21, 2004
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  3. michaelab

    ditton happy old soul

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    advice on optical pl.

    At present I have no tuner on my HiFi stack, and am planning on seeing how to make best use of Sky when it is installed soon, replacing TeleWest cable. The Sky offerings include what I understand is the higher bitrate digital signal for 'radio' stations.

    I use a AS Dax Decade as my dac. I currently use the coax input, and therefore am considering using optical for the interconnect between the Sky+ box and the Dax.

    I have my HIFi kit, including AS Dax Decade, in South East (SE) corner of 15ft x 15 ft living room, driving speakers on either side of fireplace on South wall. TV and other AV stuff, and thus the Sky+ box, are in North West (NW) corner.

    using our friend Pythagoras, the shortest straight-line distance is 7m, longer if I go around the room, turning corners.

    Questions:
    a) is the length OK for optical?
    b) how sharp can I turn corners with optical?
    c) what quality optical interconnect is suitable for the task?
    d) any makes to recommend?
     
    ditton, Jan 21, 2004
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  4. michaelab

    michaelab desafinado

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    My cheapo IXOS optical cable is as flexible as any cable I know so I don't think the going around corners thing will be a problem. I think that 7m won't work though for a normal plastic TOSLink cable. Probably need a higher quality (and much more expensive) glass one for that. You can get optical signal repeaters to boost the signal along the way but then who knows what they do to the sound...

    Michael.
     
    michaelab, Jan 21, 2004
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  5. michaelab

    michaelab desafinado

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    Cheers timpy - I was considering a sink or similar for the Teac but didn't think the difference would be worth it. Now you've definitely put me off getting one without being able to try it in advance :)

    Michael.
     
    michaelab, Jan 21, 2004
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  6. michaelab

    stebbo

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    Wouldnt the down side of going to glass be a massive reduction in flexibilty?
     
    stebbo, Jan 21, 2004
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  7. michaelab

    wadia-miester Mighty Rearranger

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    Stuart, the Glass AT&T is very flexible, I use the very one in my own clock link configuration, thee are even grades of Glass optic too (ornage anyone) :D , but the maths state a min lenght od 3m (2.999999) due to the speed of light theroy
    Interstingly Mike, on your never has my dac 64 been hard :D (but you admitted it yesterday which was nice)spat, I believe you tried one of these before and started a thread on it, and had negitive results, maybe the toslink, may sheild the signal from that nasty smps interference :eek: I'll give this a try on sat, I can also mod a glass optic to take a toslink connector see what cook against a decent digi lead, interesting thoughts though. T.
     
    wadia-miester, Jan 21, 2004
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  8. michaelab

    Sauerkraut Do I or Don't I? I did!!!

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    Ditton,
    I do the same as you SKY+ to DAC (or AV amp dpending) and use a 5m optical toslink cable. And the benefits are fantastic. The higher bitrate broadcasts are far better quality then DAB and you get a lot more stations. The cable I use is not an expensive one at all (£7.99 i think) and suprisingly well made for the price! It also has to squeeze round corners and does so with no problems. I got it form here.
    Toslink cable
    so for under a £10 your not losing much if its no good for you.

    Best of luck with it.
     
    Sauerkraut, Jan 21, 2004
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  9. michaelab

    michaelab desafinado

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    Tone - did try the optical before and didn't like it but ISTR it was only in conjunction with the upsampler. TBH though the difference wasn't huge either way.

    However, yesterday it was night and day, the optical link was clearly superior.

    As for sheilding anything from any alleged interference from the SMPS of the DAC the only thing that would be sheilded is the transport as the amp is still connected electrically to the DAC ;) The benefit of using optical is to sheild the DAC from any noise coming from the transport :p

    In my system the T1 is clearly generating some kind of HF switching noise because if I have it connected electrically to the DAC and turn the volume to max I can hear it (this is with the DAC switched off). This happens even if the T1 is switched off, just with the power cord attached. That points to either the NC power supply or the Clock4 generating the noise as they are always powered up.

    If I try the converse - T1 unpowered but DAC switched on and turn the volume right up there is nothing but deadly silence. No (audible) noise coming from the DAC's SM PSU there :MILD:

    Incidentally, it's reasonably well accepted that TOSlink is more jitter prone and so therefore generally a worse connection to use. Only on DACs like the DAC64 which have almost 100% jitter rejection is there a benefit to using it as it eliminates the electrical link (which can carry noise).

    Michael.
     
    michaelab, Jan 21, 2004
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  10. michaelab

    lowrider Live music is surround

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    Michael,

    Maybe it is the NAD that causes the extra RFI... :rolleyes:
     
    lowrider, Jan 21, 2004
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  11. michaelab

    michaelab desafinado

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    António, you should read what I posted ;) The improvement of the optical cable was whether we were using the NAD or the Arcam amp. In any case, how could the digital cable affect how the amp was working? :rolleyes:

    Michael.
     
    michaelab, Jan 21, 2004
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  12. michaelab

    MartinC Trainee tea boy

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    Michael,

    Sounds like you've come up with one of the best VFM upgrades in a while there :cool: .

    I think I remember when you first got your DAC64 you talking about trying it with a Discman type CD player, although I can't now remember if you got round to it or not I'm afraid. If you did though that may have been via the upsampler? Just thinking it might now be interesting to see how such a player worked with a straight optical connection? (Should you then end up with a spare TEAC I could probably find room for it... :D ).
     
    MartinC, Jan 21, 2004
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  13. michaelab

    merlin

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    Michael

    Maybe it's just your imagination! Or if it's really better, that's £355 you can put towards a really killer amp/preamp combo;)
     
    merlin, Jan 21, 2004
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  14. michaelab

    michaelab desafinado

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    Martin - I sold my Discman on eBay a while back. Even if it had been good a Discman make a crap transport just from a usability point of view.

    Merlin - this time it definitely wasn't my imagination, the changes were quite clear even from just listening to the first 5 seconds of a track. One of the least subtle changes I've heard.

    I haven't got all the money I "saved" back though. I've sold the upsampler and one of my digi cables but keeping the Apogee RCA as a spare. Also, I didn't sell the stuff for the same price I bought it for ;)

    Amp upgrade is still happening but it's going to be an integrated :MILD:

    Michael.
     
    michaelab, Jan 21, 2004
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  15. michaelab

    wadia-miester Mighty Rearranger

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    Mike,Very odd :D you got to be doing a wolfgang mate :rolleyes: I mean the digi signal does a dance from digi<>light source<>reciever<>digital again, one of the worse methods of digi signal transmission going, bags of reflection, we even did a test rig for a company needing to measure toslink style cables.
    Now the glass AT&T is a different ball game, a lot of companies use the use only to return the 'syn signal' to slave the transport clock, my only theroy at this time is one of some form of interference rejection, that is present in the toslink curcuit that isn't in the SPDIF/AES, or the transport, have you tried a different one?, as all the dacs we've tried with toslink are sonicaly inferior that if we use a 'cable' (same transport, the wadia could output all 4 at once). T.
     
    Last edited by a moderator: Jan 21, 2004
    wadia-miester, Jan 21, 2004
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  16. michaelab

    MartinC Trainee tea boy

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    Ah yes, I remember you selling it now... I agree it wouldn't really be practical but could be interesting. The comments by yourself and other DAC64 owners about transport and cable effects had made me think that Chord's claimed effective jitter ilimination may not have been all it was cracked up to be. If these differences were really down to differences in electrical intereference, as I think I remember Rob Watts claiming, that would be interesting. Meaning in principle a very good CD player could be formed from a DAC64 and a cheap, yet practical, transport.
     
    MartinC, Jan 21, 2004
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  17. michaelab

    michaelab desafinado

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    WM, haven't tried a different transport. Only other one I have would be my DVD player and that's a non-starter.

    Whatever the problems of TOSLink may be, they'll only cause jitter issues to which the DAC64 is immune so there's no issue ;)

    Michael.
     
    michaelab, Jan 21, 2004
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  18. michaelab

    michaelab desafinado

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    The more I think about it the more I agree with you and the more I wonder how Chord can justify £4200 for their transport :rolleyes:

    Michael.
     
    michaelab, Jan 21, 2004
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  19. michaelab

    timpy Snake Oil free!!!

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    Ermmm....! oh well....... :SLEEP:

    Cheers
     
    timpy, Jan 21, 2004
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  20. michaelab

    lowrider Live music is surround

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    I did read your post, in fact I read both your threads, and that leads me to believe the conditions are not equal, maybe your ears changed... :rolleyes:

    So my shot at the NAD beeing close by, maybe even connected, what else did you change... :confused:
     
    lowrider, Jan 21, 2004
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