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Chord Mojo DAC-amp ☆★►FAQ in 3rd post!◄★☆

Discussion in 'Portable Source Gear' started by Mython, Oct 14, 2015.
  1. Delayeed
    Ugh 3 weeks and still no email response to clarification I needed. I guess that was that.
     
  2. Mython Contributor
     
    Anything I/we can help you with, or was it an ETA?
     
  3. Delayeed
    Unfortunately not I'm afraid, thanks! "Luckily" back to school so a cable upgrade is not 1st priority. [​IMG]
     
  4. Bricki
    Yeah I am definitely not suggesting that there's something wrong with mojo[​IMG]. IMO the only dac that would be a significant upgrade would be DAVE. 
     
    I understand that the output from my CD player is gonna have better timed data than my computer (ie. worse jitter)....but other than that what differences could there be?
     
    I probably need to ask Rob directly[​IMG]
     
  5. Set845

    Yeah I use my Oppo as a transport to the Mojo. The Mojo is just so much better. I never would have thought that my portable DAC would be better than my home rig. Crazy. So now I happily use the Mojo as both. Thank you, John and Rob!
     
  6. Delayeed
    Curious about what's your home rig? [​IMG]
     
  7. Deftone
     
    Same thing happened to me brother
     
  8. Set845

    Oppo BDP-105D, Dared 845 tube amp, Paradigm Studio Monitor 20 speakers and sub, and a Mac Mini. For portable iPhone 6, Mojo, and Etymotic ER4S iem. I also have an old Xin Supermini III headphone amp that I don't use anymore.

    Edit: I also have a Dragonfly Red that's not in the same league as the Mojo but I use it for walks.
     
  9. TheTrace
    Thank you much for the information.
     
  10. Rob Watts
    Mojo actually upsamples and filters everything to 2048 FS (eventually getting to 104 MHz) and it does this in two stages. Firstly upsamples to 16 FS via the WTA filter, then there is a second filter that then takes you to 2048 FS.
     
    Its the upsampling to 16FS where the clever stuff happens - that's where the 44 dsp cores are used - and this process is orders of magnitude more advanced than what a PC can do. So what we are talking here is not the need to upsample, but how well that upsampling is done. So if you want the best sound quality, let Mojo have the original file and let it do the upsampling.
     
    To take your video example when you are upscaling to 1080p from 720p. Would you prefer to have it done crudely and very simply, or done with the best video processing possible?
     
    Rob
     
    Chord Electronics Stay updated on Chord Electronics at their sponsor page on Head-Fi.
     
    https://www.facebook.com/chordelectronics https://twitter.com/chordaudio http://www.chordelectronics.co.uk/
  11. cvbcbcmv
    Oh boy,

    I was getting out of my car today after a nice long listen with my Mojo and it fell out of my hands and onto the ground :frowning2:. I can hear something rattling around. It powers on, but I'm afraid to test it. Obviously if something is rattling, something is wrong. I emailed Moon Audio and Chord, anyone else have any ideas? So upset this happened
     
  12. Rob Watts
    I think you are worrying too much - I have dropped my Mojo lots of times, and its fine. The rattling is on new units too, its just the optical flap rattling...
     
    Modern surface mount tech is very reliable to extreme acceleration or G - it was originally invented to go into missiles to survive 100's of G.
     
    Rob
     
    Chord Electronics Stay updated on Chord Electronics at their sponsor page on Head-Fi.
     
    https://www.facebook.com/chordelectronics https://twitter.com/chordaudio http://www.chordelectronics.co.uk/
    Peter Hyatt and tomwoo like this.
  13. cvbcbcmv

    Thank you for the insight! I don't know though, this might be something different. The ratting is definitely not the optical door and wasn't present before. It's like something is loose inside. I can hear it moving from one side of the device to the other as I move it, like the old miniature marble maze toys.
     
  14. rkt31
    every time I start an evening walk with mojo, the first note itself prompts me to wonder , is there any dac on earth which can better mojo ? when I listen to hugo, hugo seems to be better than mojo in some areas. so ultimately it comes to Dave which definitely is better than both. it means no other brands can beat the chord dacs for the same price. I am so happy with mojo. I would suggest people to buy mojo both for portable and home use. in speaker set up there may be few issues due to small size of mojo but those can also be overcome with simple tricks. there are some high quality 3.5mm stereo to RCA adapter by audioquest and other brands.
     
    bixby and Peter Hyatt like this.
  15. Rob Watts
    There are two problems that USB has against toslink - and one benefit. The benefit is that timing comes from Mojo - but with toslink the incoming data has to be re-timed via the digital phase lock loop (DPLL) and this is not quite as good - but you will only hear the difference via a careful AB test, so it's in practice insignificant.
     
    The downside with USB is the common ground connection. This will mean RF noise will get into Mojo, making noise floor modulation worse. Now I go to very careful lengths to remove this problem by using lots of RF filtering, and double ground planes on the PCB, but even minute amounts of RF is significant. The other problem is down to the way that digital code works - which is in twos complement. So zero is in 24 bits binary is 0000_0000_0000_0000_0000_0000. If the signal goes slightly positive then we get just one bit changing to: 0000_0000_0000_0000_0000_0001. But if it goes 1 bit negative all the bits change to:  1111_1111_1111_1111_1111_1111. Now the problem with this is that when a bit changes, more power is needed, and this injects current into the ground of the PC - and the ground will get noisier. Unfortunately the noise is worst for small signals. Now the problem with this is that it then couples through to Mojo's ground plane, and the distorted signal currents will add or subtract to small signals - thus changing the small signal linearity. This in turn degrades the ability of the brain to re-create depth information, and so we hear it in terms of depth being flattened. What is really weird about depth perception is that there seems to be no limit to how accurate it needs to be, so the smallest error is significant.
     
    So with toslink we do not get these problems as there is no common ground - so no RF noise, no distorted signals on the ground, and it will sound smoother with better depth against a noisy PC. But the problem can be almost eliminated by using a power efficient USB source that is battery powered - such as a mobile phone. But with noisy PC's the only way of solving it is to use galvanic isolation on the USB - but this draws power from the source, and we can't do that with mobile devices. All of Chord's desktop DAC's have galvanic isolation on the USB, and then you can't hear whether its a noisy PC or a mobile phone. In this case, USB sounds slightly better than optical, because we have the (tiny) timing benefits of USB.
     
    I hope that explains - its a complex subject.
     
    Rob
     
    Chord Electronics Stay updated on Chord Electronics at their sponsor page on Head-Fi.
     
    https://www.facebook.com/chordelectronics https://twitter.com/chordaudio http://www.chordelectronics.co.uk/

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