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

Discussion in 'Portable Source Gear' started by Mython, Oct 14, 2015.
  1. Music Alchemist
    I guess it's a preference thing. For me it's a little too full-bodied already. (What sounds accurate to me is that green line in the measurements I linked to.)
    Deftone and sarang-i like this.
  2. vaibhavp

    best thing about mojo is refined enjoyable sound. i miss it when i take it out of my system. like my tube amp.

    fiio x5 sounds like warm and lacking in transparancy in comparison stand alone. however in usb dac mode it steps its game up and is very transparent. i found in usb dac mode, x5 e12 had similar detail for driving hd700. however still switching back and forth between mojo and fiio rig, that sense of something missing remains.

    i chalk this to Rob's engineering. since he has better control over how his gear sound. it sounds refined and rich almost like a tube amp.
  3. Rob Watts
    My listening test revealed no SQ change at all - so long as the data is arriving is still bit perfect. But with optical when it fails, it is fairly easy to spot bit failures. Of course, YMMV, and I guess if it's about to fail, you would hear an improvement with the odd bit error improvement. But I have not been able to hear a difference in my setup using plastic or glass.
    Why would that be? Optical actually does not have bad jitter performance; but what it does do is have uneven rise and fall times. But my digital SPDIF receiver actually measures uneven rise and fall times, then uses that measurement to compensate to extract the data correctly. And as regards jitter - the DPLL completely removes jitter from the incoming stream - I can add 2uS worth of jitter, and see absolutely nothing coming out from Mojo with measurements - and Mojo's FFT noise floor is at -170 dB. So optical typically has 2nS of jitter, so that is a thousand times lower than a level that is still not detectable, even when I can resolve -170 dB.... So there is no technical explanation why it would make a difference. So if you do hear a difference, it is either because it is not bit perfect and has data errors (almost impossible with 44.1 though), or your suffering from a placebo (it looks nicer/costs more/must be better). 
    Getting to your last point - the DAC has a big impact on this; most DAC's are very sensitive to jitter as they use analogue PLL techniques and they can't eliminate the jitter problems. So optical cables may have a SQ difference with other DAC's.
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    Arnav Agharwal likes this.
  4. baritone
    Any one has the Ultrasone ed8 with the Mojo ?
  5. WCDchee

    Is there a reason that different transports sound clearly different though, and more so on the mojo than on the Hugo? Not comparing between different inputs. The AK380 sounds clearly better to my ears than the AK100 does as as a transport. Among coaxial players the soundaware Esther m1pro sounds much better than most of the competition, and when the digital coaxial mode is activated and the amp and dac section are switched off it sounds even better.

    Any possible thoughts on the reason for this? :)
  6. sebbie2

    Yes, I read faq.
    My problem with stuttering is not only with idevices (iphone or ipad),
    i tried macbook and mac mini and even android device using official chord cable from Mojo pack
    and problem is always with dsd128 & dsd256, dsd64 or any PCM even dxd 384khz works fine.
    mojo cable accessory pack has a lot cables and i tried all of them
  7. Rob Watts
    For electrical inputs - transports can make an audible difference for couple of reasons. RF noise from the source injected into the DAC ground plane will cause increased noise floor modulation; and the ear/brain is sensitive to minute levels of noise flloor modulation, so this is important - it will make it sound brighter with more noise floor modulation, and warmer and smoother with less. Additionally, depth and detail resolution is can be degraded by very tiny signal related but distorted currents; and this will subtly change small signal fundamental linearity (this is where small signals amplitude varies with signal level) and the ear/brain is incredibly sensitive to this; the smallest possible change in small signal resolution or accuracy will degrade the perception of depth. So very tiny distorted signal related currents will damage depth perception.
    This is why optical is good; it does not suffer from any of these problems, as it is perfectly galvanically isolated.
    And it explains why ASIO sounds better than WASAPI as less processor activity so less noise and hence better sound - so anything that you do with an electrical connection that reduces RF noise such as less processor activity or less power consumption may have a small benefit.
    I have not noticed that Mojo is more sensitive than Hugo; if anything I would guess at maybe the other way around!
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    Deftone likes this.
  8. WCDchee

    How about with regards to say the ak100 vs the AK380? Both use optical but yet sound quite vastly different to my ears as transports. Any thoughts on possible reasons?
  9. Rob Watts
    Assuming that the AK100 and AK380 are both bit perfect outputs and you are listening via Mojo on optical then no reason comes to mind.
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    Peter Hyatt likes this.
  10. sebbie2
    Yesterday I found something strange.
    I read Rob's posts about using optical connection and I connected my mojo to MAC MINI (2011model) using optical cable (cable from Mojo Cable Pack)
    Big surprise - sound was very noticeably different. Tight bass and sound in general more "clear" and separated.
    Ok - it looks like difference - between USB and optical, but..
    I connected mojo to Macbook Pro Retina (2014 model) via Optic Cable and here is surprise - Sound was more like USB connection to mac mini.
    So it's weird - Optic connection is noticeably different between Mac Mini and Macbook Pro (both same settings, same player (audirvana plus) and same cable.
    I found only one difference between optical port in Mac Mini and Macbook Pro Retina - macbook can output 192khz, but mac mini only 96khz.
  11. Music Alchemist
    That reminds me about a question I had relating to timing accuracy. You have gone to great lengths to improve the timing, and it is clearly audible in a way that I feel no one would be able to miss. What "spec" does this correspond to? Is it just jitter, or is it something else? One of the reasons I ask is because I often see people claim that jitter is inaudible in modern audio equipment.
    Did you try storing everything in virtual RAM drives? As I mentioned, that's the only thing that fixed the stuttering for me.
    See, this is why I want to try the optical connection: just to see if it will sound different.
  12. Tom Blake
    Based on Rob's comments I also tried the optical digital out on my PC (ASUS Maximus Formula VIII mobo) instead of the USB connection. I hadn't even thought of using the PC's optical out instead of USB. So far I marginally prefer the optical out when testing with Tidal Masters streaming at 24/96. Sounds a bit smoother and with a touch more detail retrieval. Will keep testing but so far so good with the optical out!
  13. NNewman
    This week I have recrived my HD800 and had an evening paired them with mojo. Classical, jazz and Bon Jovi. Not the best combo I have heard. May be stock cable is the point. Adding an A2P TUR06 amp have chanched the situation dramaticaly. Unfortunately, my dream to get back to PORTABLE setup has gone. Tur06 is in any case a TRANSPIRTABLE variant. I have bought HD800 to replace my AKG K340 on the "go"...
  14. JaZZ Contributor
    Two words: equalizing and damping modification. An additional amp just acts as an effect device, mainly by adding harmonic distortion and reducing transparency and accuracy in favor of warmth and euphonic coloration. For the record: You can't bypass the Mojo's «amp» section, it remains in the signal path.
  15. MartynB85
    There is no amp section. The DAC drives the HP.

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