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

Discussion in 'Portable Source Gear' started by Mython, Oct 14, 2015.
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  1. salla45
    yeah, that was interesting. Also suggested that there would be a sort of modular series of attachments to come in future. Pretty exciting. Transport maybe? Explains also somewhat the chunky basic shape, allowing for longer overall aspect with addons.
     
  2. h1f1add1cted
    Thanks for your reply I know, with multiple driver IEM we can have really different impedance curve which needs a source with below 1 ohms output impedance for a ruler flat frequency. But the Mojo is pretty much below 1 ohms, with 0.075 ohms, this is the only big question mark I have. The same 8 driver IEM, with different dac/amp with 0.5 ohms (which is good, but the Mojo is better!) has a ruler flat frequency compared to the Mojo which has this slight treble roll off, this can't be from the ultra low output impedance from the Mojo. The reason is someting other. 0.075 ohms wins versus 0.5 ohms but in this case not, now the question is why. I don't have a problem with this, I would never use any other dac/amp for my IEMs / CIEMs in terms of SQ the Mojo wins over all devices I know, but a detailed answer would be nice.
     
  3. Currawong Contributor
     
    I'd have to find it, but Rob Watts posted that it had something to do with his very simple output stage.
     
  4. OK-Guy
     
    the DAC & Amp in the Mojo are one of the same (same as Hugo), there is no separate Amp section, hth. 
     
  5. h1f1add1cted

    I use this short (DIY) USB OTG cables for the Mojo and my Android devices:
     
    zwischenablage02_586405.jpg
     
    You an buy this kind of cable from i.e. FiiO: http://www.aliexpress.com/store/product/FiiO-OTG-cable/1473108_32240751500.html no need for generic bulky USB OTG cables.
     
  6. sandalaudio
     
    Sorry. I should re-word it as the "current buffer stage" on the Mojo then.
     
    Don't get me wrong. Mojo sounds amazing.
     
  7. OK-Guy
     
    I keep seeing that the Mojo sounds amazing, lots of happy Customers by the looks.
     
    Unfortunately I don't do 'technical' that's above my pay-grade, I just roll-out old answers that I've been advised on previously, hth... [​IMG] 
     
  8. headwhacker
     
    I don't use IEMS much as I used to and don't really perceive the treble roll-off in Mojo with my cans. I really love how the Mojo sounds with my cans. Nevertheless,  I'm also interested to know what is causing the roll off even if it's small and difficult to perceive. Thanks for sharing your findings.
     
  9. mjdutton
    I have been trying a number of headphones over the last week and did notice a change in the high frequency that might be caused by the roll off that you mentioned.  I'm very happy with the sound, but am some what confused when Mr Watts say there is a roll off with low impedance headphone by design, and JF is adamant that it is totally flat.  They both need to sing off the same hymn sheet and perhaps a mention in the user guide would be useful.  It does mean that HiFi Worlds measurements (Frequency response (-1dB)   4Hz-31kHz) are incorrect without a qualifying statement.
     
  10. JaZZ Contributor
     
    Well, that now is a contradiction to Sandalaudio's Measurements.
     
    Quote:
     
    Yes, multi-driver IEMs usually have acoustic low-pass filters, which means several drivers running in parallel at high frequencies electrically, making for an impedance drop. But according to your measurements the modded Etymotic ER-4 rated 14 ohms should have lead to a high-frequeny drop off (despite the impedance rise reaching 75 ohms at 20 kHz with the original P), which isn't the case with h1f1add1cted's curves.
     
     
    Maybe; but –0.7 dB at 12 kHz is audible. – That's not to say the Mojo's headphone out is bad, though.
     
  11. JaZZ Contributor
     
    Yet they don't sound the same. I'd like to know if the Hugo has the same measurable drop-off at low impedances, but it definitely sounds more extended.
     
  12. x RELIC x Contributor

    Rob has said he purposefully smoothed the Mojo's output SQ compared to the Hugo given the Mojo's intended portable use.
     
  13. TomGi
    Until now, I listen mainly the Mojo on amplified monitor speakers (as for my Hugo).
     
    And why ? Because Mojo (and consequently Hugo) is for my taste amongst the best DAC I listen (Benchmark, Dangerous Music, Mytek, RME, Bel Canto).
     
    I use it as converter/monitor (digital) volume control plugged directly on the amplified monitors.
     
    The input impedance of monitor speakers is often close to a constant value of 10kOhm.
     
    I measured the impulse response (left and right analog outputs are identical: green curve) of the Mojo with a load impedance of about 4kOms (the microphone's impedance of the input of my sound card) and for this use, it is perfect for different tested settings of the volume.
     
     
    MojosIR.jpg
    Mojo.jpg
     
  14. OK-Guy
    ^ what he said ^... I can't improve on Relic's post.
     
    x RELIC x likes this.
  15. JaZZ Contributor
     
    True, I remember that. Now how is this done? On other occasions it was stated both ouput stages be identical. I just wonder how (and if) the Mojo's audible drop-off compared to the Hugo can be measured. BTW, I also have to apply a 0.2 dB decrease between 100 and 300 Hz to make it sound more similar to the Hugo, beside the treble increase.
     
    But don't get me wrong: I like the Sound of the Mojo nonetheless.
     
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