1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.

    Dismiss Notice

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

Discussion in 'Portable Source Gear' started by Mython, Oct 14, 2015.
First
 
Back
747 748 749 750 751 752 753 754 755 756
758 759 760 761 762 763 764 765 766 767
Next
 
Last
  1. Ra97oR
    I have zero problems running my Mojo as desktop dac with a Anker Powerport5 powering it.

    With the Apple universal charger, sometimes it doesn't charge until you unplug the cable and plug it back in again. I had my Mojo ran dry with charge lead in due to that. Most likely the charger's issue but you can work around it by checking if the charge light is on white whenever you power it on. If the light is not white, you can always unplug it and plug it in again.

    Or in my case, using a different charger.
     
  2. Rob Watts
     
     
    I often think about this issue as yin-yang (dark-bright), and a good product has this in balance - but what the correct balance is does depend somewhat on taste!
     
    So yin - dark - is in technical terms, happens with zero noise floor modulation. Conventional DAC's have enormous levels of noise floor modulation. This means noise (bright hiss) pumps up and down with the music signal, and the brain can't separate a dark sounding instrument from the noise floor modulation - so smooth sounding instruments become bright. With Chord DAC's, including Mojo, there is no measurable noise floor modulation, so it innately sounds smooth and warm.
     
    But its possible to artificially give the appearance of more yin by contouring the sound. For example, add a lot of second harmonic distortion, and it sounds thicker and darker - but its an illusion, as everything sounds soft. You can also add LF errors too, to give the impression of more weight to the sound - adding electrolytic caps, or letting the ref circuitry amplitude modulate the output from the signal envelope. Indeed, a lot of designers rely on this, as they do not have the abilities (stuck with using chip DAC's) to solve noise floor modulation, so have to use tricks to balance the sound.
     
    On the yang side, natural brightness comes from two sides. First is transparency, and this resolves into detail resolution, and this is about how accurate the DAC/amp can resolve very small signals accurately. With my work on the reference DAC Dave, I discovered that there is no limit to how accurate the small signal needs to be - the smallest possible amplitude error is very audible, particularly in terms of sound-stage depth. Transparency is a complex issue, but comes down to two main issues - simplicity of the analogue section (each component degrades small signal linearity) and the performance of the noise shaper (before anybody says ladder DAC's these are awful for small signal linearity). Now Mojo has an extremely simple output stage - only one active stage and two resistors and two capacitors in the direct signal path, and this is done for transparency. On the noise shaper, it has 1000 times more resolution than conventional noise shapers, as the noise shaper runs at 104 MHz, not the usual 6 MHz of the best chip DAC's.
     
    The second part of yang is timing. Now digital audio is sampled data, but the original signal in the ADC is a continuous signal, and the job of the DAC is to convert the sampled signal into a continuous analogue signal with the timing of the original signal in the ADC perfectly preserved. Now I talk a lot about reconstituting timing, and have had requests to show the problem. So here is a simple illustration of the problem:
     
    Slide3.jpg
     
    Slide4.jpg
     
    Slide5.jpg
     
    Now this is a bit of a simplification - the burst signal is not bandwidth limited, but it serves to illustrate the problem of timing inaccuracies. Now how do these timing errors sound like? When the brain comes across timing errors, it can't deal with it - it can't make sense of the music. And when the brain can't process the signal, you then can't hear the transients. It is a bit like putting a picture out of focus, blurring the edges. What this does audibly is to make transients sound soft, and when one improves timing accuracies then the brain can perceive the starting and stopping of notes accurately - so things sound sharp and fast - more yang. Now what is curious about timing errors, is that there again is almost no limit to how small they need to be - before Dave, I used to think in terms of uS errors, now its definitely nS as being important - extremely small timing errors have a noticeable subjective musical impact. 
     
     
    Also it is very possible to use distortions to give impressions of good sound - use slew related noise floor modulation and you get the impression of good timing resolution - but its entirely false. The problem with using distortions like this, although it can sound superficially impressive - is that everything always sound the same. But the major problem with this approach is simply listening fatigue - I can listen to Mojo for 10 hours and still want more. It also illustrates the design nightmare of listening tests - is the sound quality "improvement" real or just more distortion or aberration? You have to be extremely careful on how one assesses sound quality.  
     
    So too conclude - Mojo can sound both rich and dark (immeasurable noise floor modulation) and very fast and dynamic (much lower timing errors) all at the same time. That's why we get so many different reactions to the sound of Mojo - some saying its rich and smooth, some saying its fast and dynamic - and the truth is both observations are correct.
     
    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/
  3. Rob Watts
    Don't ask, you will set me off on another 1000 word discourse!
     
    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/
    onsionsi, LaMosca, Carl6868 and 2 others like this.
  4. x RELIC x Contributor

    But this is always very informative, and quite frankly I find it extremely enjoyable! :)
     
  5. JimBob85
     
    This could be my issue, I have been running it as normal just powering on with the power button,  I didnt realise you could change it to line out only - this might be the reason it gets too hot and turns off.
     
  6. tkteo
     
    +1
    And this is what I call a wonderful paradox that I experience with well-mastered music of different genres as decoded by Mojo.
     
  7. headmanPL
    I would try another power supply.
    I use my Mojo when working at home from 8am to 6pm. It's powered by a Sony phone charger, the source is either my Z3 or laptop depending on whether I'm listening to Internet radio or music on my SD card. The Mojo sends the music to a Monitor Audio S200 (sounds WAY better than the S200's own DAC) via coax. Volume buttons both cyan (line out overwhelms the cable/S200). The Mojo is always warm, never hot, but it is winter. So far, it has never cut out.
     
  8. bocosb
     
    Will this "listening fatigue free" quality remain after adding a separate headphone amp? I know my Bottlehead Crack in theory adds distorsions but i like the sound (at least with my actual low cost dac)
     
  9. reihead

    Same here, really enjoyable reading
    Amazing how sound can be perceived and the little details that may affect it.
     
  10. Bourne Identity
    Sorry to potentially change the course of the thread, I am enjoying reading a 100 or so pages of this very long thread of + 700 but still remain confused due to my ignorance concerning things of this nature. I am been viewing this part of the forum for 2 plus years and yes this is my first post, I don't normally post on these forums due to my lack of knowledge. 
     
    I am no audiophile but do appreciate music and would like to obtain the Chord Mojo. However, the problem lies with the device that would be best suited to pair it with, I know this can be down to personal choice and is very subjective. [​IMG]
     
    I see little point in paying for a top DAP with an excellent DAC if I am using the Chord Mojo, just my opinion but I could be wrong.
     
    I would like a device that is
     
    1. Capable of 100gb plus, this can be internal or via external SD Cards.
    2. Ability to listen to internet radio via Wi-Fi and then when I want to listen to .flac music then I can plug it into the chord mojo.
    3. Budget will be up to £500 maybe more if justified. (Max £1000)
     
    I have considered the Pioneer new DAP and the IPod (Less so) and since I have a company phone, I can’t justify the cost of buying another phone when I get mine paid for. Albeit they provide us with the smallest on board storage [​IMG] and the company is strict on terms of use.
     
    I currently use a IPod 5.5 Classic 80GB HDD with white IPhone ear buds.[​IMG] I don’t have any IEM yet but will look into this in more detail as I work backwards so to speak.
     
    Any advice would be appreciated as I am new to all this terminology and technology.
     
    Thanks in advance.
     
    Shaun
     
  11. bikutoru

    If I wasn't reading these discourses of yours, I'd never be tempted to try Mojo in the first place. Please do tell!
     
    I'm sure there are quite a few of us who'd like to hear -
     
  12. shuto77

    You're right; pairing something like the Mojo with a top-of-the-line Dap isn't the best way to stretch your audio dollar. This is because neither daps or dac/amp combos generally ever have the power of a desktop system

    Sometimes, thinking outside the box gets you better results.

    I am using a uses Samsung Galaxy S4 as my Android transport. It has a replaceable battery, and can accommodate a 200gb micro SD card.
    I paid about $115 for it on eBay last month.

    If you're married to Apple products you can try to pick up a newish iPod Touch with 128gb memory.


    Either device can work with the Mojo, you just have to consider your priorities and budget.

    So, if everyone is stacking, what are you stacking your Mojo to?
     
  13. Ra97oR
    Your cheapest option is to get a Chinese smartphone that have USB otg and a MicroSD card slot and use it as dap.

    A decent one can be had for £100 odd.
     
  14. shuto77

    Yes, this is a good idea, but not all phones work well in OTG mode.

    My HTC One M8, one of the best phones of 2014, has many issues.

    My Samsung Galaxy S4 works like a charm, every time.

    So, yes, I agree with you about the smartphone, but you have to under how dodgy otg via Android can be.
     
  15. uzi2
    I would also suggest a second hand phone used without sim in aiplane mode as this will cover 1 and 2 well within 3, leaving most of your budget free to put something that sounds good in your ears.
     
First
 
Back
747 748 749 750 751 752 753 754 755 756
758 759 760 761 762 763 764 765 766 767
Next
 
Last

Share This Page