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

Discussion in 'Portable Source Gear' started by Mython, Oct 14, 2015.
  1. GreenBow
    Post 20530 I explained why. Frankly you have been nothing but cold or off, to me since I disagreed with you only once. It was over the Mojo missing the first second of music. You were defending the Mojo method and I said there is another option. The Meridan Explorer which pauses music playback (for about a second) until it synchronises hardware: other DACs do that too.
    You come back at me over something else I posted again. Saying AND this AND that, AND the other, yet in my 20530 there a whacking great heatsink applied. Plus full explanation of why I am saying what I said.
    Yet only two nights before I had to stop chatting back and forth because I was sick of having to re-post. To say what I had already said, then said so the next day. However for your benefit RELIC, here it is AGAIN!
    From post 20530: Therefor the heatsink could very well be needed for desktop work, especially in hot climates.
    (I was discussing heat and hoping there was a cooler battery solution. What happens when the battery gets worn was my other concern. Given we just had a mini heatwave in the UK of 35'C. Mojo would struggle to stay on as a desktop DAC if it was charging and playing all the time.)
    To be honest the general attitude to anyone who questions the Mojo in this thread is appalling. Yet it is always said, "Do not be afraid to ask". .......Why should we be afraid then. ..........Not pointing the finger at anyone but stop being princesses to anyone who asks. Maybe it's justified with some trollers if that's what they are doing. However me, I love the Mojo too.
    There is nothing wrong with modding, trying, asking, thinking out loud, if you have the spec and try safely. I would be extremely careful, and if I had any doubt I simply would not do. 
    Personally my Mojo is as perfect as it can be. I got lucky. It seems happy to charge and play at 25'C and under, but I have not tried it in hotter weather. It doesn't whine. ...However I do worry about the future. If the battery wears and will it mean it is stuck in permanent charge while playing, in desktop mode. (Said in 20530.) However I still have my eggs in the Chord basket the battery is bullet-proof.
    While I concede the Mojo is not designed as a desktop DAC many of use it as such. My Mojo has never left my home where other folks show us beautiful photos of luscious stacks for portable use.
    However I have been wanting to address my questions to Chord for a good while. Yet never did because I knew this overall general attitude would be the result. I have had other ideas, but really do you think I should ask here now; anyone?...What a waste; non-shared ideas.
    @Torq Which uses more power to drive? Low or high impedance headphones.
    I think current flows more freely in in low impedance. Yes I am concerned about another battery's current capacity. However it's also P=VI and it's power that matters too. Higher impedance headphone will drain the battery faster right at the same volume. (It's speed of discharge that causes heat.) See I have thought through my ideas and don't need to explain them. I just need the specs. Right!
  2. audi0nick128
    Hey Arpiben,

    Same here, I couldn't find an USB 1 source myself.
    Otherwise I would have tried it myself...maybe I will test it with an aged single board computer.
    So anywaye enjoy the rest of your free time :wink:

  3. x RELIC x Contributor
    GreenBow, sorry you feel that way. I'm not trying to be dismissive of you in particular and find that you've been helpful in the thread and I appreciate your posts.

    With regard to the battery, no, I don't think you'll find a better solution than the one Chord has come up with. If you wish to try that's entirely up to you. I wish you luck. However, the heat isn't just generated from the battery, but also from the FPGA chip and pulse array DAC, and the output stage. IMO you won't be making much of a dent in the heat generation by changing out the battery, but you will be changing the source of the Mojo's power, and may be risking thermal issues with a battery not meant to tolerate the heat within the case. I simply feel that trying a different battery is a fools errand to making the Mojo run cooler in hot climates.

    IMO, a better solution would be to run the device on its side (as has been recommended already), or manage the charging/listening time better so it isn't charging constantly when running. Shoot, even the giant heat sink is a better idea in my opinion over trying to change out the battery yourself, especially since Chord has mentioned time and again that this is not a typical battery in the Mojo. Who is to say another battery won't melt and explode... But hey, IMO, YMMV, Just my perspective man. We can disagree you know. :wink:
  4. SearchOfSub
    How is Mojo with HD800?
  5. Torq

    You THINK current flows more freely at lower impedance, or you KNOW it does?

    Speed of discharge is a function of current, not voltage. The battery supplies a, for our purposes, constant voltage. And you cannot say that a higher impedance headphone will use more power for the same volume without factoring in the efficiency of the transducer.

    Per Mojo's designer, earlier in this thread, you will generally get shorter battery life using lower impedance headphones.

    When you (colloquial) can't explain an idea, it is usually because you don't understand the mechanics of that idea fully enough to do so. And "thinking something through" when you lack a proper understanding of the subject matter is unlikely to yield a correct or satisfactory result. Without that understanding you simply don't have the basis to even know what has to be considered TO "think it through". Neither of those statements are conducive to effective science or engineering.

    None of this changes the fact that it is not the battery that makes Mojo run hot, nor are there "cooler running batteries". And I'm not defending Mojo, or Chord (I have my own issues with Chord as a company) - I'm simply pointing out the realities of thermal design as they relate to battery powered electronics and gated by the laws of physics.

    As for what happens when the battery loses capacity/ages, ignoring for a moment the estimated 10 year life for the particular technology/chemistry involved, Chord have already said that battery replacements would be available.

    I'll leave you to it, though ... it's pointless trying to assist someone that would rather be right than learn why their question or supposition is misplaced or incorrect.
  6. miketlse
    Just search this thread using the keyword HD800, and 538 posts are identified for you to read.
  7. miketlse
  8. Traveller
    FWIW, I measured an increase of 11C over ambient when in use and 8C (over amb.) when charging. I tested using an IR temp. gauge (gun).
    I would venture to say my LG G4's battery gets hotter than Mojo's during the first 50% charging period as it is designed as a "Quick-Charge" solution. Mojo on the other hand has a normal charging policy (as I pictured a few posts back):
    I tried to search for that but had no success; do you recall where the post was or can you perhaps explain why this is so? "Layman's sense*" would suggest the opposite...
    *and before you ask, I know squat about electronics [​IMG]
  9. miketlse
    In this post Rob Watts says that higher impedence loads will use less power from Mojo.
  10. Mython Contributor
    It's been a 'heated' topic, this past few hours, so, in spite of reservations, I've decided to make available the instructions for those of you who feel Mojos battery needs changing (please note: some double-sided sticky tape may prove helpful, if you decide to do this, and it will invalidate your Chord warranty!):
    blueninjasix likes this.
  11. Nitrile
    Just did some experimenting on a Mac with Bootcamp.
    This is on the same machine, the variable being different operating systems only.
    Spotify 44.1 KHz in Windows (USB) through Directsound -> Occasional and noticeable clicks
    Spotify 44.1 KHz in OS X (USB)  -> Pristine sound, zero clicks
    Through optical, sound is pristine on both operating systems.
    Switching to ASIO on Windows also gives a pristine sound. Upsampling to anything higher that 44.1 KHz in Windows sound settings also produces a clean sound.
    Looks like there's something going on with Windows Directsound drivers for the Mojo.
    The Mac is not mine so I have switched to using Optical on my main Windows machine for now. My listening is almost exclusively Redbook anyways.  
  12. SearchOfSub
    But there's no clicks on Mojo with optical on both OS. And we all know optical the power is isolated from MB.

    If your a gamer you would know when a frame stutters or skips when gaming. I think pretty much same concept but with video it's video frame skipping/stuttering and audio with clicks and pops. Reinstalling windows fixed that for me.
  13. Mython Contributor
    Windows allows so much unnecessary hijacking of resources, by every man and his dog, that it's not surprising some people eventually find they are getting intconsistent performance with some devices.
    There was some discussion about that in the following thread, which at a massive 2 pages long, is worth a quick read, before taking the huge step of reinstalling windows:
  14. Traveller
    ...and there is no difference between an Amp and Headphones?
    "Driving" means what it means but as I'm no expert, I don't want to jump to conclusions... [​IMG] 
  15. Arpiben
    Rob wrote in that post:
    The power consumed by the FPGA is 475 mW - less than a third of the power used in total. Using DSD should actually be slightly lower power, as most of the WTA DSP cores are not being used.
    As usual it is correct, for those still doubting hereunder an abstract of Xilinx Artix (FPGA) power data excel sheet:
    Traveller likes this.

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