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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. Em2016
    Asking why USB input gets warmer than TOSlink input? There's literally nothing for me to think about... just reach out my hand and feel the difference in heat...

    When I listen to music (like now) my brain activity is ultra low - I'm in cave man mode :o2smile:
     
  2. ZappaMan
    It’s a good question, you have a lot of good questions lol, jk.
     
  3. Em2016
    Ha, cheers.

    If I ask lots of good questions with cave man intelligence, imagine if I had half a brain ! :o2smile:

    Anyway I'm glad you find the questions interesting.

    For those that don't there's always a bunch of other threads to read... https://www.head-fi.org/forums/
     
  4. miketlse
    Just search the thread. Rob has answered the question at least once already.
     
  5. Em2016
    Done the search mate... USB consumes ~0.3W... TOSlink will be lower but can't find ball-park figure for TOSlink... hence the question to @Rob Watts ...

    Thanks for your helpful input though...
     
    Last edited: Aug 22, 2019
  6. miketlse
    Combining information from posts from Rob and John:
    • Listening to music generates 1.7W (The power consumed by the FPGA is 475 mW - less than a third of the power used in total)
    • charging from red generates another 0.91W
    • trickle charging at blue generates another 0.107W
    • The issue is power consumption; adding an extra SPDIF decoder module in the FPGA would add to power loss, and everything about Mojo is power. At the design time, there was no M scaler, so I had no inclination of the transformational possibilities at that time of the M scaler; saving a few mW of power was simply more important. https://www.head-fi.org/threads/hug...-official-thread.885042/page-26#post-14404378

    https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-1429#post-12797997
    https://www.head-fi.org/threads/chord-mojo-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-993#post-12463183
     
    Last edited: Aug 22, 2019
  7. Em2016
    Still no info about optical decoding power consumption vs USB’s ~0.3W ...

    It will be less but how much less. As per my original question, just asking Rob out of general interest.
     
    Last edited: Aug 22, 2019
  8. miketlse
    Deleted
     
    Last edited: Aug 23, 2019
  9. Em2016
    Of course I wouldn’t claim that.

    But it still doesn’t answer my original question to Rob about why USB feels quite a bit warmer thank TOSlink... Maybe it’s something else...

    Maybe it’s more like 1.8W vs 1.6W?

    I can’t guesstimate if that’s enough for the difference I feel. It depends on thermal analysis with this case design doesn’t it...

    Anyway I appreciate your efforts but would ask we leave it to Rob please, as originally intended...

    Otherwise it’s the blind leading the blind and we just clutter the thread.
     
  10. Rob Watts
    The unused inputs are shut-down to save power, so turning on USB adds about 150 mW to the total, or increase total power by about 10% - maybe 1 deg C warmer.
     
    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/
    Em2016 likes this.
  11. Em2016
    Cheers Rob. I've seen you mention the USB decoder consumes 1/3 W of power though, ~0.3W ?

    So is the USB decoder still consuming a tiny little bit of power, even with no USB source connected?
     
  12. Rob Watts
    No the USB decoder is powered down if the USB is not connected; but when USB is on, the SPDIF circuitry and SPDIF decoder (in the FPGA) is off too.
     
    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/
    Em2016 likes this.
  13. Em2016
    Got it. Cheers again!
     
  14. Em2016
    Hi @Rob Watts

    This is probably the best post I could find on Mojo's two modes of normal operation.

    For Mojo on and charging at the same time, 24/7, 365 days a year:

    When you say battery is held at a safe level, is it at 8.200V at all times? Or does it do trickle down cycles, like the other mode of operation you described (Mojo off and charging).

    Or is it safe for the battery to stay at 8.200V 24/7/365 ?

    Cheers
     
  15. Deftone
    Dude, go enjoy some music.
     
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