[franzdom]

I don't have a Mojo yet but I believe it can be powered full time with a laptop/USB cable.

 

[betula]

  I don't have a Mojo yet but I believe it can be powered full time with a laptop/USB cable.

If you mean, if it is ok to have Mojo left on charge 24/7, than the answer is yes.

 

[tretneo]

 
If you mean, if it is ok to have Mojo left on charge 24/7, than the answer is yes.

 
I do, no problems here.

 

[Muataz]

Yes, upsample everything beyond any known number  

 

[Traveller]

... Because my “listening station” consists of me plopping on the couch and playing from my laptop. I’m nowhere near a power outlet (and even if I was, it would be too much of a hassle to drag the cord and plug everything in). That’s why the DFR has been great: I don’t have to plug it into the wall, and I don’t have to remember to charge. My question is: would something like Mojo ever be similar in that it could simply be powered by laptops via USB (so I don't have to plug into the wall and I don't have to worry about the battery level)…or are the performance/hardware/etc demands just so great that the only choices will always be AC adapter or rechargeable battery?

Let's see if I get you; you want a version of Mojo that sounds like Mojo, powers any headphone/IEM/etc. like the Mojo can but is happily powered by the USB-source device (laptop)?
 
So the guys above already stated it is possible to charge and play at the same time. But... the Mojo is like any current Smartphone and will (try to) draw 1amp* from the source. That's necessary to charge Mojo's battery in a reasonable amount of time (6hrs...)*. The DFR on the other hand "consumes" 40mW on average. Not that the Mojo needs much more (35mW for 600ohms, 750mW for 8 ohms), so yeah, Chord Electronics could remove the battery - or offer a "bypass" option (like my Headroom Bithead). However "post three" of this thread for sure discusses the benefits of powering the DAC & co. directly from the battery for much better SQ.
 
I believe the designers had two key goals - "best SQ possible in a portable DAC". AQ on the other hand went for "most portable device with best possible SQ considering".
These are my words based on my assumptions and not quoted from the designers.
 

 
*Charging status assuming you start with the Mojo fully charged and connect both USB ports to a laptop would be closer to the 0.3Amps than the 1amp I stated above. So maybe one could "power" a fully-charged Mojo with a laptop (without obliterating the Laptop's own charge within hours...)
 

 

[miketlse]

  Let's see if I get you; you want a version of Mojo that sounds like Mojo, powers any headphone/IEM/etc. like the Mojo can but is happily powered by the USB-source device (laptop)?
 
So the guys above already stated it is possible to charge and play at the same time. But... the Mojo is like any current Smartphone and will (try to) draw 1amp* from the source. That's necessary to charge Mojo's battery in a reasonable amount of time (6hrs...)*. The DFR on the other hand "consumes" 40mW on average. Not that the Mojo needs much more (35mW for 600ohms, 750mW for 8 ohms), so yeah, Chord Electronics could remove the battery - or offer a "bypass" option (like my Headroom Bithead). However "post three" of this thread for sure discusses the benefits of powering the DAC & co. directly from the battery for much better SQ.
 
I believe the designers had two key goals - "best SQ possible in a portable DAC". AQ on the other hand went for "most portable device with best possible SQ considering".
These are my words based on my assumptions and not quoted from the designers.
 

 
*Charging status assuming you start with the Mojo fully charged and connect both USB ports to a laptop would be closer to the 0.3Amps than the 1amp I stated above. So maybe one could "power" a fully-charged Mojo with a laptop (without obliterating the Laptop's own charge within hours...)
 

 
The mojo has the two USB sockets:
 

• One socket is used for charging using the 5V connector in the USB plug
• the other socket is used solely for the music data signal, and the 5V connector is not used. This has the key benefit of separating the potential power supply 'noise' from the music data signal.

 
The AQ on the other hand, uses the same USB socket to carry both the music data signal, and the 5V power supply. Consequently there is a risk of the music data signal, becoming contaminated with power supply 'noise'.
 
You pays your money, and you makes your choice which of the two options that you prefer.

 

[Traveller]

The mojo has the two USB sockets:

• One socket is used for charging using the 5V connector in the USB plug
• the other socket is used solely for the music data signal, and the 5V connector is not used. This has the key benefit of separating the potential power supply 'noise' from the music data signal.

 
The AQ on the other hand, uses the same USB socket to carry both the music data signal, and the 5V power supply. Consequently there is a risk of the music data signal, becoming contaminated with power supply 'noise'.
 
You pays your money, and you makes your choice which of the two options that you prefer.

That is an awesome point indeed - thank you for making it.

 
But just so it's clear for @brent75 , even though Chord separates the power and audio inputs, the power input is still exclusively used to charge the battery and not to power the DAC. AQ's DFR has no battery and thus powers its DAC directly from the source...
 
 
EDIT: But your point also points out the difference between the Mojo and my bitHead; BitHead has a selectable power source but only one input USB port so pwr and audio signal are sent down the same cable

 

[miketlse]

  That is an awesome point indeed - thank you for making it.

 
But just so it's clear for @brent75 , even though Chord separates the power and audio inputs, the power input is still exclusively used to charge the battery and not to power the DAC. AQ's DFR has no battery and thus powers its DAC directly from the source...
 
 
EDIT: But your point also points out the difference between the Mojo and my bitHead; BitHead has a selectable power source but only one input USB port so pwr and audio signal are sent down the same cable

 
I suspect that most DACs that use ASICs, use the one input USB socket approach, and so the DAC processing becomes more complicated, by the need to try and remove any residual power supply noise.
 
Rob Watts prefers to use the two separate USB sockets, and to prevent the power supply noise being an issue in the first place.
This does have the additional benefit that the Mojo can be charging through one socket, at the same time as decoding/playing a music signal received through the other socket. 

 

[brent75]

Thanks guys. I definitely understand the concept of 2 USB ports -- one for charging/one for music. My point is, I don't WANT to charge while I'm listening to music as I'm nowhere near a wall outlet. Are you suggesting that it's possible to run 2 USB cables from my laptop into the Mojo, so I can charge (or at least maintain charge) and listen at the same time? That might be ugly...but I'm not trying to impress anyone with aesthetics when I'm listening on my couch.

 

[Mojo ideas]

Let's see if I get you; you want a version of Mojo that sounds like Mojo, powers any headphone/IEM/etc. like the Mojo can but is happily powered by the USB-source device (laptop)?

So the guys above already stated it is possible to charge and play at the same time. But... the Mojo is like any current Smartphone and will (try to) draw 1amp* from the source. That's necessary to charge Mojo's battery in a reasonable amount of time (6hrs...)*. The DFR on the other hand "consumes" 40mW on average. Not that the Mojo needs much more (35mW for 600ohms, 750mW for 8 ohms), so yeah, Chord Electronics could remove the battery - or offer a "bypass" option (like my Headroom Bithead). However "post three" of this thread for sure discusses the benefits of powering the DAC & co. directly from the battery for much better SQ.

I believe the designers had two key goals - "best SQ possible in a portable DAC". AQ on the other hand went for "most portable device with best possible SQ considering".
These are my words based on my assumptions and not quoted from the designers.



*Charging status assuming you start with the Mojo fully charged and connect both USB ports to a laptop would be closer to the 0.3Amps than the 1amp I stated above. So maybe one could "power" a fully-charged Mojo with a laptop (without obliterating the Laptop's own charge within hours...)

I think you have not counted for the power consumption of the Mojo's own processing circuitry as we've said Mojo has many times ( hundreds of times) the processing power of other Dacs. There is a cost in power usage for that processing so it would not be possible to remove the battery and still retain a comparable performance to that we currently enjoy.

 

[Mython]

  Thanks guys. I definitely understand the concept of 2 USB ports -- one for charging/one for music. My point is, I don't WANT to charge while I'm listening to music as I'm nowhere near a wall outlet. Are you suggesting that it's possible to run 2 USB cables from my laptop into the Mojo, so I can charge (or at least maintain charge) and listen at the same time? That might be ugly...but I'm not trying to impress anyone with aesthetics when I'm listening on my couch.

 
 
That would depend on the current delivery of your laptops USB ports - if they can't supply 1 amp or more, then Mojo would not draw any charge from the laptop.

 

[Soundizer]

Thanks guys. I definitely understand the concept of 2 USB ports -- one for charging/one for music. My point is, I don't WANT to charge while I'm listening to music as I'm nowhere near a wall outlet. Are you suggesting that it's possible to run 2 USB cables from my laptop into the Mojo, so I can charge (or at least maintain charge) and listen at the same time? That might be ugly...but I'm not trying to impress anyone with aesthetics when I'm listening on my couch.

Yes you can do that which is what i do. Both USB's connected to a Computer, one for charging and the other for Data.

 

[Mython]

From post #3, Battery & Charging section:
 
 
Quote:

Originally Posted by Rob Watts /img/forum/go_quote.gif

 

Hi Rob, and John,


1. If I leave the Mojo plugged in to the wall wart all the time, that should be fine, correct?
2. I presume that any time I want to resume listening in its present setup (meaning listening via the computer and with the charging cable still connected to the wall wart), the Mojo should be "ready to go" and that there is no need for me to ascertain the battery level? 
3. If I then use the Mojo as a portable, and later on connect it back to the computer for listening (with the charging cable then connected to the wall wart again), what would be the minimum color of the battery light? Green?

Thanks once again.

George

1) yes it should be fine
2) overall there is a slight net drain on the battery so starting at blue or green on the battery indicator is a good idea but not mandatory
3) difficult to answer as it depends how long you've been listening whilst mobile but see answer above. Happy listening George!

 
 
John answered 1 and 2 fine, but I thought I would clarify exactly what happens when you charge and listen at the same time.
 
I use a dedicated charging chip for the Li battery, and this has a number of safety features, and works with a number of settings to ensure safety.
 
Now one of the safety circuits is a safety timer, and this is when the charger is in full charge mode. This timer is set to about 8 hours, and normally full charge mode takes 4 hours, when the unit is off. But when the unit is on and playing, there is a risk that the safety timer will be set, as it can take 12 hours to fully charge (from flashing red) and when playing music (for those 12 hours) at the same time. If the safety timer is set, then the battery LED will slowly flash white, and no further charging will take place. To reset the timer, just disconnect the charge USB, wait 10 seconds, and reconnect, and it will recommence charging. So if you are charging and playing, then when you have finished listening, turn Mojo off, and it will be OK. When Mojo is blue, and you connect the charger, then it is trickle charge mode, and the safety charger is not operating. So if Mojo is green, the safety timer won't trip out, as it will play and leave full charge mode within 8 hours, so you will be OK. It should be OK at yellow too. I guess the easiest way of dealing with it is to turn Mojo off after listening, then you will be fine, unless you listen for longer than 8 hours starting from fully flat.
 
Note that you can get the flashing battery LED if the USB charger voltage is low, from a charger that can't supply the current, or a USB cable that has high resistance. But you will see this pretty early on.
 
I hope this clarifies.
 
Rob

 

[brent75]

Not entirely sure what my output is -- I have a MacBook Air. I'll have to look it up.

 

[Dexter Morgan]

Not entirely sure what my output is -- I have a MacBook Air. I'll have to look it up.

Works for me on a MacBook Pro