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Chord Mojo FAQ

I'm creating this to answer all the repeat questions in the main Mojo threads.

 

Power

 

Q. My Mojo gets noticeably warm while charging and playing music. Is this OK?

Yes. The Mojo uses 1.7W of power, so it will get comfortably warm during use, and has thermal cut-outs that prevent it overheating, even if charged at the same time.

Quote:
Originally Posted by Mojo ideas View Post

Mojo actually has three independant thermal cut outs a special high temperature battery and very sophisticated charging circuitry . Picking up on an earlier post Mojo actually does not dissipate a lot of heat when it's working. It's only about 1.7 watts and when it's charging it adds about another watt so its not much really. However the electronics and battery are thermally bonded to the aluminium case. The Mojo's case can only shed its heat through convection or by radiating it away. This can only work if there is a temperature differential between itself and its ambient surroundings if there is an insufficient gradient between them, the Mojos temperature will rise until there is a large enough difference to pass its heat to the air surrounding it.
If it is prevented from doing this perhaps by being insulated I some way it's temperature will rise until one of the three shut down trips operate. note the battery is safe to 150 degrees and the trips all operate up too a hundred degrees lower. Therefore it's perfectly safe. In fact if it's feeling mildly hot at first to your hand. Your hand alone will easily soon bring the unit down to a reasonable temperature.
 

Q. How do I know how much charge is left in the Mojo's battery?

Below the USB charging port is a small light. The colour of this light indicates the battery level. Fully charged is blue,  green at 75%, yellow at 50% and red at 25% Flashing red means 10 minutes left.

 

Q. I hear a sound when the charger I'm using is connected to the charging port. Is this normal?

Short answer: Try a different charger. Longer answer from Rob below. Note that this is a separate issue to the one which affected an early batch of units which were faulty.

 

Quote:

Originally Posted by Rob Watts View Post
 

The mechanical buzz is due to the USB charger being noisy. This noise modulates the PSU inductors, which creates the noise. The level of mechanical noise depends upon the PSU. If you use a lap top USB the sound should disappear as these power supplies are electrically quiet.

 

It is not a faulty Mojo as we can't stop the noise from the USB.

 

Rob

 

Full post on different charger and USB cable combinations tested (Click to show)
Quote:
Originally Posted by Ra97oR View Post

Further testing on the charger and cable compatibility. Chosen Anker PowerPort 5 for good measured performance and multi-port charging with Anker PowerLine due to good construction with braid + foil shielding. All are available at a reasonable price.


Case 1: Virtually silent, only heard very minor hiss when ear is pretty much on the unit
Case 2: Only noticeable hiss when you put your ears near the unit
Case 3: Loud whine lasting the only the first few seconds, faint charging noise after that.
Case 4: Loud whine, and it goes on for a few seconds and off for a few (voltage drop causing charging circuit to shut down)




Combo 1: Sony or Samsung charger + Sony or Samsung USB cable + extension cord = Case 4

Combo 2: Sony or Samsung charger + Any cable = Case 3

Combo 3: Apple 1A charger + Sony or Samsung USB cable = Case 2

Combo 4: Anker charger + Sony or Samsung USB cable = Case 2, slightly quieter than combo 3

Combo 5: Sony or Samsung charger + long 6ft Anker cable (same cable length as Combo 1) = Case 3

Combo 6: Apple 1A charger + Anker cable/Chord Mojo's bundled cable = Case 1

Combo 7: Anker charger + Anker cable/
Chord Mojo's bundled cable = Case 1, slightly quieter than combo 6 directly compared, with no pattern to the noise (always the same loudness)


Anker PowerPort is tested at it's worse case scenario(unloaded), the ripple and spike measurements are better when the charger is fully loaded with devices. The Anker charger have noticeable more steady noise pattern than the Apple charger even with the best cable connected, the Apple charger's noise ripples in loudness and the Anker one is very steady at the same amplitude.



In short:

If you already have a Apple charger handy, just getting a quality USB cable like the one I've tested will yield noticeable gain, especially if you are using longer cables.

If you don't have an Apple charger, getting an Anker charger with their PowerLine cables will yield the best possible result without going to go with a lab bench linear power supply. Having a multiport desktop charager will also allow you to run shorter cables.


Link where I bought them:
Anker PowerPort 5: http://www.amazon.co.uk/dp/B00VTI8K9K
Anker PowerLine: http://www.amazon.co.uk/dp/B014H3GKZ4

 

Charger tested with no noise: Apple travel charger, Anker PowerPort 5

http://www.amazon.co.uk/dp/B00VTI8K9K

 

Recommended cable: Anker PowerLine, Chord Mojo's bundled cable

http://www.amazon.co.uk/dp/B014H3GKZ4

 

 

Volume

 

Q. The volume lights are now different colours. Is something wrong?

No. Below "red-red" the "+" volume button light will stay at brown and the "-" volume light will cycle through the colours of the rainbow again for very low volume levels for highly sensitive IEMs. A similar thing will happen at very high volume levels, with the "-" light staying static and the "+" light cycling through a few colours.

 

Q. How do I set line-level output?

Any volume level can be used for a line-level output. The Mojo will also remember the previously set volume when powering on. However, you can hold down both volume buttons when powering on to set the volume to a standard output level for typical line-out use.

 

Q. Is there anyway to bypass the amp on the Mojo but still utilize the DAC? Will the line out function accomplish a bypass?

 
Quote:
Originally Posted by x RELIC x View Post

No.

For clarity, setting line level output does not bypass the analogue section as it's basically just the analogue output stage of the powerful DAC output. There is no seperate amp 'section' like in traditional setups. Mojo's headphone output is much more simple than what people are used to in a DAC/amp and is basically the same as Hugo with some minor hardware changes to accommodate the diminutive size. I think of it as always line level from the DAC with output power control. To sum up you don't activate or deactivate the analogue section. You simply set the voltage level to 3V when activating the line level.
 

Q. How do I get line-level output? 

There are two ways: Hold down the volume buttons when you switch on to lock the Hugo to line-level output. Be careful not to have headphones plugged in when you do this!

The other way is to set the volume to, say, double-blue to give you 2V of output.

 

Q. Should I use the volume control on my computer/DAP/digital source or should I use the volume control on the Mojo?

Quote:
Originally Posted by Rob Watts View Post
 

It is always better to give Mojo bit perfect files and let Mojo do the work, as the processing within Mojo is much more complex and sophisticated than a mobile or PC.

 

So when you have an app that has a volume control, and no bit perfect setting, then set it to full volume on the app on the assumption that this will keep the data closer to the original file.

 

The volume control function on Mojo is much more sophisticated than the PC as I employ noise shaping and I do the function at a very high internal sample rate. Hopefully using the volume set to max on the app will mean the volume coefficient is 1.0000000... so it will return the original data.

 

Rob 


​Q. How do I know if the volume control on my computer/DAP is affecting the sound quality?

Quote:
Originally Posted by Rob Watts View Post
 

You can always do a listening test. If set to max against 50% say, and it hardens up (becomes brighter) with loud recordings then its clipping. If on the other hand the perception of sound-stage depth is reduced, then the volume control is degrading the sound.

 

If you do that test and can hear no difference then don't worry, its a good app volume control.

 

Rob

 

PS for fun I just did a very quick test using Dave. I listen to radio 3 using the BBC iPlayer. I normally have it set to max. I reduced the iPlayer volume control to half, boosted Dave volume control by +6dB - and yes I felt sound-stage depth was worse with lower iPlayer volume. 

 

Inputs

 

Q. What's the pinout for the COAX input?

You need a TS or TRS 3.5mm plug with the tip positive and sleeve negative. The ring on a TRS plug would not be connected.

A cheap way to connect a device that uses the same type of TS coax output (such as many Chinese-made DAPs) can be found in this post

 

Q. How do I connect a FiiO X5II via coax?

The X5II uses a strange plug arrangement due to it sharing the output with the headphone socket. In the X5, the headphone socket has a TRRS (4-pole) arrangement with the tip and first ring not connected and the sleeve and last ring respectively "+" and "-". You'll either need to use the adaptor with a coax cable, or have a special cable made. 

 

 

Q. How do I connect an iPhone, iPad or iPod to the Mojo?

If your iDevice can use a Camera Connection Kit (CCK) then you'll need to get the CCK cable from apple which has a USB A socket on one end and use a USB A to micro B cable. You cannot use old scroll-wheel type iPods.

 

Q. Can I use [this USB adaptor]?

John Franks of Chord doesn't recommend using hard USB adaptors, to avoid putting excessive strain on the USB port.

USB to micro USB port adaptors, such as the one below, don't stick out far enough of the CCK to be reliable. 

Q. How do I connect a Sony DAP?

See these posts and the Amazon item mentioned: 

 

Playing Music

Q. My computer (or phone) has up-sampling built into the player. What should I set it to for best quality?

It is recommended to NOT up-sample with any software. The Mojo has a powerful FPGA built-in with programming based on Rob Watts' 30 years of research which he states is far more capable than what any computer software is capable of. It is best to set the output of your computer, phone or player to the same bit rate and sample rate of the music being played. Many audiophile players will automatically do this.

 

Q. Can the Mojo accept DSD?

Yes, it can over any of the inputs using DSD over PCM (DoP). Your player will need to support this for it to work. DSD music isn't needed for good sound quality with the Mojo. 

 

Q. Do I need a driver for Macs? (OSX)

No. OSX supports high-res PCM playback. You will want to match the output sample rate with the music sample rate. You can set this in Audio Midi Setup. Many "audiophile" players (Audirvana Plus, Amarra, VOX etc.) will auto-switch the sample rate to match the music. You don't want OSX re-sampling the music!

 

Q. Which driver should I use in Windows? DirectSound, ASIO or WASAPI?

ASIO or WASAPI to avoid Windows mixing in system sounds. 

 

Long answer here. (Click to show)

Quote:

Originally Posted by sandalaudio View Post
 

For any USB DAC, the user has to choose between whether to give the DAC an exclusive access by a particular program (e.g. JRiver) or allow multiple programs to output sound at the same time.

 

Giving exclusive access means the program can directly send the digital data (bit perfect) to the DAC without compromise, so most audiophile programs like JRiver default to this method.

 

When you install Mojo's drivers onto Windows, it actually installs three different drivers. DirectSound, ASIO and WASAPI. Windows can only see DirectSound, whereas JRiver can see all three, and you can choose which one to use. Generally ASIO or WASAPI are preferred because they are designed to give exclusive access to the DAC.
 
DirectSound is what Windows uses (this is what shows up on Windows Sound Properties). It isn't preferred for audiophile listening because it is designed to send the music to Windows Mixer, which allows multiple programs to output the sound at the same time. Because each program may be using different bit depths and sample rates, Windows Volume Mixer's job is to make sure they are all converted and mixed to the sample rate specified in Windows Sound Properties (e.g. 44.1kHz). All sound is converted to 32 bit float then dithered back to 16 or 24 bits, so it is not bit perfect.
 
Old Windows Mixer on Windows XP were horrible so people historically stay away from DirectSound. Mixer on Windows 7 and up are pretty decent, but people still prefer exclusive access via ASIO/WASAPI drivers, because we want to ensure pure playback and avoid random noise (e.g. e-mail notification sound effect etc.) to interfere with music.
 
The bottom line is, you have to choose between absolute purity vs. convenience. You can set up to have multiple programs to output to Mojo at the same time, but JRiver is not set up to do that by default, so you need to change the settings.
 

 

 

Q. Can I listen to it while it's charging? 

Yes. However the charge will take longer than charging with the Mojo powered off. 

 

Misc

 

Q. I saw someone connect their headphones with the left channel plugged into one headphone socket and one plugged into the right socket. They reckoned they were getting balanced output. Is this true?

No. Both headphone sockets are connected to the same output. The Mojo only has a single-ended output.

 

Q. Why doesn't the Mojo have balanced output?

For the best performance for the design, a single-ended output is best. A balanced output would require double the circuitry and would reduce the objective performance, not increase it. The Mojo can output 5V, which is more than enough to generate up to 120 dB of sound cleanly into most headphones.

 

Q. Are there independent measurements of the Mojo?

Yes, on Stereophile: http://www.stereophile.com/content/chord-electronics-mojo-da-headphone-amplifier-measurements

And on OhmImage: http://ohm-image.net/data/audio/rmaa-chord-mojo-24-bit

 

Q. What is the Mojo made out of?

The Mojo is made from aluminum and comes with small rubber feet pre-installed on the bottom. 

 

Q. What do the different colours on the power button refer to?

They represent the output encoding or sample frequency rate it is fed.

Sample frequencies are in KHz.

 

 

Comments (14)

Please can you add a FAQ for what are the faults with the early release Mojos. I read that it needs to be returned for repair. One is making a noise when charging. Another is hiss on the optical connection. I think I saw another on The Official Mojo Thread, but it goes that fast it's hard work keeping up.
Can you put info for connecting Android phones to the Mojo?  Some folks are saying you have to use an OTG cable and others are saying you shouldn't.
Anyone can add to this wiki. If you find something worthy of adding, please edit it. :)
I have added my finding with different chargers and USB cables to help out others having trouble with Mojo hissing while charging.
So is Mojo primarily made of plastic? It doesn't look sturdy....
It's made of aluminum and solid as a rock. I was shocked at how hefty the unit is given its size.
How good is the Mojo used as the primary line level DAC for a HiFi speaker rig? Also as a line level DAC connected to a tube headphone amplifier such as the Woo Audio WA3? It is primarily a headphone amplifier but I want to know how good it is as a stand alone line level DAC. I only wish it had RCA outputs for the line level output! Or is this (Having 3.5 mm instead of RCA's) irrelevant to the sound quality of the line level out?
@ AegisAvantGarde:
 
Mojo is superb  as a stand alone line level DAC.
 
Please read the posts by Rob Watts, in post number 3, of the main Mojo thread, where he explains how & why Mojos output stage is quite unorthodox.
 
Lower down that post, you will also find information about setting Mojo to line-level
anyone knows how to adjust the sample rate on an iPhone
Is there any way to turn the button lights off while in use?  I find them calling way too much attention to the unit and I get unwanted attention.  Love to have this as discreet looking as possible, without spraypainting the buttons or similar....
@baglunch No, there isn't a way to turn off the button LEDs other than turning the unit off. 
Are there any non-destructive mods I could try to accomplish this "no lights" idea?
 
On my garage door opener, there are three buttons, but I only want the middle one to do anything, so I put a piece of paper between the contacts of the other two buttons.  Fast, easy, reversible.  Anything like that?  I'm somewhat scared of opening the Mojo case but I have an allen key set if it's safe...
 
I just sent Chord an email with the suggestion.  I'll update if there's anything to report.
@Mython Thanks Mython, I just ordered a Mojo since its at a great price right now. Once I get it I will test it with a hybrid tube preamp with a Telefunken NOS E88CC (Vali 2) and  with a couple of solid state and Tube amps! I am curious to hear the Mojo with some serious Tubes. 
When using the Chord connected to a laptop... I need to use 2 USB cables to charge and listen at the same time, right?
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