[HalloweenJack23]

John I don't actually think there is likely to be any thing wrong with your unit there are three volume ranges of colour rainbow for volume control you've not got up to the middle range yet keep pressing the up button and when the balls advance through the colour in a stepped sequence your on the middle range until then the plus ball sits at one colour
The wistle your hearing is caused by your charger please try a more powerful one and the noise should become far less noticeable.

Hey John, many thanks for replying (much appreciated).

Well the thing about the colour range issue is that the unit was operating within the middle range at the time - started off in line-mode at 3V, then stepped down a few clicks to around 2V, which should ordinarily be the two blue balls of course. No issues with the sound at all (superb) but the hue of the middle ball was out for sure. It seemed to rectify itself the third time I used the 'line-level' startup routine.

As for the charger, it's already a 2Amp item (a 10W Apple iPad charger) which according to other posts here is more than sufficient power-wise, and one that worked absolutely fine with my original Mojo which worked together silently. The whistle was so loud it actually woke me up last night. Surely not how it should be. I tried it with another charger too and the result was the same, but it seems intermittant; no rhyme or reason.

I'll feel happier with a replacement to be honest.

 

[miketlse]

Hey John, many thanks for replying (much appreciated).

Well the thing about the colour range issue is that the unit was operating within the middle range at the time - started off in line-mode at 3V, then stepped down a few clicks to around 2V, which should ordinarily be the two blue balls of course. No issues with the sound at all (superb) but the hue of the middle ball was out for sure. It seemed to rectify itself the third time I used the 'line-level' startup routine.

As for the charger, it's already a 2Amp item (a 10W Apple iPad charger) which according to other posts here is more than sufficient power-wise, and one that worked absolutely fine with my original Mojo which worked together silently. The whistle was so loud it actually woke me up last night. Surely not how it should be. I tried it with another charger too and the result was the same, but it seems intermittant; no rhyme or reason.

I'll feel happier with a replacement to be honest.

 
Have you read the section within post #3 relating to charging noise?
 
 

Charging noise (Click to hide)
 
Quote:

Originally Posted by Rob Watts 
 
The noise is due to ripple voltage on the charger upsetting the inductors/capacitors within Mojo. If you use a clean quality PSU and a low resistance USB cable to the charger PSU the mechanical noise should be silent or insignificant. 
 
Rob

 
Quote:

Originally Posted by Rob Watts 
 
The problem is a noisy USB VBUS power line, and this makes the inductors in Mojo vibrate. Also, some USB cables have high resistance, and this makes the problem worse - so using a different cable can make the mechanical noise go away. The PSU itself can make it better or worse. Don't worry about it if you hear the noise, Mojo is not faulty and will continue to be reliable.
 
Rob

 
Quote:
Originally Posted by Ra97oR 

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

 

 

[Bulbsofpassion]

  Tried looking at post 3, but there doesn't seem to be anything in there specific to this, apologies if it's been dealt with before in this thread...
 
I got a new Mojo (with the new packaging, serial stamp on the end), charged it for a few hours until the light went off, and then started using it plugged in to a Macbook (for both data and charge).
After about 5 minutes the Mojo started hissing, not super loud but you can clearly hear it from a foot or two away. Unplugging the charge cable made the hiss stop, and turning the Mojo off made it stop too, so the hiss is related to charging (although not sure if it is actually charging, the charge light is white) whilst Mojo is on. Different cables (including Chord supplied one) did not make the hiss go away, and tried charging from an Apple iPhone charger, and it hissed with that too. So... Is this normal? Is there a soulution?
 
Also, is there any benefits to charging from the Macbook USB vs the Apple iPhone charger? Both seem to work fine (apart from the hiss) but I'm more thinking about RF noise etc.

Just to clarify: This seems to only happen when the 'charge' light is white.

 

[esm87]

What would be the maximum volume output for a 32 ohm iem/headphone? As in, if mojo was set to maximum volume, how loud would that be? Just curious...

 

[miketlse]

 
Just to clarify: This seems to only happen when the 'charge' light is white.

 
Charging noise is explained by Rob Watts in Post #3.
 
Quote:

Originally Posted by Rob Watts 
 
The noise is due to ripple voltage on the charger upsetting the inductors/capacitors within Mojo. If you use a clean quality PSU and a low resistance USB cable to the charger PSU the mechanical noise should be silent or insignificant. 
 
Rob

 
Quote:

Originally Posted by Rob Watts 
 
The problem is a noisy USB VBUS power line, and this makes the inductors in Mojo vibrate. Also, some USB cables have high resistance, and this makes the problem worse - so using a different cable can make the mechanical noise go away. The PSU itself can make it better or worse. Don't worry about it if you hear the noise, Mojo is not faulty and will continue to be reliable.
 
Rob

 
So you need to find a charger that produces less, or ideally none, ripple voltage on the VBUS line.

 

[HalloweenJack23]

Have you read the section within post #3 relating to charging noise?

Charging noise (Click to hide)

Mike, thanks for your reply. Yes I'm very familiar with the original trouble-shooting posts, and that the same charger & usb cable I used for my first Mojo worked absolutely fine not even a slight whistle. It comes and goes with this Mojo at random, but it's rather loud (everybody here could easily hear it and agreed it wasn't acceptable). I'm using an Apple 5V 2A charger with Lindy USB cable which was fine with the first Mojo I owned. I also tried another charger later today and got the same results. Thanks.

 

[miketlse]

Mike, thsnks for your reply. If you refer back to my posts you'll also see I've mentioned that I've read the original trouble-shooting posts, and that the same charger & usb cable I used for my first Mojo worked absolutely fine not even a slight whistle. It comes and goes with this Mojo at random, but it's rather loud (everybody here could easily hear it and agreed it wasn't acceptable). I'm using an Apple 5V 2A charger with Lindy USB cable which was fine with the first Mojo I owned. I also tried another charger later today and got the same results. Thanks.

The results with your first Mojo are not relevant, because your issues are with your current Mojo.
 
In simple terms, you have two choices - change your charger or change your Mojo.
I suppose that you have a third, which is sleep in a different room to your Mojo.

 

[esm87]

I wonder if chord will be releasing a hybrid style dap which mojo connects to which also streams Tidal??

 

[HalloweenJack23]

  The results with your first Mojo are not relevant, because your issues are with your current Mojo.
 
In simple terms, you have two choices - change your charger or change your Mojo.
I suppose that you have a third, which is sleep in a different room to your Mojo.

It's entirely relevant - you don't buy the same product and have to go through 'magic' combinations of charger and cable each time to get a quiet unit, that'd be crazy and mean every example has different charging & cabling demands. That would not be acceptable in a product of this price range, or ANY product for that matter.
Yes I am getting the Mojo changed, the dealer has agreed to this when I sent him an MP3 of the charging noise.
I believe I was just unlucky with this particular example.
Thank you.

 

[Bulbsofpassion]

Hey Mike, Thanks for your reply.
Am I to understand that it's normal for charge noise to be not consistent? I'm getting zero charging noise when the charge light is blue (and zero noise when the unit is off), in fact the hissing seems to begin when the battery is full, I just want to make sure this is normal. 
 
Re the different charger, I found this from Rob: "If you use a lap top USB the sound should disappear as these power supplies are electrically quiet." so assumed charging from the Macbook would be a non issue. 

 

[miketlse]

 
Hey Mike, Thanks for your reply.
Am I to understand that it's normal for charge noise to be not consistent? I'm getting zero charging noise when the charge light is blue (and zero noise when the unit is off), in fact the hissing seems to begin when the battery is full, I just want to make sure this is normal. 
 
Re the different charger, I found this from Rob: "If you use a lap top USB the sound should disappear as these power supplies are electrically quiet." so assumed charging from the Macbook would be a non issue. 

Most people experience the hissing from the start of charging, so your experience is not typical.
Presumably the amount of ripple voltage produced by your charger, increases as the charging load decreases (ie when the Mojo has a nearly full battery, and is probably in trickle charge mode, for the remainder of the charge).
 
When Rob talks about laptop power supplies being electrically quiet, he is usually talking about the amount of electrical noise they generate being much less than other computer hardware.
There is the proviso, that if the laptop is connected via a power supply to the mains, then electrical noise from your mains supply can travel through the charger, and then into your Mojo, where it can affect the final sound that you hear via headphones.
So potentially if your laptop is connected to the mains, and your Mojo at the same time, then some electrical mains noise could be affecting your Mojo.
This is easy to test - if you are experiencing the hissing, then disconnect your laptop from the mains, and see if there is any change in the hissing.
At least this might help to narrow down the root source of the hiss.
 
Ultimately there is a manufacturing tolerance to all the components in the Mojo, and the majority are hiss free, but there are a few where all the tolerances combine to make them generate a faint amount of hiss. It may be that yours is just one of the small group of hissy Mojos. 

 

[miketlse]

 
It's entirely relevant - you don't buy the same product and have to go through 'magic' combinations of charger and cable each time to get a quiet unit, that'd be crazy and mean every example has different charging & cabling demands. That would not be acceptable in a product of this price range, or ANY product for that matter.
Yes I am getting the Mojo changed, the dealer has agreed to this when I sent him an MP3 of the charging noise.
I believe I was just unlucky with this particular example.
Thank you.

 
All the components in your Mojo are manufactured to a manufacturing tolerance, so the finished engineering system (mojo) will have a performance somewhere along a normal distribution.
So although both your mojos will be the same product, the manufacturing tolerances mean that they can never be exactly identical, only similar within a certain tolerance band.
So it is quite plausible that a charger that worked ok with your first Mojo, may not work quite as well with your new mojo.
 
I will assume that you are just unlucky.
 
Have a good evening.  

 

[miketlse]

What would be the maximum volume output for a 32 ohm iem/headphone? As in, if mojo was set to maximum volume, how loud would that be? Just curious...

 
I don't think that the type of information that you mention can tell you the volume level.
 
To explain what I mean, look at this recent post http://www.head-fi.org/t/816385/shanling-m1-an-ipod-nano-competitor-dap-usb-dac-usb-transport-bluetooth-4-0-aptx-dsd/1680#post_13077234
 
The poster quotes a certain mW for a certain impedence.
This will be the electrical output power from the M1. To then progress to know the sound power emitted by the iem/headphone, you need to know how efficiently the iem converts the electrical input energy, into the sound output energy. Maybe one of the members can quote typical efficiencies, and then dB levels for those typical iems, as well.
 
The same reasoning applies to the Mojo, or any other DAC/DAP. 

 

[esm87]

I don't think that the type of information that you mention can tell you the volume level.

To explain what I mean, look at this recent post http://www.head-fi.org/t/816385/shanling-m1-an-ipod-nano-competitor-dap-usb-dac-usb-transport-bluetooth-4-0-aptx-dsd/1680#post_13077234

The poster quotes a certain mW for a certain impedence.
This will be the electrical output power from the M1. To then progress to know the sound power emitted by the iem/headphone, you need to know how efficiently the iem converts the electrical input energy, into the sound output energy. Maybe one of the members can quote typical efficiencies, and then dB levels for those typical iems, as well.

The same reasoning applies to the Mojo, or any other DAC/DAP. 

It's out of pure curiosity I ask. Im not sure how many more colours or clicks after the bright rich green there is, but thats exceedingly loud.

There's a guy in work who loves his beats pro that I can't stand, might set mojo to max colour level/clicks and let him hear how awesome mojo is lol... just joking

 

[miketlse]

It's out of pure curiosity I ask. Im not sure how many more colours or clicks after the bright rich green there is, but thats exceedingly loud.

There's a guy in work who loves his beats pro that I can't stand, might set mojo to max colour level/clicks and let him hear how awesome mojo is lol... just joking

So you are thinking in terms of the ball colours as a proxy for the number of dB.
 
If you set the Mojo to max output, then the sound pressure level from the iems/headphones will depend on the iem/headphone. I doubt that any member has performed the test, but the use of mobile phone sound pressure monitoring is discussed on some of the Chord threads, so you could well be lucky.