[miketlse]

I was more reaching for a percentage of failure “in the wild”. There’s probably a higher concentration of failure reports on this thread.

The only people who might have the best guesstimate of the total number, is Chord support - but from reading this thread, not all owners with failed batteries do bother to contact Chord, so even they do not have the full picture.

To me it feels like at most there have been a few dozen reports in this thread of swollen batteries - maybe I accidently underestimate so let's say the total for this thread is 100. That means a failure rate of 100 in 100,000 shipped units = 0.1%
This 100 does not include owners on head-fi who do not post about failures, or owners who never visit head-fi, so for arguments sake, lets introduce a contingency and multiply the 100 * 10 to include them. That means a failure rate of 1000 in 100,000 shipped units = 1%, so 99% of the shipped batteries are still OK
Even if that 1000 failures is still an underestimate by a further factor of 5, so that the real failure rate is 5000 in 100,000 shipped units = 5%, the vast majority of shipped batteries are still OK.

I think it was reported that the head-fi forum contains the most active discussion threads relating to Chord, so they probably do contain a high percentage of the reported battery failures.
Overall this explains the rationale behind my earlier comment 'the current percentage failure rate will still be low' - if for every failed battery reported in this thread, there are another 49 failed batteries worldwide, you will still only have a worst case failure rate of only 5%. I honestly believe that 49 is a large overestimate.

Unfortunately when some owners experience failed batteries, they understandably get frustrated and emotive, and then sometimes write posts implying that most (ie over 50%) owners experience battery issues - which just then scares other owners, or potential owners.

Hope this explains where I am coming from with my thoughts.

 

[miketlse]

I work for a company that's into battery development and testing for cars, and I can confirm that the industry is still learning about the aging charcteristics of batteries.
Standard testing was for loss of capacity over cycles under controlled conditions and different temperatures, and this number of cycles was stated as battery life.
These tests are done rather fast, say with 1C charge/discharge, so a 1000 cycles would be less than 2 months continuous testing.

Experience has now shown that exposing LiPo batteries to elevated temperatures can decrease their lifetime significantly, independent from cycles.
That's why car batteries now are conditioned to moderate temperatures even when the car is parked. In winter they are heated, in summer they are cooled.

Considering that the Mojo gets pretty warm when permanently charged and used, this would be an explanation for premature aging of the battery.

Thanks, that's interesting feedback.
Does suggest that the battery lifetime estimates that the manufacturer provided in good faith to Chord, when the battery was first designed approx 5 years ago, might be different if the battery was designed today with the most up to date battery aging models.
That is the relentless march of time, and the ever increasing knowledge, about how to design components.

 

[Daniel Johnston]

The only people who might have the best guesstimate of the total number, is Chord support - but from reading this thread, not all owners with failed batteries do bother to contact Chord, so even they do not have the full picture.

To me it feels like at most there have been a few dozen reports in this thread of swollen batteries - maybe I accidently underestimate so let's say the total for this thread is 100. That means a failure rate of 100 in 100,000 shipped units = 0.1%
This 100 does not include owners on head-fi who do not post about failures, or owners who never visit head-fi, so for arguments sake, lets introduce a contingency and multiply the 100 * 10 to include them. That means a failure rate of 1000 in 100,000 shipped units = 1%, so 99% of the shipped batteries are still OK
Even if that 1000 failures is still an underestimate by a further factor of 5, so that the real failure rate is 5000 in 100,000 shipped units = 5%, the vast majority of shipped batteries are still OK.

I think it was reported that the head-fi forum contains the most active discussion threads relating to Chord, so they probably do contain a high percentage of the reported battery failures.
Overall this explains the rationale behind my earlier comment 'the current percentage failure rate will still be low' - if for every failed battery reported in this thread, there are another 49 failed batteries worldwide, you will still only have a worst case failure rate of only 5%. I honestly believe that 49 is a large overestimate.

Unfortunately when some owners experience failed batteries, they understandably get frustrated and emotive, and then sometimes write posts implying that most (ie over 50%) owners experience battery issues - which just then scares other owners, or potential owners.

Hope this explains where I am coming from with my thoughts.

Thanks. I appreciate your thoughts. I wasn’t really expecting a response from Chord with specific stats. In today’s litigious environment, major companies need to be careful with what they post. I get it.

There is always a certain paranoia after reading about battery related issues. Personally I’m not too concerned. I use the polymojo and enjoy it. I’ve only had one swollen battery in my plethora of devices. It was a battery pack of a Nikon J1 camera.

I know Rob Watts has chimed in more than once on the mojo battery and keeping it plugged in constantly.

 

[adeseaso]

Good day everyone,
I'm thinking of upgrading my DragonFly Red and a used Mojo is the only sub-$500 AMP/DAC that I can think of.
Can any give me a comparison between these units? Sound differences? I'm hoping to get a wider soundstage and more bass physicality with an upgrade.

It's either the Mojo or ALO CV5, which would cost more..

Thanks!

I don't mean this as a snide remark at all but it sounds like you want a lesser DAC than the Mojo. As you reduce distortion the sound stage tends to narrow down a bit and depth perception increases. Distortion adds a certain 'structure' to the sound that makes the sound stage appear wider and it's also very beneficial if you want bass slam. Some (a lot of?) people like this, and they will probably not like the Mojo.

The Mojo is also a bit rolled off at both extremes, I haven't heard the Red but relative to all other DACs I've heard in both directions in cost the Mojo is among the leaner, bass wise.

Think of Mojo more as the lowest cost entry into the Chord timbre that comes with the WTA filtering. They sound different to other DACs, it's as if the music is cut from a slightly different cloth, one that to me and many others sound a bit more organic than the competition. Combine that quality with a nicely rolled off and comfortable filter and you get the very smooth and enjoyable Mojo. It's great, but for bass I'd look elsewhere.

 

[chimney189]

I don't mean this as a snide remark at all but it sounds like you want a lesser DAC than the Mojo. As you reduce distortion the sound stage tends to narrow down a bit and depth perception increases. Distortion adds a certain 'structure' to the sound that makes the sound stage appear wider and it's also very beneficial if you want bass slam. Some (a lot of?) people like this, and they will probably not like the Mojo.

The Mojo is also a bit rolled off at both extremes, I haven't heard the Red but relative to all other DACs I've heard in both directions in cost the Mojo is among the leaner, bass wise.

Think of Mojo more as the lowest cost entry into the Chord timbre that comes with the WTA filtering. They sound different to other DACs, it's as if the music is cut from a slightly different cloth, one that to me and many others sound a bit more organic than the competition. Combine that quality with a nicely rolled off and comfortable filter and you get the very smooth and enjoyable Mojo. It's great, but for bass I'd look elsewhere.

I appreciate the honesty. I just bought one so I'll be able to test it out and hear the results. I was also looking at the ALO Continental CV5.

 

[surfgeorge]

I appreciate the honesty. I just bought one so I'll be able to test it out and hear the results. I was also looking at the ALO Continental CV5.

Congratulations!
If you do not find the soundstage to be better, then I'd think your headphones or earphones might be the limiting factor, since the Mojo has very good, especially very deep soundstage.
And in terms of bass, the Mojo has the power to drive and control all IEMs and most headphones, which is a good start.
Looking forward to your impressions!

Oh, and if you have a good stereo system ge an adapter to connect the Mojo and listen to it through your system. I was blown away by the soundstage. My living room wall vanished acoustically.

 

[miketlse]

I appreciate the honesty. I just bought one so I'll be able to test it out and hear the results. I was also looking at the ALO Continental CV5.

Here is the post where Rob explains the trade-off between focus and sound stage width.
The Mojo will provide a flat but detailed bass response, so it will reproduce the bass that was in the original recording.
Other dacs/amps/headphones can introduce bass boost by nature of their design - so if you like the level of detail provided by the Mojo, but want more bass, then maybe use a music player app that can apply frequency equalisation to the music first, or explore alternative headphones with a stronger bass response.

 

[chimney189]

Congratulations!
If you do not find the soundstage to be better, then I'd think your headphones or earphones might be the limiting factor, since the Mojo has very good, especially very deep soundstage.
And in terms of bass, the Mojo has the power to drive and control all IEMs and most headphones, which is a good start.
Looking forward to your impressions!

Oh, and if you have a good stereo system ge an adapter to connect the Mojo and listen to it through your system. I was blown away by the soundstage. My living room wall vanished acoustically.

I'm using the Audio-Technica ATH ADX-5000 specifically for this which is actually known for its holographic sound-stage. I think I'm safe in this regard.

 

[Deftone]

I don't mean this as a snide remark at all but it sounds like you want a lesser DAC than the Mojo. As you reduce distortion the sound stage tends to narrow down a bit and depth perception increases. Distortion adds a certain 'structure' to the sound that makes the sound stage appear wider and it's also very beneficial if you want bass slam. Some (a lot of?) people like this, and they will probably not like the Mojo.

The Mojo is also a bit rolled off at both extremes, I haven't heard the Red but relative to all other DACs I've heard in both directions in cost the Mojo is among the leaner, bass wise.

Think of Mojo more as the lowest cost entry into the Chord timbre that comes with the WTA filtering. They sound different to other DACs, it's as if the music is cut from a slightly different cloth, one that to me and many others sound a bit more organic than the competition. Combine that quality with a nicely rolled off and comfortable filter and you get the very smooth and enjoyable Mojo. It's great, but for bass I'd look elsewhere.

Hugo 2 has lower distortion than mojo but the sound stage Is larger, if what you said is true then shouldn't hugo2s stage be even smaller than mojo? It's the opposite.

 

[chimney189]

I can see how people might look at measurements and start coming to conclusions... but until one listens to the unit then I don't think that the measurements mean much. Everyone's hearing is on different level.

 

[Totoxio]

Hugo 2 has lower distortion than mojo but the sound stage Is larger, if what you said is true then shouldn't hugo2s stage be even smaller than mojo? It's the opposite.

This is what Mr. Rob Watts says about the subject: "5. Sound-stage placement focus. Fairly obvious - the more sharply focused the image the better. But - when sound-stage placement gets more accurately focused, the perception of width will shrink, as a blurred image creates an artificial impression of more width. Small signal non-linearity, transient timing and phase linearity contribute to this."

The complete post: https://www.head-fi.org/threads/watts-up.800264/#post-12457933

 

[rkt31]

Headphones are not ideal for stereo imaging except binaural recordings. Lesser the cross talk between two channels as in chord dacs, more you get the effect of depth, means lesser soundstage width 'on headphones'. On other dacs there is less channel separation ( due to less micro details and less stereo depth cues) which is like crossfeed in headphones so you feel soundstage more in front hence feel of wider soundstage. So chord dacs giving impression of lesser soundstage width is due to peculiarity of headphone listening where sound to right and left ear is totally seperated means left ear can't listen what right ear is getting. No wonder adding X feed to mojo through player or in Hugo 2 with inbuilt cross feed, improves soundstage width (albeit in a better way than more cross talk in other dacs) 'during headphone listening' . Now coming to why Hugo 2 has more soundstage width than mojo. One more factor for more soundstage width perception is treble extension . More treble extension gives the impression of more soundstage width. That's the reason hugo2, Dave tt2 have even better soundstage width and along with depth perception than mojo. With speakers this effect is lesser as compared to headphones.

 

[maxsol]

The Mojo can not run without the battery. You need to take it to an authorized Chord dealer for a battery replacement (or ship it in) is the statement from Chord. I believe the cost for battery replacement would be in the ballpark of the Hugo replacement at $60 (not a confirmed price for the Mojo).

Yes It can! It's easy to open the Mojo and unplug the battery - and even take it out. Then just use it as a desktop DAC with both the power USB cable and USB data cable connected. I use two different USB cables in two different USB ports in the Laptop. Put the Mojo on a Gel pack (from the freezer) wrapped in a piece of cloth (Don't put the Mojo directly on the gel pack!). Now everything is nice and cool

 

[damorgue]

The Mojo can not run without the battery. You need to take it to an authorized Chord dealer for a battery replacement (or ship it in) is the statement from Chord. I believe the cost for battery replacement would be in the ballpark of the Hugo replacement at $60 (not a confirmed price for the Mojo).

4.Chord do supply spare batteries to dealers, so that they can install the new battery for you. A big constraint is that couriers and postal services do not like transporting individual lithium batteries to domestic properties, so usually require tracked and insured shipping. This does bump the cost of a battery up, but even so it should not be north of $100

Just to make things a bit clearer in case someone entertains the idea of buying a replacement battery from Chord.The price of the battery from mojo most certainly is north of 100$, without installation or such service. I agree with you that it shouldn't, but it is.

Would still be great if someone had a mojo with a battery pre-swelling so we could check if we could get a sub $100 battery replacement, maybe even any regular $5-10 one of similar spec:
https://hobbyking.com/en_us/quanum-fpv-headset-battery-7-4v-1500mah-3c.html?wrh_pdp=7&___store=en_us
https://hobbyking.com/en_us/turnigy-1000mah-2s-20c-lipo-pack.html?wrh_pdp=7&___store=en_us

 

[Deftone]

You can use mojo without a battery and should have a perfect fine power output for iems but it will squeal for some reason, I couldn't get this to go away.