Chord Mojo(1) DAC-amp ☆★►FAQ in 3rd post!◄★☆

Jul 31, 2024 at 2:58 PM Post #42,826 of 42,916
The reason I'm so strict about the 5.25V limit is to not blow out the protection diode.

It seems the Mojo2 has a new PCB revision with modern protection diodes, but for our pre-COVID Chord DACs we don't have that luxury. This makes DC-Power a possibility on the Mojo2 if you have the new revision PCB because it can exceed 5.25V and will just "soft-landing" shutdown without blowing out traditional diodes (hard-landing).

New Mojo 2s have protection diodes and resistors that activates when it detects abnormal voltages.

https://www.head-fi.org/threads/watts-up.800264/post-18170594

Yes there is over voltage protection on the charging port. This is intended for initial protection upon connection to avoid inductive over voltage surges damaging Mojo. The USB input must be a USB legal 5v input; the over voltage chargers have a communications protocol to set the voltage higher than the usual 5v; Mojo does not have this protocol, so a USB charger should not be able to deliver more than 5v.

Rob

https://www.head-fi.org/threads/chord-mojo-1-dac-amp-☆★►faq-in-3rd-post-◄★☆.784602/page-1344#post-12729283

No it can't - the first layer of protection is an input diode (to protect Hugo's internal charger circuit if somebody plugged a PSU that was negative). This diode means that current will only flow into Hugo, not out of it.

There is also a regulator too, that protects the Hugo's internal charger from over voltage. And another Zener diode that protects the regulator from voltage spikes that would damage the regulator! I was paranoid about over voltage damaging the batteries, hence the several layers of protection.

Rob

https://www.head-fi.org/threads/chord-electronics-2qute-dac-announced.749582/page-115#post-15441986

Yes a 24v PSU will destroy the protect diode.
Its D4 a BZV55C15 zener diode. If you have a local service guy it's easy to replace. Make sure you solder it in the correct way round.

https://www.head-fi.org/threads/chord-electronics-2qute-dac-announced.749582/page-115#post-15441986

It needs to be 5v +/-0.25v - the USB standard.

It will be fine with a USB power bank, as to get the higher voltage for fast charge requires a comms response from the slave (Qutest) which it won't supply. So you would be safe. If you did put in more than 5v, you would blow the protection input diode. These are easy to replace - but I have had no reports from Chord about this kind of failure occurring. So don't worry is my advice.

That's why I'm so skeptical on anything third-party powering via 5V.

I also love that there is a possible 7.4V external battery option on the Mojo. I H8 regulators and to be able to power @7.4V I consider a blessing. I'm sure Qutest owners would of loved that option. It's near impossible for Qutest owners to find a power supply without a regulator within the 5v +/-0.25v range.
 
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Jul 31, 2024 at 6:05 PM Post #42,827 of 42,916
I'll post this before I run out of Social Battery. The last two generations logic really drains the batteries.

I don't want to run into another post where they state any random generic FPGA board automatically sounds like a Mojo. I have to explain to them a generic FPGA board is not a Xilinx FPGA board. That the underlying computer code is not embedded with Rob Watt's 30+ years of Intellectual Property. There's a lot of Chi-Fi Marketing using buzzword 'FPGA' to try to imply it is similar to Chord DACs in quality. It's bait.

I have to show them you can build your own generic FPGA and that NO, it's not going to sound like a Mojo Gen-Zer's:

https://www.reddit.com/r/fpgagaming/

Anyways, for Mojo owners it's difficult to procure equipment for a multiple of your DAC. For example, in the Summit-Fi threads, they have no issue spending on a source 4-5X multiple of their Chord DAC. Their solution is to pay for $12,000+ PCs. It's similar that in the old days, gamers purchased $10,000 Alienware Gaming PCs thinking it will make them better gamers. Those with some know-how automatically know they can build their own for a fraction of the price. They are aware of "Moore's Law" as tech changes quickly so their $12,000+ equipment will be quickly become obsolete along with software updates over time. But these consumers are in it to flex a brand name, so they get their 6 months value before tech catches up. That's why Alienware and brand name Music Server PCs are a distant memory. Brand name grabs the bag and provide no more software updates. A decade ago, it had it's day but "Moore's Law" and tech eventually catches up. That's why I find it cringe when someone tries to mention "Alienware" because it had it's day but they can't move on because they sunk $10,000 into the machine that promised to make them better gamers and they didn't get their $10,000 worth of attention they were seeking.

Basically, these high-priced Audiophile PCs get you closer to embedded hardware behavior + proprietary software that locks you into their system for life + free open-source Audio server software. So, right away you are bottle-necked by their proprietary software. Once they get tired of providing software updates, the PC becomes a book-holder.

There's another practical way, you can procure an Audiophile OS for your own hardware but for near the price of a used Mojo so it's difficult to justify. I can justify as it's a fraction of my DAC. If it wasn't a sunk cost, I would pursue the Ubuntu Pro route and try to emulate near what my Audiophile OS does for zero cost. Diminishing returns. So at least I was able to learn the internals of an Audiophile OS, otherwise in hindsight it's smarter to build your own.

So what I recommend is for some with some know-how is to try Ubuntu Pro. Ubuntu Pro allows you to activate a realtime kernel to get you closer to embedded hardware performance.

Pro.png

https://ubuntu.com/real-time

Realtime kernels are heavily used in Investment Banks.

It's not difficult to just compile and install your own free open-source battle-tested Audio Server of your preference. I haven't tested it for Audio yet because I already sunk costs into an Audiophile OS, but it should work similarly as a Audiophile OS without the extras.

You get 12 years of updates without having to worry about someone grabbing the bag and making your machine literally obsolete (they have the power to permanently shutdown your PC anytime) not just figuratively.

realtime.png


For Gaming, I use to use an Audiophile OS but since it is based on Arch Linux, the Steam UI and Nvidia drivers are glitchy.

So I migrated my Gaming over to Ubuntu Pro 22.04. If a game is Steam Deck verified, it should work seamlessly on Linux. If it's Steam Deck playable, it still should work depending on your Proton install. I have not tried the new 24.04 yet. It was an easy choice to migrate because for Gaming, I turned off all the extras on the Audiophile OS anyways and just relied on the realtime kernel.

So it made sense to just dual-boot Audiophile OS for Music since I have more finer control and Ubuntu Pro for Gaming since both have my mandatory realtime kernel for Chord DACs.

For example, here's my low-level configuration on top of the realtime kernel layer before it hits the application layer on my Audiophile OS:

Code:
cset:
         Name       CPUs-X    MEMs-X Tasks Subs Path
 ------------ ---------- - ------- - ----- ---- ----------
         root        0-3 y       0 y   142    2 /
       system          0 n       0 n   353    0 /system
    isolated1        1-3 n       0 n     4    0 /isolated1

It isolates Core0 on the CPU for system tasks and Cores1-3 for the Audio Server

Here, IRQ 32 is set to my Chord DAC so it's fine-tuned for priority from a low-level

IRQ 32  -> 1-3
FULL LIST OF IRQ AFFINITY
(some irq affinity are not set to the configured value if the driver using that irq is not active or for some special system irq)
IRQ 0 timer -> 0-7
IRQ 1  -> 0
IRQ 2  -> 0-7
IRQ 3  -> 0-7
IRQ 4  -> 0
IRQ 5  -> 0
IRQ 6  -> 0
IRQ 7  -> 0
IRQ 8 rtc0 -> 0
IRQ 9 acpi -> 0
IRQ 10  -> 0
IRQ 11  -> 0
IRQ 12  -> 0
IRQ 13  -> 0
IRQ 14  -> 0
IRQ 15  -> 0
IRQ 16 ehci_hcd:usb1 -> 0
IRQ 17 snd_hda_intel:card0 -> 0
IRQ 18 i801_smbus -> 0
IRQ 22 ehci_hcd:usb2 -> 0
IRQ 30 ahci[0000:00:1f.2] -> 0
IRQ 31 xhci_hcd -> 0
IRQ 32 xhci_hcd -> 1-3
IRQ 40 mpt2sas0-msix0 -> 0
IRQ 41 mpt2sas0-msix1 -> 1
IRQ 42 mpt2sas0-msix2 -> 2
IRQ 43 mpt2sas0-msix3 -> 3
IRQ 44 mpt2sas0-msix4 -> 4
IRQ 45 mpt2sas0-msix5 -> 5
IRQ 46 mpt2sas0-msix6 -> 6
IRQ 47 mpt2sas0-msix7 -> 7
IRQ 48 enp4s0 -> 0
IRQ 49 enp4s0-TxRx-0 -> 0
IRQ 50 enp4s0-TxRx-1 -> 0
IRQ 51 enp4s0-TxRx-2 -> 0
IRQ 52 enp4s0-TxRx-3 -> 0
IRQ 53 enp5s0 -> 0
IRQ 54 enp5s0-TxRx-0 -> 0
IRQ 55 enp5s0-TxRx-1 -> 0
IRQ 56 enp5s0-TxRx-2 -> 0
IRQ 57 enp5s0-TxRx-3 -> 0
IRQ 58 nvkm -> 0

USB audio CARDS IRQ:
06:00.0 Chord Electronics Ltd Hugo2
IRQ: 32

INTERNAL audio CARDS IRQ:
01:00.1 Audio device: NVIDIA Corporation High Definition Audio Controller (rev a1)
IRQ: 17

DEVICES CONNECTED TO USB
In the ideal situation your DAC should not share the same USB bus (defined by the first number in the DEVICE column)

DEVICE    POWER    SPEED    VENDOR    PRODUCT    BIND    NAME
3-3    on    480    0781    5588    yes    SanDisk 3.2 Gen 1 SanDisk
3-4    on    1.5    04d9    1919    yes    DasKeyboard
6-1    auto    5000    2109    8110    yes    USB3.0 Hub              VIA Labs, Inc.
6-1.2    on    5000    245f    0815    yes    Hugo2 Chord Electronics Ltd

Here, I dedicate my Chord DAC to run on it's own USB Bus away from System Processes (Noise).  Need physical hardware to accomplish.

So what I'm recommending is to try this for Gaming. If it's suitable and sustainable, you can try building your own Audio Server software over time on top of a realtime kernel.

The realtime kernel is nice to have for Music processing. For example, Ubuntu Studio has a realtime kernel built-in for Media software usage but it's bloated not minimalist.

https://ubuntustudio.org/

So:
  1. Download Ubuntu 24.04
  2. Sign Up for Ubuntu Pro (5 Free Licenses)
  3. After install, login to Ubuntu Pro
  4. Enable realtime kernel.
  5. Update
https://ubuntu.com/real-time

Then for Gaming:
  1. Install Nvidia Linux Driver
  2. Install Microsoft Fonts
  3. Install Steam
It works pretty seamlessly and Steam is well-supported on Ubuntu. No more funky glitchy stuff. Plenty of guides available. Of course, it sounds great. I get Soundstage Depth on Open World Games.

For installing Nvidia drivers on top of a realtime kernel, not many guides but basically you just download the latest Nvidia Linux Driver then run:

Code:
sudo IGNORE_PREEMPT_RT_PRESENCE=1 bash NVIDIA-Linux-x86_64-550.100.run

if you can't find a guide.

There are a few more libraries and to blacklist the open source Nvidia driver, but it should be simple for those with some know-how. dkms definately needed:

https://gist.github.com/pantor/9786...malink_comment_id=4686645#gistcomment-4686645

Afterwards, you just run the straightforward Nvidia bash install going forward after system updates.

Each time the realtime kernel updates, you need to reinstall the Nvidia driver. Just accept all the defaults. The screen should be low-res after system updates (No driver installed), just re-install Nvidia drivers to get back to high-res (driver installed). Takes 5 minutes, may need to login multiple times for authorization to install.

This is a free realtime kernel foundation for both Gaming and Audio Server services. I'll post if I can reverse-engineer some of my Audiophile OS extras to seamlessly integrate into Ubuntu Pro realtime kernel ecosystem. I would of loved to have this available at Hugo2 launch.

For a sunk cost Mojo, you don't want to spend $12,000 much less $1,000 for a source when you can get near identical performance for FREE. Tech evolves quickly.

To me, Gaming on a realtime kernel with a Chord DAC is mission-critical.
 
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Jul 31, 2024 at 6:36 PM Post #42,828 of 42,916
Hi y'all.
So i have a Mojo 1 and i want to convert it to full time desk setup.
1000016141.png1000016142.png

I found some really nice 7.5V and 8.4 linear power supply adapter for cheap.
I wanna ask if there's any risk involve when doing the mod? (Other than voiding the warranty). Is there any safety measure i can do?

Also, when would i need to use something like this? I think it has a lot of capacitors but i have no idea what it does.
Hope you guys can help me :>
1000016145.jpg7



I like the look of the pcb in the white box, don’t know what it is or does but the pcb looks well thought out. 👍🏻
 
Sep 4, 2024 at 8:41 PM Post #42,829 of 42,916
I'm happy to report that i just completed my 4th and final iteration of converting my Mojo to a permanent desktop DAC! Special thanks go to 'The Listener' who provided a lot of info and pushed me in the direction of using an external battery charger.

Below is my evolution over the past 3 years:

1. Removed the internal battery and used a very slim external 5V USB battery bank connected to the USB charging port. Understanding fully well that the Mojo's charging port is not designed to permanently power the Mojo, it sill worked very well and it was a portable set up too. The downside with this version is that you are always charging while playing thus the Mojo gets quite hot.

2. Relocated the internal battery outside the Mojo while it remained connected internally. That took care of overheating the battery when playing and charging at the same time, however the Mojo itself still got very hot and i felt it wasn't ideal for the long term life of the parts/circuitry.

3. Removed the internal battery and connected an external 7.5V DC (SMPS) directly to the battery connector. This works very well, however some purists will say using a wall wart SMPS is a cardinal sin, is noisy, not a clean DC voltage source, etc. I never experienced any problem with this set up but the posts from 'The Listener' made me realize that i could have the PERFECT desktop solution - see below.

4. Removed the internal battery and connected an external battery charger which houses 2 x 3.7V Li-Ion 18650 batteries directly to the Mojo's battery connector - this provides a clean and constant 8.3V DC, just like having the original battery fully charged. The external power supply is still in use, only this time it is powering the battery charger, not the Mojo. I just had to change the output to 5V and insert the supplied micro USB adapter. I mounted the battery charger behind the computer with double sided tape in such a way that it is out of sight for a clean look but i can still view the charging status at a glance. The power supply is connected to a power strip which has an on/off switch and is located underneath my desk, that way i can switch everything off and the batteries are not charging when not in use (lithium batteries should not be left charging unattended).

Voila!

Edit: if you move forward with this battery charger, i strongly recommend you get the flat top version of the 18650 batteries otherwise the fit with regular top batteries is way too tight, it feels like the battery latch is going to pop out. This, even though the illustration on the case clearly shows regular top batteries.

Warning: make sure to verify the voltage polarity of the jst cable before connecting to the mojo internal battery connector, mine was in reverse!
 

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Sep 5, 2024 at 12:22 AM Post #42,830 of 42,916
Removed the internal battery and connected an external battery charger which houses 2 x 3.7V Li-Ion 18650 batteries directly to the battery connector - this provides a clean and constant 8.3V DC, just like having the original battery fully charged. The external power supply is still in use, only this time it is powering the battery charger, not the Mojo. I just had to change the output to 5V and insert the supplied micro USB adapter. I mounted the battery charger behind the computer with double sided tape in such a way that it is out of sight for a clean look but i can still view the charging status at a glance. The power supply is connected to a power strip which has an on/off switch and is located underneath my desk, that way i can switch everything off and the batteries are not charging when not in use (lithium batteries should not be left charging unsupervised).

It sounds like you took the battery out of the mojo, connected it to an external battery pack then connected that battery pack to a charger, presumably the battery pack charges during use.

How is that better than your version 3 that was wall powered when you said yourself that you didn't hear the noise that was technically potentially present from a wall wart.

Does 4 do anything in practical use that 3 didn't, is it functionally better or just technically potentially better, does the 8.3V versus 7.5V actually do anything that you can hear ?

I personally would rather just have it fully internal battery powered or fully wall powered.

Sorry if I am missing something and I am not trying to argue, I just don't see what you have gained over your version 3 based on your description.
 
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Sep 5, 2024 at 3:26 PM Post #42,831 of 42,916
It sounds like you took the battery out of the mojo, connected it to an external battery pack then connected that battery pack to a charger, presumably the battery pack charges during use.

How is that better than your version 3 that was wall powered when you said yourself that you didn't hear the noise that was technically potentially present from a wall wart.

Does 4 do anything in practical use that 3 didn't, is it functionally better or just technically potentially better, does the 8.3V versus 7.5V actually do anything that you can hear ?

I personally would rather just have it fully internal battery powered or fully wall powered.

Sorry if I am missing something and I am not trying to argue, I just don't see what you have gained over your version 3 based on your description.
Those are excellent questions. One of the reasons i proceeded with option 4 is because i'm trying to answer that question for myself since i don't know if there is anything to gain over option 3. Curiosity i suppose. I just completed the installation yesterday and have yet to perform the testing to confirm. I've also read countless times over decades in this hobby that battery power is cleaner than wall powered. Oh, one more thing; Rob Watts is adamant that under no circumstances should we be using wall powered DC supplies - but i never understood why it is acceptable for the Qutest which is supplied with a 5V USB wall wart. Go figure.

Regarding your personal preference for fully internal battery powered or fully wall powered, i'm glad these options are working for you. For many of us, the fully internal battery powered option is problematic. The very well documented reasons range from overheating when charging & playing, to swelling of the battery potentially causing damage to the circuit board, but the biggest beef i have with this option is that the battery doesn't hold its charge. Charge it fully then pick it up 3-4 days later and it already lost 50% of its charge. Leave it for 2 weeks and you're SOL. I think this is due to some kind of built in monitoring function meaning the device never completely goes to sleep, but i could be right about that.

Edit: The testing will not be so simple. To alternate between options 3 and 4 involves the following:

1. Turn off Mojo.
2. Disconnect battery power source.
3. Adjust power supply voltage from 5V to 7.5V.
4. Remove micro USB adapter.
5. Connect wall powered source.
6. Turn on Mojo.
7. Listen for differences relying on your auditory memory from approx. 1 minute prior.
8. Repeat.
 
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Sep 5, 2024 at 4:52 PM Post #42,832 of 42,916
Those are excellent questions. One of the reasons i proceeded with option 4 is because i'm trying to answer that question for myself since i don't know if there is anything to gain over option 3. Curiosity i suppose. I just completed the installation yesterday and have yet to perform the testing to confirm. I've also read countless times over decades in this hobby that battery power is cleaner than wall powered. Oh, one more thing; Rob Watts is adamant that under no circumstances should we be using wall powered DC supplies - but i never understood why it is acceptable for the Qutest which is supplied with a 5V USB wall wart. Go figure.

Regarding your personal preference for fully internal battery powered or fully wall powered, i'm glad these options are working for you. For many of us, the fully internal battery powered option is problematic. The very well documented reasons range from overheating when charging & playing, to swelling of the battery potentially causing damage to the circuit board, but the biggest beef i have with this option is that the battery doesn't hold its charge. Charge it fully then pick it up 3-4 days later and it already lost 50% of its charge. Leave it for 2 weeks and you're SOL. I think this is due to some kind of built in monitoring function meaning the device never completely goes to sleep, but i could be right about that.

Edit: The testing will not be so simple. To alternate between options 3 and 4 involves the following:

1. Turn off Mojo.
2. Disconnect battery power source.
3. Adjust power supply voltage from 5V to 7.5V.
4. Remove micro USB adapter.
5. Connect wall powered source.
6. Turn on Mojo.
7. Listen for differences relying on your auditory memory from approx. 1 minute prior.
8. Repeat.

Thanks you, that makes perfect sense.

I bought my Mojo brand new at the end of their availability just after the Mojo 2 had been released and it hasn't had a lot of use so I don't have any of those battery issues and I don't charge and play.

I can see the battery problems your described being a headache.

I did buy a spare battery for when I need one but of course I have no idea how that will work relative to the original battery.

I can see the appeal of say a 4 x 18650 x 7.4 volt battery pack sitting outside the Mojo with its internal battery removed but I think I would be inclined to still run batteries only since the others issues are removed and the 18650s can be replaced with ease when needed.

A nice tidy plug built in Mojo case and a suitable connecter on a battery pack would be a nice refinement.
 
Sep 5, 2024 at 6:19 PM Post #42,833 of 42,916
I'm happy to report that i just completed my 4th and final iteration of converting my Mojo to a permanent desktop DAC! Special thanks go to 'The Listener' who provided a lot of info and pushed me in the direction of using an external battery charger.

I'm glad everything worked out. Great Job! The OG Mojo still looks beautiful. I still don't understand how the FPGA charging process shuts down internally, but I do remember the OG Mojo can get hot while charging. So I'm glad Audiowise mentions how the FPGA will shutdown the charging process. If you no longer experience heat issues, I guess the FPGA can bypass that extra processing.

If you need future JST parts, you can get them here:

https://www.digikey.com/en/products/detail/jst-sales-america-inc/XHP-2/555485

All you need is a cheap crimper off Amazon. Plenty of Youtube videos "Crimp JST" if you want to spot the variety of crimpers.

You just crimp these, then insert into the JST-2pin:

https://www.digikey.com/en/products...27371?s=N4IgTCBcDaICwFYEFoCMqDMLXIHIBEQBdAXyA

I'm going to recommend Hugo1 users this JST part:

https://www.digikey.com/en/products/detail/jst-sales-america-inc/B2B-PH-K-S/926611

They are not as fortunate as us as they have to solder the power cables directly on the Hugo1 PCB. And it's a very tight space. Easy to make errors or overflow.

With the JST female connector, it should be simple to solder from the bottom while lightly soldering the bottom of the PCB.

I also recommend considering Silver/Gold Solid Core wiring if you custom make your own JST cables one day.

https://www.soniccraft.com/product_...644?sort=6a&osCsid=a15me7nabtopaf6f5aevkqh6k5

https://www.soniccraft.com/product_...643?sort=6a&osCsid=a15me7nabtopaf6f5aevkqh6k5

USPS is like 7 bucks, so it is a decent value.

Rob Watts had experimented with Solid Core with Mains in the 80s and he mentioned how much warmer (warm == good) it made the whole experience. Presently, I believe he only uses Solid Core for his speaker wiring. So Solid Core has RF-blocking abilities along with the PTFE sleeving.

I think he mentioned somewhere in this video:



I could be wrong and it could be another Youtube video.

Anyways, that's two out of three so far. My goal at the end of Summer was to give options to Qutest, OG Mojo and Hugo1. Since extending the life of Chord products is optimal when it's already a sunk cost. Your ears should thank you in the long run as it will be less fatiguing (Ear Health). Also, brain burn-in takes a good month before you adjust to passive power.

So thanks for the feedback. Only one left is the Hugo1 but that is a wildcard as their Hugo1 has been dormant for years.

Qutest is here:

I built the UcPure Quad ultracapacitor power supply using 2.7V capacitors, and I can confirm it measures 5.18V

https://www.head-fi.org/threads/ian...-ultracapacitor-power-supply-fabulous.973946/

So all is well. OG Mojo has another option. Qutest owners now have a Ultra Cap option.
 
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Sep 5, 2024 at 6:43 PM Post #42,834 of 42,916
The reason Qutest can get away with a wall wart is the Chord-supplied charger should be heavily certified. So they are heavily RFI-filtered. Audiophile Power Supplies have zero RFI filters.

On my wall wart chargers, I make sure they are hospital grade. For example, when visitors visit a hospital room you wouldn't want iPhones to interfere with mission critical medical life saving equipment. Imagine hospital rooms using Audiophile Power Supplies to power medical equipment while visitors are using iPhones. That should be a easy Nope.

GSN.png

That's why I also use Asynchronous or Isosychronous optical on my source side. I moved on from Toslink (S/PDIF) as it doesn't give me that perfect timing (Musicality) dopamine hit. By using Asynchronous optical, I can feed the 104.25 MHz oscillator in the Chord DAC with an Pure clean stream free on any third-party contamination. It's optimal to feed the 104.25 MHz oscillator as close as possible via the Chord DAC's USB Receiver (Powered by Ultra Caps) as the Chord DAC is in full control of the timing not the source. You can't do that with S/PDIF as their are compromises.

fibre.png

Hospital-grade Fibre Optic cabling:

pic1.jpg

Untested (above photo) as I use a simpler type of USB Fiber Optic cabling (KISS principle). But the above photo is something I would like to try one day to see if I can replicate my current results.
 
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Sep 5, 2024 at 9:36 PM Post #42,835 of 42,916
Those are excellent questions. One of the reasons i proceeded with option 4 is because i'm trying to answer that question for myself since i don't know if there is anything to gain over option 3. Curiosity i suppose. I just completed the installation yesterday and have yet to perform the testing to confirm. I've also read countless times over decades in this hobby that battery power is cleaner than wall powered. Oh, one more thing; Rob Watts is adamant that under no circumstances should we be using wall powered DC supplies - but i never understood why it is acceptable for the Qutest which is supplied with a 5V USB wall wart. Go figure.

Regarding your personal preference for fully internal battery powered or fully wall powered, i'm glad these options are working for you. For many of us, the fully internal battery powered option is problematic. The very well documented reasons range from overheating when charging & playing, to swelling of the battery potentially causing damage to the circuit board, but the biggest beef i have with this option is that the battery doesn't hold its charge. Charge it fully then pick it up 3-4 days later and it already lost 50% of its charge. Leave it for 2 weeks and you're SOL. I think this is due to some kind of built in monitoring function meaning the device never completely goes to sleep, but i could be right about that.

Edit: The testing will not be so simple. To alternate between options 3 and 4 involves the following:

1. Turn off Mojo.
2. Disconnect battery power source.
3. Adjust power supply voltage from 5V to 7.5V.
4. Remove micro USB adapter.
5. Connect wall powered source.
6. Turn on Mojo.
7. Listen for differences relying on your auditory memory from approx. 1 minute prior.
8. Repeat.
Or, make some actual measurements.
 
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Sep 6, 2024 at 7:12 AM Post #42,836 of 42,916
Or, make some actual measurements.
Auditory memory is extremely short! even 5s is too long, don't rely on it.
These discussions have come up before. I think people mostly indulge in them, just for fun, not for actually improving anything (me? guilty as charged!).
I still believe (after so many attempts myself) that the cheapest, most economical way to enjoy Mojo, is to use it in factory condition.
No amount of tinkering with PSU is going to improve it, unless something was broken (a bad PSU, or noisy something).
If you are worried about the battery, there are decent batteries on AliExpress for $20 or so, buy a couple, have one in reserve.
Charge it overnight, then listen on batteries. When not in use, and switched off, keep it on charge. The internal PSU, goes into trickle charge when the batteries have reached %95 capacity.
 
Sep 22, 2024 at 1:16 AM Post #42,837 of 42,916
I got a pretty cheap 5.1 Bluetooth receiver for my Mojo, LDAC signal of this 5.1 BT is okay, no choppy signal so far. The mojo battery can be replaced pretty easily too, after 3 years of usage the original battery when fully charged only lasted 2 hours so I bought a 3000mah replacement for $17, looking for many more years of use out of this little dac/amp
Where did you get such a short optical cable? Are you still using this scheme? How does it compare in audio quality to direct connection via USB cable?
 
Oct 26, 2024 at 5:47 PM Post #42,838 of 42,916
Hi, I have a Mojo issue 4 board with a shorted cap (c130) that needed to be removed for the mojo to power-on again. This cap was directly attached to the battery's connector pins but it has nothing printed on it. Does anybody knows its value or can measure directly on its mojo? Thanks in advance.
 
Oct 30, 2024 at 10:00 PM Post #42,839 of 42,916






Hi all. Had a friend of mine do this mod for after purchasing this dac that was connected to a 7.5v power supply. Immediately noticed noise and this thing sounds horrible and had noise so I purchased this 7.5v linear power supply and seemed to have reduced the noise to a level that made the mojo a great desk top dac. So I decided to try and improve and came across upgrading the capacitors. Which I had a friend of mine do, and we relocated the charging port to the opposite side as the previous person who did the mod had the cables running through the micro charging port. Long story short I now have a worse noise with the bigger caps, and not sure what I am missing or what needs to happen to eliminate this noise? Any help or recommendations much appreciated. Thanks much
 
Oct 31, 2024 at 6:01 AM Post #42,840 of 42,916






Hi all. Had a friend of mine do this mod for after purchasing this dac that was connected to a 7.5v power supply. Immediately noticed noise and this thing sounds horrible and had noise so I purchased this 7.5v linear power supply and seemed to have reduced the noise to a level that made the mojo a great desk top dac. So I decided to try and improve and came across upgrading the capacitors. Which I had a friend of mine do, and we relocated the charging port to the opposite side as the previous person who did the mod had the cables running through the micro charging port. Long story short I now have a worse noise with the bigger caps, and not sure what I am missing or what needs to happen to eliminate this noise? Any help or recommendations much appreciated. Thanks much
Despite the "LPS" lettering on the back, it is not a Linear Power Supply. this one is an SMPS (switched mode power supply).
But fret not! SMPS are better than LPS.
To do the ultimate, buy a battery from ebay or aliexpress, take out everything you have done, and use it in factory mode.
 
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