Chord Mojo 2 Thread ___ [product released January 31, 2022 -- starting on page 95 of thread]

[lycos]

What about plugging the mojo into the dock? Could be your work environment disables the USB on the laptop when docked or even external devices when connected to the corporate network.

It still doesn't work.
Weirdly, it's working fine with Hugo2. I have sent email to Chord Support. Hopefully this can be resolved.

 

[hakunamakaka]

In terms of galvanic isolators there aren't many. Intona is the main company making them as the ifi iGalvanic is now discontinued. (Other companies like JCAT are actually using intona isolators in a different chassis).
But they're also quite pricey.

A decent filter like the iPurifier would also likely work quite well without costing as much as an isolator

Have you tested Intona products ? My laptops USB is awful...I'm aiming now for an easy/portable HP's rig. Lot's of hype on gustard u18, which is a bit different device, but goal is the same

 

[Derivative]

Absolutely not, there's a reason the intona is expensive.

Makes sense and I thought so. even the ifi iGalvanic is quite pricey. I would probably rather invest in a Poly if anything.

 

[GoldenSound]

Have you tested Intona products ? My laptops USB is awful...I'm aiming now for an easy/portable HP's rig. Lot's of hype on gustard u18, which is a bit different device, but goal is the same

I use the Intona 7055-C regularly both in my listening setup and when doing measurements.

 

[Nick24JJ]

Does using the optical connection overcome the USB problems and which are the downsides of using optical, if any?

 

[Kentajalli]

I've posted some measurements of the Mojo 2 here: https://goldensound.audio/2022/05/26/chord-mojo-2-measurements/

Couple key takeaways:

1) Amir's measurements show some issues that neither of the units I tested have. I've no idea if it was his unit or something in his setup, but both units I've tested performed better than shown in his measurements. I suspect it might be related to him not galvanically isolating the unit, as a portable device like this will be susceptible to a noisy source like a desktop PC.

2) If using the Mojo 2 with a PC, a galvanic isolator does improve performance. Whether it's worth the upgrade is up to you, but if you have a USB filter or isolator it's probably best to use it.

3) Desktop mode had effectively no impact on performance. Well done Chord!

Thanx for posting and doing the tests, I am sure Amir would be thrilled to read them and comment on them (you know what I mean).
Question though:
- I understand that including the noise from the source and its effects into lab results of a device may not be fair, but excluding them is equally not fair.
If a device is sensitive to external noise, then it should be mentioned. It should be easy to add a little RF into USB power lines and see the effects.
- At any rate, testing the device using all three digital inputs and comparing them should shine a light on the issue.
- It is well known that Amir does not really like Chord equipments, so seeing him dishing out praise for Chord is unusual!
He tries to pick points on Chord DACs and on your measuring techniques, and you on him, which is a healthy thing.
- It is good that both of you have found that the device performs very well objectively, but as I have always said, a lab test shows how well a device is made and if it is broken in any way. How much of these excellent lab results translates into good sound is a bit of a dark science. Surely a noise of floor of -150db compared to -130db should not subjectively make a difference and so on.
- What Amir (and now you) did not do, is to devise a method of testing the DSP function. Perhaps you could do a comparative measured test between say a Roon software EQ (same parameters) to Mojo2 internal DSP to see if we can see anything!

I personally use a simple common-mode rejector on +5V and ground built into my DIY USB cables for the same reason.


A simple Ferrite core cylinder. Data wires go through the centre, +5V and ground wires are looped on creating a CM rejector.

 

[hakunamakaka]

Does using the optical connection overcome the USB problems and which are the downsides of using optical, if any?

I think chord dac's underperform with USB input from noisy sources and optical is better with these dac's if source is not clean. With added DDC between my laptop & qutest and fed via optical differences were so large that you would think that qutest was broken before. Though Mojo showed little improvement compared to qutest, but I haven't tested it while it's connected to mains. I always used mojo as a portable dac/amp.

 

[purplehazed]

Does anyone know if the Mojo 2 would ever need more than 3A to drive inefficient headphones? I'm going to test a pair of Aeon 2 Noires with the Mojo 2 at a music store.
Is there a recommended low noise USB wall charger for the Mojo 2? Thank you.

 

[flyte3333]

1) Amir's measurements show some issues that neither of the units I tested have. I've no idea if it was his unit or something in his setup, but both units I've tested performed better than shown in his measurements. I suspect it might be related to him not galvanically isolating the unit, as a portable device like this will be susceptible to a noisy source like a desktop PC.

Just his jitter measurement?

What else from the ASR measurements is notably different to yours?

Not small differences but differences worth talking about.

And your measurement seems to show some form of noise floor modulation. @Rob Watts ?

 

[GoldenSound]

Just his jitter measurement?

What else from the ASR measurements is notably different to yours?

Not small differences but differences worth talking about.

And your measurement seems to show some form of noise floor modulation. @Rob Watts ?

Just his jitter measurement?

What else from the ASR measurements is notably different to yours?

Not small differences but differences worth talking about.

And your measurement seems to show some form of noise floor modulation. @Rob Watts ?

To test noise floor modulation you need to do it with a high level and low level signal.
A DAC might have no noise floor modulation but still show a different result when idle/doing nothing/off.
Especially in something like the mojo 2 or other portable devices where at least some stuff is probably turned off when inactive to save power.

The two main issues present on Amir's measurements were the >7khz noise, which was present on my units but went away when using optical or isolating the USB.
And then also some low level spurious content which disturbed the jitter and ultrasonic attenuation measurements. This issue was not present on either of my units.

I'm not sure what caused it, and it's not meant to be some jab at Amir. It could well be that he did nothing wrong and the unit he had just had some fault. I don't know.

 

[flyte3333]

I'm not sure what caused it, and it's not meant to be some jab at Amir. It could well be that he did nothing wrong and the unit he had just had some fault. I don't know.

May just be Mojo's very sensitive USB input (he didn't use Intona or test optical) and maybe he had an SMPS powering his unit too (could result in a double whammy)

Definitely agree with you, using an Intona or optical input is advised in desktop mode. Or battery operated Mojo2 with a battery powered source where there is no connection at all to AC.

I saw the same general differences measuring with Cosmos ADC. Even grounding the SMPS output powering Mojo2 made a noticeable difference... but then overall system grounding comes into play.

 

[ubs28]

The USB on the Mojo is fine. It was originally designed for portable devices like smartphones, which are not noisy sources.

 

[jarnopp]

Does anyone know if the Mojo 2 would ever need more than 3A to drive inefficient headphones? I'm going to test a pair of Aeon 2 Noires with the Mojo 2 at a music store.
Is there a recommended low noise USB wall charger for the Mojo 2? Thank you.

I don’t know the current answer, but I use Mojo 2 daily with the Noire’s and it’s a fantastic - I would say perfect - pairing for a portable setup and there has never been an issue with power at all. I use crossfeed for these but no. Ed for any DSP to my ears.

 

[purplehazed]

I don’t know the current answer, but I use Mojo 2 daily with the Noire’s and it’s a fantastic - I would say perfect - pairing for a portable setup and there has never been an issue with power at all. I use crossfeed for these but no. Ed for any DSP to my ears.

It's great to hear that they pair well. I frankly plan to use the Mojo 2 exclusively for desktop use, I'm wondering if the Mojo can draw more power to deliver to the amplification stage when connected to an USB charger than when it's just drawing power from the battery.
It's really difficult to find recommendations for a low-noise USB charger, it's either crap or really expensive audiophile power supplies.

 

[Nick24JJ]

My plan is to use my Mojo 2 as a desktop device. I will connect it to my desktop computer - when I will buy it, around December, 2022 - using an optical cable like this one.
When I will be listening from my desktop computer, the Mojo 2 will be battery operated. When I will shut it down, I will plug it in to charge until the next day.

1) Can you, please, suggest a good charger with an on/off button, so that I will not plug/unplug it?
2) How far from my desktop computer, which will be an open-air rig, would you suggest me to place the Mojo 2?

Thank you