Jump to content

Recommended Posts

I have a Chord Mojo and love the sound. I want to make it more agreeable as a Table Top desktop D/A Converter. To that end I would like to share ideas about how to do just that.

 

My system is as such: Auralic Aries Mini --> Chord Mojo --> Integrated Amp. In this configuration, when I connect a standard cheap 5v/1a SMPS to the Mojo there is a hum through the system. Also, when I connect the USB out of the Aries Mini to the Mojo there is a hum and noise. I believe these are present because the Mojo isn't galvanically isolated.

 

In order to remove the noise and hum I'm hoping either or both of the two will do the trick.

 

  1. Intona USB Isolator
  2. iFi iPower 5v/1a or a Linear Power Supply

 

I imagine others are experiencing noise and hum with the Mojo due to it's portable design.

 

Being that I love the sound of the Mojo I want to get it dialed in for table top use.

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment

I imagine others are experiencing noise and hum with the Mojo due to it's portable design.

 

I'm using a Mojo in my primary system. No noise or hum at all - just the lowest noise floor I've heard from any DAC that I've ever owned.

 

Mojo is being fed by a microRendu.

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment

Good to hear kennyb123,

Are you using the Mojo on battery power, with 5v A/C or with any other filteration devices?

 

HiOnHiFi

 

I'm using a Mojo in my primary system. No noise or hum at all - just the lowest noise floor I've heard from any DAC that I've ever owned.

 

Mojo is being fed by a microRendu.

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment
Good to hear kennyb123,

Are you using the Mojo on battery power, with 5v A/C or with any other filteration devices?

 

The Mojo is always connected to a charger. I use the charger that shipped with an iPhone.

 

The charger had been plugged into a separate outlet. My audio system is on its own dedicated circuit.

 

You mentioned using a "standard cheap 5v/1a SMPS" to power the Mojo. That SMPS may be your source of noise. Try a different charger.

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment

I see. Thank you.

 

Thomas

 

The Mojo is always connected to a charger. I use the charger that shipped with an iPhone.

 

The charger had been plugged into a separate outlet. My audio system is on its own dedicated circuit.

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment

Drew from Moon Audio recommended to a friend that he use the Anker Poweport+ 1 to charge the Mojo. Another thing you can try.

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment

I wonder if OP has a ground loop somewhere. Is your Auralic also on the dedicated audio system circuit? If not, you should try to plug the Auralic and the Mojo charger to the dedicated audio system circuit and see if the hum goes away. If it does, it's a ground loop.

Link to comment

I had a ground loop with this system;

Aries Mini(USB) --> (cheap Raspberry Pi2 SMPS) Mojo (RCA) --> Placette Audio Passive LineStage(RCA) --> ModWright KWA-100

 

I do not have a ground loop that I can detect with this system;

Aries Mini(Optical) --> (Apple iPhone 5v/1a Charger) Mojo(RCA) --> Almarro A318B

 

 

I do not have a dedicated audio circuit in my system and so wouldn't be able to test the lines in that fashion.

 

I wonder if OP has a ground loop somewhere. Is your Auralic also on the dedicated audio system circuit? If not, you should try to plug the Auralic and the Mojo charger to the d edicated audio system circuit and see if the hum goes away. If it does, it's a ground loop.

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment
Drew from Moon Audio recommended to a friend that he use the Anker Poweport+ 1 to charge the Mojo. Another thing you can try.

 

That Anker PowerPort+1 outputs DC Output :5 V - 3 A which is more than the Mojo requires. Are you sure it's the PowerPort +1 and not the PowerPort 5 I've seen recommended on headfi?

 

I tried an iPhone 5v/1a adapter, using the optical output along with a different integrated amp eliminated the detectable hum and noise. Since the Mojo isn't galvanically I imagine there is still ground noise which can be addressed with a USB ISOLATOR like the Intona device, this according to the DAC's designer.

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment
That Anker PowerPort+1 outputs DC Output :5 V - 3 A which is more than the Mojo requires. Are you sure it's the PowerPort +1 and not the PowerPort 5 I've seen recommended on headfi?

 

No clue as I'm just relaying what a friend said. The PowerPort 5 has 5 ports, so I imagine one would go with one of those if they needed more ports than the +1 offers,

 

I tried an iPhone 5v/1a adapter, using the optical output along with a different integrated amp eliminated the detectable hum and noise. Since the Mojo isn't galvanically I imagine there is still ground noise which can be addressed with a USB ISOLATOR like the Intona device, this according to the DAC's designer.

 

I think you just have something wrong in your system that's causing a ground loop. I get no hum whatsoever with my Mojo - it's as quiet as I've ever heard.

 

And just because there isn't galvanic isolation that doesn't necessarily mean there will be more likelihood that there will be a hum. Most DACs aren't galvanicaly isolated and yet it's rare to hear complaints about hum. Though galvanic isolation might help in your case where clearly something is amiss.

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment

I do not have a ground loop that I can detect with this system;

 

I'm confused, You reported having a hum in the first post. Ground loops are the most common cause of hums.

.

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment
No clue as I'm just relaying what a friend said. The PowerPort 5 has 5 ports, so I imagine one would go with one of those if they needed more ports than the +1 offers,

 

I think you just have something wrong in your system that's causing a ground loop. I get no hum whatsoever with my Mojo - it's as quiet as I've ever heard.

 

And just because there isn't galvanic isolation that doesn't necessarily mean there will be more likelihood that there will be a hum. Most DACs aren't galvanicaly isolated and yet it's rare to hear complaints about hum. Though galvanic isolation might help in your case where clearly something is amiss.

The PowerPort 5 was "tested" by a user over on the Chord Mojo thread at HeadFi.org as being the quietest power supply of the ones he tested.

 

My system has been in flux lately and the noise and hum are present when I sub in this or that amp or preamp into the system. Presently as I stated previously, there is no agregious noise and no hum in my system. However, from all that I've read on the Mojo thread @ HeadFi.org, on which the Mojo's designer Rob Watts posts regularly, there is noise on the ground anytime a PC or Audio Processor like an Aries Mini is connected to the system. So, the way I understand it is that unless the ground plane is dealt with, their will be noise. It may not be immediately noticeable as noise however...

 

The designer states this about ground noise:

isolating the USB really helps; its smoother (lower RF noise) and with much better sound stage depth (this is normally an indication of correlated noise degrading small signal fundamental linearity - so as the PC is processing the data, it is adding audio related in-band noise into the ground, so isolating the ground stops this).

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment
So, the way I understand it is that unless the ground plane is dealt with, their will be noise. It may not be immediately noticeable as noise however...

 

Yes the Mojo, like every other DAC, will benefit from the best possible USB source. That's even true of Chord's galvanically isolated DACs, but to a lesser degree.

 

It becomes more about squeezing out the best sound that eliminating obvious noise problems.

 

A microRendu feeding a Mojo will result in absolutely stunning sound quality.

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment

My Mojo is as quiet as a nail. On charger(apple's little cube) or off. No fancy cables.

My preferred way to send a signal to it via spdif optical cable, with my good old Airport Express or mac. The airport express is 12 years old now.

Nevertheless, occasionally I do use usb signal out of old pc laptop, MacBook or even iPad.

Now I do have the 2Qute permanently connected to my main system, but before that, I used Mojo for about 7 month and never had any hum or noise, nothing but pristine and beautiful sound.

my > overly > fancy > system > with > directional > interconnects > powered > by > ego & linear fusion reactor

Link to comment

Now I do have the 2Qute permanently connected to my main system, but before that, I used Mojo for about 7 month and never had any hum or noise, nothing but pristine and beautiful sound.

 

How big of an upgrade did you get after making this change?

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment
How big of an upgrade did you get after making this change?

 

Main gain to me was the convenience of 2Qute being a permanent DAC, unlike Mojo that I'd disconnect to take with me in the morning and connect back as soon as I return from work.

Soundwise, may be 10-15%. Spent two nights doing critical/blind comparison on music I'm intimately familiar with, mostly Opera, Classical, Jazz. To my ears Mojo is just as good, which is incredible considering it cost just 1/3 of 2Qute.

 

I still use Mojo daily at work or with my desktop late at night, but 2Qute feeds the main system -> speakers.

 

Both are amazing, they let me forget about them and enjoy music. That's all I ever wanted.

my > overly > fancy > system > with > directional > interconnects > powered > by > ego & linear fusion reactor

Link to comment
Both are amazing, they let me forget about them and enjoy music. That's all I ever wanted.

 

Thank you very much for that reply.

Digital:  Sonore opticalModule > Uptone EtherRegen > Shunyata Sigma Ethernet > Antipodes K30 > Shunyata Omega USB > Gustard X26pro DAC < Mutec REF10 SE120

Amp & Speakers:  Spectral DMA-150mk2 > Aerial 10T

Foundation: Stillpoints Ultra, Shunyata Denali v1 and Typhon x1 power conditioners, Shunyata Delta v2 and QSA Lanedri Gamma Revelation and Infinity power cords, QSA Lanedri Gamma Revelation XLR interconnect, Shunyata Sigma Ethernet, MIT Matrix HD 60 speaker cables, GIK bass traps, ASC Isothermal tube traps, Stillpoints Aperture panels, Quadraspire SVT rack, PGGB 256

Link to comment
Main gain to me was the convenience of 2Qute being a permanent DAC, unlike Mojo that I'd disconnect to take with me in the morning and connect back as soon as I return from work.

Soundwise, may be 10-15%. Spent two nights doing critical/blind comparison on music I'm intimately familiar with, mostly Opera, Classical, Jazz. To my ears Mojo is just as good, which is incredible considering it cost just 1/3 of 2Qute.

 

I still use Mojo daily at work or with my desktop late at night, but 2Qute feeds the main system -> speakers.

 

Both are amazing, they let me forget about them and enjoy music. That's all I ever wanted.

High accolades for the Mojo which supports Mr. Watts assertion that it can compete with much more expensive DAC's.

 

I recently tested the Mojo against the Aries Mini analog output (9018K2M). It was no contest, in my system the Mojo smokes the Aries Mini.

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment

A couple of things to try... (I own a MOJO for portable use, but have tried it with a home system as well).

 

1. Make sure you use a USB cable which does not have continuity from between the USB plug shells at both ends; recommended choice by me for a cable like this is the Curious. Many USB cables connect both ends of the plug shells to the shield, this creates a potential (and unneccessary) ground loop path in some situations).

 

2. Get a really good linear supply made for the MOJO. The better the supply, the better it will perform. Make sure the linear supply does not connect 0VDC to the AC ground.

 

By following the two steps, you will eliminate potential ground loop problems, and raise the performance of the MOJO substantially. As mentioned by others here, the USB source will also make a big difference, with the aforementioned µRendu being an obvious upgrade choice.

SO/ROON/HQPe: DSD 512-Sonore opticalModuleDeluxe-Signature Rendu optical with Well Tempered Clock--DIY DSC-2 DAC with SC Pure Clock--DIY Purifi Amplifier-Focus Audio FS888 speakers-JL E 112 sub-Nordost Tyr USB, DIY EventHorizon AC cables, Iconoclast XLR & speaker cables, Synergistic Purple Fuses, Spacetime system clarifiers.  ISOAcoustics Oreas footers.                                                       

                                                                                           SONORE computer audio

Link to comment
A couple of things to try... (I own a MOJO for portable use, but have tried it with a home system as well).

 

1. Make sure you use a USB cable which does not have continuity from between the USB plug shells at both ends; recommended choice by me for a cable like this is the Curious. Many USB cables connect both ends of the plug shells to the shield, this creates a potential (and unneccessary) ground loop path in some situations).

 

2. Get a really good linear supply made for the MOJO. The better the supply, the better it will perform. Make sure the linear supply does not connect 0VDC to the AC ground.

 

By following the two steps, you will eliminate potential ground loop problems, and raise the performance of the MOJO substantially. As mentioned by others here, the USB source will also make a big difference, with the aforementioned µRendu being an obvious upgrade choice.

Thanks Barrows. I'm replacing the Mojo, hopefully with another Chord but that's up in the air.

Thomas Turner

 

SPEAKERS - Snell Type C/V | PREAMP/DAC -  Project Pre Box S2 Digital  | SOURCE - Auralic Aries Mini | ROOM TREATMENT - LEDE, bass traps @ Rear of room, acoustic panels @ 1st reflections point: side walls | AMPLIFIER - Acurus A100

Link to comment

I'm using the Mojo as a digital preamp via an Audioquest 3.5mm to RCA adaptor and interconnects connected directly to the Power Amp of my Rega integrated amp because the back panel gives you that input option. Improvement over the line level setting going into one of the regular Rega inputs and using the Rega preamp for volume.

Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×
×
  • Create New...