[Sonic Defender]

Removed - no need to keep this circular discussion going. Cheers

 

[IamMathew]

Absolutely - but they are from the AP ADC itself. The APX555 - the most advanced Audio Precision - does not show ADC noise floor modulation with a single tone as it incorporates 4 ADC's, 2 two to measure the residual, and two to measure the fundamental. Stereophile does not have an APX555, and this will severely limit the measured performance. But even with the APX 555, the two tone intermod test shows noise floor modulation, but this entirely comes from the AP as you would need six ADC's to do this test properly.
Of course, Davina - my ADC project - does not suffer from noise floor modulation, so using a future Davina ADC would solve this measurement issue.

Oh, wait, hold your horses! You are replying to a simpleton (me) here!

So first they feed the Mojo digital signal from PC e.g., then Mojo converts signal and at the output of the Mojo, there's zero noise floor modulation, but they need to convert the analog signal back to digital to have it analysed by PC? And that AD conversion adds modulation of the noise floor?

The thing is, that their other measurements don't show this behaviour, Dragonfly Red for example: https://www.stereophile.com/images/816AQDragfig13.jpg https://www.stereophile.com/content...lack-usb-da-headphone-amplifiers-measurements Why would such a feature of their AD converter be apparent on Mojo and not on Dragonfly Red measurements?

Other thing about the Mojo measrument's that left me puzzled is how jagged the 1 kHz sinewave looks like.
The L and R channels are very close to each other, however.

 

[jarnopp]

Oh, wait, hold your horses! You are replying to a simpleton (me) here!

So first they feed the Mojo digital signal from PC e.g., then Mojo converts signal and at the output of the Mojo, there's zero noise floor modulation, but they need to convert the analog signal back to digital to have it analysed by PC? And that AD conversion adds modulation of the noise floor?

The thing is, that their other measurements don't show this behaviour, Dragonfly Red for example: https://www.stereophile.com/images/816AQDragfig13.jpg https://www.stereophile.com/content...lack-usb-da-headphone-amplifiers-measurements Why would such a feature of their AD converter be apparent on Mojo and not on Dragonfly Red measurements?

Other thing about the Mojo measrument's that left me puzzled is how jagged the 1 kHz sinewave looks like.
The L and R channels are very close to each other, however.

I don’t know how to read that (so hope Rob will answer), burns I do question your intent. For context, here is how John Atkinson characterized the sine wave measurements he took: “And with its high resolution and overall low level of noise, the Chord DAC's reproduction of undithered 16-bit data describing a sinewave at exactly –90.31dBFS was exemplary (fig.9),” (Read more at https://www.stereophile.com/content...ne-amplifier-measurements#CulgPbbxpX63L18h.99).

 

[Rob Watts]

I am in Asia at the moment, so when I get back (mid December) I will take and post some measurements using a APX555, which is fundamentally much more capable test gear. But to give you a flavor, here is Dave's -90.31 dB 24 bit data. This is about 3dB better than Mojo:

The undithered 16 bit data - and this was taken from the exact same unit that Stereophile did it's measurements from:

Mojo would be 3 dB worse than this. As you can see, it's perfectly clean, with just the ringing that must be there. But Stereophile's published review using their test gear from the identical unit shows a mess of noise.

If anybody wants other measurements using the APX555 just ask and I should be able to do them at the same time too.

 

[maxh22]

I am in Asia at the moment, so when I get back (mid December) I will take and post some measurements using a APX555, which is fundamentally much more capable test gear. But to give you a flavor, here is Dave's -90.31 dB 24 bit data. This is about 3dB better than Mojo:



The undithered 16 bit data - and this was taken from the exact same unit that Stereophile did it's measurements from:



Mojo would be 3 dB worse than this. As you can see, it's perfectly clean, with just the ringing that must be there. But Stereophile's published review using their test gear from the identical unit shows a mess of noise.

If anybody wants other measurements using the APX555 just ask and I should be able to do them at the same time too.

Hi Rob, would you be able to include a test of one of Mojo's competitors that you've purchased to showcase the differences?

 

[Rob Watts]

I have never bought other DAC's - I would not learn anything useful from the exercise.

 

[maxh22]

I have never bought other DAC's - I would not learn anything useful from the exercise.

I was referring to this:

I have had some of Mojo's competitors at my home, and was shocked at how badly they perform sonically; but at the end of the day, that's just my personal opinion.

But as regards measurements no you are incorrect - the key measurement that Mojo has over all other DAC's is lack of noise floor modulation, and this is - again in my opinion - highly audible.

I just wanted to see a comparison of measurements between Mojo and another similarly priced dac using your state of the art Apx555, it would be interesting to me and many others I'm sure, but if you no longer have that competitors dac then I understand.

 

[x RELIC x]

I was referring to this:



I just wanted to see a comparison of measurements between Mojo and another similarly priced dac using your state of the art Apx555, it would be interesting to me and many others I'm sure, but if you no longer have that competitors dac then I understand.

Is it not against Head Fi rules for a MOT to directly compare in detail about competitors products?

 

[maxh22]

Is it not against Head Fi rules for a MOT to directly compare in detail about competitors products?

Rob doesn't have to mention the name of said competitor, it can be named "Dac B" for example.

 

[x RELIC x]

Rob doesn't have to mention the name of said competitor, it can be named "Dac B" for example.

True.

 

[Light - Man]

But Chord say on a regular basis (on Head-Fi) that their DACs measure better than all the other DACs in the Universe and then on the other hand they can't back it up with any data because they have no other competitors DACs at hand to compare theirs against?

Is is not then just a truck of hot air?

 

[GrussGott]

Besides all of the measurements, I think it would be great if, at the next Head-Fi show, they'd get a panel of 20 people to blind test DACs and amps and post the results ... 3 different groups on 3 different days would be even better.

* Does any DAC/amp consistently get identified? ie., 70% of panelists correctly identified the Mojo
* Does any DAC/amp consistently get voted best? worst?
* Does any DAC/amp consistently get tagged with a sound signature? i.e., relaxed, detailed, wide sound stage, etc

Now THAT would be some killer data!

But most vendors would be terrified of such a study and likely wouldn't actively participate or sponsor it ... which should tell us all something.

 

[RiseFall123]

Hi,

Here I need help about these questions:

1 is the dac amp really too warm for hd650?

2 is the dac really make interences noise when near an iphone?

3 which cable to use apart the apple cck? I mean brand and model that you may advice me.

 

[SomeGuyDude]

Hi,

Here I need help about these questions:

1 is the dac amp really too warm for hd650?

2 is the dac really make interences noise when near an iphone?

3 which cable to use apart the apple cck? I mean brand and model that you may advice me.

1 Hell no

2 Yes

3 Not sure, I'll leave that for someone else

 

[x RELIC x]

Hi,

Here I need help about these questions:

1 is the dac amp really too warm for hd650?

2 is the dac really make interences noise when near an iphone?

3 which cable to use apart the apple cck? I mean brand and model that you may advice me.

1. Subjective.

2. Completely depends on the network and the cellular signal strength. I don’t get any noise on LTE but my 3G network is very noisy. Others report the opposite. Some will say yes and some will say no.

3. You can look at the third post of this thread for some recommendations. Not sure how relevant it is at this point but it may be helpful as a start.