[Pulcino]

The issue here is the APx 555, in that the analogue oscillator is permanently on internally even when it's turned off - at least that's my supposition, as the APx 555 permanently creates analogue ground noise at 1kHz intervals and with careful measurements this signal will become visible. The issue is the APx 555 creates a 1kHz signal current, which flows out of the USB port, into the device under test (DUT) then back into the APx 555. Due to finite ground impedances, this creates an error voltage, which is then picked up by the APx 555 input ADC. But this error is nothing to do with Mojo 2, but a problem with the APx 555.

If you use optical from the APx 555 the problem disappears - as it's impossible to get ground currents flowing - or like @GoldenOne if you measure with USB galvanic isolation it will disappear too.

The real question is does this matter in real life? Absolutely not, as it's a specific measurement issue. I get annoyed when measurement types always assume their measurement gear is perfect, and all faults are due to the device under test. Life is very much more complicated than that.

Having said that, USB connection can have SQ issues, and it's all down to circulating ground currents (and galvanic isolation helps but doesn't entirely eliminate this issue - it works perfectly at low frequencies but does not work effectively above 1 GHz). But if you are using a battery powered source, there is no issue at all, as no ground currents can flow.



It's only a potential problem if there is a ground loop. I am surprised that Qutest would show a major difference with a USB to optical as Qutest is galvanically isolated. But optical is always the reference input; I have had many times heard no difference from optical with mains powered USB sources, but in other situations I have heard noticeable differences - it all depends upon the quality of the source and your set-up.



That's the residual noise shaper OP - and its entirely random with no distortion or signal related components, and it has zero noise floor modulation too as the noise is fixed. So it's not something to worry about.

Note when doing the noise floor modulation test the input to the ADC must be fixed and not auto-ranging, otherwise you will see false noise floor modulation due to the ADC and the measurement input stage noise floor modulation. Also the high resolution or sine wave accuracy mode needs to be on and fixed to the fundamental frequency.



Absolutely!

Hello Rob, as Poly is using the USB data connection and not toslink: Is it very close in terms of sound quality? You mentioned once a great implementation for USB is as good as a good toslink one.

 

[jarnopp]

Hello Rob, as Poly is using the USB data connection and not toslink: Is it very close in terms of sound quality? You mentioned once a great implementation for USB is as good as a good toslink one.

Rob didn’t work on Poly, as he has pointed out before, so he may not respond. But I will say, Poly is as good a source as I have ever heard Mojo (or Mojo2), both WiFi streaming and from the SD card.

 

[headfry]

Rob didn’t work on Poly, as he has pointed out before, so he may not respond. But I will say, Poly is as good a source as I have ever heard Mojo (or Mojo2), both WiFi streaming and from the SD card.

In my experience USB sounds great but my experience using the stock cable was poor sound quality (a good quality USB cable - Curious Hugo Link - with a Jitterbug sounds fantastic to me in my system). Of course there will always be those that say it's just 1's and 0's so don't fall for the "snake oil", they frequently say that any properly designed and manufactured USB cable will sound the same and that it either works or it doesn't, no shades of grey.

 

[Pulcino]

Hello Rob, as Poly is using the USB data connection and not toslink: Is it very close in terms of sound quality? You mentioned once a great implementation for USB is as good as a good toslink one.

Thank you

 

[Pulcino]

In my experience USB sounds great but my experience using the stock cable was poor sound quality (a good quality USB cable - Curious Hugo Link - with a Jitterbug sounds fantastic to me in my system). Of course there will always be those that say it's just 1's and 0's so don't fall for the "snake oil", they will say that any properly designed and manufactured USB cable will sound the same.

Yes, I have tested multiple USB cables in my stereo deck and fully agree. Going portable with high quality is my current challenge, so Poly via hotspot with iPhone 12 may be the solution. Limits me to AirPlay, so. I want to use Amazon music HD.

 

[headfry]

Yes, I have tested multiple USB cables in my stereo deck and fully agree. Going portable with high quality is my current challenge, so Poly via hotspot with iPhone 12 may be the solution. Limits me to AirPlay, so. I want to use Amazon music HD.

Of course Poly is a great solution and no doubt the very best possible sq - it would be mine if it weren't for the cost, then again I only use Mojo 2 on a desktop at home.

 

[Kentajalli]

Of course Poly is a great solution and no doubt the very best possible sq - it would be mine if it weren't for the cost, then again I only use Mojo 2 on a desktop at home.

OR . . . .
Get a used Android phone with a large screen and SD card capability.
Use it as a DAP only! meaning keep your iPhone as a phone, do not put a sim card into the Android phone, so you won't have RFI or EMI issues (put it on Plane Mode but enable wifi.
Use a cable to connect it to your Mojo2 - Bob's your uncle .....
Stream, play from SD card, youtube the lot at your command, will cost a quarter of a Poly.

 

[headfry]

OR . . . .
Get a used Android phone with a large screen and SD card capability.
Use it as a DAP only! meaning keep your iPhone as a phone, do not put a sim card into the Android phone, so you won't have RFI or EMI issues (put it on Plane Mode but enable wifi.
Use a cable to connect it to your Mojo2 - Bob's your uncle .....
Stream, play from SD card, youtube the lot at your command, will cost a quarter of a Poly.

The same thing can be done with an iPhone (using its internal storage though obviously), although depending on the cable used the sound quality can be very compromised (in my opinion and experience), back to original issue as far as sq is concerned.

 

[surfgeorge]

After a month's wait the Mojo 2 was finally delivered.
For reference, I have the original Mojo and a Hugo2Go and the Mojo 2 slots right in between them.
To me, the original Mojo is really musical and enjoyable especially in the midrange, with warm bass and sweet high. But compared to the Hugo 2 the sound is much more in your head, imaging is fuzzy and the stage feels more like a sound cloud. The music sounds right (which is a BIG achievement), but not as open or accurate as the Hugo 2.
The Hugo 2 is very precise, with much more definition, nuance and focus of all notes and elements. This shows in the whole frequency range, but especially in the bass which is so much more textured, defined and extended compared to the Mojo. Hugo 2's detail is excellent IMO, with cross-feed deactivated you get the most of it, even feeling the sound reflections of the venue where the music was recorded.

The Mojo 2 to me is a great blend of the Mojo and Hugo 2. It retains the more relaxed and sweet musical character of the original Mojo with a much more even presentation over the whole frequency range, good stage width, depth and imaging focus, and it even has some of the "room sound" effect of the Hugo 2. In this sense, where the Mojo 1 was distinctly different, the Mojo 2 is the little brother to the Hugo 2, overall softer and more relaxed, but with very similar core values of an even, precise and detailed music reproduction.
The cross feed and DSP functions are incredibly useful and IMO make the Mojo 2 an even more outstanding product.

I was really wondering how close the Mojo 2 would get to the Hugo 2 whether I might end up selling the Hugo 2.
I will keep the Hugo 2, since the level of clarity, openness, detail and precision it provides is still a significant step up from the Mojo 2. But I have to say the Mojo 2 is giving the H2 a run for it's money and it's sheer incredible how that little brick can sound so good, just like a sweeter and more relaxed version of the Hugo 2. And I can imagine that for sheer musical enjoyment, some people might even prefer it over the Hugo 2.

Well done @Rob Watts and Chord!

 

[rlanger]

Curious to hear what people think would be the ultimate headphone pairing with Mojo 2?

As higher-end headphones become easier and easier to drive, there's probably a lot of choice out there now. For example, Arya SE, LCD-X, HD800s, etc.

Obviously, there are better sources for the cans I mentioned, but that's not my question. The question is, if you were unable or unwilling to upgrade from Mojo 2, what would be your end-game headphones?

 

[Reactcore]

I have only One thing to say..
V V V V V V

 

[Slim1970]

After a month's wait the Mojo 2 was finally delivered.
For reference, I have the original Mojo and a Hugo2Go and the Mojo 2 slots right in between them.
To me, the original Mojo is really musical and enjoyable especially in the midrange, with warm bass and sweet high. But compared to the Hugo 2 the sound is much more in your head, imaging is fuzzy and the stage feels more like a sound cloud. The music sounds right (which is a BIG achievement), but not as open or accurate as the Hugo 2.
The Hugo 2 is very precise, with much more definition, nuance and focus of all notes and elements. This shows in the whole frequency range, but especially in the bass which is so much more textured, defined and extended compared to the Mojo. Hugo 2's detail is excellent IMO, with cross-feed deactivated you get the most of it, even feeling the sound reflections of the venue where the music was recorded.

The Mojo 2 to me is a great blend of the Mojo and Hugo 2. It retains the more relaxed and sweet musical character of the original Mojo with a much more even presentation over the whole frequency range, good stage width, deph and imaging focus, and it even has some of the "room sound" effect of the Hugo 2. In this sense, where the Mojo 1 was distinctly different, the Mojo 2 is the little brother to the Hugo 2, overall softer and more relaxed, but with very similar core values of an even, precise and detailed music reproduction.
The cross feed and DSP functions are incredibly useful and IMO make the Mojo 2 an even more outstanding product.

I was really wondering how close the Mojo 2 would get to the Hugo 2 whether I might end up selling the Hugo 2.
I will keep the Hugo 2, since the level of detail and precision it provides is still a significant step up from the Mojo 2. But I have to say the Mojo 2 is giving the H2 a run for it's money and it's sheer incredible how that little brick can sound so good, just like a sweeter and more relaxed version of the Hugo 2. And I can imagine that for sheer musical enjoyment, some people might even prefer it over the Hugo 2.

Well done @Rob Watts and Chord!

Agreed, the Mojo 2 indeed gives the Hugo 2 a run for it’s money. The EQ and other added features where enough to convince me I could live without my Hugo 2 so I sold it. The smaller footprint of the Mojo 2 is also a win. It’s a lot more portable.

 

[dsrk]

After a month's wait the Mojo 2 was finally delivered.
For reference, I have the original Mojo and a Hugo2Go and the Mojo 2 slots right in between them.
To me, the original Mojo is really musical and enjoyable especially in the midrange, with warm bass and sweet high. But compared to the Hugo 2 the sound is much more in your head, imaging is fuzzy and the stage feels more like a sound cloud. The music sounds right (which is a BIG achievement), but not as open or accurate as the Hugo 2.
The Hugo 2 is very precise, with much more definition, nuance and focus of all notes and elements. This shows in the whole frequency range, but especially in the bass which is so much more textured, defined and extended compared to the Mojo. Hugo 2's detail is excellent IMO, with cross-feed deactivated you get the most of it, even feeling the sound reflections of the venue where the music was recorded.

The Mojo 2 to me is a great blend of the Mojo and Hugo 2. It retains the more relaxed and sweet musical character of the original Mojo with a much more even presentation over the whole frequency range, good stage width, deph and imaging focus, and it even has some of the "room sound" effect of the Hugo 2. In this sense, where the Mojo 1 was distinctly different, the Mojo 2 is the little brother to the Hugo 2, overall softer and more relaxed, but with very similar core values of an even, precise and detailed music reproduction.
The cross feed and DSP functions are incredibly useful and IMO make the Mojo 2 an even more outstanding product.

I was really wondering how close the Mojo 2 would get to the Hugo 2 whether I might end up selling the Hugo 2.
I will keep the Hugo 2, since the level of detail and precision it provides is still a significant step up from the Mojo 2. But I have to say the Mojo 2 is giving the H2 a run for it's money and it's sheer incredible how that little brick can sound so good, just like a sweeter and more relaxed version of the Hugo 2. And I can imagine that for sheer musical enjoyment, some people might even prefer it over the Hugo 2.

Well done @Rob Watts and Chord!

Agreed, the Mojo 2 indeed gives the Hugo 2 a run for it’s money. The EQ and other added features where enough to convince me I could live without my Hugo 2 so I sold it. The smaller footprint of the Mojo 2 is also a win. It’s a lot more portable.

Hugo 3 may be around the corner

 

[hakunamakaka]

Curious to hear what people think would be the ultimate headphone pairing with Mojo 2?

As higher-end headphones become easier and easier to drive, there's probably a lot of choice out there now. For example, Arya SE, LCD-X, HD800s, etc.

Obviously, there are better sources for the cans I mentioned, but that's not my question. The question is, if you were unable or unwilling to upgrade from Mojo 2, what would be your end-game headphones?

The best sound that I've heard via Mojo Org was with Focal Utopia. If you are a bit tight on the budged I think Clear's should be considered too. Not as detailed as Utopia and has a bit of harshness in treble, but in terms of technical performance comes close to it. Very precise and impactful sound. I've heard Arya/HD800s and Clear bested both of these HP's to me, though Arya sounds amazing with ambient music. It should boil down to your preferences and taste in music

Another thing to note is that Mojo2 will drive Clear to it's full potential

 

[Derivative]

Hugo 3 may be around the corner

This makes sense - however I can see a price hike to distinguish it even further from Mojo 2...