[Roscoeiii]

For digital signals it is important to get am actually coax digital cable. 75 ohm. To use anything other than that is ridiculous.

 

[noobandroid]

For digital signals it is important to get am actually coax digital cable. 75 ohm. To use anything other than that is ridiculous.

some people don't go that specific, if it works, it works

 

[x RELIC x]

For digital signals it is important to get am actually coax digital cable. 75 ohm. To use anything other than that is ridiculous.

It's been covered to death earlier in the thread. The 75 Ohm rating and coaxial geometry is most beneficial at longer lengths and for electromagnetic shielding. It also prevents reflection in the cable, but again, at these lengths it shouldn't matter. When using the cable mentioned it's just copper transmitting the signal with a separate ground. It's not 'optimal' but it works and if there is a difference it's barely audible, if at all. I've tested it in depth.

Of course here is a link to a proper coaxial cable that's not overpriced to use with the Mojo. This is actually what I recommend, but if a user wants to be cheap then the 3.5mm stereo interconnect mentioned earlier does work and it sounds fine.

Short 3.5mm Coaxial Cable

If purchasing this you should contact the seller and let them know what source device plug you need.

 

[sabloke]

Impedance on a 10cm cable makes bugger all difference. To believe otherwise is indeed ridiculous.

 

[Mython]

 

For digital signals it is important to get am actually coax digital cable. 75 ohm. To use anything other than that is ridiculous.

.... if a user wants to be cheap then the 3.5mm stereo interconnect mentioned earlier does work and it sounds fine.
 

 

  Impedance on a 10cm cable makes bugger all difference. To believe otherwise is indeed ridiculous.

 
 
Some people like to be cheap.
 
Others like to be ridiculous.
 
Some like to be both cheap & ridiculous.
 
 
I try not to judge

 

[deuter]

It's been covered to death earlier in the thread. The 75 Ohm rating and coaxial geometry is most beneficial at longer lengths and for electromagnetic shielding. It also prevents reflection in the cable, but again, at these lengths it shouldn't matter. When using the cable mentioned it's just copper transmitting the signal with a separate ground. It's not 'optimal' but it works and if there is a difference it's barely audible, if at all. I've tested it in depth.



Of course here is a link to a proper coaxial cable that's not overpriced to use with the Mojo. This is actually what I recommend, but if a user wants to be cheap then the 3.5mm stereo interconnect mentioned earlier does work and it sounds fine.



Short 3.5mm Coaxial Cable



If purchasing this you should contact the seller and let them know what source device plug you need.

 


Given the rf noise issues and shielding requirements , should I get a dap with optical out instead? The jitter rejection in Mojo is up to mark ?

 

[NaiveSound]

Is optical better to use with mojo? Or is coax?

 

[Mython]

Is optical better to use with mojo? Or is coax?

 
No offence, mate, but how many times have you asked this question?

 

 

[NaiveSound]

I just can't tell a difference, I like to know what others hear, I'm Interested in their opinion, and so I ask from time to time and not always do the same people answer... I see you stuck along tho

 

[x RELIC x]

It's been covered to death earlier in the thread. The 75 Ohm rating and coaxial geometry is most beneficial at longer lengths and for electromagnetic shielding. It also prevents reflection in the cable, but again, at these lengths it shouldn't matter. When using the cable mentioned it's just copper transmitting the signal with a separate ground. It's not 'optimal' but it works and if there is a difference it's barely audible, if at all. I've tested it in depth.



Of course here is a link to a proper coaxial cable that's not overpriced to use with the Mojo. This is actually what I recommend, but if a user wants to be cheap then the 3.5mm stereo interconnect mentioned earlier does work and it sounds fine.



Short 3.5mm Coaxial Cable



If purchasing this you should contact the seller and let them know what source device plug you need.

 


Given the rf noise issues and shielding requirements , should I get a dap with optical out instead? The jitter rejection in Mojo is up to mark ?

Jitter is handled very well on the Mojo. Rob has posted about it earlier. Basically he says that unless the jitter is extraordinarily terrible the source won't matter for jitter.

 

[Mython]

  Just to make it 100% clear - the USB input will measure absolutely identically to the coax or optical inputs if the USB data is bit perfect.
 
I have set up my APX555 so that it uses the USB via ASIO drivers, and I get exactly the same measurements on all inputs - 125 dB DR, THD and noise of 0.00017% 3v 1k 300 ohms. I have done careful jitter analysis, FFT analysis down to Mojo's -175dB noise floor, and can measure no difference whatsoever on all inputs (with the APX always grounded on the coax).
 
If somebody does measure a difference its down to mangled data on the USB interface (or perhaps poor measuring equipment - Mojo is way better than most test equipment). Mojo can't convert 16 bit data back to 24 bit....
 
Rob 

 

[x RELIC x]

To expand Rob's posts on cables and jitter in the thread....... Bold emphasis added by me.

Just to clarify:

1. SPDIF decoding is all digital within the FPGA. The FPGA uses a digital phase lock loop (DPLL) and a tiny buffer. This re-clocks the data and eliminates the incoming jitter from the source. This system took 6 years to perfect, and means that the sound quality defects from source jitter is eliminated. How do I know that? Measurements - 2 uS of jitter has no affect whatsoever on measurements (and I can resolve noise floor at -180dB with my APX555) and sound quality tests against RAM buffer systems revealed no significant difference. You can (almost) use a piece of damp string and the source jitter will be eliminated.

2. USB is isochronous asynchronous. This means that the FPGA supplies the timing to the source, and incoming USB data is re clocked from the low jitter master clock. So again source jitter is eliminated.

So does this mean that any digital cable will do?

Sadly no. Mojo is a DAC, that means its an analogue component, and all analogue components are sensitive to RF noise and signal correlated in-band noise, so the RF character of the electrical cables can have an influence. What happens is random RF noise gets into the analogue electronics, creating intermodulation distortion with the wanted audio signal. The result of this is noise floor modulation. Now the brain is incredibly sensitive to noise floor modulation, and perceives this has a hardness to the sound - easily confused as better detail resolution as it sounds brighter. Reduce RF noise, and it will sound darker and smoother. The second source is distorted in band noise, and this mixes with the wanted signal (crosstalk source) and subtly alters the levels of small signals - this in turn degrades the perception of sound stage depth. This is another source of error for which the brain is astonishingly sensitive too. The distorted in band noise comes from the DAP, phone or PC internal electronics processing the digital data, with the maximum noise coming as the signal crosses through zero - all digital data going from all zeroes to all ones. Fortunately mobile electronics are power frugal and create less RF and signal correlated noise than PC's. Note that optical connection does not have any of these problems, and is my preferred connection. 

Does this mean that high end cables are better? Sadly not necessarily. What one needs is good RF characteristics, and some expensive cables are RF poor. Also note that if it sounds brighter its worse, as noise floor modulation is spicing up the sound (its the MSG of sound). So be careful when listening and if its brighter its superficially more impressive but in the long term musically worse. At the end of the day, its musicality only that counts, not how impressive it sounds.         

Rob

Clock jitter is timing uncertainty (or inaccuracy) on the main clock that is feeding the digital outputs. Its often expressed as cycle to cycle jitter as an RMS figure, but can be total jitter which includes low frequency jitter too. Total jitter is the most important specification. If you want here is a good definition:

https://en.wikipedia.org/wiki/Jitter

As you can see, the jitter subject can get complicated and its often abused by marketing...

But with all of my DAC's you do not need to worry at all about source jitter, so all of the above AK numbers are fine. So long as its below 2uS (that is 2,000,000 pS) you are OK, and nobody has jitter that bad!

Rob

That is not the case with Chord's windows drivers. If faulty data is sent through, then the DAC requests a repeat, and so ensures perfect data transfer.

It is possible with all other OS; but having said that, the data failure rate is very low (otherwise DoP would not work).

The USB connection making a difference to the sound is not data related - its down to RF and correlated noise (not jitter as this is completely removed too) - take a look at my previous posts if you are interested. 

Rob

The reasons why sources and digital interconnects sound different are well understood - see some of my posts. In a nutshell it is not jitter (all my DACs are source jitter intolerant) but down to RF noise and distorted currents from the source flowing into the DAC's ground plane. The RF noise inter-modulates with the analogue electronics, creating random noise as a by product, which creates noise floor modulation, and that makes it sound brighter or harder. The correlated or distorted currents very subtly add or subtract to small signals, thus changing the fundamental linearity, which in turn mucks up depth perception.

But I also agree in that lots of people hear changes that are not there - I for one have never heard any difference with optical cables (assuming all are bit perfect) with my DAC's, but lots of folks claim big differences. Placebo, or listening with your wallet, plays a part here. Then there are cases of people preferring more distortion... Listening tests must be done in a very controlled and careful fashion, particularly if you are trying to design and develop things.

Rob

 

[Deftone]

I just can't tell a difference, I like to know what others hear, I'm Interested in their opinion, and so I ask from time to time and not always do the same people answer... I see you stuck along tho

 
if you cant hear a difference then use either LOL

 

[wahsmoh]

So what is wrong with a short toslink cable? Why all the hate on the Toslink? People talk about a BNC coax cable having the best connection. What is the truth behind that? Also I remember Theta, EAD, Madrigal Audio Labs (Mark Levinson) always used the AT&T ST Glass Coax since it was supposedly the superior connection at the time.
 
I heard if a Toslink cable is under 5 meters it will be fine. Any longer and it loses signal because the signal is carried on strands of plastic fibers and it loses signal strength after that length.

 

[xtr4]

I just can't tell a difference, I like to know what others hear, I'm Interested in their opinion, and so I ask from time to time and not always do the same people answer... I see you stuck along tho

 
Hi Naive, if it makes no difference to you and if you ask a subjective question like that, would the answers alter your opinion and perspective?
So if someone answers that Optical is the absolute best to their ears and the details, transparency and transient response trumps all other connections, would you consider going to the Optical route?
 
Btw, how's your cable shopping coming along? Did you manage to get the cable you wanted from Sysconcepts?