[Mython]

   
i thought i'd read somewhere in which mr watts preferred a toslink connection...but for what sort of purpose I'm not sure.

 
 
LOL - I reposted Rob's quote just 3 pages ago
 
 
 
Also discussed here:
 

 

   
 
Digital transmission is based on SPDIF standard which transmits data and clock information as an encoded signal usually using PCM, that information is decoded on the Mojo into data and clock signal so it's important that the encoded information be jittered free and not degraded over short distance.
 
The USB transmission on the other end is a device to device transmission mechanism using an encoding scheme and handshaking mechanism, it is usually stream based so more tolerant to poorer wire as frames are transmitted and decoded from the source to the target device. The target device will reconstruct the data and clock signal from the frame and then feed it to the DAC to be analog reconstructed and eventually band pass filtered to remove any residual high and low frequency signals out of the audio band.I still think you need to keep the USB cable short but it is more tolerant of longer lengths up to a limit.
 
To make a story short, the short USB cable is fine but an analog cable used as a digital one is just a bad idea. Again, that's just my opinion.

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

 
 
In addition to these quotes, there are a few other bits & pieces, on the topic, in post #3:
 
 

1. Informative posts by Rob Watts¬

                                                       Influences *upon* RF noise and *of* RF noise
 
 

1. Is one of the input types better than the others

 
 
 
 
but it's interesting to also note:
 

  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 

 

[canali]

hey Mython...lol...small world...but i didn't read it from you...i'd read it some 9-12 mo ago or something.
but had i been a consistent partcipant on this thread i would have noticed your contribution and so noted
it...so my bad...thanks for the info.
 
guess i'll pay penance by keeping my DF red a bit longer...

 

[maxh22]

@Torq @SearchOfSub Just ordered the Lifeatec cable. Will it report on the sound impressions when I get it.

 

[SearchOfSub]

I actually find my microusb cable to be quite smooth and transparent already. But if this raises the bar like you say it does, I'm going to order one soon.

Just one question, does the cable come with caps attached to it? it seems like optical cables need to be carefully watched after in order to preserve the sound quality. 

Yes, the Lifatec cable came with 2 caps attached on both ends.

 

[Wyd4]

From the Audeze Sine thread. Nice.

http://www.head-fi.org/t/793518/audeze-sine-series/1350#post_12629669

 
Happy to report that Mojo + Sine does in fact sound very very good.

 

[rynogee]

Did anyone find a short high quality L shaped (at both ends) USB OTG cable. Saw this but not sure it's any good/reputable http://www.ebay.com.au/itm/like/182092841149?lpid=107&chn=ps 

 

[Wyd4]

@Rob Watts
 
Thank you sir for the explanation of RF noise and Noise floor modulation.
 
I have no idea how audio equipment works.  I know what I like to hear.
 
I have always been a firm believer in analogue cables.  Scientifically, knowing nothing about audio, my brain could accept this as different materials have different conductivity.
 
However on the digital side, my brain struggled.  If the cable is good enough to allow the 1's and 0's to get from one end to the other with no packet loss, I was at a loss as to why one would be better than another.
 
I did a test with a friends dac.  Not a mojo but obviously point stands.  He had 2 cables, a cheap generic one and a more expensive shielded cable.
 
Blind testing I noted the expensive cable to be smoother, less bright.  This holds true to your explanation.
 
I thought I was losing my marbles, however it was literally a blind test with my friend in control of the cables etc.
 
I have since been looking for a cable for my mojo.

 

[canali]

no one has any insight into the eta for this?
 
and what of chord's customer service...i did hear from one person who was disappointed
ie tech support/followup from cust service...hopefully it was a one off.
 
Quote:

  any ETA on chord's new 'module' to reduce the added cable and make it similar in length to a smartphone
(sorry don't know the name of it...)

 

[Anwer]

How does the lifatec cable compare to the QED performance cable?

 

[Delayeed]

How does the lifatec cable compare to the QED performance cable?

Also intrested. Opinions of the QED reference also welcome

 

[x RELIC x]

@Rob Watts


Thank you sir for the explanation of RF noise and Noise floor modulation.

I have no idea how audio equipment works.  I know what I like to hear.

I have always been a firm believer in analogue cables.  Scientifically, knowing nothing about audio, my brain could accept this as different materials have different conductivity.

However on the digital side, my brain struggled.  If the cable is good enough to allow the 1's and 0's to get from one end to the other with no packet loss, I was at a loss as to why one would be better than another.

I did a test with a friends dac.  Not a mojo but obviously point stands.  He had 2 cables, a cheap generic one and a more expensive shielded cable.

Blind testing I noted the expensive cable to be smoother, less bright.  This holds true to your explanation.

I thought I was losing my marbles, however it was literally a blind test with my friend in control of the cables etc.

I have since been looking for a cable for my mojo.

Well, my take is that there are no 1's and 0's floating around. There are no magical virtual numbers, only different states in different mediums. On a magnetic hard drive it's positive or negative to represent a value (0 and 1 - on or off). In a cable it's current and voltage pulses, not virtual numbers, that travel down the copper. Everything we experience is still represented in the physical world by something in a certain state depending on the medium, so with this train of thought it is very easy to take the 'leap' that 'digital' signals (which really only means sampled data as opposed to continuous data) can and do become affected by other influences.

 

[music4mhell]

  @Rob Watts
 
Thank you sir for the explanation of RF noise and Noise floor modulation.
 
I have no idea how audio equipment works.  I know what I like to hear.
 
I have always been a firm believer in analogue cables.  Scientifically, knowing nothing about audio, my brain could accept this as different materials have different conductivity.
 
However on the digital side, my brain struggled.  If the cable is good enough to allow the 1's and 0's to get from one end to the other with no packet loss, I was at a loss as to why one would be better than another.
 
I did a test with a friends dac.  Not a mojo but obviously point stands.  He had 2 cables, a cheap generic one and a more expensive shielded cable.
 
Blind testing I noted the expensive cable to be smoother, less bright.  This holds true to your explanation.
 
I thought I was losing my marbles, however it was literally a blind test with my friend in control of the cables etc.
 
I have since been looking for a cable for my mojo.

Even i was not a believer of Cable
But after a lot of testing with my cheap micro usb cable, Amazon basics, monoprice and now with high quality silver cables, yes i can clearly say something is going on.
 
SQ is far better with high end good quality cables.
 
Now my last testing is to test between pure silver cable and 6N copper cables I have the silver, but will order copper one's soon.

 

[Wyd4]

Well, my take is that there are no 1's and 0's floating around. There are no magical virtual numbers, only different states in different mediums. On a magnetic hard drive it's positive or negative to represent a value (0 and 1 - on or off). In a cable it's current and voltage pulses, not virtual numbers, that travel down the copper. Everything we experience is still represented in the physical world by something in a certain state depending on the medium, so with this train of thought it is very easy to take the 'leap' that 'digital' signals (which really only means sampled data as opposed to continuous data) can and do become affected by other influences.

 
Hahah while I understand it is not literally 1 and 0, but in one way shape of form derived from that theory, on off, current pulses etc.
 
But to use the 1 and 0 in a literal sense, are you telling me say a copper cable may send 1 and 0, however a gold cable may send .5 and 0? (I know we aren't literally seeing numbers)
Or perhaps the entire 1 makes its way from one end to the other, however does so slower.  But wouldn't this mean ALL 1's do so slower?  If so what difference would this make?
 
I have always been of the opinion that better digital cables are better, but only in terms of bandwidth eg poor HDMI cable not capable of transmitting the data required to sustain 1080p for example (or 4k in todays world, man I am getting old )
 
To use the HDD as an example, positive and negative.  I store a movie.  I store the same movie on an SSD.  Both have ample cache/speed to deliver the movie file to my GFX card to be decoded and turned to video and then output to my monitor.  Both movies look and sound identical.  What differs between this example and your explanation?
 
I am not disagreeing with you as such, just interested. As to my lack of knowledge, all things would work out equal, whether it be all slower or all faster, unless there were some sort of change to digital data through introduction of something external or data loss entirely.
 
Baring in mind small words would be good as know nothing about electronics hahaha
 
 
*** EDIT *** Please note that I say the above, having heard first hand their is a difference, so not defying you in aid of an argument

 

[Torq]

How does the lifatec cable compare to the QED performance cable?

 
 

  Also intrested. Opinions of the QED reference also welcome

Are you talking about the QED USB cables vs. the Lifatec optical cable, or the QED Optical cables?
 
If we're comparing optical-to-optical, then on spec alone the Lifatec cables are in a different, higher, class.  And I mean that from a technical perspective not a musical one.  Generally when you measure optical cables, the spec tells you all you need to know (you care about bandwidth, attenuation and jitter), and in this case I don't know of another optical fibre product that out specs the Lifatec glass and that is available terminated for audio use.
 
They're also cheap, comparatively speaking.
 
But if you want listening impressions, I can't help you.   

 

[Torq]

   
Hahah while I understand it is not literally 1 and 0, but in one way shape of form derived from that theory, on off, current pulses etc.
 
But to use the 1 and 0 in a literal sense, are you telling me say a copper cable may send 1 and 0, however a gold cable may send .5 and 0? (I know we aren't literally seeing numbers)
Or perhaps the entire 1 makes its way from one end to the other, however does so slower.  But wouldn't this mean ALL 1's do so slower?  If so what difference would this make?
 
I have always been of the opinion that better digital cables are better, but only in terms of bandwidth eg poor HDMI cable not capable of transmitting the data required to sustain 1080p for example (or 4k in todays world, man I am getting old )
 
To use the HDD as an example, positive and negative.  I store a movie.  I store the same movie on an SSD.  Both have ample cache/speed to deliver the movie file to my GFX card to be decoded and turned to video and then output to my monitor.  Both movies look and sound identical.  What differs between this example and your explanation?
 
I am not disagreeing with you as such, just interested. As to my lack of knowledge, all things would work out equal, whether it be all slower or all faster, unless there were some sort of change to digital data through introduction of something external or data loss entirely.
 
Baring in mind small words would be good as know nothing about electronics hahaha

In computer-based digital systems, particularly storage, the data is transmitted with checksums, which allow for detection of errors, and also with re-transmit schemes so that when an error is detected the block or packet of data can be rejected and another copy is sent.
 
That doesn't happen with any digital audio standard, electrical or optical, except for with HDMI audio (which has it's own special set of issues).
 
There's NO error detection and NO re-transmit option.
 
With an error-corrected digital transmission a poor, or sub-spec (or run that is too long), cable will first result in slower transmission ... as more errors occur and have to be corrected and, eventually, will either overwhelm the error-correction mechanism, or simply fault out from too many errors per second to maintain a useful connection.
 
Remember that in "digital" systems, the ones and zeroes are simply modulated analog voltages.  Depending on the slew rate of the transceiver, and the capacitance of the conductive medium that joins them, it becomes progressively harder to delineate between a 0 (typically 0 volts) and a 1 (typically 5 volts).  At audio data rates this isn't too much of a problem, but at higher frequencies it rapidly becomes so.  You can wind up with a signal that looks, from the receiver's perspective, more like 1.5 volts and 3 volts (I'm exaggerating to make a point) - which is only 1/3rd the potential difference between 1 and 0 that the spec calls for ...
 
Different metals have different conductive properties (attenuation/resistance, capacitance).  Different dielectrics (the insulator on the cable) also have different properties.  And, most importantly, shielding has an effect on the cable too ... good and bad ... while it helps reject noise, it typically adds capacitance.  Depending on your circuit that may be irrelevant or it may be catastrophic.  These factors can exacerbate other issues.
 
In short, since digital audio standards are actually analog voltage modulations, with no error correction, and cables have the ability to capture, transmit and radiate/inject noise into a receiving circuit, there's a great deal of potential variance in any cable and any transmit/receive pairing.
 
One easy way around this is to use an optical connection; however, there is no such thing as a free lunch and there are issues here too.
 
Using a simple RAM buffer on the receiver, with an error-corrected/re-transmitting protocol, would fix most of the issues, at the cost of some playback/control latency.  Of course, again, there are no free lunches, and there are similar issues that can occur between such an internal RAM buffer than the sensitive electronics in, say, a DAC (especially on the analog side of the circuit).