building a digital rca coax to mini cable.. questions

[qusp]

the above suggestion makes no sense, if there is a way to autosense what type of input its getting, you would confuse the hell out of it and may end up feeding the raw digital data stream to the analogue input...... ouch
 
as for the pinout, yeah looks non-standard, either try it out, or wait for official release of the pinout. perhaps ask on facebook? and yes i know its not always that simple

 

[ClieOS]

Here is the one I built for HM801 digital-in, basically the TRS is ground-signal-ground. For what I know, the upcoming FiiO X3's digital out will likely be signal-signal-ground. You should figure out how the TRS is configured on the JH3A first before trying to build the cable.
 
 
Quote:

Just build myself a digital coax for HM801: Cardas GRLM RCA plug, Nexans RG179 75ohm coax, Neutrik 3.5mm plug.
 

 

 

[qusp]

looks like its a TRRS

 

[samsquanch]

yep, trrs.  The picture seems to show:
 
Tip: N/C (Probably Left Analog)
Ring 1: N/C (Probably Right Analog)
Ring 2: Shield
Sleeve: Data +

 

[Br777]

^ so does that mean it HAS to be TRRS?

 

[samsquanch]

If the picture from the JH3A thread is correct, then yes, it has to be a trrs connector.

 

[Br777]

Quote:

.....may end up feeding the raw digital data stream to the analogue input...... ouch

just out of curiosity, what would happen if you did this?
 
 

 

[Br777]

realtive to the suggestion that having 75ohm cable may not be necessary in my case, lets pretend i decide to use coax...is 75ohm resistance crucial?  what if i get coax cable that is different resistance?
 
what difference could one hear betweein using standard, and coax cable?
 
thanks

 

[High_Q]

http://en.wikipedia.org/wiki/Characteristic_impedance  enjoy!

 

[wdahm519]

Blank.

 

[Br777]

Quote:

http://en.wikipedia.org/wiki/Characteristic_impedance  enjoy!

 
 

- not a clue what any of that means...

 

[ClieOS]

Quote:

just out of curiosity, what would happen if you did this?

Some static noise. SPDIF signal is usually on 44.1kHz (red book CD standard) and up, so the main signal is out of audible range.
 
Quote:

- not a clue what any of that means...

This wiki is perhaps easier to understand.
 
For a very short cable (like within a few inches), you can probably get away with regular cable without any noticeable ill effect.

 

[samsquanch]

With a cable that is the wrong impedance, the signal may reflect from the receiving end back to the transmit, and possibly back yet again.  This will cause data loss, which may be barely noticeable, to intermittent noise, to signal drop out (think packets lost on an ethernet system).  But at the same time, your connectors must also be of the proper impedance, and since "true" 75 ohm RCA's are rare, and 75 ohm 3.5mm plugs probably don't even exist, it's moot to debate cable impedance, especially at that short of a distance.  Spdif should be run on BNC, but consumer level gear rarely uses them.

 

[Br777]

so i'm guessing with a digital signal its all or nothing.. in other words, if i wire this thing wrong i'll get nothing, and if i wire it right i'll get perfect sound, and there's no in between, such as wiring out of phase, or only getting one channel?

 

[samsquanch]

The internet is full of the rumor that digital is either perfect or not working, it's not true, reflections and interference are still an issue for digital signals just like they are for analog signals, sometimes more-so with bandwidth limitations of cables...
 
But, as long as you wire your connectors correctly, you probably won't notice any issues.