[Br777]

Hi all
I plan to build a digital cable that has an RCA connector on one end, and a Mini plug on the other.
This will be used to feed a digital signal via the RCA to my jh3a via the mini plug.
 
I also plan to make a mini to mini for use with the upcoming fiio x3 to feed my 3A digitally (x3 has mini digital out, 3A has mini digital in)
 
here is a photo of rca to mini digital cable to give you an idea of what i'm talking about.
 

 
 
my questions:
 
How many wires does this require?
2?  1 signal and one ground?
or if its a stereo connector as above then it uses 3 wires? - Left and right are basically put together on the same signal path, and the 3rd is the ground wire?
Since the wire will be pretty short does it need to be 75 ohm, and shielded, or can i just use standard wire and braid/twist some it together?
 
thanks
 
 
 
 

 

[High_Q]

2.  One signal and ground since is for digital spdif.  Do you know which(L or R) is the signal?  Or is it a mono plug?  Interesting they are using mini as digital input.

 

[Br777]

thanks a lot
 
so what about this wire here.. its "coax wire"
this must be coax for a different application as it only has one conductor, and thus would not have a ground
 
i dont really understand  how "the signal" as you called it, would work in a cable like this.  I guess L vs R doesnt really make a difference since its all going to a single pole rca connector and its a digital signal
My only guess with that is that since its a digital signal, the dac does the job of seperating left and right. 
 
any idea about my other question reg. needing "coax/75ohm wire" vs just using normal single conductor wire and braiding it?

 

[High_Q]

No, its one conductor signal(spdif), L and R are 2 signal channels, 2 conductors, so it's like mono.  Is it two conductor(signal and ground) plug or 3 (stereo) for the JH3A?  You can twist or shield, your choice.  I don't know about the 75ohm.
 
Quote:

thanks a lot
 
so what about this wire here.. its "coax wire"
this must be coax for a different application as it only has one conductor, and thus would not have a ground
 
i dont really understand  how "the signal" as you called it, would work in a cable like this.  I guess L vs R doesnt really make a difference since its all going to a single pole rca connector and its a digital signal
My only guess with that is that since its a digital signal, the dac does the job of seperating left and right. 
 
any idea about my other question reg. needing "coax/75ohm wire" vs just using normal single conductor wire and braiding it?

 

 

[Br777]

ok, let me see if i get this..i get the feeling i did not understand... so in the cable above that i showed would transmit a mono signal? that doesnt make sense since that cable was specifically designed for a hifiman 801 (which has a dac) so was i correct in that the digital signal is not dependant on mono or stereo and gets sorted by the dac?
otherwise, how would that cable be wired to create stereo?
 
Is it two conductor(signal and ground) plug or 3 (stereo) for the JH3A? - i dont know, but again, if its going to a single rca... how does that work?
 
 

 

[High_Q]

The cable above is a mono cable. but the mini plug looks to be stereo.  
 
You have to find out what plug JH3A takes, stereo or mono.  If it takes stereo, only 2/3 contacts are used, signal and ground, and you have to know which is which, since you have to solder the wire to the right contact at the mini connector.  If mono, there shouldn't be a problem.  You said digital, that leads me to believe it is a coax, spdif connector from the digital source. That is one conductor signal so, it wouldn't make sense to have both stereo connections being used at the output would it?  

 

[Br777]

my confusion is the word mono...  your wiring explaination makes sense now, but the dac must take that "digital mono" signal and make it into stereo right?
clearly you would not buy a hifiman 801, feed it with a digital source and end up with a mono into your headphones right?
 
 
 

 

[High_Q]

So, you can have two types of spdif, optical or copper.  Thats just one signal(what I mean by mono), being fed to the DAC via the cable you are trying to create.  Then the DAC takes the signal converts it to Analog, and sends out multiple channel analog audio signal channels, in your case two analog channels from the DAC to Amp to the headphones.

 

[digger945]

I think the jh3a has just one mini jack that accepts both analog and digital coax to that same jack, unless the whole design has changed since last June, and it very well could have.
 
Br777,  spdif, whether coax or optical, contains both L and R within the signal. They alternate in a single data stream.

 

[samsquanch]

they might be doing a jumper between shield and sleeve to tell the device that it needs to start pumping spdif out.  whether that jumper is just a piece of wire, or a resistor would need to be known.

 

[samsquanch]

Also, since they're not following any dictated standards for 75 ohm data transmission, I wouldn't worry about 75 ohm cable.

 

[High_Q]

There must be a switch then.  It's not a conventional approach, but there is no reason why mini jack shouldn't work.
 
Quote:

I think the jh3a has just one mini jack that accepts both analog and digital coax to that same jack, unless the whole design has changed since last June, and it very well could have.
 
Br777,  spdif, whether coax or optical, contains both L and R within the signal. They alternate in a single data stream.

I don't know about alternating, but it is a single stream data.
 

 

[Br777]

well there's been on ongoing discusion in the JH3A thread about which cable to use in the context of: rca on one end, mini jack on the other for use with a digital signal being fed to the JH3A, and one thing thats been confusing everyone is what kind of mini jack is needed.. mono, strereo, or 4 conductor..
 
here is a snipped where it seems they may have established that  4 conductor is necessary, but i dont really get it and am not sure yet...
other peoples words are in blue
 
Quote:

Originally Posted by bneiderman 

Well, I emailed Jerry about the mini plug issue and here is a diagram/picture he sent me back (on a Sunday!). It is definitely 3 rings. I thought the 3 rings was required to run in analog but 1 for digital. I don't know much about this cable stuff but it looks like I need to talk to Blue Jeans about this.
 

My guess...and it's just a guess that it's a proprietary configuration required to support three different type of inputs:
 

• Analog stereo
• SPDIF digital
• Ambient microphone input (for pro applications)

 

[wdahm519]

Here's my guess:
 
From the stereo plug, run three wires -- Left, right, and ground.  Just merge the left and right into the single mono on the mono phono plug, and ground to ground.  Its all just bits and bites anyways.  The DAC doesn't care.

 

[Br777]

Quote:

Here's my guess:
 
From the stereo plug, run three wires -- Left, right, and ground.  Just merge the left and right into the single mono on the mono phono plug, and ground to ground.  Its all just bits and bites anyways.  The DAC doesn't care.

i'd love it if you were right.. i get the feeling the only way to figure this out is gonna be to try it.