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PostPosted: Fri Dec 17, 2021 11:27 am 

Joined: Thu Jun 18, 2020 3:35 pm
Posts: 8
Hello,

I have a ESI Juli@ soundcard which has balanced jack 6.3 outputs and also unbalanced RCA outputs. I need to run around 30 meters of cable from the soundcard to the MPX input of my transmitter.
I know this is a little bit long but I do not seem to have another option at this point.
The input connector on my transmitter is a BNC connector.

Which outputs would be best to use (6.3 jacks or RCA)? And which kind of coaxial cable would be best (RG213?)

Thanks in advance


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PostPosted: Fri Dec 17, 2021 8:41 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
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Use RCA, No point of balanced since your MPX input is not balanced. Also for Juli@'s balanced output you need custom cables! (3pin)
For 30m cable you really need good one. Just look to be 50ohm, also to be double shielded.
Cables for 5GHz WiFfi can also be good. Just dont waste money on that cable.

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PostPosted: Sat Dec 18, 2021 12:41 pm 

Joined: Thu Jun 18, 2020 3:35 pm
Posts: 8
Quote:
Use RCA, No point of balanced since your MPX input is not balanced. Also for Juli@'s balanced output you need custom cables! (3pin)
For 30m cable you really need good one. Just look to be 50ohm, also to be double shielded.
Cables for 5GHz WiFfi can also be good. Just dont waste money on that cable.
Thanks for the quick response!
Is there a specific reason to not use the 6.3 jacks with just a mono plug (unbalanced) at the end of the cable?

https://messi.it/dati/immagini/RG213MIL ... N-Ante.jpg

Would this cable be good enough? Or would you recommend an even better coaxial cable?


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PostPosted: Sat Dec 18, 2021 1:00 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4151
Quote:
Quote:
Use RCA, No point of balanced since your MPX input is not balanced. Also for Juli@'s balanced output you need custom cables! (3pin)
For 30m cable you really need good one. Just look to be 50ohm, also to be double shielded.
Cables for 5GHz WiFfi can also be good. Just dont waste money on that cable.
Thanks for the quick response!
Is there a specific reason to not use the 6.3 jacks with just a mono plug (unbalanced) at the end of the cable?

https://messi.it/dati/immagini/RG213MIL ... N-Ante.jpg

Would this cable be good enough? Or would you recommend an even better coaxial cable?
RG213U. That cable is older then me, and i am old. There is better cables today and not that thick. It will be hard to mount RCA on that too. Double shielded RG58 like, might be better idea.
Balanced output on Juli@ does not use 'mono' plug. There is 3pins inside. It must be since it's balanced output. You can convert those 3 pins to 2 by connecting ground with one hot pin but what's the point since you again start with unbalanced. Also signal is +4dB more then RCA so sometimes it's too much for MPX input on transmitter (depending on transmitter).
I would also consider to put that PC near transmitter, and with another PC from studio send audio over LAN.

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PostPosted: Sat Dec 18, 2021 1:40 pm 

Joined: Wed Dec 04, 2019 6:12 am
Posts: 28
NEVER connect one of the hot pin to the ground on a balanced OUTPUT!

It only needs when you have an unbalanced source and need to connect to a balanced INPUT.


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PostPosted: Sat Dec 18, 2021 3:55 pm 

Joined: Thu Jun 18, 2020 3:35 pm
Posts: 8
Quote:
Quote:
Quote:
Use RCA, No point of balanced since your MPX input is not balanced. Also for Juli@'s balanced output you need custom cables! (3pin)
For 30m cable you really need good one. Just look to be 50ohm, also to be double shielded.
Cables for 5GHz WiFfi can also be good. Just dont waste money on that cable.
Thanks for the quick response!
Is there a specific reason to not use the 6.3 jacks with just a mono plug (unbalanced) at the end of the cable?

https://messi.it/dati/immagini/RG213MIL ... N-Ante.jpg

Would this cable be good enough? Or would you recommend an even better coaxial cable?
RG213U. That cable is older then me, and i am old. There is better cables today and not that thick. It will be hard to mount RCA on that too. Double shielded RG58 like, might be better idea.
Balanced output on Juli@ does not use 'mono' plug. There is 3pins inside. It must be since it's balanced output. You can convert those 3 pins to 2 by connecting ground with one hot pin but what's the point since you again start with unbalanced. Also signal is +4dB more then RCA so sometimes it's too much for MPX input on transmitter (depending on transmitter).
I would also consider to put that PC near transmitter, and with another PC from studio send audio over LAN.
Thanks for the clear explanation, it's gonna be RCA then.

I was thinking to buy a cable from this site: https://www.handelsondernemingveenstra. ... coax-kabel (its dutch). RG50 seems hard to find here.
Is there a cable you could recommend me from this site?

I'll probably buy one with 2 BNC connectors and add a RCA -> BNC adapter which I already have, if that's a good idea..

Thanks in advance


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PostPosted: Sat Dec 18, 2021 8:23 pm 
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Joined: Tue Mar 17, 2009 2:56 pm
Posts: 4151
https://www.handelsondernemingveenstra. ... -2007.html
https://www.handelsondernemingveenstra. ... -flex.html
Those are kinda nice. I hope it's real copper.

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PostPosted: Sat Dec 18, 2021 11:13 pm 
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Joined: Wed Nov 08, 2017 3:16 pm
Posts: 191
Quote:
I would also consider to put that PC near transmitter, and with another PC from studio send audio over LAN.
i second the idea of placing the PC (with ST) in the TX shack and streaming your unprocessed digital audio via PTP-WLAN or LAN.
you will incur additional latency in this manner but it will be more reliable, stable and robust than dealing with an analog unbalanced cable of 100 feet that will undoubtedly pick up some analog noise.


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PostPosted: Wed Dec 22, 2021 10:08 am 

Joined: Wed Apr 06, 2016 4:06 am
Posts: 38
RG-213 is roughly the equivalent of old mil-spec RG-8. Great if you are running an 1000-watts RF output with a HF (shortwave) amateur radio station. Probably way more than anyone needs for transporting audio, but otherwise, yeah you could use it. ;)

I dabble in RF more than audio. Audio frequencies are *very low* compared to most common RF purposes. For example a 20000Hz analog signal is 20KHz. Coaxial loss at 20KHz tends to be minuscule even at moderate distances with all but the most garbage of feedline.

You can use a RF coax loss calculator for a general idea of loss if truly interested. For example, if again using 20000Hz audio, enter the frequency as .02MHz. Load is 1:1 due to both connected devices being approximately 50 ohms. Select the coax type, then look at the matched loss.

https://www.qsl.net/co8tw/Coax_Calculator.htm

Loss at 20KHz for a 90m run of Belden RG-58 is 0.148dB. Probably not worth concerning yourself assuming you are using coax of similar quality, be it Belden, Davis, etc. You likely will fair better with RF or CATV suppliers instead of audio suppliers for coax pricing. Also, if you are buying a cable made to your length, ask for Amphenol or similar quality connectors to be installed.

As noted by Bojcha, shielding can be a concern if in an environment with lots of EMI/RFI. Common RG-58 is single-shielded design. If needing to deal with EMI/RFI mitigation, a dual- or even quad-shielded coax can be used.

With EMI/RFI noted, commonly available RG-6 quad-shield coax could be another good option. It is 75-ohm feedline, but the impedance mismatch losses are not enough to matter for audio purposes IMO. You can buy it at common lengths with F connectors already installed if desired, and decent F connector to RCA connector adapters are readily available for low cost.

Run a vector network analysis on cheap bulk RCA-style audio cable anyway, and you likely will find the impedance to be all of over the place, from way under 50-ohms to even over 100-ohms. o.0


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PostPosted: Mon Mar 27, 2023 1:47 pm 

Joined: Thu May 20, 2021 8:28 pm
Posts: 4
Quote:
Use RCA, No point of balanced since your MPX input is not balanced. Also for Juli@'s balanced output you need custom cables! (3pin)
For 30m cable you really need good one. Just look to be 50ohm, also to be double shielded.
Cables for 5GHz WiFfi can also be good. Just dont waste money on that cable.
ESI's RCA is Digital Output. Can MPX out be get from it?


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