Digital Spy

Search Digital Spy
 

DS Forums

 
 
 

CAT5 baluns - can video ones be used for audio?


Reply
Thread Tools Search this Thread
Old 12-09-2013, 14:41
Chris Simon
Forum Member
 
Join Date: Mar 2000
Location: Snowdonia
Posts: 2,723

I'm having trouble finding a CAT 5 quad audio balun, i.e. 2 stereo pairs. The only one I could find is the Muxlab 500033 but I'm confused about its bandwidth - http://muxlab.com/wp-content/uploads...udio_Balun.pdf says it's 20Hz - 20Khz but http://www.canford.co.uk/ProductResources/ig/6468.pdf and http://www.canford.co.uk/ProductReso...udio_Balun.pdf say it's 60Hz - 200KHz. I would obviously prefer full bandwidth.

Anyway, there are other baluns that, for example, have 3 phonos for component video and another for SPDIF audio. Is there any disadvantage to using these for analogue audio - I would have though the specs/bandwith would be in excess of what's required for analogue audio but not sure whether the difference in expected impedance would hamper the performance in any way.
Chris Simon is offline   Reply With Quote
Please sign in or register to remove this advertisement.
Old 12-09-2013, 15:20
Nigel Goodwin
Forum Member
 
Join Date: Apr 2006
Location: North Derbyshire
Posts: 36,861
Video uses 75 ohms impedance, audio is MUCH higher - but why not just try the Muxlab ones, which sound just what you need - I would hope the manufacturers data sheet is more accurate than a third parties?.

What are you trying to send down it anyway?, that you're obsessing about going down to 20Hz?.
Nigel Goodwin is offline   Reply With Quote
Old 12-09-2013, 15:30
Chris Simon
Forum Member
 
Join Date: Mar 2000
Location: Snowdonia
Posts: 2,723
Video uses 75 ohms impedance, audio is MUCH higher - but why not just try the Muxlab ones, which sound just what you need - I would hope the manufacturers data sheet is more accurate than a third parties?.

What are you trying to send down it anyway?, that you're obsessing about going down to 20Hz?.
One of the datasheets above is on the web site of a third party but it looks an official Mux Labs one.

I'm not obsessed about going down to 20Hz.

Are you saying that lower impedance wouldn't make any difference to analogue audio?
Chris Simon is offline   Reply With Quote
Old 12-09-2013, 15:36
chrisjr
Forum Member
 
Join Date: May 2004
Location: Reading
Posts: 20,387
The Muxlab and Canford specs need not be mutually exclusive. Canford quote the bandwidth at the -3dB points. Muxlab don't quote any dB limits. What Canford's figures mean is, feed a signal at 1kHz at a fixed level into one end and measure the signal received at the other end. This is the reference level. Change the input to 60Hz, but at the same level, and the output will be 3dB lower than the reference level.

That does not mean it won't go down to 20Hz, it probably does. But what you don't know is how many dB lower the output is at 20Hz than the reference level.

In addition the Canford spec mentions it is for a distance of 300m. Again Muxlab don't mention any distance figure.
chrisjr is offline   Reply With Quote
Old 12-09-2013, 15:40
chrisjr
Forum Member
 
Join Date: May 2004
Location: Reading
Posts: 20,387
One of the datasheets above is on the web site of a third party but it looks an official Mux Labs one.

I'm not obsessed about going down to 20Hz.

Are you saying that lower impedance wouldn't make any difference to analogue audio?
No. Audio sources expect to be feeding a much higher impedance load, typically 10kohms or greater. So feeding a CD player for example into a 75ohm load probably won't do it any harm but it could well have a serious impact on sound quality.
chrisjr is offline   Reply With Quote
Old 12-09-2013, 15:40
Chris Simon
Forum Member
 
Join Date: Mar 2000
Location: Snowdonia
Posts: 2,723
The Muxlab and Canford specs need not be mutually exclusive.
LOL, thanks, just a different way of quoting stats!
Chris Simon is offline   Reply With Quote
Old 12-09-2013, 15:43
Chris Simon
Forum Member
 
Join Date: Mar 2000
Location: Snowdonia
Posts: 2,723
So feeding a CD player for example into a 75ohm load probably won't do it any harm but it could well have a serious impact on sound quality.
OK, thanks. The video ones tend to be cheaper, which is counter-intuitive to me, I wonder if there's more circuitry involved in the higher impedance.
Chris Simon is offline   Reply With Quote
Old 12-09-2013, 15:49
chrisjr
Forum Member
 
Join Date: May 2004
Location: Reading
Posts: 20,387
OK, thanks. The video ones tend to be cheaper, which is counter-intuitive to me, I wonder if there's more circuitry involved in the higher impedance.
There is no circuitry, well unless you count a transformer as a "circuit". It's just two coils of wire flying in close formation.

The way the transformer is wound determines the impedance.
chrisjr is offline   Reply With Quote
Old 12-09-2013, 19:43
Nigel Goodwin
Forum Member
 
Join Date: Apr 2006
Location: North Derbyshire
Posts: 36,861
One of the datasheets above is on the web site of a third party but it looks an official Mux Labs one.

I'm not obsessed about going down to 20Hz.
Then go for the Muxlabs one then - or buy two AV ones and wire the audio channels from them to give the four you need - but the Muxlabs are probably the same sort of transformers anyway,


Are you saying that lower impedance wouldn't make any difference to analogue audio?
No, it will stop it working decently at all - or might not even work at all?, I'll have to give it a try - I happen to have a pair set up for transferring audio across to a fixed amplifier at work.
Nigel Goodwin is offline   Reply With Quote
Old 18-09-2013, 16:58
Nigel Goodwin
Forum Member
 
Join Date: Apr 2006
Location: North Derbyshire
Posts: 36,861
No, it will stop it working decently at all - or might not even work at all?, I'll have to give it a try - I happen to have a pair set up for transferring audio across to a fixed amplifier at work.
OK, sorry for the slow response, but I finally found time to give it a try today.

Using the video channel worked better than I thought it would, volume was much the same, but there was a VERY pronounced lack of bass.
Nigel Goodwin is offline   Reply With Quote
Old 19-09-2013, 13:03
Chris Simon
Forum Member
 
Join Date: Mar 2000
Location: Snowdonia
Posts: 2,723
OK, thanks for trying!
Chris Simon is offline   Reply With Quote
 
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search

 
Forum Jump


All times are GMT +1. The time now is 06:55.