[sugarinthegourd]

Maybe I'm missing something, but XLR connectors have 3 pins, and each channel of a headphone only uses 2 conductors. So it seems that you could do just as well with 2 mono phone plugs, right? Or am I missing something? There must be some reason why balanced rigs use XLR jacks. Is the 3rd pin connected to anything?

 

[Icarium]

Ground

 

[Kees]

Quote:

Originally Posted by Icarium /img/forum/go_quote.gif Ground

No. With a balanced headphone cable the third pin is indeed empty.

 

[Kees]

Quote:

Originally Posted by sugarinthegourd /img/forum/go_quote.gif Maybe I'm missing something, but XLR connectors have 3 pins, and each channel of a headphone only uses 2 conductors. So it seems that you could do just as well with 2 mono phone plugs, right? Or am I missing something? There must be some reason why balanced rigs use XLR jacks. Is the 3rd pin connected to anything?

You are quite right.
In fact it has been proposed (by lots of different folks) to use a single 4pin XLR for balanced headphone cables. Makes more sense to me too.
But I'm afraid that the de-facto standard of dual 3pin XLRs just "happened" and it is difficult to go a different road from here....

 

[909]

the hd-2 uses a single 4pin xlr for the balanced headphone cable.

 

[SK138]

I am using two TRS (1/4 stereo plugs) for my balanced system. They share the same points as the XLR; tip = +, ring = -, stem = ground

 

[TreAdidas]

According to Headroom's Tyll at the LA and Orange County Audio Society Meet. They made the first balanced headphone amplifier and the reason they used the XLR type connectors was because Neutrik makes a combo 3-pin XLR and 1/4" plug chassis jack. That makes it convenient to do both balanced and single ended in just two chassis points.

From http://www.neutrik.com/us/en/lightin...oductlist.aspx
"First XLR / jack hybrid panel mount connector combining a 3 pole XLR receptacle and mono or stereo ¼" phone jack in one XLR housing."

 

[grawk]

Here is my solution to the problem...

4pin in the middle, 2x 3pin combo jacks, wired so that the 1/4" are + on one side and - on the other, so you can swap polarity if you'd like.

 

[swt61]

Nice solution grawk.

 

[Spiug31]

http://www.faqs.org/faqs/theatre/sta...ection-25.html

 

[grawk]

Was the pinout for xlr ever in doubt? The discussion was about connector selection.

 

[Jon118]

I've heard some people say XLR tends to be very durable and has a lot of surface area for a lot of contact, so that's why they use them. I say balanced TRS myself, but whatever.

 

[grawk]

The problem with TRS is you short the connection whenever you insert your connector.

 

[MaloS]

Quote:

Originally Posted by grawk /img/forum/go_quote.gif The problem with TRS is you short the connection whenever you insert your connector.

Ya but we tend to connect our system before we even turn it on so that does not really matter. Also TRS is fairly standard in quite a bit of professional systems I've seen. Generally more comfortable >.< I get constantly bothered by how big XLR is, when electronically having pair of mini-plugs is as good as pair of 3-pin XLRs..hell, a pair of mono mini-plugs is just as functional (you only need in and out pins, which can be easily substituted by + and ground points of a mono mini-plug).

 

[SK138]

Hmm... I never looked at it that way. You are correct there is always that inherent flaw in TRS design. Time to change it to 4pin XLR...I have few rolling around here somewhere

Quote:

Originally Posted by grawk /img/forum/go_quote.gif The problem with TRS is you short the connection whenever you insert your connector.