[sdiy] stereo output questions.....

[Adam Schabtach]

Um, no, Jure is right. TRS refers to the physical connector; it has nothing
to do with the signal you carry on the connector. Consider a pair of stereo
headphones: it uses a TRS plug and carries an unbalanced pair of signals.
TRS jacks are also used on some mixing desks for patching insert effects.
One conductor carries the "send" signal, the other carries the "return"
signal, and the sleeve is used for ground.

Or, for a second opinion: http://en.wikipedia.org/wiki/Tip_ring_sleeve
(Not that Wikipedia is the definitive reference, but it does have a lengthy
article on this topic.)

--Adam

> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl 
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of 
> Graham Atkins
> Sent: Thursday, November 27, 2008 11:39 AM
> To: jure zitnik
> Cc: sdiy
> Subject: Re: [sdiy] stereo output questions.....
> 
> Jure,
> 
> You are wrong. A TRS jack is defined as a 3 circuit connector 
> carrying balanced audio.
> 
> Graham
> 
> On 27 Nov 2008, at 16:48, jure zitnik wrote:
> 
> > since he wrote "2 XLR cables", he obviously means balanced stereo.
> >
> > again, when you say TRS, what exactly do you mean? "TRS" does not 
> > describe a signal, it merely describes the mechanical 
> connector. so if 
> > you take the 6.3mm jack (male) connector with 3 contacts an look at
> > it:
> > T(ip) - the end of the jack
> > R(ing) - the middle section
> > S(leeve) - the rest, this contacts is the biggest
> >
> > the other 3-contact mechanical connector is called XLR, again, it's 
> > just a name for the connector, meant to fit on a 
> 3-conductor (3 wire) 
> > cable.
> >
> > now you can use those 3 contacts - on a TRS or an XLR 
> connector - and 
> > the corresponding 3 conductors in the cable for different purposes, 
> > but mostly the following two:
> >
> > 1. unbalanced stereo audio - usually TRS is used for this, i don't 
> > think i've ever seen XLR used for stereo.
> > the TIP and the RING contacts are used for left and right audio 
> > signal, the SLEEVE is used as ground for both. that way you get a 
> > stereo signal on 3 conductor cable, with TRS jacks.
> >
> > 2. balanced mono audio - both TRS and XLR are commonly used 
> here, but 
> > TRS are usually used in studio. they are less bulky but also less 
> > durable. on stage, you'll usually see XLR.
> > the idea of balanced audio is to use two "copies" of 
> signal, using two 
> > separate conductors, to eliminate the noise that is common to both 
> > copies. the general idea is to send the signal and an 
> inverted copy of 
> > the same signal. then at the receiving end the inverted copy is 
> > inverted again and the copies are added together, but the 
> common noise 
> > between the two subtracts (because of inversion). so at the end you 
> > get the signal twice the amplitude, minus the noise. for this, you 
> > again need 3 conductors. one for the original signal 
> ("hot"), one for 
> > the inverted one ("cold") and again one ground for both together.
> >
> > so, which one do you need, the question is not "TRS or stereo". the 
> > question should be first "stereo or mono", then "balanced or 
> > unbalanced", and then "XLR or TRS".
> >
> > On Thu, Nov 27, 2008 at 3:51 PM, John Mahoney <jmahoney at gate.net>
> > wrote:
> >> Here are 2 ways to carry stereo signals:
> >>
> >> 1) A pair of 2-conductor cables, one for L and one for R. 
> Each cable 
> >> has a hot (signal) line and a ground.
> >> 2) One 3-conductor cable, with a hot line for L, a hot for 
> R, and a 
> >> common ground.
> >>
> >> 3-conductor stereo cables typically have TRS connectors. Example:
> >> headphones.
> >>
> >> However, TRS connectors are also used for mono, balanced cabling, 
> >> which also has 3 wires (signal+, signal-, and ground).
> >>
> >> XLR connectors can carry stereo signals but they are 
> usually used for 
> >> balanced mono.
> >>
> >> When you say "stereo not TRS", do you mean separate Left and Right 
> >> cables instead of one stereo cable?
> >>
> >> John
> >>
> >>
> >> At 08:47 AM 11/27/2008, Dan Snazelle wrote:
> >>
> >>> no i think i mean just plain stereo..not trs
> >>>
> >>> the guy wants to convert a stereo signal (left and right) into an 
> >>> adapter that goes into 2 XLR cables...
> >>> i was pretty sure he said STEREO not TRS but he might not 
> know the 
> >>> difference.
> >>>
> >>> so basically if i send an inverted signal to one side and 
> a normal 
> >>> to the other, that is TRS?
> >>>
> >>> thanks
> >>
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