ProSoundWeb Community

Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Lounge FUD Forum Archive => Topic started by: Tom Roche on April 26, 2004, 10:02:36 PM

Title: Wiring Balanced Cables
Post by: Tom Roche on April 26, 2004, 10:02:36 PM
I'm getting conflicting advice for the proper wiring of cables that have TRS 1/4" on one end and XLR connectors on the other end.  I was told the tip goes to pin 3, ring to pin 2, and sleeve to pin 1.  Is this correct?  It's for an aux send to an amp.  Thanks,

Tom
Title: Re: Wiring Balanced Cables
Post by: Baron Gray on April 26, 2004, 10:29:36 PM
Hi Tom

Well....yes....and no.

"Pin 1 ground, pin two hot, pin three not" is the norm but they use a different standard in some equipment so the best way is to download the manuals for your desk and amp and just make sure. Also make sure that your aux sends are balanced.

You could also use a phase checker to bell it out and if you didn't buy the gear new this would be preferable as you don't know who has been "under the hood".

Baron
Title: Re: Wiring Balanced Cables
Post by: John Roberts {JR} on April 26, 2004, 10:29:40 PM
Tom R. wrote on Mon, 26 April 2004 21:02

I'm getting conflicting advice for the proper wiring of cables that have TRS 1/4" on one end and XLR connectors on the other end.  I was told the tip goes to pin 3, ring to pin 2, and sleeve to pin 1.  Is this correct?  It's for an aux send to an amp.  Thanks,

Tom


Ironically the TRS connector may easier to call than the XLR.

"Most" TRS will be wired Tip=+, Ring=-, Sleve=Gnd. The IEC and AES specs for XLR are pin 2=+, pin 3=-, pin 1-gnd.

However there are some manufacturers who have been around since before the standards were enacted or have some other good (I'm sure) reason. So some manufacturer's will use pin 3=+, pin 2=-. Everybody pretty much agrees that pin 1 is ground.

I try to silk screen a legend somewhere on the chassis with the wiring approach I used in that product, and manufacturer's should at least tell you "how" they're interfacing. If not call them at home, late at night... Very Happy

JR

Title: Re: Wiring Balanced Cables
Post by: ThomasA(lbenberger) on April 26, 2004, 10:33:49 PM
Hi Tom!

That's not correct in most cases. Usual wiring on an XLR is

Pin1: Ground
Pin2: Hot
Pin3: Cold

and on a TRS

Tip: Hot
Ring: Cold
Sleeve: Ground

So Tip->Pin2, Ring->Pin3 and Sleeve->Pin1 would be right.

Mind you these are just the standards and the situation might differ for your brand of mixer or amp, although this is very unlikely to be the case. Check the manual to be sure, and also check that you really have a balanced Aux Output on your mixer.

ThomasA

PS: If you are unsure about wiring of cables, for instance Mackie includes wiring schemes for the most common adapter cables in their downloadable manuals!
Title: XLR pins 1-2-3 MY favorite mnemonic I learned on LAB.
Post by: Lee Patzius on April 26, 2004, 11:34:14 PM
I remember awhile back someone posted an easy to remember 1,2,3, pin assignment for XLR's.

Assign pins 1,2,3, in the same order as X,L,R.

Then you can remember the following:

X for eXternal shield = pin 1
L for Line out (hot or +) = pin 2
R for Return (cold or -) = pin 3

That's the way I remembered it.
Title: Re: Wiring Balanced Cables
Post by: Alex_C on April 27, 2004, 06:19:56 AM
A little off topic, but...

About a year ago, I bought some real cheap XLR cables from a guy that just couldn't sell them -
Title: Thank You Everyone
Post by: Tom Roche on April 27, 2004, 08:51:35 PM
Thanks for the info....I suspected something wasn't right when I compared the earlier given advice to a vague diagram I had.  Oh well, the good news is I have only two cables to fix and easy access to the snake.  Thanks again,

Tom
Title: XLR = stereo
Post by: Brent Handy on April 28, 2004, 09:40:07 AM
The XLR connector was originally a stereo connector, hence the L, for Left and the R for Return.  Not everyone follows pin 2 hot (BSS, Hill, etc, etc)
Title: Mackie has it backwards
Post by: Brent Handy on April 28, 2004, 09:42:02 AM
If you own the original CR1604's, they wired the auxes backwards.  So, don't look at that manual.
Title: Re: XLR = stereo...No, not really
Post by: Dave Dermont on April 28, 2004, 10:57:06 AM
Brent wrote on Wed, 28 April 2004 08:40

The XLR connector was originally a stereo connector, hence the L, for Left and the R for Return.  Not everyone follows pin 2 hot (BSS, Hill, etc, etc)


This certainly sounds reasonable, but it's untrue.

XLR was originally a registered trademark of ITT Cannon. It has since become a generic audio term.

X is the connector series
L means that it has a Latch
R means the center insert is Rubber

See the Rane Audio Reference page for more info.
Title: Re: XLR = stereo...No, not really
Post by: Brent Handy on April 28, 2004, 12:17:23 PM
Sorry about the dry humor.  I was going to say that the initials were for Ron and Larry.

Anyone who posts questions like the original should know that www.rane.com has a good reference for terms like this.  It is funny too.
Title: Re: XLR = stereo...No, not really
Post by: Bob Currier on April 29, 2004, 04:10:28 PM
I just teach my junior high kids that it means extra large.  Smile

--bc
Title: Re: Mackie has it backwards
Post by: ThomasA(lbenberger) on April 30, 2004, 12:33:29 AM
Hi Brent!

OK if you want to split hairs then yes, the (long discontinued) CR1604 has balanced main L/R outputs with tip=cold and ring=hot.

Aux sends and returns are all unbalanced, Mic inputs and main mono output are pin2=hot and Line inputs are Tip=hot.

But thanks Brent for getting me to review this because then I recognized that I wasn't thinking about the manuals but about the "Hookup Guides".

Here is the link:

http://www.mackie.com/support/hookup/index.html

Thomas



Title: Re: Wiring Balanced Cables
Post by: Dave Bigelow on April 30, 2004, 02:19:54 PM
I just had to do this the other day.

The other guy that works at the club I work at ordered some new crossovers for one of the PA's. Well of course they passed up the 2 different driveracks I suggested and bought 2 dbx 233's. In the process of ordering these you would think somebody would have actually looked at the wiring. Dude ordered the wrong ones (the 233's not the 233XL's) so I spent a while chopping off the XLR's and soldering up TRS just so these could be installed.

Another instance is just yesterday where on the other sysytem the main eq took a dump. (an old ultrashit, I mean curve) After me having to mix one of the biggest nights we have all year with no FOH eq (it's derby week around here for those that don't know), this guy orders an Alesis (MEQ230 I think, I call it "paperweight"). I even told the club "I don't know how you did it but you actually found something worse than the "B" we had". As I was pulling out the eq and patching the drive lines together (thank god for dual sweepable mids but then again it's a mackie so I don't put alot of faith in them), I notice that the guy did me the favor of not cutting off the ends and making them TRS, he used adapters that weren't even balanced.

I think the best part was the opener seeing me ripping the eq out of the rack and telling them that I wasn't gonna use it. The look on their faces was priceless since the new guy had soundchecked them before he went home. I could tell they were worried but when they started I just did some changes to the strips and corrected the gain structure and all was good, the look on their faces then was even better since at the end of their set one of them was telling me how "that other guy" couldn't get rid of a low-mid ring in the vocal mics. Best part was seeing the headliner's guy freak out at not having an eq and he's mixed on that rig almost as much as I have, he ended up calling somebody and had a dbx 231 ran out to him.

I think that my place of work needs to start having me order gear since I know what we need and won't settle for junk. I've tried everything as far as explaining why you don't buy junk and they still look at the (instant) dollar figure instead of what would be spent long-term. (You know the "You can buy a Yugo now and replace it next year or buy a omid level Caddy and have it for a while if you take care of it) Then again I've worked there close to 3 years and they hired this guy in as the "head tech", at least he knows not to try and tell me what to do since I'll yank out all the cables out of the back of the amp racks and erase my driverack program (on the system that has one) if they REALLY piss me off.