Pin 1 Problems

Got speaker theory questions? This is where you'll find the answers.
Message
Author
Grant Bunter
Posts: 6915
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Pin 1 Problems

#16 Post by Grant Bunter »

escapement:

Please qualify; are you using XLR to XLR leads (which if wired up correctly should be balanced leads) or 1/4" to XLR leads (unbalanced, which should be wired pin 1 wire shield to sleeve, pin 2 to tip, pin 3 also to sleeve at the 1/4" end)?

There is benefit in noise cancellation with pin 1 to plug shield tab, but it has to be at the right end.
Yes, it does make a difference which end is connected to the tab.
I can never remember for the life of me which end that should be.

Since occassionaly one might turn a lead over for a specific connection, I don't connect the tab to pin 1 ever when I make my leads up at either end.
However, at a show where my system was used, the SE asked for another short XLR to XLR because "that one is noisy". Turned out, when I had cut down a pre made lead to make a few shorter patch leads, I left the factory applied plug as it was, without looking at it. It had pin1 to tab connected. At the wrong end...

edit: IIRC the connection of pin 1 and tab at the right end (whichever one it be lol) is useful only if you are running gear from different power supplies that have different ground points. So if there is only one power distro wherever you are ie all power outlets are on the same ground point, the tabs simply don't require connection to pin 1.

Some people carry around DI's, that have earth lift on/off switching to eliminate that hum when there are different ground points, or, say, when 2 mixers are connected together and hum is introduced...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

User avatar
Rune Bivrin
Posts: 521
Joined: Tue Aug 19, 2008 5:42 pm
Location: Stockholm, Sweden

Re: Pin 1 Problems

#17 Post by Rune Bivrin »

It's very rare (read: never happens) that you get white noise - which is pretty much the sound of a waterfall - from cables. White noise generally comes from poor components and bad gain structure.
In build order:
O12 with no tweeter.
3 x WedgeHorns.
2 x Jack 10 without tweeters.
2 x DR250.
2 x 16" T39
1 x Tuba 24
2 x SLA Pro (sort of...)

88h88
Posts: 1603
Joined: Mon Jul 04, 2011 10:20 am
Location: Coventry, UK

Re: Pin 1 Problems

#18 Post by 88h88 »

escapemcp wrote:First you moan at my Berry amps... now you are having a go at my Ching-Won XRL connectors. I wonder how long until you'll be telling me my LAB1A drivers are total flaps. :lol:
:loler:
4xOT12s, 2xT39s@22", TTLS@18", 2xT60@18"

User avatar
Chris_Allen
Posts: 3355
Joined: Wed Jul 11, 2007 2:43 pm
Location: Huddersfield, UK

Re: Pin 1 Problems

#19 Post by Chris_Allen »

I had a noise problem with a DDX3216->DEQ->DCX combination with AES/EBU. Turned out to be the Crown Xti amp at the end!
Built:
6xDR200, 2xT39, 2xT48, 2xJack110, 1xOmni10.5, 1xAutotuba, 1xT18, 1xSLA Pro, 1xW8, 1xW10

Post Reply