Watch your polarity!

Is this amp OK?
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Monomer
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Watch your polarity!

#1 Post by Monomer »

Apparently pin 2/hot/+ isn't a standard.

Bar show. I tied into their tops (an omni just didn't sound good in the room, and I didn't pack the geq this time)

One of the other soundguys (from a future competing company, even) tapped me on the shoulder and told me to check my polarity, and to switch it for a minute. He then went on to talk about QSC's having a different pin-out then crown (just checked and macrotechs and rmxs have the same pinout, I don't know about other models though)

He was indeed right, it sounded much better flipped. I learned not to assume that its all good. This is the first time it's been as loud as it was, I'm not accustomed to it yet. the house sound was a couple of 10 inch community tops and a powered mixer. wiring a rats nest - This might turnout to be my first BFM club install, if they ever come up with the money. :fingers:


p.s. I'm glad people who are truly into audio help each other out. I try not to have an ego and be completely open mined - I'm one to shutup and listen unless I'm sure of what I'm talking about. This was the third show I've done at this venue, and this same soundguy stops by every week, and each week he gives me a new perspective on stuff I've been reading about online for years.
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bitSmasher
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Re: Watch your polarity!

#2 Post by bitSmasher »

Nice one, it's good when people are positive.

Ron K
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Re: Watch your polarity!

#3 Post by Ron K »

He then went on to talk about QSC's having a different pin-out then crown
Not that I was ever aware of unless someone changed it.Maybe some older Crest Amps do and I'm sure there are a few others but as I recall QSC has always been Pin 2 Hot on the XLR. The older MX series came with barrier strip terminals if you wanted them that way or they had 1/4" unbalanced inputs.They may have been on the 1/4" TRS jacks but i cant remember. That I do remember the 1/4" TRS and the XLR had to be purchased as a module for the MX series. The XLR was Pin 2 Hot but the TRS may have been tip Cold and Ring Hot!

Crest was definitely backwards and there were some British boards who did this as well.

Back in the day when there was no standard you simply rewired your gear to one or the other! Then when you sold it you didn't say a word and the purchaser either knew to check this or was a complete newb and paid the price! I think JBL still uses Red as Neg on polarity for their drivers.All the JBLs I have are done this way!
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AntonZ
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Re: Watch your polarity!

#4 Post by AntonZ »

I installed a preamp in a bass guitar some time ago and had quite some trouble getting it to function properly. Until in utter despair, after going over my wires again and again, I started working out part of the schematics. Then I noticed that a red wire was supposed to be connected to ground. Black carried the signal. I was not into pro audio gear in the days that you mentioned Ron, so it came as a complete surprise to me.

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WiSounds
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Re: Watch your polarity!

#5 Post by WiSounds »

Factory termed speakons killed my stack of THTs the one and only time I had em all out at once.
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Monomer
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Re: Watch your polarity!

#6 Post by Monomer »

WiSounds wrote:Factory termed speakons killed my stack of THTs the one and only time I had em all out at once.

a batch of speakons had reversed poles, whoever changed the die out put it in backwards!

I just noticed my omni's piezo array was off. I though because I didn't bring out the GEQ to the show to tweak it to the room is why it sounded so off. Very musical now!


I'm going to have to go back and rewire the bar, as I have a feeling whoever wired it didnt know what was going on. One of the tops was also cutting in/out the entire night (I flipped the omni off, overkill)
-AutoTuba; Tang Band 8 inch (x1)
-T39; KappliteLF, 22 wide (x2)
-More to come!

Rickisan
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Re: Watch your polarity!

#7 Post by Rickisan »

Lesson: It is imperative to confirm polarity!

Very informative thread.

:clap:
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