sub phasing

[conan]

Hi there

 

My work have just got a couple of new powerd subs and they have a 180 degree phase switch on them... I was wondering what is this for and what does it do?

 

Any ideas

[Ben Langfeld]

Are they horn loaded subs? If so, it's for use when using front loaded tops, to keep subs and tops in phase. I'll leave it to someone else to explain the theory.

[J Pearce]

Also when arraying subs it can be useful to be able to adjust polarity.

[paulglave]

If either the bins or the tops are reflex loaded then you'll have one driver pointing towards you and one pointing away. so when one driver is pushing air the other is pulling. 180 degree phase correction will mean they push and pull together. Now for time alignment...

[J Pearce]

*cough* polarity correction...

 

180 degree phase correction would only be correct at a single frequency.

[Rob_Beech]

True, very true, however products are often labeled incorrectly, so it would not surprise me if the OP has just asked the question after reading the label.

[paulears]

polarity vs phase labels - something that has kept the theatre sound group burbling on for years. I guess the only real solution is in the subject area we are talking about to accept happily both, but understand that what we say is not always what we mean. After all, the desk has the 'phase' symbol, the manual calls it 'phase' - so insisting that it is really 'polarity', while factual, isn't helpful over a mobile with a noisy background, and a manual being read with a torch! Shouting "press the phase button" is trouble free, explaining that the manual incorrectly calls the polarity switch something else just adds to the bafflement.

[Simon Lewis]

Shouting "press the phase button" is trouble free, explaining that the manual incorrectly calls the polarity switch something else just adds to the bafflement.

 

Thankfully, certain luminaries* now put "pol" on their channel strips to denote polarity. There was a brief discussion as to whether a ying/yang symbol might be self explanatory, but this was deemed likely to p**s off 2/3rds of the world's religions (thus cutting manufacturers out of the HOW market) and might even be thought to add instant karma to the mix...

 

 

 

* It is pleasing to be able to use this word in the right context - instead of that perennial bugbear " I wuld use frennel luminaries". (sic)

[Chappie]

Are they horn loaded subs? If so, it's for use when using front loaded tops, to keep subs and tops in phase. I'll leave it to someone else to explain the theory.

Using a polarity reversal on a horn loaded sub with a front loaded top will not magically bring the two together in a cohesion of phase.

 

Polarity reversal switches are common on many self-powered boxes, not just being limited to subs. They are useful for many reasons such as as aligning a system with both powered and unpowered components (if you know it's needed), integrating pin 2 hot systems with older pin 3 hot stuff, problem solving, specific needs of certain system designs etc, etc.

 

They can, however, be a headache, unless you check each box is switched correctly before they get to site.

[paulglave]

Hang on.... What I meant to type was.

 

If it doesn't say "Self Destruct" or "Anihilate all known life in the universe" Press it and see what happens. Maybe if it says "40db pad" it might be worth turning down first.