# BFD 1124 reverse the Polarity



## Began (Oct 3, 2011)

Hi,

I have two subs and when I switch on my 2nd Sub there are no changes in db at all. I was told that probably is the polariy is reverse. 

Can I use the BFD to reverse it or I have to open up the driver or amp to switch it.

Thanks
Began


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## JohnM (Apr 11, 2006)

Most sub amps have a polarity switch, but if the sub has no effect when you switch it on best check the wiring to it first and measure the 2nd sub on its own to make sure it is working properly.


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## Began (Oct 3, 2011)

Hi John,

Yes, the sub is ok. When I play individual sub no problem the sound very good. However when I switch on the 2nd sub it doesn't make any different and I put my hand on the driver yes is working. 
Unfortunately my amp do not have phrase and polarity adjustment. It speaker power amp. MY Sub is JTR S1.

Began


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## JohnM (Apr 11, 2006)

Another way to switch polarity is to swap around the connections at the driver.


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## Began (Oct 3, 2011)

JohnM said:


> Another way to switch polarity is to swap around the connections at the driver.


Hi John,

Thanks, yes I took out the amp and switch the polarity and now when I switch on the 2nd sub there is 3db increase in SPL.

Cheers
Began


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