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9 volt battery speaker polarity test for JBL phase

dksound

Is this OK to do to test the polarity/phase of the speaker system? A very knowledgeable friend of mine has said that I need to test my JBL tops (JRX 115's) so that they won't be out of phase versus my Peavey SP4's, since JBL's are wired differently from all other manufacturers.
Believe me, he has done 1000's of sound gigs and has decades of experience, but I've looked at the schematics for the JBL's, Peavey's, and my amps, and to me, everything seems to indicate that tip is + / sleeve is minus, just like all other speakers. Maybe it's something from the past and JBL's are now the same?
He said I should do the 9 volt speaker test and see which way the cone moves (forward or back) for both speaker systems, and if the JBL's are out of phase with the Peavey's then I would need to reverse-wire my cables to the JBL tops.
Now, I've seen him do these tests before, but is it really safe to do, and then, also, do you think he's right that I need to check them?
dksound
December 4, 2009 @02:27am
sansuithumper

if they are out of phase you would know it, they would sound very flat and low sound output
December 4, 2009 @02:55am
dksound

Yeah, but has anyone heard of JBL's being wired in reverse of all other manufacturer's, and will I hurt a speaker by applying a 9 volt battery voltage to test it?
dksound
December 4, 2009 @03:21am
sabianq

your talking about polarity right?
it is different than phase
Unlike phase, polarity is either in or out. It's absolute.
reversing the connection changes the polarity.
a processor can change the phase as phase can be anywhere between 0 and 180 degrees.
the more complex the system the more ways for the polarity to become switched so polarity is ambiguous in any system which is why most high end equipment have polarity switches...
id stay away fro using a 9 volt battery and get a passive polarity detector like a dedicated polarity tester. then you can look at a couple of lights to give you the info and not have to worry about shorting your voice coils with DC current.
December 4, 2009 @03:35am
sabianq

jbl doesn't wire their stuff backwards. :)
December 4, 2009 @03:37am
dksound


id stay away fro using a 9 volt battery and get a passive polarity detector like a dedicated polarity tester. then you can look at a couple of lights to give you the info and not have to worry about shorting your voice coils with DC current.

Yeah, that's what I was thinking, too. Thus, my question about applying a 9 volt battery current. I know that phase/polarity are two different things--that's why this didn't make any sense to me to begin with.
For the show, I'm just going to hook up and go...I'm sure I would notice if something's out of phase.
Thanks.
dksound
December 4, 2009 @03:40am
sabianq

yea i wouldn't worry about it either.
you really will know if something is out of whack
the bass goes away...
December 4, 2009 @03:57am
sansuithumper

thats what i said-rock out,you will know right away if something is not right
December 4, 2009 @04:55am
sansuithumper

if you still think there is a pol problem just reverse and you will know right away. 9volt-try it if you can buy new speakers if voice coils fry,they may be really efficient and not take the dc current,
December 5, 2009 @02:43am
dksound

As I said, when I got the advice I was pretty aprehensive about trying it. That's why I asked you guys, just for confirmation of my apprehension to try this.:)
As a Physics major in college, the idea seemed somewhat dangerous. Perhaps my friend was trying to put me out of business for a while?
dksound
December 5, 2009 @06:46am
TimmyP1955

For a time, JBL wired their drivers backwards (they were reverse polarity as compared to the norm). But not necessarily their loudspeaker systems.
As to complete systems, that's a lot more complicated, owing to the phase response of the system and decisions made by the manufacturer (which might actually have included "which sounds best when playing music?"). Some are + in the woofer, moving to - in the highs. Some are - in the woofer and + in the highs.
When combining different models (which is usually a bad idea - oftentimes combining two of the same model is a bad idea), fire them up and listen, then reverse the polarity of one and see if it sounds better or worse. In some cases, it won't sound good either way.
December 5, 2009 @12:36pm
dksound

For a time, JBL wired their drivers backwards (they were reverse polarity as compared to the norm). But not necessarily their loudspeaker systems.
As to complete systems, that's a lot more complicated, owing to the phase response of the system and decisions made by the manufacturer (which might actually have included "which sounds best when playing music?"). Some are + in the woofer, moving to - in the highs. Some are - in the woofer and + in the highs.
When combining different models (which is usually a bad idea - oftentimes combining two of the same model is a bad idea), fire them up and listen, then reverse the polarity of one and see if it sounds better or worse. In some cases, it won't sound good either way.

The system I'll be using for the show includes Peavey SP4's and JBL JRX 115's. The JRX 115 schematic shows tip + to + on both the horn and woofer, and gnd - to minus on the horn and woofer. I don't have a schematic for the Peaveys, but the input plate shows Pin 1+ (Pos) and Pin 1- (Neg) at the Neutrik connection. So I believe we're talking apples and apples.
I'm just going to hook up, watch (the cones) and listen. That should tell me if anything's wrong.
dksound
December 5, 2009 @04:12pm