4333/L300 Network/Driver Polarity Question

Hi everybody,
I am in the process of breaking in my DIY 3 way system and have reached a point where I need some help.

If I interpret JBL polarity conventions correctly, I think that all three drivers are considered to be negative, the 2231A, 2420/2312/2308 and the 2405H.

Okay, so assuming this is right, if I interpret the 3133 network schematic correctly, it appears that the 2420 is wired with the same polarity as the 2231A, despite the fact that there is a second order filter (i.e. 270 degree shift) in there. Maybe because of horn length?

The 2405H looks like it's polarity is wired in opposite to the other two drivers.

Have I got this right? I have tried listening to various polarity combinations and I think I have got it right. :confused:
Charles.

You got the network schematic transducer polarity read correctly, and each of those are negative.

Got any pic's...? :yes:

Thanks Bo, no pics yet, I have to borrow a digital camera. Another question: to those who use mirror image JBL 3 ways with the offset side mounted 077/2405. Do you have your tweets inside or out?

I believe 2nd order crossovers (12dB/ octave) produce a 180 degree shift.
In any case, JBL figured this all out and the wiring diagrams indicate the proper wiring...UNLESS you want the cabinet to "play forward". The only reason to want this is if you may be hooking these up with any other drivers that follow the other polarity convention. (most others, as well as most modern JBLs)
The right way to do this is to follow the polarity on the wiring diagrams up to the actual drivers. Then vreverse the leads so the black wires go to the red binding posts and the colored wires go to the black posts. You can check th polarity, at least with the woofers by briefly touching a 9 volt battery to the speaker inputs. Touch the + of the battery to a wire that connects to the red input post...the woofer cone should move outward.

Tom

Tom, of course you are correct, I had third order on my mind....I must have been under the influence from listening to some terrifyingly high SPL's on some Telarc CD's! I was physically shaking....! Scary stuff how transients are reproduced by these things.
Charles.

Quote:

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Originally posted by Chas
...to those who use mirror image JBL 3 ways with the offset side mounted 077/2405. Do you have your tweets inside or out?

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The greatest (apparent) spatial separation would be for the UHF to be toward the outside of each cabinet. It isn't much, but you can convince yourself it improves imaging.

And, thanks, Tom. I was frequently puzzled by that 270-degree comment while mixing last night - I figured Chas meant 180. Had to be. So as Giskard might point out, the 2420 is acoustically out-of-phase with the 2231. But, we really don't need to get into all this again, do we? :slink:

And, thanks, Tom. I was frequently puzzled by that 270-degree comment while mixing last night - I figured Chas meant 180. Had to be. So as Giskard might point out, the 2420 is acoustically out-of-phase with the 2231.

I'm glad to help fill your time with my mental seizure....:)

Acoustically out of phase? Are you referring to phase or polarity?
I might be s*** disturbing here and being a JBL rookie, I don't want to rock the boat:wtf:
Charles

Quote:

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Originally posted by Chas
I'm glad to help fill your time with my mental seizure....:)

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No, sweat. At times, I find myself thinking the oddest things whilst sitting out at the FOH board...

Oh - it's only that there's electrical polarity (i.e., both as designed in the transducers and as imposed by the network wiring) and then acoustic phasing, as you alluded to by the 270-degree comment, in your initial post.

In terms of 2405 positioning, I chose to put the 2405s to the inside of my speaker positions partly because I have them so far apart, there are hard walls just outside the speakers and I wanted to reduce wall reflections, and I didn't want the lenses interfering with the direct "line-of-sight" to the 2405 slots from my sitting position.
Just my thoughts.

Tom

I have just gone up an old pair of 4333a. I am always skeptic also on the polarity of the cables. If the diagram of jbl is read, the cables of colors go on + and the black cables on -? It is thus well the color on the black terminals of the HP and the black cables on the red terminals?

herve...

I'm confused... :spin:

Red -> (+)
Black -> (-)

But, what do you mean by "HP"...? :confused:

Sorry, HP= transducer in french.

for jbl, terminal of the transducer: black=+ and red=-
And for cables ?

Quote:

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Originally posted by herve M
HP= transducer in french.

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Ha! I thought you meant HansPeter... ;)

Herve, you're about to get confused, or confuse me! :eek:

JBL transducers are designed to be connected:

Red = (+)
Black = (-)

However, since many/most JBL transducers are reverse polarity, this will give a negative cone movement (cone in on positive signal).

Please explain more - what are you trying to do?

*****

NB: I noticed this in the manual from the Ashly XR1001, a wonderful crossover I've lately been using - first time I've seen a manufacturer aware of JBL's polarity convention... :thmbsup:

If the colors are respected, then the membrane of the low register is inward. I suppose then, as on the series 4400, which should then be reversed the polarities with the connector block of the enclosure.

Quote:

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Originally posted by herve M
I suppose then, as on the series 4400, which should then be reversed the polarities with the connector block of the enclosure.

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My broken english is not this good... :rotfl:

I may still be confused - but attached is the 4412 network (excerpt) as example.

The LF 128H-1 is at top-right, and connected GREEN wire to Red post. However, look on the top-left and the GREEN wire is connected to the BLK input. Through the network the 128H-1 is "cross-wired" and runs positive in this cabinet. So, if you connect the 128H in any JBL cabinet, connect the GRN or GREEN wire to the Red post, and you are fine.

Any help?