View Full Version : Driver polarity for JBL 4355's

03-03-2016, 09:08 PM
Hello All,

Its been about 8 months since I completed my JBL 4355 clones. They are 99% perfect! The veneer trimming was a real challenge! I decided to build a CC version of the crossover as per Giskard and Timbers design. All the driver polarities are wired per JBl spec. Today I performed a polarity check on the entire system using the BSS AR-130 phase checker set. Very nice and very accurate piece of equipment. I used the sender signal via input of my preamp. Here are the results: 2235's -(negative) 2202's -(negative) 2441's -(negative) 2405 +(positive) I am not sure what the final polarity should be of all the drivers? All the SAME polarity or some 180 out of phase? I'm pretty sure at 10,000 hz( 2441-2405 x-over point) I will not be hearing this phase reversal but just wanted to know how they were originally setup and designed. BTW this speakers do sound very dynamic and have a beautiful soundstage!

NOTE: the 2405's are the Alnico versions. I am almost certain they have the original JBL diaphragms in them.

Mike Kehr

03-04-2016, 11:42 AM
I just wanted to update my post from yesterday. It may have been a bit unclear. ALL drivers are moving forward with + voltage to the RED + terminal on the cabinet EXCEPT for the 2405. When the test was performed yesterday there was a phase reversal on the XLR-RCA adapter I used to connect to the BSS AR-130 sender to the preamp input. Pin 2 and 3 swapped resulting in a inward excursion of the drivers. So should all the drivers be of the same phase or some 180 out of phase. I have read that the 4350 had the 2440 wired out of phase to compensate for the position of the set back compression driver. Helping with time alignment per say...



03-04-2016, 02:46 PM
Polarity issues on the 4 way monitors has driven a few folks mad. It might be easier to do a frequency response measurement and look for unusual peaks or valleys near the crossover points.

03-04-2016, 04:21 PM

You may already be aware of this archived thread. I think that if you read it you will find the answer to your question and understand it as well.

I do have a question, though. What crossover are you using for the woofer/midbass handoff?

03-04-2016, 05:13 PM
I am using a JBL/Urei 5235 for the active network. The unit has been modified with gold RCA's muse caps and updated opamps.