JBL2231A, 2441+2350 and 3115A

[smartpolo]

Hello,

I am currently using 3115A passive crossovers (500 Hz) to connect my 2231A woofers and 2441 drivers, I'm confused how to connect the 2441 in correct polarity since someone said blk to blk and red to red, but the other said blk to red and red to blk.


Does someone know how to connect them in correct phase? What is the difference if I connect them in wrong polarity?

Thanks,
Carlos

[Guido]

Bo is specialized in polarity questions. But I'll try to jump in.

Both is right :confused:

Blk to Blk and red to red is the way JBL did. But then the speakers are negative which mean positive signal to red gives inward cone movement.

Blk to red and red to blk mean positive signal to red gives outward cone movement. Which is more common.

Hope this do not confuse you.

[smartpolo]

Hi Guido,

So you mean blk to red and red to blk is more suitable for 2441 horn drivers, isn't that right?

Thanks,
Carlos

[Guido]

If you run them alone it really doesn't make any difference!

If you run them together with other speakers (Home cinema) then try to connect blk to red and red to blk

It is the common way.

[Zilch]

Most JBL speakers are manufactured with cone travel polarity the reverse of that conventional in the rest of the industry. If you wire red-red, black-black, you will be conforming with JBL standard.

If you then use the speakers in combination with others of different manufacture, as in a mixed-speaker home theater setup, you'll have to reverse the polarity to either the JBL's, or the "Others" for everything to be "in phase." This can be easily done either at the amp outputs or the speaker inputs. You don't have to mess with the wiring of the individual drivers.

Some JBL drivers follow the opposite cone travel convention, and they're listed somewhere here in the forum. A search might find the list, but I don't think any of the drivers you're using fall into that class.

See also your 3115 instructions. There ARE situations when it's advantageous to reverse the polarity of the mid driver and/or tweeter, depending on their mounting configurations. Others here may be able to advise you better on that aspect; it's beyond my expertise.

I just wire according to the instructions. Only time I've gotten it wrong was in assuming that the tip of 1/4" phone jack connecting to Cabaret series boxes would be (+), i.e., red. Nope, its the shield. I guess JBL may have done that intentionally, so as not to burden portable equipment guys with having to figure out that they had to reverse all the polarities going to JBL's in their mixed systems.

Good question, tho, is the polarity reversed on contemporary JBL consumer gear as well? Did they cross-wire B380 and B460, since they were consumer products? Would Citation 7.4's be cross-wired? Guess I gotta go check some stuff. LOL

[smartpolo]

So I would like to ask how to know they are in phase.


In my comparison, I found red to red for JBL 2231A woofers, red to blk for 2441 drivers with 10db attenuation is better than red to red (2231A) and red to red (2441) with 10db attenuation, but according the 3115A instruction, all drivers shound be connected in the same polarity.
:confused:

[Zilch]

It says:


The connections shown for the components of a three-way system will result in correct electrical phasing. If the component voice coils, however, are not in the same plane or arc, proper acoustical phasing should be determined experimentally.

Note that in the Recommended System Settings, some have the mid/high horns wired reverse polarity.

I'm just pointing out what I referred to above. It's NOT hard and fast; it depends on the mounting configuration of the drivers. Somebody else is gonna have to help you with the specifics for your particular setup, tho....

[smartpolo]

I need to describe my system in more detail, I'm now using 3115A and 3105 crossovers to connect the 2331A woofers, 2441 horn drivers and 2405 tweeters, the polarity is as follows:

Woofer - red to red, blk to blk

2441 - red to blk, blk to red and they are placed 12" behind the woofers

2405 - red to blk, blk to red and they are in the same plane of woofers

Does someone tell me if they are correct ? Otherwise can someone provide some suggestion for my system?

Thanks!

[boputnam]

Hey, Zilch...

Good post(s), and thanks for sharing some of your experiences with this. Lemme add a bit, by number...

Originally posted by Zilch
1) Most JBL speakers are manufactured with cone travel polarity the reverse of that conventional in the rest of the industry. If you wire red-red, black-black, you will be conforming with JBL standard. Precisely correct. When in-doubt, stay color coordinated.

2) If you then use the speakers in combination with others of different manufacture, as in a mixed-speaker home theater setup, you'll have to reverse the polarity to either the JBL's, or the "Others" for everything to be "in phase." This can be easily done either at the amp outputs or the speaker inputs. You don't have to mess with the wiring of the individual drivers. :no: If you cross-wire at the cabinet posts of a multi-way cabinet, you'll be driving the crossover "backwards"; i.e., the filter(s) will be "after" the driver. Best is to re-wire AT the transducers.

3) Some JBL drivers follow the opposite cone travel convention, and they're listed somewhere here in the forum. A search might find the list, but I don't think any of the drivers you're using fall into that class. :yes: There are a few exceptions, that's why this is a Rule! :rotfl: Since Giskard has taken-on the Technical Reference area, I hope to now clean-up my compilation so we can add to that info provided in Tech. Note Vol. 1 No. 12B (http://www.jblpro.com/pub/technote/tn_v1n12b.pdf)

4) See also your 3115 instructions. There ARE situations when it's advantageous to reverse the polarity of the mid driver and/or tweeter, depending on their mounting configurations. Others here may be able to advise you better on that aspect; it's beyond my expertise. True, intra-cabinet phasing (between drivers) is critical to the imaging and resolution designed by the engineer.

5) I just wire according to the instructions. Only time I've gotten it wrong was in assuming that the tip of 1/4" phone jack connecting to Cabaret series boxes would be (+), i.e., red. Nope, its the shield. I guess JBL may have done that intentionally, so as not to burden portable equipment guys with having to figure out that they had to reverse all the polarities going to JBL's in their mixed systems. Sound advice. But the comment on the T-S of the Cabaret has me wondering - how did you determine the T was "shield"...? It's unlikely JBL would wire unconventionally - I think the Cabaret series is negative.

6) Good question, tho, is the polarity reversed on contemporary JBL consumer gear as well? Did they cross-wire B380 and B460, since they were consumer products? Would Citation 7.4's be cross-wired? Guess I gotta go check some stuff. LOL It's not uniform - however, while JBL maintains it's driver polarity, some of their current products are phased positive (through the network) so they can be readily paired with other brands. Best to check, first.

[boputnam]

Originally posted by smartpolo
Does someone tell me if they are correct ? Otherwise can someone provide some suggestion for my system? Hey, smartpolo...

Since you're DIY, the best approach, I think, is to keep the LF negative as is JBL convention for this vintage.

2331: red to red

The 3115A (http://www.jblproservice.com/pdf/Network%20Schematics/3115A%20Network.pdf) is wired with the LF and HF in-phase. Same for the 3105 (http://www.jblproservice.com/pdf/Network%20Schematics/3105%20Network.pdf) .

Elsewhere, there are times when JBL phased the MF(HF) opposite the LF and UHF, and times when both the MF(HF) and UHF are opposite the LF.

Why not listen to different wirings, and select what you think has the best sound stage and imaging? :hmm:

[Zilch]

Bo: See the tech note you posted above. Cabaret is positive.


This situation began to change when JBL first introduced systems intended primarily for musical instrument (Ml) applications. Since these systems traditionally used l/4’ phone plugs for signal input, there was no easy way for the user to invert the input signal polarity. However, there was a need for JBL’s Ml products to be consistent with the rest of the industry, since there is considerable mixing and matching of systems of different manufacturers in the field.

See also http://www.jblproservice.com/pdf/Cabaret%20Series/4625B.pdf. The red terminal of the E140 connects to the "sleeve" or shield of the 1/4" input connector. Surprised ME, too, when I first discovered it.

Thank you for your clarifications. I don't understand "crosswiring at the system input terminals imposing the filters after the drivers," tho. Perhaps my original text was not clear....

I'm thinking smartpolo likes the 2441 reverse-wired, and is looking for "license" to do it. Truth be known, nobody's ever gone blind from doing it that I know of.... :D

[boputnam]

Originally posted by Zilch
See also http://www.jblproservice.com/pdf/Cabaret%20Series/4625B.pdf. The red terminal of the E140 connects to the "sleeve" or shield of the 1/4" input connector. Surprised ME, too, when I first discovered it. Hey...

Well, since the Tech note didn't specifically mention the Cabaret, I can't know. At this point, if something ain't listed, I'm gonna check it! :)

Now, the above quote makes better sense, to me. It's not that the shield is connected to positive, per se, it's that the Red terminal of the E140 is connected to shield of the cabinet connection. THAT makes sense. Ah....!! :bouncy: They are doing what I suggested - crosswire AT the transducer.

It's important that the filters be in the circuit on the positive lead in the network. So, if you really need to cross-wire for polarity / phasing purposes, do it AFTER the network and AT the transducer (do not merely cross the wires coming out of the amp).

[Zilch]

Cabaret Series; all models positive:
4602B
4604BAdmittedly, the list is incomplete.

See also: http://www.jblproservice.com/pdf/Network%20Schematics/4628%20Network.pdf, a Cabaret with crossover circuitry (albeit minimal).

Here, by the positive convention, with (+) coming in the "tip," the positive is the common to all drivers (tho, of note and potential interest to smartpolo, the 2118 mid driver is reverse-wired,) and the high and mid-pass capacitors are in the (-) lines. JBL flipped the polarity at the input, not at the drivers, in Cabaret series. To have everything conform to the JBL convention, you merely connect (-) to Cabaret tip.

Indeed, the tech note specifically addresses the issue of where to perform the inversion:


JBL has always recommended that absolute polarity standards be maintained throughout an audio system, from microphone input to loudspeaker output. Since most microphone and electronics manufacturers adhere to the “pin-2 hot” convention, this ensures that a positive-going signal at the input of a microphone will produce a positive-going signal at the non-ground output of a power amplifier. If JBL negative convention loudspeakers are used, the required polarity inversion should be made at the loudspeaker’s input terminals themselves. Note carefully: making the polarity inversion anywhere else in the system is an invitation to confusion.
The 4648 illustrated in Fig.2 comprises dual woofers, as we know. The inversion is made at the input, not the drivers.

Bottom line, it don't matter one whit, as long as we remain unconfused and have everything in the desired phase. We're talking AC here; it's why we use non-polarized capacitors.... :p

[speakerdave]

Originally posted by Zilch
(tho, of note and potential interest to smartpolo, the 2118 mid driver is reverse-wired,)
It is not unusual to reverse polarity on a driver that is connected to another driver through a 12 dB/octave crossover because theoretically (I think) that crossover slope creates a 180 degree lag. This was the recommendation of Drew Daniels on an early version of his ancient audiophile system to connect the 2245 subwoofers as normal, the 2225 bass units reversed, the bass mids the reverse of that (the same as the subs) and then the horn/tweet combo empirically.

The connection of each driver is done based on the 1) delay effect of the crossover, 2) the relative physical position of the acoustic centers, 3) how it sounds.

David

[smartpolo]

So, how to know they are in correct phase when just listen the sound? Does the better sound represent they must be in phase?
:confused:

[Robh3606]

"So, how to know they are in correct phase when just listen the sound? Does the better sound represent they must be in phase?"


Measurements are the best way to go. Phase is complex it depends on frequency, horn path lenghts, baffle spacing, and crossover order. If it's not right you will get a null. Rule of thumb is always what sounds best but that said sometimes it not that easy to tell. What I do is look for the worst null on my RTA and them just reverse the phase one driver.


Rob :)

[boputnam]

Originally posted by Zilch
JBL flipped the polarity at the input, not at the drivers, in Cabaret series. That, you have correct (and is why I don't use their line...).

Does the network perform as-designed when connected T = (+); i.e., with the capacitors AFTER the transducers? :hmm: Guess the answer is an easy yes, or JBL wouldn't have designed it so.

[Zilch]

Originally posted by boputnam
Does the network perform as-designed when connected T = (+); i.e., with the capacitors AFTER the transducers?

Consider the simplest case: a capacitor in series with a speaker. Does it matter which terminal of the speaker the capacitor is connected to? Or whether (+) or (-) is connected to it? The answer is "No," because the signal is AC. There is no "before" or "after" here. The (+) and (-) are NOT polarities, rather, merely phase convention designations....

[boputnam]

Well, I recognize it is only phasing, but still wander around the DC-AC thing...

[Zilch]

Originally posted by boputnam
Well, I recognize it is only phasing, but still wander around the DC-AC thing...

The statute of limitiations has long since expired on any propensity I may have ever had for a gender crisis here.

[I HAVE been known to dabble with an occasional L100 or two tho....] ;)

:rockon1: :bouncy:

[boputnam]

:rotfl:

[smartpolo]

I know the phase of cone speaker can be checked by connecting a 1.5 v battery to speaker nand observing which way the cone moves, is there any method for checking the phase of compression drivers?