Polarity and 4343 wiring

[Tom Loizeaux]

I read all this response to my original post - and got more confused.

I wired my 2231s so they move out with + voltage going to the red input terminal. (Though I bi-amp these 4343s, I don't see why this would make any difference.)
I wired my 2121s to be in phase with the 2231s, which put the white wire to the speaker's red terminal. Is this a mistake? (I ran the + voltage to the 2121s through the crossover to determine cone direction)
I wired the 2420s with the red wire going to the red speaker terminal.
I wired the 2405s with the red wire going to the red speaker terminal.
Remember that I'm trying to wire these to all "play forward" or be "positive".

I may still not have these correct for a complete "In Phase" system, so let's not drop this until we figure this out.

Thanks,

Tom

[boputnam]

Thanks, Tom...

Whew - this has been one struggle today. Too bad you were in surgery all day

To start, for all not yet in therapy - there is no intrinsic need to be one polarity or another. It only matters when you are pairing cabinets that each same-frequency transducer be same-phased (all LF (+) or (-), etc.) to avoid frequency cancellation.

So, reading your most recent post, here's what you done:

2231's: (+) voltage to Red terminal = (-), and also factory. That is the GRN wire, correct?
2121's: WHT to Red terminal = (+), and also factory.
2420's: RED to Red terminal = (+), and also factory.
2405's: RED to Red terminal = (+), and also factory.

According to your latest post, you have connected the tranducers to factory spec, as Giskard recommended (and just re-posted ), and your first post on this (07-17-2003 07:36 AM) was somewhat in-error.

However, your LF cone is moving IN on positive voltage, opposite what you posted.

+ voltage going to the red input terminal

...on the 2231H would make the cone move in.

Now, if you are pairing these 4343's with other cabinets, just make sure those other transducers are like-phased. That is, make sure the LF's are all (-), and all other transducers are (+) to compliment what you have in the 4343 configuration.

Thanks greatly for re-posting on this.

Now, to some fine old-vines Zin... Takers?

[Tom Loizeaux]

To Bo's statements:
(quote) Your change only impacts the area of crossover (or more correctly "roll-off") overlap between the 2231H and 2121H - that is, you are now getting a doubling of those overlap frequencies, where as-factory would have cancelled those.
Are you saying that the woofer and mid bass are supposed to be out of phase with each other? That doesn't sound right to me.

In answer to the questions from your most recent post:
First, remember I've reversed all these drivers to "playing forward" (positive).

No, I put the green wire to the black speaker terminal on the 2231s.
I put the white wire to the red speaker terminal on the 2121s.
I put the red wire to the red speaker terminal on the 2420s.
I put the red wire to the red speaker terminals on the 2405s.

I realize this is not consistant with the JBL 3134 schematic, but when I wired it to the schematic the music was not coming from between the cabinets the way it should.

My quote of "+ voltage to RED terminal" was refering to the INPUT terminals - on the cabinet - not the speaker terminals. Is any of this helping? I reversed the 2121s, 2420s and the 2405s - and things got better. I don't know what I should try at this point. All I know is that my cabinets sound better then the way they were wired. But I still want to know "the truth!"

Tom

[boputnam]

Are you saying that the woofer and mid bass are supposed to be out of phase with each other? That doesn't sound right to me.

Yes, that was factory spec. It may improve the imaging of the 2121H. A "doubling" as you have done is not bad, only not-as-designed.

And to the rest:

No, I put the green wire to the black speaker terminal on the 2231s.
I put the white wire to the red speaker terminal on the 2121s.
I put the red wire to the red speaker terminal on the 2420s.
I put the red wire to the red speaker terminals on the 2405s

...is fine. No problem. The only change you have affected is you are running the 2231H's (+), giving a doubling in the "area" of the crossover between the 2231H and 2121H. If YOU like it, GREAT!! The entire upper end (MF, HF, and UHF) is (+), as is factory, so the imaging in that range is spec.

Is any of this helping?

Yes - all this improved description is helping a great deal - many thanks. Many mysteries resolved.

Now this, could be confusing...

I reversed the 2121s, 2420s and the 2405s

...wrt the above quote as to "white and red wire(s) going to red terminals". If the wiring quote is correct - white and red wire(s) going to red terminals - whatever "reversing" you did, corrected the MF, HF and UHF to factory spec.

Now - out of interest to your initial "imaging" frustration - are you pairing these 4343's with anything? If so, what? They may have been out-of-phase with the "factory" wiring for the 2231H.

All I know is that my cabinets sound better then the way they were wired.

That is what matters.

But I still want to know "the truth!"

The truth is "out there somewhere" and if "factory" truth is what you seek, it is as Giskard and I posted:
LF would be (-)
MF (+)
HF (+)
UHF (+)

To get there, all you need do is put GRN wire to Red terminal of the LF.

[Tom Loizeaux]

This has been a real goose chase and I must apologize for some of this.
Something Bo said got me thinking. He said that the mid bass 2121 should be out of phase with the woofer. I assumed that these two should be in phase, so testing them with a battery seemed logical. Thinking I had this right is what started my confusion. See, a little knowledge can be a dangerous thing! I also colored in the speaker terminals on my copy of the JBL schematic, but then I started to question my accuracy on this.
Anyway, after reading all the above posts, I went down to my studio room this evening and pulled the top panels off my 4343s. I switched the wires to the 2121s, 2420s and 2405s. After re-assembly I found that I still had the sound stage I found recently and, when switched to MONO, had the music coming from between the cabinets, proving the drivers were working in phase! They sound wonderful!
So now I have these wired to match JBL's schematic...only reversed at each driver!

Thanks to all of you for your help and patience. The next time someone asks about wiring a vintage JBL 4 way cabinet, we'll know!

Tom

[4313B]

"The next time someone asks about wiring a vintage JBL 4 way cabinet, we'll know!"

The previous discussion applies to the 4343, 4344, and 4345.

The 4315B is wired as follows:

The following wires are "hooked" up to the RED input of the enclosure:
Green - which goes to the RED terminal on the 2203
White/Black - which goes to the BLACK terminal on the 2108
Yellow - which goes to the RED terminal on the 2105
Orange/Black - which goes to the BLACK terminal on the 2405

The following wires are "hooked" up to the BLACK input of the enclosure:
Green/Black - which goes to the BLACK terminal on the 2203
White - which goes to the RED terminal on the 2108
Yellow/Black - which goes to the BLACK terminal on the 2105
Orange - which goes to the RED terminal on the 2405

Note that JBL did use several previous color code schemes for earlier production runs of the 4315's. The point to note is the phasing as opposed to wire colors.

[boputnam]

switched the wires to the 2121s, 2420s and 2405s.

... by doing this, you put these out-of-phase with the LF (2231H's), as was the design.

Now, your 4343's are reversed from factory, but honor the engineered phasing for the cabinet (only 180-degrees out-of-phase).

Your report confirms that switching the wiring to all the HF transducers as a group keeps them in-phase (as a group) as designed, and that would have no effect on the "recent sound stage" you enjoyed. But by doing that, you re-established the cancellation in the crossover point between the 2231H and the 2121H which might improve the imaging in the ~290 Hz range.

Thanks to you for pushing on through this confusion - it provided a great deal of confimation, and much to ponder!

[4313B]

"Now, your 4343's are reversed from factory, but honor the engineered phasing for the cabinet (only 180-degrees out-of-phase). "

Yeah but if he's using 4355's as mains and these 4343's as rears everything on the top end will be in phase

[boputnam]

Yeah but if he's using 4355's as mains and these 4343's as rears everything on the top end will be in phase.

THAT is an interesting point, and correct! But the LF's will be regrettably out-of-phase. See? You too can teach a geologist to read network schematics...

It seems that this is the point in the discussion that we hear from martinleewin...

My head is .

[boputnam]

The point to note is the phasing as opposed to wire colors.

From the Sage of the Forum.

Perfect.

As always, thanks, Giskard.

[John Nebel]

Thanks to Giskard and Bo for clarifying this.

So recently I learned that surrounds rot, and indeed mine were. Spiders fatigue, and mine likely were. Things inscrutably change with frequency, phases shift, sometimes cancel as the factory intended, but maybe that is not what you wanted. Cabinets are negative, the room is full of standing waves, and 1 watt
goes a very long way.

Maybe computer nerds like myself should stay away from audio, it's too complex.

John

[boputnam]

Maybe computer nerds like myself should stay away from audio, it's too complex.

No WAY!! We NEED you guys to provide us with these Forums and to help us build avatars!

[Tom Loizeaux]

One last question concerning crossovers and my 4343s:
I am bi-amping these 4343s and using a 24dB/octave Rane active crossover, and setting it at the suggested 300Hz. When I adjust the delay on the crossover, I find that max. level at the crossover point requires some delay. This delays the woofer to be in phase with the rest of the drivers, though I'm only going to hear the relationship of the 2231 with the 2121s. In this "delayed" setting the low end is slightly stronger. Is this correct, or am I incorrectly excentuating the crossover point? Is "no dely" what JBL intended (having these 15s and 10s out of phasewith each other) even when using these 4343s in bi-amp mode?
What do you think? Bo, Giskard, ...anyone?

Thanks,

Tom

[Robh3606]

Hmm

My question would be if the 5234 or other JBL electronic crossovers designed to be used with the 4343 inverted phase on high pass output??? Do those crossovers maintain phase coherence at both high and lowpass outputs???

Tom can you change phase on the Rane?? On the M552/553 you can invert phase on High Pass outputs.

Rob

[Tom Loizeaux]

[QUOTE]Originally posted by Robh3606
[B] outputs???
Tom can you change phase on the Rane??

Robh,
The Rane lets you dial in delay on the low pass section to bring the low and high signals in to phase.
If I was using a 12dB/ octave crossover, which would have a 180 degree shift, then would the 2231 being wired "out of phase" with the 2121 make sense? But since I'm using a 24dB/ octave crossover, which has a 360 degree shift, shouldn't these drivers be wired "in phase"?
Just looking for an informed answer.

Thanks,

Tom