JBL L112 - Crossover Confusion

[scubadude]

Thanks Boputnam, hehe, yeah here we are again
I think what David said was correct but misunderstood. The factory wiring had the white/black striped wires female connector on the LE5s male connector as the ---< shows. I think the misunderstanding stems from the fact that the white/black wire connects to the male/neg side of the LE5 then goes to a terminal on the crossover marked negative which is how the average joe (like me) sees it. When in fact that negative midrange terminal is routed to the positive rear input via the Lpad and PC board which isn't noticed until one starts tracing back that circuit. You don't see that swap up on the schematic, only on the actual crossover markings. The terminals aren't shown on the schematic. So, the LE5 is out of phase with the LF and HF. Of course, this is all true if the LE5 negative is indeed the male, there are no red dots or anything on the LE5s I have (four of them) compounding the confusion, I'm trusting from another thread on this site that the females are positive, males negative on the LE5s.

My big problem was that the handwired xover was in the vintage factory mode but the pc board model had been reversed as you said, so they were out of phase up to now with regard to the other speaker. I read about the mids possibly being 180 out of phase on the 112s but until you look at the schematic then the crossover it isn't all that clear, but they are. To make matters worse, the 044 has a + stamped into the casting where the negative terminal is. Still waiting on the verdict for that one. I hooked up following the schematic and JBLs original wiring and connector scheme thinking maybe the diapram was install backward and that I could trust the terminal gender to set things straight.

[DavidF]

Uh, no.

The BLACK striped lead (???/BLK) connects to the Black terminal of the drivers in all cases. You will note this on drivers like the LE5-XX's which have the M/F connectors - the networks are pre-wired this way.

If I read correctly, your post is exactly opposite of convention (not withstanding the specific MF comment).

Also, to scubadude, the intended "POS" terminal of vintage JBL drivers is marked with a (+) and/or a red dot (even though these are the (-) post by current industry convention).

Here we are once again...

Thanks for the correction, Bo. Quite right. The point was meant to be that the mid driver polartiy should be opposite of the others and avoid going into the whole negative-is-positive in the JBL world again. As long as the orignal crossover-to-driver connections are respsected then you should be OK.

DavidF

[DavidF]

...To make matters worse, the 044 has a + stamped into the casting where the negative terminal is. Still waiting on the verdict for that one. I hooked up following the schematic and JBLs original wiring and connector scheme thinking maybe the diapram was install backward and that I could trust the terminal gender to set things straight.

Follow the schematic and don't try to equate the "+" indicator on the driver to how the schematic reads in terms of "+" or "-". The connection from the male terminal on the 044 follows back to the black input terminal.

David.

[scubadude]

Sigh,,,,, I think I'm suffering from bi-polarity...
I'm still not sure if I got it right. I'll get some kind of readable documentation of my wiring and post it for review. Thanks again

[4313B]

I guess I don't understand what the problem is.

The wht/blk wire gets the female faston and the wht wire gets the male faston. The yel wire gets the male faston and the yel/blk wire gets the female faston.

[boputnam]

So, the LE5 (MF) is out of phase with the LF and HF.

Yes, by this design, and is a common topology for a three-way system.

Of course, this is all true if the LE5 negative is indeed the male...

I'd worry less about "sex" and more about polarity... Truly, if you use the connectors pre-fitted on the crossover leads - like they do in the factory - the drivers will all get hooked-up as intended. (see Giskard's post above, and quoted here...)

To make matters worse, the 044 has a + stamped into the casting where the negative terminal is.

If it is stamped (+), why are you characterizing it as "negative"...? Again, I think you might be too focused on what the pre-wired connectors are, versus where they are meant to connect.

I guess I don't understand what the problem is.

The wht/blk wire gets the female faston and the wht wire gets the male faston. The yel wire gets the male faston and the yel/blk wire gets the female faston.

Yea, bingo.

JBL, as we have reminded ourselves, designed things in one room, but planned for things to be assembled in another room - call it an assembly line - where people not trained in crossover topology or acoustic theory were tasked with assembling things unformly to spec. This is called Quality Assurance / Quality Control (QA/QC). JBL could not risk things be be assembled wrongly, so the QA/QC focussed on the wiring from the crossover. So long as it was color-coded correctly, THERE WERE NO DECISIONS ON ASSEMBLY. It was truly "plug-and-ship".

[scubadude]

If it is stamped (+), why are you characterizing it as "negative"...?

Ok, I'll try to make sense of my take on this question:
As far as the 044 is concerned, I'm confused becuase the yellow/black that is connected to the xovers negative faston HF output has a female faston on the other end that connects to a male faston on the tweeter that has a "+" stamped on it. Plus is positive but it's the negative wire connected to it. In contrast, the green/black LF wire connects to the xovers negative input and the woofers negative input. So, ???/stripe is negative for the woofer but ???/stripe is positive for the tweeter. Therefore one convetion is followed for the woofey and different one for tweety, so the consistency varies among drivers in the same cabinet. I'm only talking about connections from the xover fastons to the driver, no other normally unseen criss crossing on the pc board to rear terminals. It seems that there are varying layers of inconsistency through out, I think. Inconsistency on where the polarity switch occurs, sometimes on the driver, others on the rear terminals or pc board. I think I may change my handle to "Wingnut"
I'm going to prepare a PPT to fully illustrate my wiring, will take some time but may be a reference for future neophytes

[scubadude]

PS: Don't get any ideas, I'm the official wingnut. That handle is officially copywrited on this site

[Zilch]

Sorry, prior use:

http://audioheritage.org/vbulletin/s...1&postcount=16

[License fees now due and payable.... ]

[boputnam]

As far as the 044 is concerned, I'm confused becuase the yellow/black that is connected to the xovers negative faston HF output has a female faston on the other end that connects to a male faston on the tweeter that has a "+" stamped on it. ...

Scubadude...

Without reading the rest of your post, it occurs to me that some moron mucked around inside these cabinets, right? Surely, they switched the "faston" connectors to work with the wiring the seller needed to feel "smart". That is why I suggested ignoring the connectors, per se, and focus on the wire colors/striping, which JBL installed. RARELY are these switched at the crossover connections, but you should have a lookie and see if there is obviously redone soldering there. More commonly, the wires are clipped, stripped and different "fastons" attached at the transducer end, only.

Make sense? Follow the network schematic and trust that JBL marked the intended (+) terminal on the transducers with either a RED dot, or a "+"...

[boputnam]

Follow the network schematic and trust that JBL marked the intended (+) terminal on the transducers with either a RED dot, or a "+"...

IGNORE what the present connectors are, and see if you can achieve the connections as JBL designed.

Looking at the schematic, starting bottom of cabinet to top:

LF (+) = GRN wire
LF (-) = GRN/BLK wire

MF (+) = WHT
MF (-) = WHT/BLK

HF (+) = YEL
HF (-) = TEL/BLK

Anything with a BLK strip or BLK solid goes to a (-) transducer terminal. Solid non-black colors go to (+) terminals.

Are we helping you...?

[scubadude]

Yes, you guys are definitely helping, thanks for sticking with me on all of this and sorry to be so confusing. The fact that we are dealing with the physical (the actual xover), the virtual (the schematic), the oddities (multiple versions of the xover some of which had been rewired), and this darn 044 with the + on the negative side,,,,,,. I'm thinking I need some vintage of another sort at this point, now I know you west coast guys can relate to that, 01' Sin Zin it is
Seriously, I am putting together a quick powerpoint to show what I've got, will post when done. Good news is my next two projects are simple (famous last words...). My sister's L60ts rotted surronds and one of my 4408s which a cat attacked. The 4408s still live here, that cat has been exported.

[edgewound]

I'll add to the confusion here.

The 128H woofer in the L112 is a "positive to black" terminal woofer. As JBL often stated in lit, "positive voltage to the black terminal will result in outward cone movement...

Anything with a BLK strip or BLK solid goes to a (-) transducer terminal. Solid non-black colors go to (+) terminals

So that preceding quote is, unfortunately...incorrect....Sorry Bo

Therefore, on the crossover schematic the black/grn wire goes to the black terminal on the woofer; solid green wire goes to the red woofer terminal.

The other drivers are pre-polarized with the crossover wire connectors as Giskard pointed out...with the polarity of the mid driver reversed for phase of the crossover....just hook'em up how they are, provided they havent' been tampered with. The negative terminal on each driver should be treated as if it were red...and would receive the solid color wire. Notice on the schematic that midrange "wht/blk (-)" wire traces back to the red input, and the "wht(+)" wire traces back to the black input. The wiring in this case takes into consideration the crossover phase relationship.

On the input terminals of the speaker system, positive voltage to the black terminal will result in outward cone movement. I know it's wierd....but that's the way JBL did things with the exception of a very few models.

This decades long confusion is the reason JBL has phased in the "positive to red" convention over the last two decades with their newer driver and system models.

[boputnam]

I'll add to the confusion here.

The 128H woofer in the L112 is a "positive to black" terminal woofer. As JBL often stated in lit, "positive voltage to the black terminal will result in outward cone movement...

That is completely true.

But edge...

Almost all the vintage JBL tranducers are as you describe - i.e., of negative polarity (+ signal to red = inward cone movement; the 123A-1 is perhaps the sole exception in this vintage, as it is a "positive" driver).

When you open a vintage JBL cabinet the woof is connected non-BLK to Red terminal, that is, solid color (non-BLK) to Red - always. I don't work on raw drivers like you do, but I have opened dozens of un-tampered cabinets and it's always the same - absolutely consistent. The scheme is steadfast. Any wire with anything "BLK" goes to the black terminal.

These vintage cabinets "sucked", if you will, which is why JBL issued that Tech note suggesting users might reverse connections to the back of the cabinet, so the cabinet performance will conform to "revised" industry practice.

Connecting a 128H as you recommend will absolutely do what you say - but that was not the original build.

[edgewound]

That is completely true.

But edge...

When you open a vintage JBL cabinet the woof is connected non-BLK to Red terminal, that is, solid color (non-BLK) to Red - always. I don't work on raw drivers like you do, but I have opened dozens of un-tampered cabinets and it's always the same - absolutely consistent. The scheme is steadfast. Any wire with anything "BLK" goes to the black terminal.

Bo.....that's what I said too....at least I thought I did.