L100A Hookup polarity issues again

[lgvenable]

I refinished my L-100-A's and they look great. Trouble was I hooked the first one done up as per the handbook that came with them; (it shows the woofer black to greeb black, green to red) ; and I had put a note on the wires(when I disconnected) showing black to red.

Since it appears that what I wroteconflicted with the instruction manual, I hooked them up as per the instruction manual. I then went to play the first one done on the left channel, with my 4312 on the right channel. After a bout 1 minute, it activated my amp protection circuit (ouch!!)

First, I suppose I need to play the L-100s in pairs, will a 4312 on one speaker and a L100 on the other channel cause an imbalance in my amp to activate the circuitry, or did I just drop the ball on the hookup??

How can I trouble shoot the problem to absolutely verify correct hookup, since I really dont want to fry anything in either speaker set; as I'm already working on three other JBL speaker pairs for my media room; and they're costing enough already...

Did I damage the speaker in doing this??

the woofer involved is a 123A-3

I'm going to to the battery (polarity) test described here:
http://www.audioheritage.org/vbullet...ghlight=123a-3


the battery test showed a positive AA battery to red was a negative displacement of the woofer; and when reversed (black to AA positive, the speaker had a positive movemtn toward you.

however any further help is appreciated.

[duaneage]

Do you have a capacitor across the input terminals? Capacitors can only be in parallel when an inductor is in series in front of it. A capacitor will appear as a short above the crossover frequency if wired this way.

[lgvenable]

I'll check, but the only thing I did was to plug the woofer back up to the x-over w/o any mods to the x-over. After checking the woofer in my 4312's there is a green wire/black stripe, and a green wire in the x-overs. The 123a-3 plays ok in that speaker.
Do you think it might be my x-overs? If I were to use a different set of x-overs, or rebuild them which would you suggest? These speakers were bought in 1978 to 79, and have been in service in perfect working order ever since; the surrounds are still good, although the foam grills left the Earth long ago...
Larry

[boputnam]

Hi, Larry...

I'm a bit confused, so pardon some lame questions.

The factory connection for the L100A (123A-3 LF) is GRN -> Red terminal of LF. This will be OPPOSITE the 4312 connections, too (even though the 2213H is a direct replacement for the 123A-3). You can get into trouble pairing L100's with the 4312's, but that is for another thread...

Amp brand, and model? I don't know if your amp would be confused - if it is not a dual mono-block, it might. Connect the 123A-3 properly and see.

As well:

MF LE5-2: WHT -> Red terminal
HF LE25: RED -> Red terminal

[Mr. Widget]

After a bout 1 minute, it activated my amp protection circuit (ouch!!)

First you need to find the source of your problem. Having too low an impedance will trigger a protection circuit as will a short or partial short. Having mismatched speakers or out of phase speakers will not.

Were you running multiple speakers on the same channel of the amp?

Once you find and fix the protection issue, you can sort out the polarity issue with Bo... he likes that stuff.

Widget

[lgvenable]

Unforetuately in the last move my reciepts for these speakers got misplaced, so I dont show them as L100A's on the reciept. However when I opened them up, they had black to red , green no stripe to black; just like the L100 tech sheet shows????

They sounded great, no amp protection circuitry, although they do have 123A-3 woofers; which does mean a L100A correct??

I'm confused why they were hooked up like an earlier L-100, but what a difference one night made. I finished refinishing the second speaker, and played selections from the farewell I DVD from the Eagles (last tour); and it sounded great.

Anyone have any ideas why they might be hooked up that way, as the L-100A ts (in the L100 series pdf) agreed with my manual (search Bo). Or should I trust the late model L-100A schematic and hook both up with the black to black, and green to red??. If they were hooked up weong, then they were out of phase?? correct?? then I should be able to here an audible difference., correct?

Is there any way to test polarity?? (without a cricket polarity tester), as they sound right, then again my ears aint what they used to be.

Thanks to everyone in advance.
Larry

[boputnam]

Through the fog, we go...

I can't know why the past. Following the techsheets is the only pure path. - it is simple, and by-design. Taht would be GRN to Red. Period.

However, if you will be PAIRING these with maybe the 4312's, then you will need to alter connections to avoid phase cancellation. There are two ways to go:

1) cross-wire the LF in the L100. I'll need to see if the MF and HF are compromised by this pairing. Otherwise...
2) after CORRECTING the L100 internal wiring to spec, connect the L100 cabinet backwards. That alone may provide a good pairing with the 4312, but again, I need to compare the polarity of the MF and HF....

[lgvenable]

I'll trust the pdf and wire them GRN to red period. Weird, they were unopened since 1978 to 79 when I refinished them, and I wrote the connections on a post-it note. While I am red-green color blind, since there was only GRN and BLK; it was not a case of not seeing the right colors.

Anyway off to change the wiring in each, and thanks.
FYI they're paired with the L-36 as surrounds, the L100's as the rear surrounds, and the 4312's as front channel, on a Denon 5803.

BTW in measuring speaker impedances, are they maesured dynamically while playing or static?? The L-100s show staic impedance of 6.2 ohm each, my L-36's show 7.1 each, and the 4312's show 6.6 ohm. Do the xovers need rebuilding ultimately, or is there some amount of variation below and up to 8 ohm??

Bo, I've looked for the refoam tutorial, didn;t find it yet, could you post a link; I must be using the wrong keywords in the search.

Best Regards,
Larry

[boputnam]

Bo, I've looked for the refoam tutorial, didn;t find it yet, could you post a link; I must be using the wrong keywords in the search.

Done!

http://audioheritage.csdco.com/vbull...d+step-by-step

[Lancer]

BTW in measuring speaker impedances, are they maesured dynamically while playing or static?? The L-100s show staic impedance of 6.2 ohm each, my L-36's show 7.1 each, and the 4312's show 6.6 ohm. Do the xovers need rebuilding ultimately, or is there some amount of variation below and up to 8 ohm??

Impedance - The apparent resistance in an electric circuit to the flow of an alternating current, analogous to the actual electrical resistance to a direct current, being the ratio of electromotive force to the current. It is equal to R2 + X2, where R = ohmic resistance, X = reactance. For an inductive circuit, X = 2/fL, where f = frequency and L = self-inductance; for a circuit with capacity X = 1 / 2/fC, where C = capacity.

Almost everyone has heard of Ohm’s Law, which relates voltage to electrical current flow in an electrical circuit.

E = I · R

R is the resistance of an electrical circuit. It has units of ohms. A resistance has the important property that its value is independent of the frequency of an alternating current (AC) signal applied to it.

Often current flow depends on AC frequency. In this case a more general form of Ohm’s Law is used.

E = I · Z

Z is called the impedance of the circuit. It is a complex number with a magnitude expressed in ohms. Unlike a resistance, an impedance can change value with frequency.

Here's a quick impedance plot of the JBL 240Ti.
DCR is 5.7 ohms.

[Akira]

JBL color code has traditionally been, all combinations of black (ie: green/black) go to the black terminal throughout the speaker. again traditionally, all JBL drivers where wired reverse phase. sometime ago (not sure when) they started wiring positive phase, my guess is because many amp manufactuers have started wiring negative phase. i've read lots of arguements pro and con and could never hear the difference, but there are other advantages.

as far as putting different speakers on opposite channels of your amp it will make absolutely no difference (within reason) the amp is designed to function as two separate entities. quality amps only share the same incoming power supply. besides, the L100's and 4312's aren't that different load wise compared to bi-amping operations the amp was designed for.

[lgvenable]

following Bo's advice got the L-100's cooking, I just put them like the manual showed, regardless of the note I left as I disassembled them. They work great.

Lancer...if impedance changes with frequency, then the 8 ohms quoted for JBL speakers is at what frequency?? When I measured the impedances staticly, they only showed the previously quoted impedances on the VOM.