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ironman
01-12-2006, 06:39 PM
Hello,

I followed the advice of "grumpy" and decided to get to the bottom of my L-112's performance problem. I just removed the 128H and noticed the green wire with black stripe is to the positive terminal. On my L-110's (LE111A) this black striped wire was to the negative. Which is correct ? Thank
you !

ironman
01-12-2006, 07:21 PM
Decided to "go for it" and wire as I do on other projects - green with black stripe = neg. I know, "duh", but I've done
home wiring (110/220) where what appears to be neg. is actually hot. It appears whomever did the last refoam was rushed - even taped the Pos. with blue to be sure he had it correct - however, he did it backwards. I checked all the crossover wiring and they appear to be identically wired in both cabs. Imaging has improved but ain't perfect (lopsided vocals). Time to check the wiring at the terminals of the LE5-12's and 044's. Bobby D. is singing "Mac The Knife" through the left speaker only - intstruments though seem evenly distributed. This is a "burned" CD off the net, maybe part of the problem.

pelly3s
01-12-2006, 07:26 PM
I dont know exactly how they are supposed to be in that case. JBL had some very odd ways of handling phase and polarity.

ironman
01-12-2006, 07:37 PM
Thats what I was afraid of ! Can I damage anything if I've guessed wrong ? The L-110's LE-111A & the L-112's 128h's
have the identical color coded wiring.

pelly3s
01-12-2006, 07:48 PM
you cant damage anything. i would safely assume that you fixed your problem though

ironman
01-12-2006, 08:14 PM
I don't know - about to trash these things. Decided to go with some George Martin produced stuff off a store bought CD - Beatles "1". I was heartened to hear great balance on "Elanore Rigby", next song "Penney lane"I've got vocals, drums and bass out of the right speaker only - back and forth. Throw on Greenday and it seems to be ok - then I remember I turned the balance on my Sansui 8080 to 11 oclock ! When I got my L-110's up and running Sunday there were no issues - perfect imaging song after song. I've always been under the assumption that the vocals are always (except for an effect) mixed across both channels which gives you dead center vocals. I wrote to Rick Cobb for refoams for the L-110's, I CAN NOT WAIT to be able to A/B these pairs ! I've also read here that the L-112's can be finicky placement-wise. If they are this finicky the L-110's will be my mains - as I said, effortless !

DavidF
01-12-2006, 09:22 PM
Hello,

I followed the advice of "grumpy" and decided to get to the bottom of my L-112's performance problem. I just removed the 128H and noticed the green wire with black stripe is to the positive terminal. On my L-110's (LE111A) this black striped wire was to the negative. Which is correct ? Thank
you !

The last page of the the L112 manual shows the wiring connections.

http://manuals.harman.com/JBL/HOM/Owner%27s%20Manual/L112om.pdf

As you found out, the solid green wire goes to woofer red, the green/black to woofer black. The mids and tweeter have quick-connect fastners and are not likely to be contrary to the original connection scheme. But the crossover leads also have quick connect fastners input and output from the circuit board and may have been altered. The color codes are shown at each terminal if you can see enough into the cabinet.

DavidF

Harkness
01-12-2006, 10:45 PM
go get yourself a nice 1956 mono recording to check your speakers. something like thelonious monk plays duke ellington on riverside. that will help you figure out your phase issues much more easily.

ironman
01-13-2006, 08:12 AM
Thank you all again, looks like I'll have a busy weekend !
At least I now know the neg/pos woofer wiring is correct,
good start ! :bouncy: