jbl L80T Gi crossover issue

nan · 30th May 2011, 10:54 AM

Hello!
Does anyone have the correct wiring schematics for JBL L80T Gi.. the ones i bought are connected all 3 transducers running same phase... and out-of-phase from the colorcoding at the inlet that is!! Drivers are 127H-1, 104-4, 035 Ti. Any help would be gratefully accepted, saving me alot of measuring to get all polarities right.

nan · 5th June 2011, 08:57 AM

just lifting this thread...
Still noone that knows anyting about this drivercombination and its XO in JBL L80?

rabbitz · 6th June 2011, 08:18 AM

Had a pair back in the 80s and according to a review, the input wiring needed to be reversed for correct phase. This was confirmed by one of the heads (can't remember his name) at Northridge. It was very obvious as when wired as per the colours, the bass was low and sound plus imaging was diffused.

I can't help with the internal wiring but do the drivers have different sized lugs (markings) to ensure correct connection to the xo?

nan · 6th June 2011, 09:31 AM

Hi and thanks for the feedback!
The lugs are different, yes, males and females... but checking polarity on each driver with a battery and then crosschecking with the XO-board connections tells me that ALL three drivers are running in phase... pretty unusual from a three-way.. :-/... either mid or both mid and tweeter usually has reversed phasse to the woofer... seems theres only one way to find out... dig out the measuring rig and look if theres a deep suckout somewhere in the crossover regions on the frequenzy sweep and reverse connections there and sweep again and see if it turns for the better...
or maybe this is how it should be..little do I know about these speakers at this point..

pinkmouse · 6th June 2011, 10:06 AM

Just be aware that a lot of JBL drivers are reverse polarity to normal, i.e. connecting a positive going signal to the positive tag makes the driver move inwards rather than outwards. This could be the reason for Rabbitz's advice.

nan · 6th June 2011, 10:23 AM

Yes, Im aware of this, especially on the old LE-5´s... but in this case Ive made batterycheck looking for cone movement on the mids and woofers on both speakers to determine whats positive and negative... on the tweeter I just went for the lmarkings + and - besides the lugs... never seen that wrongly marked on tweeters, and should it be so, its still unusual having mid/woofer not reversed as I stated before.

nan · 6th June 2011, 10:27 AM

BTW.. Rabbitz is correct about the reversed colormarkings on the inlet... but that i knew before since te black went to the woofer inductors positive side on the XO-board...

30th May 2011, 10:54 AM	#1
nan diyAudio Member Join Date: Dec 2010 Location: Kristianstad	jbl L80T Gi crossover issue Hello! Does anyone have the correct wiring schematics for JBL L80T Gi.. the ones i bought are connected all 3 transducers running same phase... and out-of-phase from the colorcoding at the inlet that is!! Drivers are 127H-1, 104-4, 035 Ti. Any help would be gratefully accepted, saving me alot of measuring to get all polarities right.

6th June 2011, 10:06 AM	#5
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Just be aware that a lot of JBL drivers are reverse polarity to normal, i.e. connecting a positive going signal to the positive tag makes the driver move inwards rather than outwards. This could be the reason for Rabbitz's advice. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

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5th June 2011, 08:57 AM	#2
nan diyAudio Member Join Date: Dec 2010 Location: Kristianstad	just lifting this thread... Still noone that knows anyting about this drivercombination and its XO in JBL L80?

6th June 2011, 08:18 AM	#3
rabbitz diyAudio Member Join Date: Jul 2003 Location: Newcastle, Australia	Had a pair back in the 80s and according to a review, the input wiring needed to be reversed for correct phase. This was confirmed by one of the heads (can't remember his name) at Northridge. It was very obvious as when wired as per the colours, the bass was low and sound plus imaging was diffused. I can't help with the internal wiring but do the drivers have different sized lugs (markings) to ensure correct connection to the xo?

6th June 2011, 09:31 AM	#4
nan diyAudio Member Join Date: Dec 2010 Location: Kristianstad	Hi and thanks for the feedback! The lugs are different, yes, males and females... but checking polarity on each driver with a battery and then crosschecking with the XO-board connections tells me that ALL three drivers are running in phase... pretty unusual from a three-way.. :-/... either mid or both mid and tweeter usually has reversed phasse to the woofer... seems theres only one way to find out... dig out the measuring rig and look if theres a deep suckout somewhere in the crossover regions on the frequenzy sweep and reverse connections there and sweep again and see if it turns for the better... or maybe this is how it should be..little do I know about these speakers at this point..

6th June 2011, 10:23 AM	#6
nan diyAudio Member Join Date: Dec 2010 Location: Kristianstad	Yes, Im aware of this, especially on the old LE-5´s... but in this case Ive made batterycheck looking for cone movement on the mids and woofers on both speakers to determine whats positive and negative... on the tweeter I just went for the lmarkings + and - besides the lugs... never seen that wrongly marked on tweeters, and should it be so, its still unusual having mid/woofer not reversed as I stated before.

6th June 2011, 10:27 AM	#7
nan diyAudio Member Join Date: Dec 2010 Location: Kristianstad	BTW.. Rabbitz is correct about the reversed colormarkings on the inlet... but that i knew before since te black went to the woofer inductors positive side on the XO-board...

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