my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » JBL Horns (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: JBL Horns Michael Voiland Expert Film Handler Posts: 219 From: Naperville, IL US Registered: Aug 2009 posted 05-20-2010 02:26 AM                     Ok so we have a single 15 for the middle of our theater. The horn on top of the cabinet is a jbl compression driver 16 ohms i am not sure about the model i didn't think to look. It has to have a diameter on the back of the horn about 4 inches but i am going to assume its a 2 inch compression driver. The connectors on the back of it suck and they are not holding a good connection speaker vibration has caused it not to say connected. It looked almost like it was threaded into a socket and i gave it a slight turn well its loose now. Is their a way to tighten this connection on these stupid push button connectors up so they don't rattle loose and keep a good connection. This is on our center channel.  |  IP: Logged Sean McKinnon Phenomenal Film Handler Posts: 1712 From: Peabody Massachusetts Registered: Sep 2000 posted 05-20-2010 10:48 AM                        There is a way to tightn the push in plugs down but I would be more concerned about the excessive vibration. Is this horn properly mounted to the LF cabinet?  |  IP: Logged Michael Voiland Expert Film Handler Posts: 219 From: Naperville, IL US Registered: Aug 2009 posted 05-20-2010 06:22 PM                     Yes its just that it has come loose over the past 6 years and since no one ever sees it they never worry about it. I found it out after their were complains about sound being muffled.  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 05-21-2010 01:10 AM                     Three solutions, Remove the binding post and solder the cables directly! Make sure that you have a secure point so as not to have the inner cable being forced by the input cable. Do not solder directly the binding posts! Replace the binding posts (if you can find a replacement) Buy new speaker  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 05-21-2010 12:07 PM                     LOL good ones Demetris Fourth solution: Remove the cover that the posts are mounted on, on the backside will be pigtail leads and nuts holding the binding posts on. Tighten your nuts and it'll be good to go.  |  IP: Logged Michael Voiland Expert Film Handler Posts: 219 From: Naperville, IL US Registered: Aug 2009 posted 05-22-2010 02:09 AM                     I did the forth solution tonight before i got a chance to read it. Whoever put these things in had half of them wired backwards to the crossovers aka pos to neg and neg to pos so my 3 screen channels are now all in phase to each other. Now to check the rest of the theaters.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 05-22-2010 04:54 PM                     Be careful... Some of them should be wired backwards or out of phase. Depends on model... You may want to ask Steve Guttag. He can tell you which models off the top of his head Mark  |  IP: Logged Jeremy Weigel Phenomenal Film Handler Posts: 1062 From: Edmond, OK, USA Registered: Mar 2007 posted 05-22-2010 05:11 PM                     I have a pair of JBL subs that were out of phase. After checking numerous times that the polarity was connected correctly from the amp to speakers and removing the drivers to check the connections between the drivers and push terminals (all of which were correct based on color coding) I ended up reversing one of them inside the cabinet and leaving a note for future reference.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-22-2010 05:33 PM                     On should always verify speaker phaseing with a tick box like the easy phase that smart used to sell  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 05-22-2010 05:59 PM                     As I recall JBL coded all drivers so a positive voltage on the red terminal moves the voice coil out of the magnet assembly. Since the horn diaphragm is mounted opposite to cone drivers, the horn sound waves will be "out of phase" with the bass bin's if you connect both with amp + to the red terminal.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 05-22-2010 07:36 PM                     What would be the reasoning over this from JBL to have each driver to "pull" opposite if the positives were tied together? Seems a bit confusing and kinda goes against logical wire terminations.. -Monte  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 05-22-2010 09:51 PM                     Positive voltage on red or "+" terminal having a cone driver move out of the magnet is the convention of most. JBL did it in reverse in a "retaliation" to Altec convention since James B Lansing was the father of both. As for what drivers are in "normal" phase versus reverse...if a JBL driver is a legacy driver (can be a direct replacement of an earlier driver) then it will follow the traditional JBL convention of reverse phase. If it is a NEW JBL driver that does NOT DIRECTLY REPLACE a legacy driver, then it will follow normal phase. Thus 2225, 2226 drivers will follow reverse phase. 2425, 2426, 2445, 2446, 2450 drivers will also follow reverse phase. Subwoofers is where it gets tricky. The 4645 (original) used the 2245H, it is reverse phase. The 4645B and 4645C use the 2242...this is NOT a direct replacement of an earlier driver so it follows NORMAL phase. The 4642A subwoofer uses 2241 drivers...the 2241 IS a replacement of the 2240 driver so it follows REVERSE phase! JBL states that the 4141 and the 4642A follow NORMAL phase...which means the cabinets have to be wired reverse internally. I can and have found them wired wrong and, in the case of the 2242A, with each driver wired opposite (to the terminals on the cabinet)! As Gord says...use a phase checker to ensure you are wired in-phase. The CP650 and CP750 even give you the "thump" for the phase checker to work from. Steve  |  IP: Logged Michael Voiland Expert Film Handler Posts: 219 From: Naperville, IL US Registered: Aug 2009 posted 05-22-2010 09:57 PM                     I will go back up their and get the model of each but only the center and left were wired backwards only for the horn. The right was wired correctly.  |  IP: Logged Cameron Glendinning Jedi Master Film Handler Posts: 845 From: West Ryde, Sydney, NSW Australia Registered: Dec 2005 posted 05-23-2010 12:16 AM                     I was under the impression that the positioning of the horn and the miss allignment of the magnets for both the woofers and mid horns could also effect the phasing. Also some if not all 12db per octive crossovers reversed or introduce a 180 shift the phasing as well? If one looks at the eq one can see the effect of either the peak or dip in response created by the miss match! I remember reading an altec manual that discribed the sound effect of a miss matched phasing. Is it possible that the person who wired it up also eqed it? If so perhaps you have now made it out of phase? At least a new eq would probably be required as the wiring does effect the frequency response of the system, as it has probably been eqed in its last configeration?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 05-23-2010 01:19 PM                        Also: on Legacy JBL units, it was necessary to reverse the phase in order for explosions to be "positive" phase. See the original THX drawings for reference. Louis  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.