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Author Topic: Speaker wire gauge Tom Wienholt Master Film Handler Posts: 371 From: Towson, MD, USA Registered: Dec 2002 posted 01-15-2003 12:21 AM                     I just got done reading old topiics about proper speaker wire gauge. Is there a chart somewhere that gives this information. Basically, i need to know what gauge speaker wire to use for an auditrum that is 50 feet long. Each wire will be at most 100 feet in length. Any help would be appreciated.  |  IP: Logged Jean-Michel Grin Expert Film Handler Posts: 222 From: Geneva & Lausanne, Switzerland Registered: Jul 2002 posted 01-15-2003 02:16 AM                        Hi, In ours Theaters we use at least for short distance, 16 AWG ty cable (almost 1.5 square milimeter for HF) and 14 AWG (almost 2.5 square milimeter for LF and Sub) For very big auditiorums, i mean that 14 AWG must be sufficient or better for LF use 12 AWG. Good Luck ! Jean-Michel  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 01-15-2003 03:05 AM                       I always used #12 for stage channels, #10 for subwoofers, and #14 for surrounds. In a small house, you can probably get by with a size smaller on each. All conductors 600v, THHN stranded, and make sure the electrician either numbers or runs different colors for each. I also have them pull an extra conductor or two while they're at it, you never know what lies ahead.  |  IP: Logged Jon Bartow Master Film Handler Posts: 287 From: Massachusetts Registered: Nov 1999 posted 01-15-2003 07:34 AM                     I'm with Tim: #12 for stage (unless it's a big triamp system then the LF will have #10) #10 for sub and #14 for surrounds (a home run to the booth for every speaker) I allways have the electricians pull extra wires for the stage and for the back wall if no rear surrounds are originally installed. For the stage I usually have them pull 6 pair #12 for the three stage channels (bi-amped) and two pair #10 for the subs and a spare pair of each , just in case. And I have them leave a string or two in the conduit for the future. Jonathan  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 01-15-2003 08:03 AM                        For what it's worth, John F. Allen had an article on this topic in a recent issue of Boxoffice magazine.  |  IP: Logged Don E. Nelson Expert Film Handler Posts: 138 From: Brentwood, CA, USA Registered: Nov 2001 posted 01-15-2003 03:20 PM                     Tom, In order to ensure the best possible sound out of your theatre sound system, I would recommend you research this speaker wire subject throughly before buying just any old gauge of speaker wire from the local hdwe. store. Years ago, (1974) my roommate at the time realized that interfacing the amplifier to the speaker system on any type of sound system was the most overlooked component. He researched the cable industry and did some electronic/physics research and started buying samples of specially produced wire from Japan. From this humble begining ,he started a company called The Monster Cable Co in San Francisco. He is now the "head monster", and his name is Noel Lee. It is critical that the signal from the amplifier to the speaker system is not limited in any way by the connection wire. That is why a lot of concert sound companies do away with speaker wire completely by physically locating the amps aon back of the sound cabinets. (directly coupled) To make a long story, not quite so long, Noel found that there are three basic electrical properties which combine to form the total impedance of a wire: resistance, capacitance, and inductance . The capacitance effects the high frequencies that travel on the outside of the wire. Resistance (resistive impedance, measured in Ohms) is usually not a problem, even with inexpensive electrical cables. The real culprits in cable transmission are capacitance, measured in picofarads ) per foot, and inductance, measured in microhenrys (µH). The damping control of the amp is critical to controling the speaker cone movement accurately. The types of wire connectors you use at both ends are also critical. Now this may sound like info that only an audiophile, with a high end system, has to worry about t but if you don't think of you theatre sound sytem as a really good stereo system, your in big trouble and it will just sound like a PA. system . I believe something as simple as speaker wire is the reason some theaters sound "great " with good stereo imaging, presence and dynamic range while others are just (ho hum)average. Best of luck.  |  IP: Logged Kenneth Wuepper Phenomenal Film Handler Posts: 1026 From: Saginaw, MI, USA Registered: Feb 2002 posted 01-15-2003 06:38 PM                     Avoid at all cost the temptation to use multi-conductor cable for the amp to speaker connection. Additional coupling of the signals from one amplifier output into the others in a multi cable will cause some very queer problems. In one occasion, the amplifiers were running very warm and the signal was sort of fuzzy. The volume was not sufficient to have caused amplifier overload yet the sound was second rate. A scope check of the outputs from the amplifiers showed that there was an oscillation at pitches above human hearing range and these signals were overloading the power amplifiers. Sound amplifiers with negative feedback compensation for achieving good frequency response are most likely to have this problem. Amplifiers without transformers in the output circuits also are susceptible to ultrasonic oscillations. Capacitive coupling in bundled cabled wires is greater than in open wires or even wires in counduit. The idea of locating the power amplifiers back stage and feeding them input signal with balanced and shielded cables is a sound one. (Pun Intended) KEN  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-15-2003 07:54 PM                     Also when your electrician does the wire install be sure that he twists EACH PAIR by either using a drill, or by getting the wire pre-twisted. The Drill is LOTS CHEAPER to do though. Expect pre-twisted wire to be AT LEAST double in price!! Yes, you have to up-size the conduit as well! Twisting the pairs will eliminate mutual coupling between channels, and cancle out any RF that may want to feed back down the speaker runs to the booth. The picture is of a large install job we did last September. Each run was about 200' long and we used #10 wire. The system was Quad-amped so the electricians installed a 4" couduit run for us and pulled in two extra strings as well. Notice that one roll has the wire comming off the top and the other off the bottom. This helps the wire twist together better and also makes the wire relax a bit better. Ya have to let off slowly to relax it...run the drill backwards a bit or else it'll turn into a tangled mess, or might whip back at you...no joke . Use an eyebolt in the drill and have a seciond person keep some back tension on the rolls of wire, or you'll tangle!. Use stranded wire, THHN insulated(double insulated). Stranded is lots easier to work with and sounds much, much better than solid because of skin effect. Definately the longest rune I've ever twisted in the field...ok parking lot. Only took about 5 hours to do all the twisting...we had great weather for it..... Mark @ CLACO  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 01-17-2003 10:42 AM                        quote: Noel found that there are three basic electrical properties which combine to form the total impedance of a wire: resistance, capacitance, and inductance Wow! I would have thought that that was already known by the 70s. Your friend is a pioneer of electrotechnics! Is there a unit named after him?  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 01-17-2003 12:37 PM                        Nothing negative intended toward Noel... but I found one product of Monster Cable to be a bit over the top... probably rampant marketing at its "best"... Monster sells a short piece of telephone cable with modular connectors on each end... intended to patch between a modem and the wall jack. The product description highlighted how super wire and gold connectors could "help" raise data rates and reduce errors. I guess you weren't supposed to wonder about all the wire going between the other side of the wall and the central office...  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-17-2003 12:58 PM                     Specialty speaker cables are vastly overated  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 01-17-2003 02:45 PM                        Some articles about speaker wire and damping factor: http://www.tnt-audio.com/clinica/cat5questions_e.html http://www.canare.com/cat10pdf/p31.pdf http://www.procosound.com/downloads/guides/htc_speaker.pdf http://www.procosound.com/downloads/speaker_guide.pdf http://www.sweetwater.com/insync/word/dampingfactor  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-17-2003 07:30 PM                     As always, I never recommend to use a drill to twist wires into cables...it increases the stress on the individual conductors, and ultimately the individual strands. A proper lay will not add any rotation to the individual conductors and will have zero spring to the cable (without having to go backwards). Steve  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-17-2003 08:07 PM                     Steve, I don't dispute that you will be ading at least some stress tothe twisted pair....Twisting wire yourself however is sometimes the only way to make deadlines and keep within budget most of the time. I've also used alot of pre-twisted pair as well. Try getting that much thhn #10 twisted pair sometime...good luck! Has to be custom done even here in SLC where there are almost 60 electrical supply houses. None of them have proper equipment to twist wire. Also pre-twisted wire will normally at least double in price and sometimes be triple. Myself, and and I also know Gord have always twisted wire with only excellent results from doing so. Have yet to have any sort of problems in 20 years from the slight stress that twisting might add to the conductors. Copper is one of the most resilient of the metals and is quite good at taking the small stress added. Perhaps though you have had problems from doing it this way...but I have yet to. Mark @ CLACO www.clacoequipment.com  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-17-2003 08:19 PM                     Gord said, "Specialty speaker cables are vastly overated" ___________________________________________________________________ Sorry Gord, You're a bit off with that statement. First, you have to have quipment with high enough resolution before you can hear the differences. Few, if any theatres, or dubbing stages fall into the high resolution catagory. There are alot of things that affect how a cable sounds, some of these differences can even be measured, and some cannot. Capacitance plays a big factor, how much resistance, and how much reactance the cables introduce will also cause differences in overall sound. Moleculuar structuire of the copper, or what ever metal is another big factor. Different amplifiers and different speakers all behave differently with differing amount of capacitance, reactance and resistance....ya can't deny that! Just don't expect to be able to hear huge differences, usually they are slight. Another thing that does have effect on sound is the braid of the conductors, and how the cable is braded together. There is alot more to it but these are just some of the reasons. If ya want to know more research it........ Mark @ CLACO www.clacoequipment.com  |  IP: Logged

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