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Author Topic: Speaker Wire
Adam Fraser
Master Film Handler

Posts: 498
From: Houghton Lake, MI, USA
Registered: Dec 2001


 - posted 04-19-2002 10:49 PM      Profile for Adam Fraser   Author's Homepage   Email Adam Fraser   Send New Private Message       Edit/Delete Post 
This is just a question out of curiosity...
How much loss of sound is there with hundreds of feet of speaker wire between the amplifier/processor and the speakers? And what effect does the quality of speaker wire have on sound loss? Most theatres I have seen seem to use a fairly mid grade of speaker wire and I was wondering how much difference (sound quality and loss) there may be between running the top of the line wire compared to average run-of-the-mill wire.
Thanks for your comments.

------------------
Adam Fraser
www.pinestheatre.com

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David Stambaugh
Film God

Posts: 4007
From: Eugene, Oregon
Registered: Jan 2002


 - posted 04-19-2002 11:16 PM      Profile for David Stambaugh   Author's Homepage   Email David Stambaugh   Send New Private Message       Edit/Delete Post 
I was kind of surprised when I saw a sample of the type of speaker wire typically used in theaters. It looked like 14-gauge stranded copper zip cord to me, like lamp cord (I think that's 14-gauge). Now I'm not a big believer in high-end audio cable voodoo myself, but for those long runs, and considering the huge power being pumped out, zip cord seems kind of questionable. That kind of speaker cable would be considered the absolute minimum for decent home audio, where the distances are much shorter. I don't have any data, but have done a lot of reading about exotic cables and such as it applies to home audio. Some high-end audiophile believers would have a coronary if they found out their favorite THX-certified 1000-seat SRD/DTS/SDDS movie theater is running the stage speakers on Radio Shack Zip Cord.

A THX-certified Mann theater in Laguna Hills or Laguna Niguel (Calif) or someplace close to that advertised that it used Monster Cable speaker wiring. They had a big one-sheet in the lobby promoting it. This was in the late 80s.


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Dave Macaulay
Phenomenal Film Handler

Posts: 1938
From: Toronto, Canada
Registered: Apr 2001


 - posted 04-19-2002 11:25 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
The loss depends on the length and wire gauge. There is a purely resistive loss of power in the wire that does not directly affect the sound quality but long runs and small wire can waste a good percentage of the amp power as heat. Essentially, larger wire will compensate for a longer run.
The sound is affected by resistance indirectly because speaker cable resistance reduces the effective damping factor of the amplifier. A high damping factor helps control the speaker cone movement and improves the "fidelity" of the sound.

Quality of wire? I may get flamed for this - but "high quality" wire is ridiculous. If you think paying extra for "Monster Cable" or other "superwire" is a good idea, go ahead. You get a nice looking wire and it's really flexible. So what. Compared to the same gauge "normal" stranded wire there is absolutely no electrical difference that will affect the sound quality.

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David Stambaugh
Film God

Posts: 4007
From: Eugene, Oregon
Registered: Jan 2002


 - posted 04-19-2002 11:46 PM      Profile for David Stambaugh   Author's Homepage   Email David Stambaugh   Send New Private Message       Edit/Delete Post 
The only thing I would add is that by using something like Monster Cable, you would probably be assured of having better than the minimum gauge to do the job efficiently. But you would be spending way more $$ than necessary to get there.

(You mean you don't believe that oxygen-free 99.99%-pure copper wire with the the crystals aligned in the direction of current flow and a genuine Teflon jacket would improve a theater's sound??)


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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 04-20-2002 02:36 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Dave Macaulay is correct.

Some amplifier operator's manuals have a chart which explains the damping factor characteristics. It is nothing more than an arbitrary number, but the higher the better. The chart usually gives an idea as what might be expected by the size and length of the wire used. The higher the number, the better.


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John Anastasio
Master Film Handler

Posts: 325
From: Trenton, NJ, USA
Registered: Sep 2000


 - posted 04-20-2002 06:41 AM      Profile for John Anastasio   Author's Homepage   Email John Anastasio   Send New Private Message       Edit/Delete Post 
If you're concerned about resistance, just run another length of the same 14AWG wire and you'll have the same resistance as 7AWG wire....but you'll just be wasting wire and increasing something else that will have more of an effect on the high frequencies....the capacitance of the wire. The capacitive reactance (dynamic resistance to certain frequencies) increases with surface area. The longer, or the wider, the wire, the more the capacitance. The more the capacitance, the more the filtering effect on high frequencies. Eventually, after a few miles of wire, they all disappear....ask any telephone engineer. It's why you can't get DSL out in the boonies...the wire can't handle the higher frequencies. I'd say not to worry about that 14 gauge zip cord. It should handle a constant draw of up to 15 amperes of current at very low resistance over the distances you're working with....more than enough to blow out any speaker you've got without affecting frequency response.

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Bruce Hansen
Jedi Master Film Handler

Posts: 847
From: Stone Mountain, GA, USA
Registered: Dec 1999


 - posted 04-20-2002 09:09 AM      Profile for Bruce Hansen   Email Bruce Hansen   Send New Private Message       Edit/Delete Post 
It would be my guess that the THX theater mentioned above, got the Monster Cable for free by putting that one sheet in their lobby. In my opinion, the only thing you are improving by using Monster Cable, is Monster Cable's bottom line.

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Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000


 - posted 04-20-2002 10:01 AM      Profile for Phil Hill   Email Phil Hill       Edit/Delete Post 
The comments from Paul and Dave Macaulay are on target.

Also, circuit resistance does become half of the original resistance if you parallel a conductor with another of the same AWG. The new equivilant AWG is 3 wire sizes smaller, NOT cut in half. 14AWG + 14AWG = 11 AWG.
In high-power special venue and large format theaters where it's common that the audio power exceeds 30kW to use 14 AWG, 12 AWG, and 10 AWG for each of the HF, MF, and LF drivers of a speaker system. What is sometimes overlooked is the voltage rating of the insulation. High-power amplifiers can put out more than 120 volts of signal and require class I speaker wiring usually something like THHN in conduits.

>>> Phil

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Gordon McLeod
Film God

Posts: 9390
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 04-20-2002 10:23 AM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
I use twisted pairs of 12 AWG minimum and 10 for longer runs
West Penn makes a nice jacketed twisted pair if you like purple colour
Twisting is important to eliminate RF pick up
Monster cable and the like is for the birds
And bareing the wrath of S.G. I still use the drill to twist THNN stranded wire

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Adam Fraser
Master Film Handler

Posts: 498
From: Houghton Lake, MI, USA
Registered: Dec 2001


 - posted 04-20-2002 11:04 AM      Profile for Adam Fraser   Author's Homepage   Email Adam Fraser   Send New Private Message       Edit/Delete Post 
Thanks for all the reponses guys.. Very helpful

------------------
Adam Fraser
www.pinestheatre.com

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John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999


 - posted 04-20-2002 11:14 AM      Profile for John Walsh   Email John Walsh   Send New Private Message       Edit/Delete Post 
We like regualar 10ga also, twisted with a drill. Although, people complain about getting all the strands into the terminations at the speaker and amps.

Monster cable does look good, and does have nice terminations on the ends. Sometimes for hi-end jobs, you might need that. But, there is no difference in sound quality, unless basic physics has changed since I was at school.


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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 04-20-2002 04:17 PM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
If you twist your wire in an electric drill, be careful what direction you twist it. If you go the opposite direction of the lay of the strands, damage to the wire will result. Also, keep in mind not to "Over-twist" the wire.

One idea of twisting the wire is to cancel each other's magnetic induction. This will make the wire look resistive to the amplifier, and not inductive.

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Jerry Chase
Phenomenal Film Handler

Posts: 1068
From: Margate, FL, USA
Registered: Nov 2000


 - posted 04-20-2002 05:40 PM      Profile for Jerry Chase   Author's Homepage     Send New Private Message       Edit/Delete Post 
..and remember that more isn't better. The amount of twist needed is quite small - something like 1 twist every 18" is plenty, IIRC. I used to get the grunt work helping my dad install PA systems and stuff.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11749
From: Annapolis, MD
Registered: Dec 1999


 - posted 04-21-2002 12:42 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
John,

Check your math before giving someone bad advice. 14awg is often inadequate wire in theatre applications.

Lets say your subwoofer line needs or will demand 2000 watts of power and you use say 4 8-Ohm subwoofers to handle the power and present a 2Ohm load to the amplifier...you will need nearly 32 amps of carrying capacity from your wire. 14awg won't cut it and you wont be blowing your speakers, necessarily. Heck, only 750 watts into an 4-ohm LF cabinet of a typical stage speaker (that can hanle 1200 watts) will bring you nearly up to 14amps. The JBL 4648-4, when driven to full power will draw over 17 amps without damaging the drivers. Instantaneous power consumption can double that!

Both of the above examples are valid for typical theatres today.

This isn't a case where we want the wire to current limit our signal either thus larger wire should be used. While damping factor is almost never a concern for speaker wire, power limiting is.

As for THX, they do have their hand in choosing the speaker wire gauge. I believe it was HPS-4000 though that got on the Monster cable bandwagon.

However, there are plenty of cases where 14awg is just fine. It really depends on the length of run and the power needed.

BTW Carol and Belden also make fine jacketed red/black speaker cables down to 12awg. If you don't mind wht/blk then one can often go larger, West penn just introduced a 10awg. International Wire and Cable will make larger gauges in red/black...I've seen them use 10awg.

Steve

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"Old projectionists never die, they just changeover!"

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 04-21-2002 02:31 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
Steve, is some of that wire nickel or silver plated like some of the wiring I have seen in ORC equipment? I am not sure what it was plated with, but I do remember seeing lots of that type of wire used in military applications (especially aircraft) that had heavy current draw using small AWG wire.....Enlighten me.


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