This is topic long interconnect ( balanced ) to amp and short wires to subwoofer or the opposite ? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by David Baum (Member # 568) on 12-30-2000, 06:34 PM:
ie, short interconnect and long speaker wire. I would favour the first option, a balanced signal allowing long cables vs using long wire ( AWG 10 ), which would reduce the damping factor and increase dB loss.
subs are JBL 4645C (2x), amp will be QSC DCA 3422H. max AWG allowed with the QSC ( speakon ) is 4mm2 or AWG 10. another reason why I would favour a short wire and long balanced cable from the bass processor.thanks and Happy New year.
David
Posted by Scott Norwood (Member # 30) on 12-30-2000, 07:29 PM:
I've had this argument with someone before. He wanted to run a long balanced line through the theatre attic and put the amps behind the stage. The thinking here is that good-quality speaker wire is expensive and the signal loss is less for a balanced line, anyway.
To a certain extent, this makes sense, although I personally have a pretty strong preference for keeping the amps in the booth in order to make troubleshooting easier in case of a total or partial loss of sound during a show.
One compromise which I have seen in an early mag installation from 1954 was to run 70v lines (with transformers at the amp and speaker end) between the amps in the booth and the loudspeakers, which was supposed to minimize cable loss at the expense of some quality loss due to the transformers. I kind of like this idea assuming that good 70v transformers are used, but I've never heard of anyone doing this for a recent installation...
Posted by David Baum (Member # 568) on 12-30-2000, 07:51 PM:
hi and thankswell, I have "visual" access to the subs and their amp , this is why I would favour the option of running 2 long balanced XLR cables from the bass processor to the amp.
Thanks for this idea of transformers but I would rule that out.
Btw, this is for my home theater ( film freak but even more a home theater freak 
). The funny part is that I have never gone so much to theaters since the last 2 years. 2 or 3 movies a month generally.
regards
Posted by Paul G. Thompson (Member # 655) on 12-30-2000, 08:18 PM:
Ummmm, David - I used a 70 volt line once on a surround speaker setting. The problems I had were line noise, RF from the local CB'r with a foot warmer, hash noise from neon lights, etc. Some sound engineers have advised me that this would happen, and it did. Although I was able to swamp most of that crap out with filters, I have to agree with the ones who told me not to use it. Too much of a hassle.For subwoofers and stage speakers, I have used 4-conductor 8AWG cable, configured the way John Allen recommends for his HPS-4000 sound systems. There was never any problems, and the sound quality, in my opinion, beat the THX system quite handsomely. I agree with Scott - keep the amplifiers in the booth.
Posted by David Baum (Member # 568) on 12-30-2000, 08:27 PM:
Hi PaulThanks. Mmh, 8AWG ? with speakon ? The QSC DCA use NL4FC speakon, and they only accepts 4mm2 wires ( ie, 10 AWG if I am correct ). 8 AWG would be great ( this is what I have currently with my current power amp and I CAN feel/hear the difference between 8AWG and the former 10AWG I had previously).
on the other hand, looking at what JBL recommends in its technical sheet on the 5000 screen speakers, even 12 AWG or 16 AWG would be enough for such short distances ( less than 50ft for instance ), which amazes me, knowing how much the wire can "eat" ( dB loss and damping factor loss ).
Regards
Posted by Paul G. Thompson (Member # 655) on 12-30-2000, 08:30 PM:
David - a junction box next to the amplifier will fix that. 
Oh, it can eat alot. But a damping factor is just a figure of merit. The closer to 200 you can get, the better off your are going to be. But if you approach 150, you probably won't hear much of a difference (if any) from 150 to 200..
There are some mighty fine sound engineers on this forum, and they know more that I do. They can give you some good advice, and some suggestions they will make won't drain your bank account.
Posted by Daryl Lund (Member # 356) on 12-30-2000, 09:06 PM:
I would run 12 gage stranded wire, like they use in conduit. ACT III did it and so did I. Run the wire from the amps in the booth to the speakers behind the screen.
Posted by Paul G. Thompson (Member # 655) on 12-30-2000, 09:09 PM:
Daryl - Please be sure to "twist" the wires. I twisted my AWG 12 wires by chucking the the pair in an electric drill. (makes a good Yo Yo, when you turn the drill off, too).
Posted by John Eickhof (Member # 323) on 12-30-2000, 09:57 PM:
I've used both balanced & direct low imp. lines in many situations. The large theatres 500+ seats. I prefer the balanced line feeds, as a little higher signal is used from pre-amp to power-amp, thus the signal to noise ratio benifits! Using good amps like QSC and good sheilded cable I have never had noise or RF interference. (some runs up to 200 feet long!) Figure out voltage drop
under low impedence situations and you will find that watts are wasting on the long transmission lines! Thus, #8 awg or larger is best over long runs and always twisted in pairs and run through metal conduit! Transients are actually more succeptable on open low impedance lines than high impedance!
They make great shortwave antennas! Happy holidays!
Posted by Paul G. Thompson (Member # 655) on 12-30-2000, 10:16 PM:
But I certainly would not put high-impedance balanced lines in a conduit. It could cause ground loop hums up the gazoo!
Posted by Steve Guttag (Member # 268) on 12-30-2000, 11:08 PM:
I have very strong position on this one...That is keep the amps in the booth. It isn't that the amps can't be put next to the speakers with success because they can and have. It is much more difficult to accomplish this without noise problems and no matter how you cut it, it is more difficult to troubleshoot an amp behind the screen than one in the soundrack with the rest of the equipment.
As to the loss in the wire, use a suitable wire size. Don't was your money on high-brow speaker cable either....use THHN stranded. 10awg will be fine but #8awg may make you feel better.
Oh and on damping factor, it is mostly a bogus number used by amplifier manufacturers to show some sort of superiority. The driver itself will be the big operator in that, not the cable. If you have two 4645C then run two pairs of cable.
Twisting cable is a good idea, running in grounded conduit is a VERY good idea...every once in a while a surface mounted speaker run finds out what a cabbie or walkie talkie can do.
When twisting cable (in general) DO NOT USE A DRILL!!! you are then actually twisting the strands themselves which is not the goal (you are actually breaking the cable)...the goal on twisting the cable is to create a "lay." Either get it twisted properly by the manufacturer or you will be twisting by hand. A properly twisted cable is such that if before twisting you were to put a straight line on the top side of the cable and then twist the cables the line stays straight. This will not stress the cable and not create a "spring"
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by John Walsh (Member # 168) on 12-30-2000, 11:39 PM:
If I can add my own two cents worth....I agree with Scott; it would be better to keep the amps in the booth for both troubleshooting and EQ'ing (if you have to adjust the gain pots.)
On two installations I know of where the amps were remote (to the processor) there was a slight 60cy hum in the sound. It's just too hard to keep those low-level runs quiet.
If the amp has XLR/Cannon type (3-pin balanced) plugs, use them rather than hard-wiring them to terminals. Look carefully at the documentation that shows which pin is "high" "low" and "ground." It seems that someone always reverses them somewhere.
Paul's idea of twisting them is good also. Run them in conduit if possible. If not, you will probably have to buy plenum-rated wire to adhere to building codes.
Run the thickest gauge speaker wires you can to the stage. Try to make each wire one 'unspliced' run. If you are having electricans do the work, tell them specifically there should be no splices. You might be surprised at how many times this is forgotten, and the speaker run ends up with 2-3 splices in it. Leave a lot of slack at both ends, because you may have to change around the rack equipment or the way the wires are routed at the speaker.
When you "dress" the wires in the amp rack, leave enough length to enable you to disconnect the wires from one amp and reach another; ie: the speaker wire from the bottom amp will reach the top amp, etc. Not only is this good for troubleshooting, but if (say) the center amp goes out, you can easily switch to another, less important amp (like a surround channel) until the amp is repaired. Do the same with the XLR amp inputs.
A suggestion is to color-code the wires by making the "low" or "return" wire the same color for all channels, and buying a different color for the "high." I used the resistor color code to remind me which is which during installation; ie: twist white and black for "LEFT;" white and brown for "Le," etc. You might have to order some colors in advance, because that are not commonly used. Lable them properly when you are done (nylon tie-wraps with a writing area on them.) They will probably get treated very roughly over the years, and you don't want them to come off.
Personally, (depending on the distance- up to 120 feet/ 40 meters) I think 10 or 12 gauge is fine. While it's true the bigger the gauge the better, the law of diminishing returns comes in. It's just not going to sound any better with 00 gauge wire.
The 70.7 volt transformer system is pretty much out nowadays. The transformers must be fairly large to handle the lower frequencies which means they are expensive. In addition to the benifit of "stepping up" the voltage to avoid loss in the speaker wire, it allowed you to match the impedence of several speakers to one source. Also, by using different transformers, you could tailor the sound volume at each speaker. So, a single wire-pair from an amp could go outside to a big loudspeaker array, then inside to smaller speakers in a hallway. One type of transformer would be used in the outdoor array (and be loud) and then another type would be used for the smaller speakers indoors (and be quieter.)
In the two original Cinemascope installations I helped rip out, it seemed to me that the 70.7 volt system was used only for it's ablity to match impedence and to tailor the volume (such as reducing a surround speaker output in a corner of the auditourium.) I'm sure the designers welcomed the benefit of 'high voltage-lower loss,' but with what they paid for a Cinemascope install, I think the price of wire was not a factor.
Posted by David Baum (Member # 568) on 12-31-2000, 05:02 AM:
Lots of inputs here, thanks!
Ok, so most agree to run long wires and keep the amps together. But how do you use 8 AWG wire ( !!) with speakon connectors ! they can't accept it and the DCA only accept NL4FC connectors, which accepts max 12mm cable ( 2 x 6mm or 2 x AWG 10 ).oops, must be blind: the DCA has screw terminals so AWG 8 might fit, right ? seems my brainstorming about wiring is coming to a good end !
happy new Year to all.
David
Posted by Gordon McLeod (Member # 33) on 12-31-2000, 10:16 AM:
I am always in favour of Amps in the booth
Also most amps have electronicaly ballanced inputs not transformer balanced and typically they do not offer as much imunity to noise
Posted by Bruce McGee (Member # 131) on 12-31-2000, 10:18 AM:
This is a perfect time to ask this question:I have a long length of 10 gauge solid UF (underground feeder) cable that has 3 wires with a ground. Does anyone see a problem in using this wire as the main speaker feed wires to run under the house from the booth to the screen? This run is just under 18'. The cable is flat and will be run so that there are no twists between the junction boxes that I will install at either end.
I will use the naked ground, and the white wire as the 2 negative lines, and the red and black wires for the right and left channel positives.
This wire is left over from when I ran a new 30 amp 220v line out to my garage, and had to buy a 250' roll of this wire. I also used it to supply power to my A/C system. Plus, I've already run a new pair of 20a lines out of this wire for each of my projectors. I just love working in my crawlspace!!
Anything that I need to do? Should I twist the wires at all? Is the 18' run long enough to cause any problems?
Thanks. I bear a total likeness to the guy that is sucking down the FG in the photo on the left.
Happy New Year, Everyone!!!
Posted by John Walsh (Member # 168) on 12-31-2000, 10:52 AM:
There are several places to get wire termination parts... It hard to suggest exactly what you would need since there are so many choices, and we don't know your paticular requirements...How about these crimp pin/socket terminals? The wire gets crimped in the socket end and the pin goes in the hole of the binding post and gets screwed down. Look here:
SUPER LONG URL HIDDEN TO MAINTAIN NORMAL PAGE WIDTH
Or a larger lug.. that is screwed down by the binding post, like this:
SUPER LONG URL HIDDEN TO MAINTAIN NORMAL PAGE WIDTH
Also, general wire plugs/jacks...
Here's a dual banana jack so you can unplug the speaker from the amp... (bottom of page)
http://www.brimelectronics.com/BanPlugs.HTM
Others...
http://www.hhsmith.com/insulatedbanana.html
http://www.johnsoncomp.com/bjack.htm
Posted by John Walsh (Member # 168) on 12-31-2000, 11:01 AM:
Bruce...18 feet is not very long, but I would feel uncomfortable with two parallel runs right next to each other.
But it will probably be OK for home use. The run is not very long and the power levels are low.
You do look like you are enjoying that FG... have you tried mixing in a little JD with it??
Posted by David Baum (Member # 568) on 12-31-2000, 11:19 AM:
the drink seems tasty indeed !!btw, someone knows what max AWG size I can use on the screw terminals of the QSC DCA ?
if they are the same as those I have on my JBL 3677, AWG 8 should fit ( but this is the maximum ).
Posted by Mark Gulbrandsen (Member # 72) on 12-31-2000, 12:18 PM:
Personally, I prefer long low level balanced lines for subs. I usually use a BGW M1100 or M2200 sub anyway and these have internal amplifiers. Without a doubt the best made and performing subwoofers on the market and totally reliable so there is no worry to have to troubleshoot behind a baffle wall!
My second choice is to use at least #8 AWG stranded THHN wire as per J.A. if the amps are located in the booth, as in JBL or E-V situations. I have never really had a problem with hum, RF or anything else interferring with either situation and the Salt Lake area has more RF garbage than most other large citys have. For surrounds 70 volt systems are long obsolete. In the almost 20 years I have been in this buisness I don't think I ever installed one anyplace. I also do not agree with J.A.'s autoformer theory. Can cause too much phase shift at certain frequencys..... you can see it on a scope! I stick with mainly prallel wiring. I try to stay away from series parallel if possible. For all parallel I simply use more amps and also I install amps rated for 2 ohm loads so there is never a problem.
Happy New Years everyone!
Mark
Posted by Paul G. Thompson (Member # 655) on 12-31-2000, 12:44 PM:
Bruce, don't use that UF for speaker wire. The wires are not twisted in that stuff. Besides, most UF I have seen contain solid conductors. Drive-in theaters used lots of that crap, but in that case it really didn't matter. The sound quality from that little 3 inch speaker sucked anyway.Oh, by the way, when I mentioned twisting speaker wires with an electric drill, I meant twisting them. I didn't say anything about strangling them! A little common sense prevails here...
Posted by David Baum (Member # 568) on 12-31-2000, 05:28 PM:
Markat least AWG 8 wires to feed the subs ?? then how bigger would you even recommend ???
back to my question, how big wires can I use on the screw terminals of the QSC DCA then ? (in this configuration, the wires will be maximum 45ft long, probably 30ft )
but now since you raise the quite acceptable option of running long balanced cables to the amp sitting next to the subs, I am back to my former option
argh!, Happy 2001!
Posted by David Baum (Member # 568) on 12-31-2000, 06:17 PM:
since we are deep into subs speakings, what would U do here:
QSC DCA 2422 bridged per each 4645C or
QSC DCA 3422 stereo (higher damping factor then) ?
money is an issue ( go to get a Barco projector too, sec-hand ) so.... option 1 ( 2422H first would allow me to start in stereo and then add a 2422H later on ...) seems more "reasonnable" for now
room is 10,000 cbic meters, max length is 53ft ).
Posted by Scott Norwood (Member # 30) on 12-31-2000, 06:26 PM:
Seeing that this is for home use, isn't the speaker-cable issue kind of moot, assuming that the run is fairly short? I've always just used lamp wire (which, I believe, is 18 gauge) for 5-10-foot speaker wire runs at home and it works fine. Probably not ideal, but it's cheap and readily available.
BTW, what's the difference between the QSC DCA amps and the MX series that I'm more familiar with? From the ads, it looks like the DCA amps are easier to set up with the QSC booth monitor, but what's the difference with respect to the actual "guts" of the amp? I don't think I've actuallly seen these in use anywhere yet, and would be interested to know if they sound substantially better than the MX series.
Posted by David Baum (Member # 568) on 12-31-2000, 06:37 PM:
Hi ScottWell, I had the chance to listen to some DCA with DAS speakers ( French brand ) at a HT fair 2 years ago and their sheer power, dynamics and violence of sound I should say was amazing. They now start to become THE amps of choice for pro-style home theaters in France for instance. Here in Belgium, the Kinepolis group is now switching entirely to these DCA amps starting this year ( mix of BGW and QSC USA were used so far ). Kinepolis is the largest European cinema complex group.
The main difference I think is the powerwave technology and the full control of the amp functionning. It's really super high tech, super solid hardware. There's full remote computer control too via DCMs controllers.
As for the wire size, I can REALLY tell the difference when feeding my subs with 4mm2 wires and 6mm2. I imagine the sound with AWG 6 from a QSC DCA sitting on top of the sub ( I think I will go that way, long balanced XLR and short wires ).
regards
David
Posted by Steve Guttag (Member # 268) on 12-31-2000, 08:33 PM:
Paul:No kidding, using a drill or like method of twisting the wires is incorrect no matter how few revolutions you put on the cable...it is undo stress on the conductors and should be avoided.
If after creating the lay there is a spring action to the cable, it was done wrong.
Using a drill or like system to do the twisting actually twists each wire in the cable (not the goal) in addition to twisting the various conductors. It is simply wrong and should be avoided. (Kinda like wrapping up a mic cable over your shoulder and arm).
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Paul G. Thompson (Member # 655) on 12-31-2000, 09:06 PM:
Steve, I'll take you word on that. But, there were several applications where I had to do it to cancel out the magnetic field. Mutual induction into adjacent high impedance cables is not too cool. When I twist them, I usually throw away the first and last 6 feet of the wire. The remaining have about 4 to 5 twists per foot, and they are loose twists, no straining. If the wire size I need is larger than AWG 12 THHN, I'll use the stuff John Allen recommends.
Posted by John Eickhof (Member # 323) on 12-31-2000, 10:12 PM:
Twisting cable is acceptable with a power drill as long as you check the lay of the strands of the conductors you are twisting, the new twis must lay the same direction as the strands in the conductors, Visualize wire rope...Wire factories do this exactly the same way, only they have fancier machines to do the work!!! Happy new year!
Posted by Paul G. Thompson (Member # 655) on 12-31-2000, 10:26 PM:
Thank you, John. The strand lay is clockwise, and that is the way I have been twisting them. Happy New Year!
Posted by Steve Guttag (Member # 268) on 01-01-2001, 11:44 AM:
Nope, I'm standing firm on this one...twisting with a drill is just plain wrong! You are actually increasing the amount of twist within each conductor in addition to twisting the conductors together. A proper lay does not do that. Again, if you were to mark the top side of each conductor's jacket and then perform your twist, that line should stay on top for the whole length of th cable...with a drill it will twist as well.
I don't care how many of you stand up and say it is ok or that you have done it that way (cuz I have too), it is still the wrong way to twist wire and it increases the stress on each conductor.
------------------
"Old projectionists never die, they just changeover!"
Posted by Gordon McLeod (Member # 33) on 01-01-2001, 12:50 PM:
I twist them in a drill as well
What I do is I have a bar that is 8" long with 2 holes in the ends and a bolt welded in the centre
THe wire is put on in each hole and the drill run on slow with a person walking up and down the run pushing the twist along. I do about 1 twist per 6" and I have only had the odd one spring. Also I usually use fine stranded type TEW wire rather than the stiffer THNN
Posted by Randy Stankey (Member # 64) on 01-01-2001, 02:13 PM:
Let me ask this...I understand it that electrons travel primarily along the surface of a conductor, so having many small strands of wire increases the surface area and therefore the carrying capacity of the wire.
If you want to have a better run to your speakers, then it's better to have many small strands than a few big ones..... Right?
Posted by John Pytlak (Member # 331) on 01-01-2001, 02:38 PM:
Randy --- for DC and AC current, the entire conductor carries the electrons, so it is the total cross-sectional area and the conductivity of the material (e.g., aluminum vs. copper) that determines current carrying capacity / line loss. AFAIK, surface conductivity only starts to occur in the radio frequency spectrum (RF).------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Posted by Steve Guttag (Member # 268) on 01-01-2001, 03:21 PM:
John is on the money. Surface resistivity is a function of frequency and for copper, the frequency must be quite large (way beyond hearing) before the current distribution comes into effect (the skin effect). The advantage of using stranded wire is in the connection and flexibility (included in that is the less likely to break). Increasing the number of strands helps out the installer on the pull/dress, and in the connection plus the long term reliability of the connection. In strict current carrying capacity, the solid conductor will work as well.
Gordon:
Presuming your twisting jig is fixed and someone is pulling the twisted cable through, what is keeping the conductors from twisting together before they "go in?" If it requires that someone feed the jig as well...that is cut the conductors to length and have someone at the end keeping up with the drill so they don't pre-twist, that method would work.
Please explain.
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Randy Stankey (Member # 64) on 01-01-2001, 03:25 PM:
Well, that all makes sense because the book I was reading when I saw that was an introductory course to Ameteur Radio.I've been meaning to get a license and I've been studying up on the side.
Posted by Paul G. Thompson (Member # 655) on 01-01-2001, 03:35 PM:
I cannot locate my NEC handbook, which is the Electrician's Bible. But it seems to me more damage can be done when the wire is pulled through raceways. When the wire is bent at 90 degree angles when dressing it in power panels, seems to me that is a stressful situation. Can anyone site what the NEC manual specifies? Or any other official document that addresses wire twisting. Thanks. I am very curious as to how much wire damage is done by simple finger or machine twisting. I think it would be minimumal. It is done all the time in motor rebuild shops, etc. I think I will twist some in an electric drill, then cut them apart and measure the strand thicknesses with a micrometer. That should tell the story. But one thing I am reasonably sure of - twisting Monster Cable with a drill or any means would be a total disaster. Happy New Year to all!
Posted by John Walsh (Member # 168) on 01-01-2001, 08:13 PM:
Everyone has different experinces, of course. But, I've been just stuffing wire ends into a drill chuck and twisting away, and never had any problems. Usually, the end closest to the drill gets twisted the most. I twist until I get about 1 twist per 6in.I mean, I didn't strip back the entire length to check, but I've striped back short sections at the ends, and didn't see any breaking.
I didn't see anything on twisting wire after a quick look through my NEC book. Only size of pipe and how many (of what gauge) wires can be used.
Posted by John Eickhof (Member # 323) on 01-01-2001, 11:34 PM:
I'm with you Paul! First, we must consider the purpose of this wire! Mainly it carries low amperage signals of A.C. origin and is generally laid inside a conduit or is supported well, thus, strength / integrity of conductors is not an issue as the wire is basically way over rated for this application, and the individule strands are carrying the signal anyway, (whether they are tightly wound or not.)as compared to: max. current @max. volts continuously! Next, 'Skin effect' comes into play at high A.C. voltages ie: 2500 V. A.C. or greater, with high current passing. ie: long distance A.C. transmission lines that are 5kv or more, the conductors for these are in fact HOLLOW!(Aluminum outer structure, with steel strand inside structure for strength, Generally filled with an inert gas to help prevent ionization and deterioration of these conductors) In these cases, 85-90% of current is travelling on the outside skin of the wire! This is NOT a factor in low voltage A.C. lines. Of course, RF energy is even more severe! so don't hook up that 1kw linear HF amplifier to you're loudspeaker lines! And if you do, dont touch the conductors! Happy new year to all! & Happy B-Day Film Tech!
Posted by Bruce McGee (Member # 131) on 01-02-2001, 08:46 AM:
I've read the replies to my UF questions. Yes, the cable is solid 10ga. I will be installing terminals and installing everything in a small terminal box so that I can run other wire out to the amps. How's this:?
Use the 2 outer wires as the hots, and use the 2 center wires as the grounds? It's no problem, as I will have everything tagged and identified.I dont think that there will be a problem using this wire considering the short run. I have lots of 18ga lamp cord, but I want something "permanant" so that I dont have to go back under there for a **long** time.
Is there an issue with harmonics in the wires? Is this going to overload the amp? Questions, questions....
Posted by Paul G. Thompson (Member # 655) on 01-02-2001, 12:43 PM:
Bruce - I might have missed something. What is it that your are trying to do? Is this a home theater thing? A drive-in thing? a thingy thing? Whatever you are doing, there'll be some line loss. If I understand something correctly, the line will appear inductive to the amplifier since the conductors are not twisted. And, inductive reactance is directly proportional to applied frequency. XsubL = 2PiFL. Don't expect high fidelity, although it may sound "ok"
Posted by Bruce McGee (Member # 131) on 01-02-2001, 02:38 PM:
OK. I wish I had a real theater!This set-up using the 10ga solid UF cables is going to be at the most 15-18 feet, and have terminal boxes at each end. I'm doing this because my house has a crawl-space under the theater/booth, and is a major pain to get into due to my large stomach! (Thank you, Michelob! ) I'd rather pull the one heavy wire rather than a group of lamp cords.
As I said before, the wire can be run so that there will be no twists, and since the wire is flat, I can use the two outer wires as the hots, and the inner two as grounds. My amp is a 100 watt Sony Pro Logic and will be hooked to a pair of Advent speakers.
I think that non-sync CD music will be the best quality that these wires will ever carry. My Holmes projectors are mono! As for interference, there are radio stations nearby, but these have never caused any trouble for me in the past.
I wont try this if you brains think it is a bad idea. I've never doubted you before...
Thanks!
Posted by Paul G. Thompson (Member # 655) on 01-02-2001, 06:20 PM:
Bruce, if you are running only 15 to 18 feet, you could almost get by with insulated paper clips .....
Posted by Mark Gulbrandsen (Member # 72) on 01-03-2001, 03:44 AM:
I don't agree with twisting wire with a drill either at least from a stress standpoint. Wire manufacturers equipment for twisting wire is highly specialized equipment that puts zero stress on the wire when its twisted. Sure, pre twisted pairs are more expensive, but then so is the equipment to do it the right way.
In the past I have twisted wire with a drill and it always worked out ok. On occasion we would get some interesting comments from passers by when they would see us doing it. One time while working with Gord Mcleod in Toronto we got some store owners pissed at us for jamming up the sidewalks with twisted pairs on a busy Toronto street.
Mark
Posted by Gordon McLeod (Member # 33) on 01-03-2001, 02:35 PM:
Mark the week after you left I got a ticket for obstructing traffic when we twisted a 500 run of #8 down the centre of a back street at 3 in the morning
Posted by Paul G. Thompson (Member # 655) on 01-03-2001, 07:46 PM:
Gordon, for some unknown reason, I can see that cop issuing a citation clear as a bell. It just seems to fit! Maybe his coffee and doughnut shop was closed and had nothing better to do. I remember a FCC engineer friend of mine doing some field intensity readings for a local radio station. He was in a farmer's field, and the sheriff arrested him for cattle rustling...
Posted by Tom Sauter (Member # 616) on 01-04-2001, 09:16 AM:
Bruce, 10ga is way overkill but since you have expressed a desire to use up the wire go ahead. 15-18 feet is so short you could just pretend the wires are there and it'll probably work! On the order of the original topic, since your amp is a Sony Pro-Logic jobber with unbalanced inputs you should avoid the line-level run at all costs, esp. with radio stations nearby.
Posted by Bruce McGee (Member # 131) on 01-04-2001, 10:21 AM:
Tom: I have lots of wire here, but this wire will be easily run thru the crawlspace. Yeah, 10 gauge is overkill, but you never know when I might need to have a big piece of wire for a house-wiring project!