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Old 22nd March 2007, 02:45 AM   #11
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Have you taken into consideration the "skin effect"? How those sneaky jumbo electo like to slide along the shiney surface of the wire!
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Old 22nd March 2007, 03:28 AM   #12
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The current carrying capacity is one parameter to consider for "best" possible performance from a given wire. Other things that might be considered is total resistance/impedance presented to the amp or the insulation voltage rating (with a 1200W amp).

The current (and voltage) through the speaker, and therefore the wire is always AC so it's the RMS current that is of concern. It's true the bass will tend to be more steady state than the higher frequencies but it be far from constant. Trasient (impulse) sounds like the kick drum will require the amp deliver very high instantaneous power. The RMS power is still quite low but for very brief instant, the amp could be putting out near full power. If the amp is truely capable of 1200W into even 16ohm (giving it the benefit of the doubt) the amp's rail voltage will need to be capable of 80V and double that if the amp is rated into an 8ohm load. That's RMS so the peak voltages will be ~1.4 X that or over 200V. The insulation will need to be able to handle this. Of course most insulation will so it's usually not an issue,... at least when its new. Once it ages and gets kicked around and stepped on some, that situation will change. Insulation with marginal voltage ratings could fail.

The 18ga mentioned for NP's article seems to have low resistance at only 0.014 ohm/ft but 20 feet of this is 0.28ohm. This is not a high value but what would be the sense of paying what you do for amps and speakers only to put the bare minimum into the speaker cables. This is not to say you should go buy $300 cables but 10ga "zipcord" (like Monster Cable from Best Buys) would cut the resistance to a third for a few dollars more in cost.

Stranded or solid will make little difference in terms of performance in the bass region. Of course stranded will be a lot easier to work with. Skin effect will lower the effective current carrying cross section of the wire and stranded would help in this regard but skin effect won't come into play until the frequency is above 1kHz and even than will not be significant until you're into the upper 2 octaves of the audible range and higher.
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Old 22nd March 2007, 05:20 AM   #13
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Roddyama, thanks for the info.

FYI on this amp/subwoofer, I am expecting a total of about 6 feet of cable total. 18 inches to the first terminal, 18 inches connecting the 2 drivers (in series), 36 inches back from the second driver to the amp.

This may end up being less, but I'm allowing for being tidy rather than the shortest possible wiring path.

The long run will probably be from the crossover to the amp (balanced XLR run). But I don't know how long it will be, yet.

The amplifiers manual says for bridged mono:
1300W 20-20kHz at 8ohms, 0.1%THD
1500W 1kHz at 8ohms, 0.1%THD
2400W 1kHz at 4ohms, 1%THD
Voltage gain is specified as 34dB and power consumption at 5A for the 240V model. Output circuit is a Class H complementary linear output type (whatever that is).

I have many pieces of cable as left-overs. Depending on my feeling at the time, I might even use more than one for each run, to allow those "sneaky jumbo electrons...to slide along the shiney surface" of more than one wire

When I do 2 runs of cable, it subtracts 3 from the AWG rating, doesn't it? So, 2 runs of 16, gives 13, and 4 runs of 16 gives 10. that's right, isn't it?
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Old 22nd March 2007, 05:33 AM   #14
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Quote:
Originally posted by Cloth Ears
Roddyama, thanks for the info.

FYI on this amp/subwoofer, I am expecting a total of about 6 feet of cable total. 18 inches to the first terminal, 18 inches connecting the 2 drivers (in series), 36 inches back from the second driver to the amp.

This may end up being less, but I'm allowing for being tidy rather than the shortest possible wiring path.

The long run will probably be from the crossover to the amp (balanced XLR run). But I don't know how long it will be, yet.

The amplifiers manual says for bridged mono:
1300W 20-20kHz at 8ohms, 0.1%THD
1500W 1kHz at 8ohms, 0.1%THD
2400W 1kHz at 4ohms, 1%THD
Voltage gain is specified as 34dB and power consumption at 5A for the 240V model. Output circuit is a Class H complementary linear output type (whatever that is).

I have many pieces of cable as left-overs. Depending on my feeling at the time, I might even use more than one for each run, to allow those "sneaky jumbo electrons...to slide along the shiney surface" of more than one wire

When I do 2 runs of cable, it subtracts 3 from the AWG rating, doesn't it? So, 2 runs of 16, gives 13, and 4 runs of 16 gives 10. that's right, isn't it?
It sounds fine and should not be a problem. If you already have the extra cable it doesn't cost and it surely won't hurt. Be careful with your connectors. Multiple cables in a single connection can be troublesome if you're not careful to be sure the crimp is good and tight and all the wires have been captured. Don't be afraid to give the cables a firm tug. If you can pull them out, the connection was no good anyway.
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Old 22nd March 2007, 05:37 AM   #15
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Quote:
Originally posted by roddyama


It sounds fine and should not be a problem. If you already have the extra cable it doesn't cost and it surely won't hurt. Be careful with your connectors. Multiple cables in a single connection can be troublesome if you're not careful to be sure the crimp is good and tight and all the wires have been captured. Don't be afraid to give the cables a firm tug. If you can pull them out, the connection was no good anyway.
If I do that, then I'll be heat-shrinking them together also. But I do expect only about 4 inches of cable will actually be 'exposed'. The rest will be inside the sub-woofer enclosure or under the binding posts plastic shield.
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Old 24th March 2007, 01:28 PM   #16
AndrewT is offline AndrewT  Scotland
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Hi,
our mains cables running at 220/240Vac must be double insulated.
Would your 110V supply to the speakers need to consider the same safety?

What speaker connectors are rated for 110Vac use?

How do the commercial riggers do this?
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Old 26th March 2007, 09:46 PM   #17
cujo75 is offline cujo75  United States
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To quote Ugly's Electrical References, 14 awg can carry 34 amps at 302 deg.F.. 12 awg can carry 43 amps at the same temp. the ohmic value respectiv. is 5.06 and3.18 ohms per 1000 feet.

Hope this helps
Cujo
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Old 27th March 2007, 04:06 PM   #18
OzMikeH is offline OzMikeH  Australia
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I see you are an Aussie, go buy an extension cord, cut the plugs off and cut it in half.

Good for 2.4kW at 240V, safe and cheap. Those with golden ears might hear the difference, but not in a sub.

I use supermarket extension cord wire for all sorts of stuff, you can't buy the cable at trade prices for what they charge.
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Old 28th March 2007, 12:35 AM   #19
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Quote:
Originally posted by OzMikeH
I see you are an Aussie, go buy an extension cord, cut the plugs off and cut it in half.

Good for 2.4kW at 240V, safe and cheap. Those with golden ears might hear the difference, but not in a sub.

I use supermarket extension cord wire for all sorts of stuff, you can't buy the cable at trade prices for what they charge.
Not a bad idea - I can twist the 3 wires together. And being round is much easier to seal going into the cabinet (I'm doing direct connections).

Do you recommend Coles, Safeway, Woolworths or Big W as having the best sound? Click the image to open in full size.
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Old 28th March 2007, 08:49 AM   #20
OzMikeH is offline OzMikeH  Australia
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just make sure you put the cords in opposite directions, you don't wants the electrons twisting anticlockwise on the way back to the amplifier in the southern hemisphere.

har har har
can even use white and grey cords for polarity.
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