OK. I've done some figuring, and I've already got enough good cable sitting around. But, is there any way to work out heat dissipation from cables?
From my figures (and these would only be if I went insane and turned the thig up all the way), and a deal of help from the guys at the12volt.com, I've worked out that I'd have:
Does anyone have an idea of what sort of temperature change this causes for the run of cable (or do we then get into surface areas of cable and such)?
And Cal, don't those big electrons go by another name once they reach a certain size (big cojones)?
From my figures (and these would only be if I went insane and turned the thig up all the way), and a deal of help from the guys at the12volt.com, I've worked out that I'd have:
- 1200 Watts
- into 11 ohms
- running 10.5 amps
- at 115 volts
Does anyone have an idea of what sort of temperature change this causes for the run of cable (or do we then get into surface areas of cable and such)?
And Cal, don't those big electrons go by another name once they reach a certain size (big cojones)?
I use 16 ga inside the box, 14 ga for runs up to 20 feet and 10 ga for when I take the speakers next door.
The hair dryer probably uses 16 - 18 ga and would warm slightly so why not up it to 14 or 12 and be done with it? How long is the run?
I think the really big ones are called jumbo electrons.
And don't forget to elevate your amp above the speakers so they flow easier.
The hair dryer probably uses 16 - 18 ga and would warm slightly so why not up it to 14 or 12 and be done with it? How long is the run?
I think the really big ones are called jumbo electrons.
And don't forget to elevate your amp above the speakers so they flow easier.
Cal: " ... I use 16 ga inside the box, 14 ga for runs up to 20 feet and 10 ga for when I take the speakers next door. The hair dryer probably uses 16 - 18 ga and would warm slightly so why not up it to 14 or 12 and be done with it? ..."
What he said ... stranded, of course. (FYI: 1200 watts into 11 ohms is enough voltage to exceed commercial building codes in the USA for running outside of EMT pipe ... down under, burn baby burn that ol' dance hall down.)
The "golden ear" types will suggest teflon insulation ... so I look for THHN (the stuff with the shiney skin).
What he said ... stranded, of course. (FYI: 1200 watts into 11 ohms is enough voltage to exceed commercial building codes in the USA for running outside of EMT pipe ... down under, burn baby burn that ol' dance hall down.)
The "golden ear" types will suggest teflon insulation ... so I look for THHN (the stuff with the shiney skin).
Cal Weldon said:And don't forget to elevate your amp above the speakers so they flow easier.
No problem. I'm looking at mounting it vertically, so that the jumbo electrons flow out the back of the amplifier at the bottom and straight into the subwoofer box. It's going to be mounted rather like a child in a back-pack - but hopefully no squealing or funny smells
Excellent. From this, if I'm running 10amps though 20awg, the wire will heat up to 80 degrees Celcius. So, by using 10awg, I would be barely above ambient temperature.454Casull said:
Now, gents (and ladies), I'm not planning on running that sort of current, although after I've finished EQ, I might end up with 5amps (not sure yet). So hopefully, I won't be burning anything down.
Fasteddy, this is a commercially available, plug in the wall (ie. not 3-phase) amplifier - the Behringer EP2500. And it's also available in the US of A, so hopefully it self-protects before any fires start. It does have plastic covers for the speaker binding posts, to prevent shocks, and they recommend no exposed wiring. I expect that if I follow recommendations then I will probably be safe
Did you mean TSWTSS?
" ... From this, if I'm running 10amps though 20awg, the wire will heat up to 80 degrees Celcius. So, by using 10awg, I would be barely above ambient temperature. ..."
This will make a nice hand warmer, too. You want to take those charts with a grain of salt. They were designed as absolute minimums for inexpensive construction, not optimosed for audio. There is a serious school of audiophile thought that believes that bigger speaker wires are better ... and even I can tell the difference, if the difference is great enough or the speaker run is long enough. A compromise would be to follow Cal's advise = #12 AWG stranded.
And it is really not the heat so much as the downstream resistance of a long run to the speakers. Fortunately your case is a very short run, so #14 will probably be plenty. Especially if none of them jumbos have to run up hill ...
Also, at least here in the states, the costs between ten feet of #12 and ten feet of #14 or even #18 is about a wash ...
This will make a nice hand warmer, too. You want to take those charts with a grain of salt. They were designed as absolute minimums for inexpensive construction, not optimosed for audio. There is a serious school of audiophile thought that believes that bigger speaker wires are better ... and even I can tell the difference, if the difference is great enough or the speaker run is long enough. A compromise would be to follow Cal's advise = #12 AWG stranded.
And it is really not the heat so much as the downstream resistance of a long run to the speakers. Fortunately your case is a very short run, so #14 will probably be plenty. Especially if none of them jumbos have to run up hill ...
Also, at least here in the states, the costs between ten feet of #12 and ten feet of #14 or even #18 is about a wash ...
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.
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.
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?
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?
Cloth Ears said: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.
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.
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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