this is a pretty simple problem/question, I have my amp at least 2.5 meteres of wiring away from my subs, and was wondering since i have themn wired in parallel whether i should have 2 pairs of wires running from the amp to the subs, or 1 pair, witht the second from one sub to the next. thanks for any help! oh, and wire sizes would be good, the amp is ratted at 600 wrms @ 2 ohms, and the subs are both 4 ohm 600 watt max. (300 rms i think).
Replies (4)
cplkittle on 11/11/2003 08:31:26
I have always heard, but haven't yet tested, that wire length does make a difference with subs. The explination for this is that at higher bass frequencies the resistance of a longer wire can actually 'slow' down the signal to the subs where one gets the signal before the other one. In a dual bandpass box this can be detrimental, causing one speaker to push as the other pulls-cancelling out the sound completely. ofcourse this would only happen on a single frequency equivalent to the difference in the wire lenght. Enough about that though. The bigger the speaker wire the better, I would go with 14 or 12 gauge wire. If it were me I would use two seperate pair. If you want to only use one, I recommend 10 or 12 gauge to cover the distance and split it into two equal lengths of 12 or 14 to feed each speaker.
I would also wait to see what Swez thinks also as I am just getting my feet wet in this area.
ttocs on 11/11/2003 12:07:54
one wire is fine..
Swez on 11/11/2003 12:02:45
CPL has a point and I would say you can do what he mentioned if you so desire. However, I would be more inclined to run 1 heavy gage wire pair (8-12 gage) back to the subs. The resistance per meter is very low and will have negligable affect on power (dB losses) from the amp to subs.
QUOTE: Resistance in Speaker Wire:
"Many people are told that they need to use very large speaker wire to prevent a noticeable loss in output. For most situations, 16g speaker wire is absolutely fine. In the following calculator, you can see just how little loss you'll have with a given wire size. Keep in mind that 1 dB is generally the minimum difference you'll be able to hear. If the loss is less than 1dB, you'll never hear it. "
The math:
#12 wire = 0.0254 ohms @ 2.5 M (dB loss to speakers = 0.11 dB)
#10 wire = 0.0160 ohms @ 2.5 M (dB loss to speakers = 0.07 dB)
#08 wire = 0.0101 ohms @ 2.5 M (dB loss to speakers = 0.04 dB)
http://www.eatel.net/~amptech/elecdisc/wire.htm
You can wire the subs inside the box (12 gage wire) parallel... 2 ohm load and use only 1 termination cup for both subs. This is fine if you have a Class D amp that can manage a 2 ohm load (90% + can).
However, if you have a 2 channel amp and bridge it to MONO, it may only take a 4 ohm load in bridged MONO mode. High current 2 channel amps can run 2 ohm loads (and lower) if needed, but a typical 2 channel Mosfet amp may not handle loads below 4 ohms when bridged. What amp do you have now? (make & model)
In short form, 600 watts RMS, you have 2.5 meters ( a shade over 8 feet...~98 inches) so #8 - 12 gage is a good choice, from amp to sub ternination. Minimal resistance here if high quality braided copper wire at this overall length. All gages noted will net well under 1 dB loss from Amp to Subs.
Swez
PS CPL is correct that long runs of speaker wire build up inducive/capacitance resistance (impedence) in the wire. This inductive/capacitive loads (changes with frequency) can add more resistance to the circuit in general. But we are splitting hairs at this length.
bairsjw on 11/14/2003 08:48:39
beauty, that's all i needed to know. thanks for the help, swez its a class D alpine amp mrd 500 i think, its no worries at 2 ohms. thanbks guys!
Replies (4)
cplkittle on 11/11/2003 08:31:26
I have always heard, but haven't yet tested, that wire length does make a difference with subs. The explination for this is that at higher bass frequencies the resistance of a longer wire can actually 'slow' down the signal to the subs where one gets the signal before the other one. In a dual bandpass box this can be detrimental, causing one speaker to push as the other pulls-cancelling out the sound completely. ofcourse this would only happen on a single frequency equivalent to the difference in the wire lenght. Enough about that though. The bigger the speaker wire the better, I would go with 14 or 12 gauge wire. If it were me I would use two seperate pair. If you want to only use one, I recommend 10 or 12 gauge to cover the distance and split it into two equal lengths of 12 or 14 to feed each speaker.
I would also wait to see what Swez thinks also as I am just getting my feet wet in this area.
ttocs on 11/11/2003 12:07:54
one wire is fine..
Swez on 11/11/2003 12:02:45
CPL has a point and I would say you can do what he mentioned if you so desire. However, I would be more inclined to run 1 heavy gage wire pair (8-12 gage) back to the subs. The resistance per meter is very low and will have negligable affect on power (dB losses) from the amp to subs.
QUOTE: Resistance in Speaker Wire:
"Many people are told that they need to use very large speaker wire to prevent a noticeable loss in output. For most situations, 16g speaker wire is absolutely fine. In the following calculator, you can see just how little loss you'll have with a given wire size. Keep in mind that 1 dB is generally the minimum difference you'll be able to hear. If the loss is less than 1dB, you'll never hear it. "
The math:
#12 wire = 0.0254 ohms @ 2.5 M (dB loss to speakers = 0.11 dB)
#10 wire = 0.0160 ohms @ 2.5 M (dB loss to speakers = 0.07 dB)
#08 wire = 0.0101 ohms @ 2.5 M (dB loss to speakers = 0.04 dB)
http://www.eatel.net/~amptech/elecdisc/wire.htm
You can wire the subs inside the box (12 gage wire) parallel... 2 ohm load and use only 1 termination cup for both subs. This is fine if you have a Class D amp that can manage a 2 ohm load (90% + can).
However, if you have a 2 channel amp and bridge it to MONO, it may only take a 4 ohm load in bridged MONO mode. High current 2 channel amps can run 2 ohm loads (and lower) if needed, but a typical 2 channel Mosfet amp may not handle loads below 4 ohms when bridged. What amp do you have now? (make & model)
In short form, 600 watts RMS, you have 2.5 meters ( a shade over 8 feet...~98 inches) so #8 - 12 gage is a good choice, from amp to sub ternination. Minimal resistance here if high quality braided copper wire at this overall length. All gages noted will net well under 1 dB loss from Amp to Subs.
Swez
PS CPL is correct that long runs of speaker wire build up inducive/capacitance resistance (impedence) in the wire. This inductive/capacitive loads (changes with frequency) can add more resistance to the circuit in general. But we are splitting hairs at this length.
bairsjw on 11/14/2003 08:48:39
beauty, that's all i needed to know. thanks for the help, swez its a class D alpine amp mrd 500 i think, its no worries at 2 ohms. thanbks guys!
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