What would happen if you wired a 4 ohm DVC sub with one coil to each channel of a 2-channel amp, and had one of the coils accidentally wired reverse polarity?
It would seem to me that the sub wouldn't be able to move at all in theory, and only minimally in reality.
This is one for you "thinkers" out there.
Replies (4)
uochronos on 02/1/2005 18:09:59
umm that would be bad very bad hehe.... not sure 100% what would happen but i'm 99% sure it would nto end well for that poor sub,
Chronos
audeogod on 02/1/2005 21:31:28
OK, I say we make this kind of like a little contest. Post what you think would happen and then we'll see how often one answer appears over another.
Some possibilities would be:
1. One coil would burn out and the other one would start playing all of a sudden.
2. Solder would melt off of a speaker terminal and the voice coil connection would be lost. The same affect as above would apply.
3. The speaker output terminals on the amp would get hot from just being connected to the same wires as the overheating coils are, and possibly damage the amp's output circuit(s). Severity, or even possibility of this would depend on total wattage handling of the sub, total output of the amp, wire gauge, and length of wire, I'd say.
4. The woofer itself might actually ignite or melt a hole in the poly cone, being made from poly or paper and other combustible materials. Since this might be possible, I suggest if you try this to not do it in your car since car trunks are near the gas tank. Not that you would try it on your own gear anyway.
Myself, I say it would get hot and burn a coil in two. Then for the remainder of the other coil's lifespan(about 10 seconds longer....well, maybe not that short) it would start thumping on the other coil that was still intact.
audeogod on 02/1/2005 21:36:55
Hey, I wonder if you did this with a big amp and lotsa watts, and somehow kept the voice coils from melting in half, if you could de-polarize the speaker magnet by doing this?
Victor on 02/2/2005 01:44:58
hmmm.. what makes you think all this ..huh..!! audeogod.. hehe
anyways, lets see what in theory would happen to the sub if one of the voice coil polarity would change.
in the first case lets see when the channels are wired +ve to +ve and -ve to -ve (ie. correct polarity )
in the positive cycle of the current both the coils would push the cone upwards and in the negative cycle the cone wil move downwards. thus moving air and sound in a sinosoidal wave form.
now if both the coils are wired with reversed polarity it would happen exactly the opposite. in the negative cycle the cone would move upwards and in the positive cycle the cone would move down.
now if the polarities of both the voice coils are not matching, then
when coil one moves up the coil 2 would move down ( 180' phase difference).
in this case, theoritically if the signal to both the coils is exactly the same with the same power then the cone would not move at all.
since the polarities of the both the coils will be different at any given time they will repell, there will be high amount of heat energy produced.
also considering the effect of the magnet, the coils will go haywire.
all i see possible here in terms of physical damage is burnt or melted voice coils , burnt connections of the coils with the cone and the spider.
I dont see a sub blowing off to pieces, or the cone tearing off or anything expolsive like that.
now about the effect on the amp.
as we see above the coils are definitely getting shorted. this will short the connections and blow off the fuse on the amp, or the amp will go in protection mode
only if the amp is not properly fused or the protection circuitry is damaged do i see further damage to amp.
And no you cannot depolarise the magnet.
so all you can do by reversing the polarities on the voice coil is blow up the coils and the fuse on the amp. you cant create a bomb...hehe
anyways.. one piece of unwanted advice.. "lets be more creative than destructive."
comments...??
Victor...
It would seem to me that the sub wouldn't be able to move at all in theory, and only minimally in reality.
This is one for you "thinkers" out there.
Replies (4)
uochronos on 02/1/2005 18:09:59
umm that would be bad very bad hehe.... not sure 100% what would happen but i'm 99% sure it would nto end well for that poor sub,
Chronos
audeogod on 02/1/2005 21:31:28
OK, I say we make this kind of like a little contest. Post what you think would happen and then we'll see how often one answer appears over another.
Some possibilities would be:
1. One coil would burn out and the other one would start playing all of a sudden.
2. Solder would melt off of a speaker terminal and the voice coil connection would be lost. The same affect as above would apply.
3. The speaker output terminals on the amp would get hot from just being connected to the same wires as the overheating coils are, and possibly damage the amp's output circuit(s). Severity, or even possibility of this would depend on total wattage handling of the sub, total output of the amp, wire gauge, and length of wire, I'd say.
4. The woofer itself might actually ignite or melt a hole in the poly cone, being made from poly or paper and other combustible materials. Since this might be possible, I suggest if you try this to not do it in your car since car trunks are near the gas tank. Not that you would try it on your own gear anyway.
Myself, I say it would get hot and burn a coil in two. Then for the remainder of the other coil's lifespan(about 10 seconds longer....well, maybe not that short) it would start thumping on the other coil that was still intact.
audeogod on 02/1/2005 21:36:55
Hey, I wonder if you did this with a big amp and lotsa watts, and somehow kept the voice coils from melting in half, if you could de-polarize the speaker magnet by doing this?
Victor on 02/2/2005 01:44:58
hmmm.. what makes you think all this ..huh..!! audeogod.. hehe
anyways, lets see what in theory would happen to the sub if one of the voice coil polarity would change.
in the first case lets see when the channels are wired +ve to +ve and -ve to -ve (ie. correct polarity )
in the positive cycle of the current both the coils would push the cone upwards and in the negative cycle the cone wil move downwards. thus moving air and sound in a sinosoidal wave form.
now if both the coils are wired with reversed polarity it would happen exactly the opposite. in the negative cycle the cone would move upwards and in the positive cycle the cone would move down.
now if the polarities of both the voice coils are not matching, then
when coil one moves up the coil 2 would move down ( 180' phase difference).
in this case, theoritically if the signal to both the coils is exactly the same with the same power then the cone would not move at all.
since the polarities of the both the coils will be different at any given time they will repell, there will be high amount of heat energy produced.
also considering the effect of the magnet, the coils will go haywire.
all i see possible here in terms of physical damage is burnt or melted voice coils , burnt connections of the coils with the cone and the spider.
I dont see a sub blowing off to pieces, or the cone tearing off or anything expolsive like that.
now about the effect on the amp.
as we see above the coils are definitely getting shorted. this will short the connections and blow off the fuse on the amp, or the amp will go in protection mode
only if the amp is not properly fused or the protection circuitry is damaged do i see further damage to amp.
And no you cannot depolarise the magnet.
so all you can do by reversing the polarities on the voice coil is blow up the coils and the fuse on the amp. you cant create a bomb...hehe
anyways.. one piece of unwanted advice.. "lets be more creative than destructive."
comments...??
Victor...
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