impednce rise

[tumminellon]

What exactly is impedance rise??? how does it work ???

[tumminellon]

What exactly is impedance rise??? how does it work ???

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[Neo_frog]

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The DC resistance is the measurement of the coil at rest. When the cone starts moving, the magnetic field associated with the magnet and the moving coil increases the resistance of the voice coil. Usually the more resonant the enclosure, the higher the impedance rise. Most competitors try to factor rise into the equation so they can get the most power out of their amps.

[tumminellon]

would i have to really worry about this ??

If so how do i remedy it?

[skittlesRgood]

impedance is the measure of AC resistance. when a speaker plays, pressure builds around the cone that seems to create more resistance. so now instead of 2ohms your getting 4 (just an example). impedance will always change when the speaker is playing and can vary greatly depending on the tone being played.

[IH8PunkRok]

if you like the way your system sounds then no.

impedance rise is really only a concern for competitiors who burp at a specific frequency everytime

daily there will always be some kind of imp rise

Edited January 19, 2010 by IH8PunkRok

[skittlesRgood]

would i have to really worry about this ??

If so how do i remedy it?

dont worry about it. more rise means less power = less chance of blowing your sub.

[Neo_frog]

would i have to really worry about this ??

If so how do i remedy it?

You only have to start thinking about it when you're competing big or going for records. Some ways to reduce it are having sufficient amperage, using more conductive material (i.e. bussbars, copper wire, etc..), planning the shortest wire routes, etc..

I'm sure others will chime in with more ways. It's probably something you don't need to worry about. I do the little things here and there, but I'm not too concerned with it.

[bkolfo4]

The DC resistance is the resistance of the coil when DC current is applied. Has nothing to do with the position of the coil.

The impedance is the resistance of the coil when AC is applied. Since the coil acts like an inductor, the impednace changes with frequency.

What people call impedance rise is due to the woofer being put in a box. If you look at the impedance plot of a woofer in free air, the impedance rises at the resonant frequency of the driver. Once in the box, the cone has a different reaction with pressure behind it, which can change the impedance plot. You also have new impedance spikes due to the box size, port tuning, etc.

Impedance rise may in fact not even be a higher impedance at all frequencies (more than likely will be an increase in the overall average, but the spike at the driver's resonant frequency may still be the highest impedance). Many times it is just additional humps/spikes in the impedance plot, or even changing of the impedance spike seen with the woofer in free air. For someone playing music, the additional humps/spikes will increase the average impedance seen while playing music. For someone burping at a single frequency, they need to know the impedance at their frequency to match the amp to the sub. There is a good chance the impedance will be higher near the frequency they burp at, since it not far above port tuning.

For the average person, ignore "impedance rise". The hardcore competitor uses the actual true impedance to his advantage to get all the power he can from the amps

Brian

Edited January 20, 2010 by bkolfo4

[bkolfo4]

Some ways to reduce it are having sufficient amperage, using more conductive material (i.e. bussbars, copper wire, etc..), planning the shortest wire routes, etc..

Sorry, but none of those things have anything to do with the impedance of the subwoofer when placed in the enclosure.

Edited January 19, 2010 by bkolfo4