impedance rise?

[vee333gp]

What causes impedance rise in an enclosure and what will it do to output

[cracker]

What causes impedance rise in an enclosure and what will it do to output

i was going to ask about the same thing today ha. ill be watching to learn a lil too

[Neo_frog]

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

[Decaf]

a current moving inside and out of a magnet

heat

motion itself

box design

all create an added resistance to the power u are tryin to send

most of the time a larger box will yield lower rise, but thats not a rule/law

just some minor input

[bkolfo4]

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

I remember that post. . .

[Twistedchild420]

Fuck imp rise...i'm prolly gettin like 1500 watts right now!

[Neo_frog]

I remember that post. . .

Yes sir.

Good info, Brian.

[vee333gp]

Neo thanks for great info by the way in terms of box size and port tuning how will it make a difference on impedance rise

[dohckiller808]

gotta love the design of alpine pdx amps to counter box rise. 1000 watts 2-4ohms

[Boon]

Power at 4 ohms won't do shit.

At Fs you'll probably hit 30 ohms+

Like this: (8 ohm woofer plot by the look of it)