subwoofer impediance rise on an amp

[talon2nr7588 10+ year member]

is there a way to minimize ohm rise?

 

[dkguitarist 5,000+ posts]

is there a way to minimize ohm rise?

find a way to create minimal heat for one. and also you can't help box rise so not really. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[thch 10+ year member]

as an end user, its not normally a good metric, especially in a wide-band sense*. for competitive purposes, you can focus on a single freuqency, in which case impedance rise can be affected by box tuning, including to some degree the shape and dimensions of the port.

for instance, a sealed box may allow for an SPL of 130dB @ 50hz @ 40ohm, and also a SPL of 130dB @ 90hz @ 5ohm, yet have a peak SPL of 133dB @ 60hz @ 8ohm. going by impedance (magnitude) only would indicate that either 90hz or 20hz would be loudest. going by impedance (phase) only indicates 50hz to be a good choice.

 

[explorer2 10+ year member]

This is why the impendance is usally listed as nominal impendance, it can and will change but for the average person the difference will never be noticed.

 

[talon2nr7588 10+ year member]

i saw a thread on the zx2500.1 and the orion 2500d and the zx went up 8 ohms! does the impediance stay at that many ohms when it rises? it's kind of a waste of money if you buy an amp that does 2500 @ 2 ohms and it rises that muich because you won't be getting the 2500 watts anymore.

 

[mazdakid 5,000+ posts]

so get different subs and wire them lower

 

[PhatTonyDeMarco 5,000+ posts]

i saw a thread on the zx2500.1 and the orion 2500d and the zx went up 8 ohms! does the impediance stay at that many ohms when it rises? it's kind of a waste of money if you buy an amp that does 2500 @ 2 ohms and it rises that muich because you won't be getting the 2500 watts anymore.

The impedance rise will greatly vary frequency to frequency, but you will most likely never see an actual 2500w from a 2500w amplifier. No, it is not a waste of money because if you buy an amplifier that is rated for 1000w then you will receive even less power, you are still getting the power for your money.

 

[talon2nr7588 10+ year member]

but you are paying for 2500 watts at 2 ohms. the zx2500.1 had to be wired at .5 ohms for it to put out 2550 watts with a 2.2 ohm rise. will the impediance stay at that load?

 

[prochobo 10+ year member]

but you are paying for 2500 watts at 2 ohms. the zx2500.1 had to be wired at .5 ohms for it to put out 2550 watts with a 2.2 ohm rise. will the impediance stay at that load?

No, as others have said before, it's dynamic which means it changes. One of the larger factors is the frequency.

 

[thch 10+ year member]

as i've mentioned, the normal goals in audio are good, loud sound. this combination says nothing of impedance rise.

the only people who should care are SPL competitors.

notes:

* in a sealed box, the speaker's output is not necessarily maximum when impedance is maximum.

* in a sealed box, efficiency is maximized when impedance is maximimed.

* thus the SPL does not decrease as much as would be expected.

* cone movement limits the amount of power to the speaker in a sealed box, when played at this frequency of high impedance.

* a ported box fixes that (excursion lower, impedance lower), giving a large SPL gain at some frequency, but not across the board. (you have high efficiency and the ability to dump safely a lot of power to the speaker)

* this only happens for a small bandwidth -- near the tuning only.

* this isn't good for music, so normal uses shouldn't care.

* SPL competitors should care.

 

[talon2nr7588 10+ year member]

i have will have a ported box tuned to 32 hz. should i worry about it?