subwoofer impediance rise on an amp

[talon2nr7588 10+ year member]

how much does it rise when you wire subs to an amp? what factors influence this? such that if i wire two subwoofers at .5 ohms( two DVC 2 ohm subs) will it rise to 1 ohm?

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[Symon_say 10+ year member]

you mena like this



if this is the case the res will stay 0.5ohm

 

[photocrazy8 10+ year member]

there is no way to figure rise. it could rise well above 1 ohm when playing dynamic music. some factors are heat, the way your box is designed. and most of the time the actual DCR of a subs voice coil is different from the nominal resistance.

 

[photocrazy8 10+ year member]

you mean in parallel with make each sub 1ohm and then the 2 sub in parallel again that make the 2 sub .5ohm, if that's the case, they will stay .5ohm

no they will not stay at .5 ohm. do you know what impedance(sp) rise is?

 

[Symon_say 10+ year member]

not really, but the change vary a lot, and the real impedance of the sub are not dual 2ohm they are generally a little less when not in use, cause heat and other factors rise the res, so they put less and with the normal use the res is aprox the nominal res.

 

[thch 10+ year member]

rise is caused by various factors. among the easiest to explain is heat. hot wire is more resistive.

the less obvious reason is that the speaker is a "transducer". it converts electrical energy into mechanical energy. but it also converts mechanical energy into electrical energy. this is mostly given by the T/S specs and is fairly well classified. this "reflected load" of the moving cone/air combo can make the speaker seem like a high impedance.

if you look at it, its neat because (at a resonance) the SPL plot shows a decent SPL, but with low power. that is high efficiency. but all the SPL is delivered by the cone, and that means high excursion. a ported box has a similar high efficiency, but the sound is delivered by the port (less cone excursion) AND the impedance is lower allowing for more power.

 

[squeak9798 5,000+ posts]

and the real impedance of the sub are not dual 2ohm they are generally a little less when not in use, cause heat and other factors rise the res, so they put less and with the normal use the res is aprox the nominal res.

http://www.bcae1.com/resvsimp.htm

Read. Learn. Enjoy.

As to the original question....it's hard telling. The impedance will vary based on frequency alone. Then the other factors such as enclosure design, power (heat), etc etc. There are just too many variables involved....

 

[iamamp3pimp 5,000+ posts]

but how do you measure it?

 

[Beat_Dominator 5,000+ posts]

With test tones and a DMM if you're patient.

 

[lilmaniac2 5,000+ posts]

with a dmm on the speaker leads

 

[JimJ 5,000+ posts]

but how do you measure it?

RMS clamp meter makes the job go a lot faster //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[TypeRBass 10+ year member]

RMS clamp meter makes the job go a lot faster //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

werrrrrrd rms clamp meter is a useful tool //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif and a DMM of course.

 

[talon2nr7588 10+ year member]

so sya an amp like the kx2500.1 that is rated at 2500@ 2 ohms. if you wire the subs to 2 ohms the impediance will most likely rise so you won't be getting the 2500 watts anymore?

 

[vetkilr 10+ year member]

yep

 

[luvinthebass 5,000+ posts]

so sya an amp like the kx2500.1 that is rated at 2500@ 2 ohms. if you wire the subs to 2 ohms the impediance will most likely rise so you won't be getting the 2500 watts anymore?

it varies that's why amps don't alwayz do their rated rms power, who cares if as long as your setup is loud enough for you and your satisfied, shit your amp could be puttin out 100 watts of power at some frequency/s and still have it be loud for you. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif