Top Secret Impedance Of Ford/JBL Subwoofer

[Longjohn119]

Anyone have a definitive answer to the impedance of a 1991 JBL/Ford 6 1/2" subwoofer and/or the impedance (and **RMS** wattage) of the subwoofer amp

Cripes trying to get any information from Ford or JBL you'd think it was a matter of National Security or something ....

Why do I have the sneaking suspicion that the only thing truly JBL in the entire system is the name on the nameplate?

 

[Longjohn119]

Never mind, I estimated it by measuring the DC resistance (5.5 ohms) which means it's probably in the 7 ohm range so the common 8 ohm load would be used .... I'd run an impedance test to get the actual value if the surround wasn't all gone, although I'd still get a rough idea even with no surround.

 

[mmmmark]

A stereo guy (reliability unknown) told me he thought it was 8 ohm and cautioned me against putting a 4 ohm speaker in its place. (mine blew recently)

I'm still looking for a suitable replacement without re-doing the whole thing. I want a drop-in replacement and am just starting to look.

I saw an ancient post from 1999 from this forum where someone said that the amp was 85W (they did not say whether it was RMS or max).

FYI, there are two complete units on ebay right now that includes both amps, sub and enclosure. I'm holding out since all I need is the speaker itself.

 

[Stuman78424]

ive got just the speaker out of my 1998 sport if i can find it and you want it e-mail me Stuman78424@aol.com

 

[Nate1]

Wtf. Nominal DC impedance is easily calculated with a multimeter. What the hell kind of formula are you using? Every woofer I have ever tested that is not creating EMF (IE the cone is stationary) measures the spec nominal impedance from the factory plus the slight offset from my multimeter.

 

[Longjohn119]

If you measure the DC resistance of a speaker coil you can estimate the dynamic impedance. 4 ohm speakers usually measure around 3.2 ohms , 8 ohm speaker measure around 6.5 to 7 ohms DC resistance ...

I have yet to see any speaker that measured a higher DC resistance than the dymanic impedance of the unit .... this is just a basic 'rule of thumb' .... if I had a working subwoofer I could give you the impedance curve, the Theile-Small parameters, and a few other things that become relevent in crossover design in about 30-45 minutes with Speaker Workshop and my calibrated microphones .... If you are into speaker, enclosure and crossover design then go to www.speakerworkshop.com which I was a Beta tester for and have used for nearly 7 years now ... and the price is right too, FREE

 

[Nate1]

You are out of control.

Dynamic impedance is irrelevant since it fluctuates with frequency. Nominal impedance is the figure that every manufacturer I have ever seen uses.... nominal impedance is what people speak of when they refer to their woofers as "4 ohm, dual 2 ohm coild, 8 ohm" etc. I don't know about you, but I don't measure the resistance of my drivers while they are in motion.

I am into speaker, enclosure, and crossover design. I use LEAP and WinISD thankyouverymuch... why are you advertising this speakerworshop website all over explorerforums?

Do you work for them or something...?

 

[fliedlice]

lol...this thread is hilarious....

 

[JTX]

Nate calm down killer! LMFAO

 

[jimbo74]

nate hes jsut a newbie.....

 

[davesexplorer]

wow

 

[davidmmm69]

2nd that