Thanks for any help.Impedance measurements
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roadkingbluzs
- Posts: 212
- Joined: Tue Mar 06, 2007 3:57 am
- Location: chino hills ca.
Impedance measurements
Hello folks, I need some help hear with regards to speaker impedance. Parting out some JBL speakers. HF drivers are labeled 16ohms and multimeter reads 6 +/-. What gives? I would have thought it would read about 12 or 14 ohms. Any ideas? Thanks for any help.
Thanks for any help.-
Turbojunkie
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Re: Impedance measurements
Sorry if this seems like a dumb question, but do you have the HF drivers removed/disconnected from any/all other drivers in the cabinet?
First 25 years of playing, I never got along with EL84's...Now I think, WHAT THE HELL WAS WRONG WITH ME????
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Stevem
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Re: Impedance measurements
JBL did some starnge crap!
My friends Fender champ has a stock JBL 8 incher in it and its magnet tag is stamped 8 ohms, yet it is the needed 3.2 ohms that the champs OT needs to have.
Also a big time thing to note with JBL cone drivers is that red is not positive, yup!
If you hook up a 9 volt battery with its positive small terminal to the red of the driver the cone will move backward!!
So make note of this if you will use the JBLs with other speakers off of the same amp so you get them all working in phase!
My friends Fender champ has a stock JBL 8 incher in it and its magnet tag is stamped 8 ohms, yet it is the needed 3.2 ohms that the champs OT needs to have.
Also a big time thing to note with JBL cone drivers is that red is not positive, yup!
If you hook up a 9 volt battery with its positive small terminal to the red of the driver the cone will move backward!!
So make note of this if you will use the JBLs with other speakers off of the same amp so you get them all working in phase!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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roadkingbluzs
- Posts: 212
- Joined: Tue Mar 06, 2007 3:57 am
- Location: chino hills ca.
Re: Impedance measurements
Speakers removed and metered. Checked a couple of other sources and seems to be correct. Buyer ok with readings. Hate to see these go. Hope to replace at later date. Thanks
Re: Impedance measurements
I chatted with some JBL engineers and former employees...I asked them why professional HF drivers etc were labeled 16 ohms while their "home" counterparts were labeled 8 ohms. The engineers laughed and said there was actually no difference between them..we all know these are nominal ratings any way. The DC resistance, which is what you are measuring
can vary quite a bit...since most of these units were used from 800Hz and up( and the impeadance could vary alot in the passband) its kind of hard to pin down. Id say just think of them all as 8 ohms. They said if they labeled them all as 16ohms then home hifi people would think they could put 4 of them in parellel and get 4 ohms...but the impeadance would fall dangerously below that at certain frequencies.
can vary quite a bit...since most of these units were used from 800Hz and up( and the impeadance could vary alot in the passband) its kind of hard to pin down. Id say just think of them all as 8 ohms. They said if they labeled them all as 16ohms then home hifi people would think they could put 4 of them in parellel and get 4 ohms...but the impeadance would fall dangerously below that at certain frequencies.
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roadkingbluzs
- Posts: 212
- Joined: Tue Mar 06, 2007 3:57 am
- Location: chino hills ca.
Re: Impedance measurements
Wow! That's interesting in itself. I hated to unload my 2420's but circumstances are killing me at this time . Things will be improving, and when they do what late model driver would be comparable to the 2420's, as I am looking to replace drivers in my PA system. There are so many HF drivers by JBL, vintage and modern, it makes your head spin around. Thanks
That's interesting in itself. I hated to unload my 2420's but circumstances are killing me at this time . Things will be improving, and when they do what late model driver would be comparable to the 2420's, as I am looking to replace drivers in my PA system. There are so many HF drivers by JBL, vintage and modern, it makes your head spin around. Thanks