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Checking Impedance?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=78017
Printed Date: May 09, 2024 at 6:37 PM


Topic: Checking Impedance?

Posted By: Jweb
Subject: Checking Impedance?
Date Posted: May 19, 2006 at 10:55 AM

Is there a way to test how many ohms a speaker circuit has?   Thanks




Replies:

Posted By: xtremej
Date Posted: May 19, 2006 at 10:58 AM
a multi meter.

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Posted By: DYohn
Date Posted: May 19, 2006 at 11:41 AM
A multimeter will tell you the DCR (DC resistance) of a circuit but not the loudspeaker load impedance.  Measuring actual impedance requires things like sweep generators... what is it you really need to know?

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Posted By: Jweb
Date Posted: May 19, 2006 at 3:07 PM
I am upgrading the amp on my motorcycle (GoldWing) and it's 4 channel, bridgeable. A LA (Lightning Audio) tech told me I couldn't bridge it with the high level inputs (speaker outs) unless I had 4 inputs. The stereo is 2 channels with 4 speakers and until I find a way to tap into the preamp section to get a low level output, I have to run it with the speaker outputs. I wanted to measure the impedance of the 2 right and left channel speakers to see if I could parallel them to the 4 inputs of the amp so I could bridge it in order to get 200 WRMS per channel (4ohms) instead of 75 WRMS (4ohms).   What do you think?  Thanks,  Joe




Posted By: DYohn
Date Posted: May 19, 2006 at 4:25 PM
I think the tech was correct in that you need an input to both the left and right sides of a stereo amp in order to bridge it, but there is no reason why you can't use the two channels from your HU to drive that amp.  You should be able to use the left speaker output from your HU to drive the speaker-level inputs for channels 1 and 3 and the right output to drive channels 2 and 4.  But the safer way to do this is simply to use a line output converter and Y-cables to connect the RCA signals (left to 1 and 3, right to 2 and 4, for example.)

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Posted By: Jweb
Date Posted: May 19, 2006 at 5:38 PM
I thought about that but figured the converter circuit in the amp would be much better quality than anything added on. What do you think? Thanks




Posted By: DYohn
Date Posted: May 19, 2006 at 6:21 PM
Usually converter circuits in amps are crap and external LOCs are far better.  :)

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Posted By: Jweb
Date Posted: May 20, 2006 at 9:33 PM
Thanks for all the info. Bought a P50 and I'm done.





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