Negative 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=51973
Printed Date: May 14, 2025 at 7:36 AM
Topic: Negative impedance
Posted By: Poormanq45
Subject: Negative impedance
Date Posted: March 15, 2005 at 10:19 PM
What are the pros and cons of Negative vs. Positive Impedance?
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Replies:
Posted By: auex
Date Posted: March 15, 2005 at 10:33 PM
You sure ask alot of discussion questions don't you?
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Posted By: Poormanq45
Date Posted: March 15, 2005 at 10:42 PM
yep, I like starting technical discussions about stuff.
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Posted By: Steven Kephart
Date Posted: March 16, 2005 at 1:19 AM
Could you provide an example to put your question into a practical medium. That should help us answer your question. Steven Kephart Adire Audio -------------
Posted By: DYohn
Date Posted: March 16, 2005 at 8:29 AM
"Negative impedence" is an term used to describe an amplifier condition where the output voltage increases as load increases. It leads to unstable amplifier operation and is in general a bad idea except for very specific and specialized applications (usually in broadcast amplifiers.) In audio it is something to be avoided. Impedence as we normally use the term on this board, meaning the combination of resistance, inductance and capacitance caused by AC current flow in loudspeakers, cables, etc. is neither "negative" nor "positive". ------------- Support the12volt.com
Posted By: Steven Kephart
Date Posted: March 16, 2005 at 11:14 AM
DYohn] wrote:
p> Impedence as we normally use the term on this board, meaning the combination of resistance, inductance and capacitance caused by AC current flow in loudspeakers, cables, etc. is neither "negative" nor "positive".
Thanks Dyohn. That's what I figured, which is why I was looking for a "for instance". Steven Kephart Adire Audio -------------
Posted By: Poormanq45
Date Posted: March 16, 2005 at 1:02 PM
Ok, I think I figured out what negative impedance actually means in audio terms.
Basically it is a measurement of the difference between the output impedance from an amplifier and the return impedance signal. As we know, a voice coil changes temperature, and the impedance also changes. So from what I've read, this changing impedance can be compensated for by the amplifier.
Also, as the impedance changes, the drivers ability to acurately reproduce the signal from the amplifier can change significantly.
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Posted By: Poormanq45
Date Posted: March 16, 2005 at 1:08 PM
Also, IIRC, this negative impedance circuitry combined with a sensitive microphone can be used to tune a system to a uniform sound in almost any environment.
I think this is what Bose and Yamaha are currently using.
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