Reply to thread

Message

<blockquote data-quote="JohnEJanowitz" data-source="post: 4528664" data-attributes="member: 584636">No offense taken.&nbsp;&nbsp; The basics of it is to measure the transfer function is to take a sealed woofer, measure the response outside the vehicle and then again inside the vehicle.&nbsp; The difference is the cabin gain or transfer function of the vehicle.&nbsp; You can do this with measurement equipment or with test tones on a CD and a cheap SPL meter from radio shack.&nbsp; Speaker Workshop is free and will do what you need.&nbsp; <a href="http://www.speakerworkshop.com/" target="_blank">http://www.speakerworkshop.com/</a>As far as the other stuff goes, mechanical distortion would be noise from parts moving.&nbsp; A surround clicking, a resonance in the cone or surround, lead wires slapping, etc.&nbsp; Non-linear distortion is distortion due to the woofer not acting the same on the inward stroke as on the outward.&nbsp; A voice coil acts like an inductor.&nbsp; When the coil goes inward, it is fully around the pole.&nbsp; In a typical woofer, as it goes outward it goes past the end of the pole.&nbsp; Inductance changes greatly as the &quot;core&quot; of the inductor is now different.&nbsp; This is a huge cause for distortion.As current is applied to the coil it becomes an electromagnet itself.&nbsp; The magnetic field from this moving electromagnet moves around the permanent field created by the magnet.&nbsp; Another huge cause for distortion that most woofers don&#039;t address.Heat causes the VC resistance to rise so you can&#039;t deliver as much power now.&nbsp; This is known as compression.&nbsp; Basically it&#039;s not able to play as loud as it needs to.&nbsp; A well designed woofer needs to properly remove heat to get rid of this issue.A good woofer should do something to address all these issues to accurately reproduce the signal put into it.John</blockquote>

[QUOTE="JohnEJanowitz, post: 4528664, member: 584636"] No offense taken. The basics of it is to measure the transfer function is to take a sealed woofer, measure the response outside the vehicle and then again inside the vehicle. The difference is the cabin gain or transfer function of the vehicle. You can do this with measurement equipment or with test tones on a CD and a cheap SPL meter from radio shack. Speaker Workshop is free and will do what you need. [URL="http://www.speakerworkshop.com/"]http://www.speakerworkshop.com/[/URL] As far as the other stuff goes, mechanical distortion would be noise from parts moving. A surround clicking, a resonance in the cone or surround, lead wires slapping, etc. Non-linear distortion is distortion due to the woofer not acting the same on the inward stroke as on the outward. A voice coil acts like an inductor. When the coil goes inward, it is fully around the pole. In a typical woofer, as it goes outward it goes past the end of the pole. Inductance changes greatly as the "core" of the inductor is now different. This is a huge cause for distortion. As current is applied to the coil it becomes an electromagnet itself. The magnetic field from this moving electromagnet moves around the permanent field created by the magnet. Another huge cause for distortion that most woofers don't address. Heat causes the VC resistance to rise so you can't deliver as much power now. This is known as compression. Basically it's not able to play as loud as it needs to. A well designed woofer needs to properly remove heat to get rid of this issue. A good woofer should do something to address all these issues to accurately reproduce the signal put into it. John [/QUOTE]

Verification