What is Re?

crissty · 28th December 2005, 09:35 AM

As per the specs of Drivers the nominal impedance is 8 Ohms(when checked with an ohm meter), so what is Re ? and its importance in the given Thiele Param.

Regards

Vikash · 28th December 2005, 09:41 AM

Nominal Impedence of a diver is not usually calculated with a meter. This is the approx. average impedence of the driver over its passband. Re is the DC resistance, measured with a meter with the driver at rest.

Google is your friend for basic T/S stuff

crissty · 29th December 2005, 07:20 AM

Sorry i still did not get,
Re is the resistance of voice coil checked with a Ohm Meter (i.e. say 6.5Ohms), and the specs. of Driver says 8Ohms.

Travis Gibby · 29th December 2005, 09:55 PM

Vikash is right. Re is simply the DC resistance.

Impedance is more complicated. Impedance by definition varies with frequency. The impendance rating is a nominal impedance rating and is the parameter to look for when you are matching a speaker to an amplifier.

Travis

kelticwizard · 30th December 2005, 04:15 AM

The DC resistance is just the resistance of the wire in the voice coil.

When a speaker actually plays, the impedance goes up. Usually around 25% or so. So an 8 ohm speaker usually has a DC resistance between 5 and 6 ohms.

kelticwizard · 30th December 2005, 04:27 AM

Here is a chart of both the frequency response, (colored oines) and the impedance, (black line).

This is a Peerless HDS 205 8 inch woofer.

The Re is 5.8 ohms.

But you can see that throughout the frequency range, the impedance varies. However, at most frequencies it is pretty near 8 ohms. The impedance has a large peak at Fs, the way all conventional speakers do. And the impedance gradually rises as the frequency rises, as all conventional speakers do as well.

crissty · 31st December 2005, 03:05 AM

Thank you all,

kelticwizard
Travis Gibby
Vikash

28th December 2005, 09:35 AM	#1
crissty diyAudio Member Join Date: May 2005 Location: Greenland	What is Re? As per the specs of Drivers the nominal impedance is 8 Ohms(when checked with an ohm meter), so what is Re ? and its importance in the given Thiele Param. Regards

28th December 2005, 09:41 AM	#2
Vikash diyAudio Moderator Emeritus Join Date: May 2003 Location: UK	Nominal Impedence of a diver is not usually calculated with a meter. This is the approx. average impedence of the driver over its passband. Re is the DC resistance, measured with a meter with the driver at rest. Google is your friend for basic T/S stuff __________________ "The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)

30th December 2005, 04:15 AM	#5
kelticwizard diyAudio Member Join Date: Sep 2001 Location: Connecticut, The Nutmeg State	The DC resistance is just the resistance of the wire in the voice coil. When a speaker actually plays, the impedance goes up. Usually around 25% or so. So an 8 ohm speaker usually has a DC resistance between 5 and 6 ohms. __________________ "A friend will help you move. A really good friend will help you move a body." -Anonymous

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

29th December 2005, 07:20 AM	#3
crissty diyAudio Member Join Date: May 2005 Location: Greenland	Sorry i still did not get, Re is the resistance of voice coil checked with a Ohm Meter (i.e. say 6.5Ohms), and the specs. of Driver says 8Ohms.

29th December 2005, 09:55 PM	#4
Travis Gibby diyAudio Member Join Date: Oct 2005	Vikash is right. Re is simply the DC resistance. Impedance is more complicated. Impedance by definition varies with frequency. The impendance rating is a nominal impedance rating and is the parameter to look for when you are matching a speaker to an amplifier. Travis

31st December 2005, 03:05 AM	#7
crissty diyAudio Member Join Date: May 2005 Location: Greenland	Thank you all, kelticwizard Travis Gibby Vikash

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)