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Re: 4 Pi Design Questions [message #72746 is a reply to message #72745]

Thu, 17 May 2012 22:46

Wayne Parham
Messages: 18678
Registered: January 2001

Illuminati (33rd Degree)

You may have the woofer or tweeter leads reversed. But redo your measurement first, because measurements made like you are doing always create notches from boundary reflections.

Lay the speaker on it's back and position the microphone one meter (or more) above it, facing the upper half of the midwoofer cone. This orientation will prevent a floor bounce notch, and it puts the microphone in the center of the forward lobe. You can usually get away with indoors measurements when done this way, if all you care about is response in the crossover region, but you'll have no visibility below a few hundred Hertz. It will be peaky if ungated, or meaningless if gated. Of course, it never hurts to take the speakers outdoors, which is truly anechoic. You'll still want to lay the speaker on it's back, or you can put the microphone on the ground and angle the speaker down to face it.

This is what you should expect to see, measurements from two different people using two different measurement systems:

four π loudspeaker measured on Ominmic and LMS
four π loudspeaker performance data, LMS data, including off-axis charts

I realize your speaker is a modded version, but if the only difference is box size, then I would expect most changes to be below 200Hz. So setup your measurement as described above, and if you don't see a chart like this, check your connections and crossover.

http://www.pispeakers.com/Measurements/fourPi_response.gif

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[Message index]

		4 Pi Design Questions By: Nichol1997 on Sun, 17 January 2010 22:09
		Re: 4 Pi Design Questions By: Nichol1997 on Mon, 18 January 2010 06:36
		Re: 4 Pi Design Questions By: Wayne Parham on Mon, 18 January 2010 08:46
		Re: 4 Pi Design Questions By: Nichol1997 on Wed, 20 January 2010 20:59
		Re: 4 Pi Design Questions By: Wayne Parham on Wed, 20 January 2010 21:09
		Re: 4 Pi Design Questions By: Nichol1997 on Thu, 01 April 2010 21:15
		Re: 4 Pi Design Questions By: Wayne Parham on Fri, 02 April 2010 09:25
		Re: 4 Pi Design Questions By: Nichol1997 on Fri, 02 April 2010 20:58
		Re: 4 Pi Design Questions By: Wayne Parham on Sat, 03 April 2010 09:32
		Re: 4 Pi Design Questions By: Nichol1997 on Wed, 07 April 2010 21:17
		Re: 4 Pi Design Questions By: Wayne Parham on Wed, 07 April 2010 21:55
		Re: 4 Pi Design Questions By: Nichol1997 on Sun, 20 June 2010 08:18
		Re: 4 Pi Design Questions By: Wayne Parham on Sun, 20 June 2010 08:54
		Re: 4 Pi Design Questions By: Nichol1997 on Thu, 11 November 2010 21:11
		Re: 4 Pi Design Questions By: Wayne Parham on Fri, 12 November 2010 07:52
		Re: 4 Pi Design Questions By: Psychoacoustic on Thu, 11 November 2010 22:06
		Re: 4 Pi Design Questions By: Doc Jr 8156 on Fri, 12 November 2010 09:41
		Re: 4 Pi Design Questions By: Wayne Parham on Fri, 12 November 2010 14:44
		Re: 4 Pi Design Questions By: Nichol1997 on Thu, 17 May 2012 19:38
		Re: 4 Pi Design Questions By: Wayne Parham on Thu, 17 May 2012 22:46
		Re: 4 Pi Design Questions By: Nichol1997 on Fri, 01 June 2012 19:30
		Re: 4 Pi Design Questions By: Wayne Parham on Fri, 01 June 2012 21:35
		Re: 4 Pi Design Questions By: mantha3 on Sat, 02 June 2012 08:56
		Re: 4 Pi Design Questions By: Wayne Parham on Sat, 02 June 2012 10:30
		Re: 4 Pi Design Questions By: Nichol1997 on Mon, 18 June 2012 19:50
		Re: 4 Pi Design Questions By: Wayne Parham on Mon, 18 June 2012 21:12
		Re: 4 Pi Design Questions By: mantha3 on Tue, 19 June 2012 07:52
		Re: 4 Pi Design Questions By: Wayne Parham on Tue, 19 June 2012 07:55
		Re: 4 Pi Design Questions By: Nichol1997 on Tue, 19 June 2012 19:08
		Re: 4 Pi Design Questions By: Wayne Parham on Tue, 19 June 2012 21:34
		Re: 4 Pi Design Questions By: Nichol1997 on Sun, 24 June 2012 20:04
		Re: 4 Pi Design Questions By: Nichol1997 on Sun, 24 June 2012 20:08
		Re: 4 Pi Design Questions By: Wayne Parham on Mon, 25 June 2012 07:48
		Re: 4 Pi Design Questions By: mantha3 on Mon, 25 June 2012 17:15
		Re: 4 Pi Design Questions By: Wayne Parham on Mon, 25 June 2012 18:12
		Re: 4 Pi Design Questions By: mantha3 on Fri, 31 August 2012 15:13
		Cabinet design, port placement and internal standing waves By: Wayne Parham on Fri, 31 August 2012 18:28
		Re: 4 Pi Design Questions By: mantha3 on Fri, 31 August 2012 18:39
		Re: 4 Pi Design Questions By: Wayne Parham on Fri, 31 August 2012 18:51
		Re: Cabinet design, port placement and internal standing waves By: dheflin44 on Wed, 27 February 2013 15:16
		Re: Cabinet design, port placement and internal standing waves By: Wayne Parham on Wed, 27 February 2013 15:50
		Re: Cabinet design, port placement and internal standing waves By: dheflin44 on Wed, 27 February 2013 17:06
		Re: Cabinet design, port placement and internal standing waves By: Wayne Parham on Wed, 27 February 2013 17:25

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