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Re: Cabinet design, port placement and internal standing waves [message #75654 is a reply to message #75653]

Wed, 27 February 2013 17:25

Wayne Parham
Messages: 18787
Registered: January 2001

Illuminati (33rd Degree)

He used to supply a spreadsheet for ported cabinets tuned primarily using Helmholtz resonance. While his main focus was transmission lines, he also had a spreadsheet that covered bass-reflex boxes at one time. I'm sure he still does, or perhaps he morphed its functionality into one of the other spreadsheets. It would make sense, because in order to accurately predict response, you have to calculate both pipe mode resonance and cavity resonance.

You know, there is never really any sort of cabinet that is tuned solely by pipe modes or by cavety resonance. Both things are always present. That's kind of the point - It's important to realize that fact when designing cabinets. Most DIYers focus only on the mechanism they are trying to use, and that's fine as long as the other one is shifted out of the pasband. So for example, if the box is small, the pipe modes are high enough they are all attenuated by insulation. You can disregard them. Or if making a transmission line, if the port is sized where the Helmholtz frequency is really high or really low, then the cavity mode can be disregarded. But in the cases where both mechanisms might come into play - like most medium to large boxes and/or tower enclosures - it is important to model both mechanisms when simulating response. Otherwise you don't get the whole picture. Martin's spreadsheets do take these things into account, and that's what makes them so accurate.

So just tell him what you're trying to do when you send him your licensing fee. He'll suggest the spreadsheet that will work best for you.

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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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