Home » Sponsored » Pi Speakers » A couple questions about Pi-alignment
A couple questions about Pi-alignment [message #42549] Tue, 23 September 2003 18:40 Go to next message
Tightwad is currently offline  Tightwad
Messages: 41
Registered: May 2009
Baron
I am designing an enclosure for a high-Q full-range driver, simple BR design.

In terms of calculating the optimum enclosure volume, resonance, and bandwidth, is the Pi-align whitepaper the best source? I only ask since it is dated 1979, wondering if it is state-of-art for Pi-alignment.

Also, in the formulas on page 5, I don't recognize some of the parameters from the typical T/S params.

Anyway, any advice would be appreciated.

PiAlign terms [message #42550 is a reply to message #42549] Tue, 23 September 2003 21:16 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18006
Registered: January 2001
Illuminati (33rd Degree)
The formulas used to calculate the cabinet from the speaker's electro-mechanical properties are the same whether you use T/S specs or the PiAlign equivalents. Specifically, the T/S compliance figure is Vas and equal to PiAlign's Vad, Fts is the same as Frd and Qts = 1/Qd.

You can also use the sealed box method or the added mass method to find these values. Measurements of the electro-mechanical properties of a speaker are much more likely to be reasonably accurate than measurements that involve the acoustic domain, because finding electro-mechanical parameters doesn't require any acoustic measurements. So these kinds of measurements can be obtained with probably something like 20% tolerance using equipment that is commonly available to DIY builders.

Re: PiAlign terms [message #42552 is a reply to message #42550] Wed, 24 September 2003 07:06 Go to previous messageGo to next message
Tightwad is currently offline  Tightwad
Messages: 41
Registered: May 2009
Baron
Thanks for the response! I'll need to take a closer look later.
C4, B4, QB3 and EBS [message #42554 is a reply to message #42552] Wed, 24 September 2003 10:39 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18006
Registered: January 2001
Illuminati (33rd Degree)
If you're interested in looking at several alignments, I suggest reading Davies' T/S implementation, and studying the popular generalized alignments such as C4, B4, QB3 and EBS. Davies was the one responsible for suggesting a popular critically damped alignment, used in several modern software packages, and based on prior work by Thiele and Small. Thiele and Small described the relationships between motor cabinets and electro-mechanico-pneumatic specifications, but they focused mostly on the relationship and its effects on response, not so much on specific alignments. A couple of specific alignments were mentioned, but most popular alignments are implementations based on their prior work.
Re: C4, B4, QB3 and EBS [message #42556 is a reply to message #42554] Wed, 24 September 2003 16:43 Go to previous messageGo to next message
Tightwad is currently offline  Tightwad
Messages: 41
Registered: May 2009
Baron
I'll have to track down that Davies paper. Thanks so much for your help.
"Vented Speaker Systems" article by Brian Davies [message #42557 is a reply to message #42556] Wed, 24 September 2003 18:28 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18006
Registered: January 2001
Illuminati (33rd Degree)

http://www.pispeakers.com/Davies_01.gif
http://www.pispeakers.com/Davies_02.gif
http://www.pispeakers.com/Davies_03.gif
http://www.pispeakers.com/Davies_04.gif
http://www.pispeakers.com/Davies_05.gif
http://www.pispeakers.com/Davies_06.gif
http://www.pispeakers.com/Davies_07.gif
http://www.pispeakers.com/Davies_08.gif
http://www.pispeakers.com/Davies_09.gif
GIF files un-readable... [message #42559 is a reply to message #42557] Wed, 24 September 2003 22:31 Go to previous messageGo to next message
AR is currently offline  AR
Messages: 5
Registered: May 2009
Esquire
Hi Wayne - thanks for posting this article, but the files were unreadable. Any other suggestions?? TIA AR
Use an image viewer or paint program [message #42560 is a reply to message #42559] Wed, 24 September 2003 22:48 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18006
Registered: January 2001
Illuminati (33rd Degree)
Download and install a copy of the free version of Paint Shop Pro. I think that's the easiest way to solve this. So grab a copy of "Paint Shop Pro" from JASC Software and give that a go.

Wayne

Re: GIF files un-readable... [message #42561 is a reply to message #42559] Wed, 24 September 2003 22:49 Go to previous messageGo to next message
ToFo is currently offline  ToFo
Messages: 219
Registered: May 2009
Master
Hi AR,
Hmmm? I find the attached files readable (they open) and readable (legible). What OS and browser are you using? Maybe save them and use an image editor to zoom to a magnification that renders less aliasing than fit to page.
Re: "Vented Speaker Systems" article by Brian Davies [message #42567 is a reply to message #42557] Thu, 25 September 2003 15:05 Go to previous messageGo to previous message
Tightwad is currently offline  Tightwad
Messages: 41
Registered: May 2009
Baron
Thanks so much for the files. I've scanned the first couple pages, and it looks like JUST what I need. Now I got something to read over lunch :)
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