From: Roy Allison                                                                        Refer# 494
To: Steve Brunkow
Subj. Misc. speaker questions                                                  Conf: (1) SoundAdvic
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Hello Steve

Sorry for the delay in responding. Your questions are short, but they require answers 
that aren't!

The F-1 is very similar to the Allison CD-8 except in the middle range; the CD-8 has a 
separate midrange driver and the F-1 does not. One other difference: price! The retail 
price of the CD-8 was $950/pair, while the F-1 price is $549/pair.

The standing-wave formula is fnx, ny, nz = 565[(nx/x)2 + (ny/y)2 + (nz/z)2]1/2, where x, 
y, and z are the room dimensions (in feet) and n is any whole number. 

If you set two of the n values to zero (nx and ny, for example) the formula reduces to f = 
565n/z. Plugging in whole numbers for n beginning with 1 gives you the series of 
resonance frequencies for room dimension z. Single-dimension resonances are called 
axial modes, and there is a set for each room dimension.

Setting only one n value to zero yields three sets of two-dimension resonances, called 
tangential modes. And if you assign non-zero whole numbers to all three n values, you 
are rewarded with a set of oblique modes. 

Software is available for such calculations. Sitting Duck sells one version. However, they 
and some others appear to believe that only the axial modes need be considered 
significant. That certainly simplifies matters, but I find no basis for the claim. 

As for calculation of speaker power-handling capacity, I dunno. The experimental 
approach is what I've used: You apply X power at Y frequency for increasing time 
periods (allowing for cooling time in between), and when failure occurs you've got one 
point on a complex time/frequency grid. Unfortunately it isn't a practical thing for home 
speaker-builders!

Roy