Keele-Hoge and Margolis-Small formulas and equations. The origins.

[lupanar]

Hello.

Some time ago I was asked where the Margolis - Small and Keele - Hoge formulas appear for the first time, related to the simplified calculation used in vented-box loudspeaker alignment. (See pages 20 and 21 of this book, marked in red in the attach image). cajas acusticas 2a edicion altavoces teoria diseno

There is hardly any information on this subject, this is what I found out:

1- The simplified method formulas were initially developed in November 1977 by P. J. Snyder in the Journal of the Audio Engineering Society: "Simple formulas and graphs for design of vented loudspeaker systems".

2- W.J.J. Hoge, based on the work of D. B. Keele, in August 1978 published in the Audio magazine the article "Confessions of a loudspeaker engineer" in which these equations appeared. Apparently Keele never published anything officially about this procedure, but they were transmitted by "private communication" between the various sound engineers.

3- In June 1981 G. Margolis and R. H. Small publish in JAES: "Personal calculator programs for approximate vented-box and closed-box loudspeaker system design" in which they improve the behavior of Keele-Hoge equations.

🙄 I don't know if you can add something else...

Additional info:
Lansing Heritage Forums

Kind regards.

 

[DoctorAcoustic]

What is “S”?

What is the coefficient “S”? It translates to “box surge coefficient” and seems to be some sort of measure of Qtc.

 

[lupanar]

S (N in the image) is the "overvoltage coefficient" of the vented-box , used by J. P. Snyder in "Simple formulas and graphs for design of vented loudspeaker systems".
Typical values: 2 2.8 4 5.7 8 11.3 16
In the formulas Vb = S Vas Qts ^ 2 . If S increases, Vb increases and f3 decreases.