Tweaker's Asylum

Posted by Jon Risch on April 13, 2000 at 21:59:06:

In Reply to: what's the best woofer to tweeter ratio? posted by Bod on April 13, 2000 at 14:51:47:

This kind of thing is usually not approached in the form of ratio's.

It is more of a form follows function kind of thing. The size of the wavelengths of very HF sound in air tend to make a 1" (25 mm) diameter tweeter usefull up to the top octave in terms of dispersion, and provides an adequate amount of power handling for a 1" voice coil, and reasonable demands for tolerances, and so on. While there are some successful 3/4" (19 mm)tweeters, they tend to have a restricted LF response, and are hard pressed to meet even a 6 1/2" (17 cm) mid-bass sometimes at decent power levels. Larger diameter tweeters in the 1 1/2" (34 mm)range are begining to lose the ability to disperse in the last octave, and also begin to lose HF response due to mass, etc. So a good tweeter size is 1" (25 mm).

Woofers to match such a tweeter will usually have to respond decently up to at least 2-3 kHz, as well as have decent dispersion at these frequencies too, and this rules out most woofers over 10" (25 cm) in nominal diameter. Many would not use a woofer over 8" (20 cm) with a 1" (25 mm) dome tweeter, after this they would go three way or more.

If a rule of thumb is what is desired, then it would be safe to say that a maximum practical limit is about 10 to 1. If a three way design is an option, then this ratio can be kept well within about half this limit, and use decently sized woofers.

Jon Risch