Anyone know how the various driver sizes came about, particularly woofers?

[River757]

In the early 80s when I was building my first two sets of speakers, as far as woofers were concerned, these were the sizes that were most commonly available: 4".....5.25"......6.5".....8".....10"......12".... and 15".

Did a standards commmittee choose these diameters or did they just come about "naturally"?

And nowadays there are more sizes to choose from, but they are so close to the above I'm not sure why they exist: 4.5"......5".......7".......9".

[Moondog55]

You ask a good question; one I never thought about either.

I would guess it is a basic engineering question about SPL, efficiency and amplifier power and like a lot of things would depend a lot on what size the very first electromechanical speaker happened to be.
It could how-ever be that it follows on from the size of the horns fitted to early mechanical record players.
I have to say "Congratulations" for asking a very interesting question.

Let's see how the members respond

[454Casull]

Maybe we should push for driver sizes matching a preferred number series like E6.

[Moondog55]

I have always assumed that each driver size up was an approximate doubling of the piston area.

[rob g]

Engineer: " The driver needs to be size X to produce bass and have reasonable efficiency."

Speakers start to sell, market created. Following growth of sales market research is performed.

Sales and marketing research: "Our research shows Speaker needs to be smaller."
Thus years and years of hard R&D which actually have more to do with ringing the most performance out of ever smaller designs developed to improve WAF than in developing speakers with absolute performance.
-AND REPEAT...............................

Through innovation and development some benefits to smaller drivers are discovered. So it's not all bad.

[DrDyna]

My guess is after a couple of the first companies started making drivers, others followed suit competitively, or as replacements which needed to fit.

Bear in mind that there are some that are metric too, which don't "exactly" line up with the inch sizes, but they're still close.

[rob g]

More theory.

Standardization of driver size?
I guess if you have shelled out for tooling and machines to stamp or cast a certain size of basket you stick to it for as long as possible.

The most successful manufacturers sell the most drive units thus setting the standard sizing. Companies lower in the pecking order simply copy successful models and engineering....................

[rob g]

C'mon, someone's gotta have a better answer than mine!
You know, real engineering based.

[dantheman]

Rob, I'd bet between the 2, you got it. Where's Speaker Dave?

Dan

[speaker dave]

Originally Posted by dantheman

Where's Speaker Dave?

Dan

Why, because I'm the old fart here?

The first company I worked for (Essex Cletron) was heavy into automotive units. The auto business tended to have uniform sizes for interchangeability. The confusing thing was that nominal sizes weren't related to cones but to the frame. So, round units were measured across the diameter, but pincushion units were the short dimension halfway between the mounting holes. A 4 1/2" pincushion was a 5" round.

3 1/2, 4, 4 1/2-5, 5 1/4, 6 1/2, 8, 10, 12, 15,18 (inches) have always been the common round sizes. The steps seem to be a near constant 20 to 25% diameter increases for roughly 50% increases in area. Useful step sizes but not too fine to be silly.

4 x 6", 5 x 7" and 6 x 9" where the standard oval sizes then Ford messed it all up by coming out with a 5 x 7 that was totally different than the Chrysler size. Thanks. Oh, and 4" and 4 x 6" were always considered "European", (the 100mm connection).

Thats all I know. I'm sure the sizes where standardized before the war, hence before my time.

Why 3.2 ohms?

David S.