25W8565-01 / 12M4631 / OW1

© November 2005 by David L. Ralph

This design is provided for personal use only. It may not be used in whole nor in part for any commercial purposes.

Updated 11 November 2005 with on-baffle raw measurements for download

I've been designing and building speaker systems for 10 years. This one is my favorite to date. It's not named, I may do so at some point. It's a 3-way that comprises the following drivers:

The crossover is 2nd order Linkwitz-Riley for both W/M and M/T. The crossover frequencies are 300Hz and 3000Hz. My original target was 85db flat, but a slight downward slope sounded better. I ended up with 85db at the low end with a gentle rolloff to 84db at 20KHz.

I designed this crossover with CALSOD using measurements made with LAUD. I transferred it into SoundEasy because I am moving towards its use and so that I could confirm that my SoundEasy setup was correct. It also allowed me to create a schematic graphic as CALSOD does not have this capability.

The woofer box is about 70L. I haven't carefully measured it since inserting the brace that reduced the size, but this is close. I'll update this info later. A 10" passive radiator tuned to 18Hz yields a box tuning of 30Hz. The box is empty except for for one large, diagonally placed center brace and a smaller, solid one at the small end in the back used to reduce the cabinet size as I had originally oversized it for some experimentation.

The midrange box is 4L and is reasonably stuffed. It's oversized a bit because I do not use the driver/box highpass, I use a passive crossover highpass. Larger midrange volumes allow the use of smaller highpass components, primarily for the capacitors. They also have the added benefit of allowing the use of more stuffing to damp the rear wave better.

One important point needs to be made here. I now always make fairly extensive use of real wool felt for diffraction control. It's an integral part of the design. If you don't use it, there will be a cost, that being a much more ragged response on most axes.

One of the nicer qualities of the crossover is the impedance profile. The range is about 3.5-7 ohms, 20-20KHz. Even the double reflex peak for the woofer stays between 4 and 8 ohms. In addition, the phase angle remains within ± 30° from 20-20KHz.

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