> obviously not much more than a toy
It may be a very excellent thing, within its obvious limits. Of course it may be junk, no way to know from the catalog. But the similar Fostex FE-103 is a really good full-range small-room speaker.
> ported cabinet
Insufficient data to calculate a port-box.
> not much bigger than the speaker itself.
The leverage in a small-cone ported box comes from LARGE box volume.
Also, unless you can shift the port-resonance far below the working band, the cone will un-load and flap horribly.
Despite insufficient specific data, I can guess what typical speakers of that type will do.
Your first-hack is to compute 1.1 times the speaker nominal diameter, or 3.3". Cube that, 36 cubic inches. Sealed box. This will very likely bring Q near unity, a good balance between bass extension and boom. Figure a box that volume, non-equal dimensions, largest on the face. Is the speaker 2" deep? Then we want 18 square inches of face, say 4"x5" or 3"x6". Your board thickness can be 1/20th of span, quarter-inch stuff. Or since face is braced by speaker, sides are 2", and rear-panel radiation may go-away and get-lost, perhaps 1/8" stuff.
I would expect this to cut-off at 200Hz or 250Hz. Yes, you lose several octaves of guitar-ballz. However half-Watt at nominal 88dB SPL/W will give just 85-86dB SPL peaks in an apartment, and at that level, bass is weak due to ear effects (Fletcher-Munson) so we may not know the difference even with a ballsy speaker. Guitar sings above 200Hz, and low-notes spray ample harmonics up the frequency band so you hear them at correct pitch even when the fundamental is inaudible.
You can try a larger box, 4x to 8X volume, 150-300 cubic inches. Instead of being bumped-up at ~~240Hz, it will droop from 300Hz all the way down. The large sealed box will give "more" efficiency at 80Hz, but that may be 20dB down from mid-range level.... you won't hear it. However a 11"H 3"W 9" deep box is a great fit on a bookshelf, and set near-flush with book-spines you have plenty of acoustic support for midband waves, and damping for flimsy side-panels.
This would be a possible size for a vented box. However the naked cone is sure to be falling below 200Hz. We can't set the box resonance more than a half-octave lower (140Hz) or we get a dip/peak which will "miss" half the notes. And all notes below ~~120Hz will just slap, forcing a high-pass filter in the amp. (With just 0.5W into a "10W" speaker, maybe only your lowest note will slap.) My main objection is that box-tuning calculations are hard, and we don't have any speaker parameters.
You should also try just a square foot of heavy cardboard with a 3" hole a bit off-center. Open-back baffle. Bass will droop; but that happens in any case. The total acoustic power to the room doubles; back-radiation adds to the reverberant field. The sound field is more complex, more interesting to the ear. It sounds less like a 3-inch hole and more like a good-size instrument. I dunno how it fits on your bookshelf; you could build it 11" tall and 2" wide like a book, and pull it off the shelf to play.
Topic: amp cabinet design (Read 6697 times)