Small Advent woofers for subs

[Guest crusty]

Having collected three pairs of Small Advent speakers over the years, I have used the drivers from one pair that had non restorable cabinets for various projects. My current undertaking has been a subwoofer for an install of the sound system in my new pickup. The original Small Advent cabinet has an internal volume of approx .73 cu.ft. I began designing a behind the seat box of this size but when cruising ebay one evening I saw that one of the car audio stores had a sale on sub enclosures at a very reasonable price and they had one that was .75 cu ft and of the dim. I needed to fit behind my seat. The enclosures were constructed of 3/4 inch MDF, carpeted and had a good quality binding post terminals. At $35 delivered I couldn't build one myself for this price so I ordered one cutout for a 10 inch sub.

The enclosure I received was impressive for the price. I made some mods by sealing all the interior joints with silicon sealant and fabricated two front to back 1x2 braces to tame panel vibration which were glued and screwed into place on either side of the woofer cutout. The Small Advent woofers frame is slightly odd sized but with foam speaker sealing tape and careful mounting the woofers frame does overlap the cutout by about 1/8", enough for a good seal. Initially I stuffed the box with fiberglass equal in amount to what were in the original Advent cabinets, which is quite tightly filled, but this proved to raise the output at FC (45 hz +-) and slightly above. So I cut a piece of R30 to the height x width of the box and laid it flat inside. After the fiberglas had swelled and loosely filled the box I reinstalled the woofer and gave a listen, the bass became much more relaxed and deeper.

I power this with an Alpine mono amp with approx. 200 watts into 4 ohms and a 24db per oct. low pass filter set at 75 hz.

I couldn't be more happy with the results I've obtained using the Small Advent woofer for this sub, and in fact I believe it outperforms many current sub drivers for this given size of cabinet. While probably not as loud and irritating as the one note thumpers you hear next to you at the stoplights, the bass it does provide is deep, clean and satisfying.