As I said before that I’m not into music but I do listen to them and now the speakers are reaching its end of life. Having years of exposure to the high humidity of the tropics, the box’s boards are losing its bonding property. It is chipping away at the edges and the joints are opening up. Also the woofers have weakened and are not producing solid bass sound anymore. Since I have a few speaker drivers lying around I decide to rebuild the two speakers.
I have two pairs of 4Ohm car subwoofer drivers, one is a pair of an old 8inch and the other is a new pair of 10inch which are not up to par for the car amplifier. Each of the two different sizes woofer drivers will be paired in a single box connected in series so as to give an impedance of 8Ohm. The mid-range drivers which itself replaced the original mid-range drivers shall be reused. New tweeters and two-way crossovers salvaged from old speakers and kept will complete the setup for an 8Ohm nominal impedance speaker boxes.
The first step is the removal of all the drivers and tweeters followed by the stripping off of the dark coloured wood looking laminating sheets. A layer of fibreglass sheet is laminated at the bottom of the boxes and two layer of resin coats are applied to the rest, filling-in the gaps and cavities. Once the resin has cured, it is sanded before a layer of undercoat/filler paint is applied with a brush. The undercoat paint is then sanded and later covered with a layer of black paint. Again the surfaces are sanded but this time using fine grit sandpapers. Finally the boxes are sprayed with black paint followed by clear lacquer as the final touch.
Originally the boxes are of the vented type with tuning holes but are now covered and turned into sealed boxes for better sound clarity. Also as a departure from the norm, I have separated the boxes into two segments, one for the woofers and the other for the mid-range and tweeter.
I am quite happy with the sounds, the bass is more solid and does not baffle even if the bass is cranked up. No problem in the high frequencies either, in fact now I can hear the instruments played clearly except that the mid-range is slightly muted. This could be the mid-range drivers itself or the two-way crossovers of which I do not know its crossover frequency, or whatever it is. A quick refresh reading on filters and crossovers, I come to know again about the 180 degrees phase change on the high frequency side. A reverse in polarity for the connections to the terminals of the mid-range drivers and tweeters solved the problem.