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Speaker Rescue - Philips Norelco

I was intrigued by these little Norelco speakers (measuring approx 300x170x220mm hwd) as the midrange/tweeter dual cone driver looks so much like the larger Philips 9710 dual cone, both in structure and materials used. I've enjoyed what the 9710 full-range speakers do in the various Sonab speakers I have which use them. Others must like them too, judging by the prices usually asked for them.

Due to one woofer being cactus I picked them up cheaply, then set about trying to find a woofer that would fit the size of the old one. That's proved impossible to date - all the so-called 5" ones are smaller, while all the 6" are too big, and 5.5" are not that common anyway. All woofers are rather loosely quoted in inches, while the critical dimensions are the outside diameter, the inside or cutout size, and then in some cases the depth might be a limiting factor.

With an outside size of 155mm (octagonal as well!) and no space to go larger, I had to opt for something smaller at 147mm and make an adaptor plate to take the smaller woofer. It's a Jmax and they use it in speakers of similar size to the Norelco I have, so I thought it'd do for a trial run.

My first instinct was to get a local metal fabricator to cut the adaptor out for me to my drawing. Couldn't find one, so set about it myself. Quite difficult to do the 120mm circular cutout, but made in it the end! Using the old woofer I marked where the 8 outside screw holes should go, then did the same with the new woofer for the four screws it needs.

Things never seem to line up quite as they should, but the new arrangement was pressed and screwed (with cardboard gaskets to maintain the airtightness!) into place with wires re-attached, then we had an audition of the finished product. I'm thrilled with the result. These are enchanting little speakers, lively top-end, great midrange and quite adequate bass! They are efficient and really nice to listen to. The crossover is the simplest - one capacitor, which as Ralph Waters told us in The Truth About Loudspeakers, is a good thing as it introduces a minimum of issues. If you can arrange it - not all designs can be that simple. All it has to do here is stop the tweeter from being overpowered.

So there they are, the finished product. Old-fashioned, but nice. And another surprise, the cabinets are solid timber, not chipboard with veneer. The front baffle is plywood, the tweeter-midrange is isolated by a back cover, while the bass is in a sealed and not a vented enclosure.