Kenwood KFC-WPS1D

Described by Kenwood as a super-woofer, the WPS1D’s huge three kilowatt rated peak (momentary) power handling puts it into the Weapons Grade woofer segment for our purposes. It has a handsome domeless concave carbon and glass fibre cone and a massive aluminium die cast chassis. It comes with a big rubbery hoop top gasket that is squished into interference fit after you have installed the speaker and badges you stick on that once fitted. These gaskets can be used on either face of the woofer’s chassis and the manual shows how you can mount the sub magnet-in (normally) or sticking out, which helps with show car use and with smaller spaces allowed for enclosures.
A twelve inch driver with two 3 Ohm voice coils, rated at 700w RMS power handling, it features two pairs of gold plated binding post type terminals controlled by the Kenwood Smart Switching system. This is a bank of four fuse locations and a switch that is really a simple slider that covers two of the four fuse positions depending on how you set it. This works to run the woofer either in parallel or series hook up so as to show either 6 Ohms or 1.5 Ohms to the amplifier or else as two separate 3 Ohm voice coils for bi-amplification. This is when you can use say two sets of bridged channels in a four channel amplifier just to run this woofer. It means how ever your watts are configured, WPS1D is liable to be able to be made compatible with your amplification.
A gold plated jumper is in place when you buy it and is used when you are set to parallel coil operation. (Default delivery mode.) For the purposes of this test we removed this jumper and hooked the coils up in series. These 5A fuses, the jumper and the Smart Switch slider thingy obviate the need for bits of speaker cable to provide series connection. (See editor’s review)
If you fit it so the two fuses are in the highest two slots and the slider is at the bottom it is a series connection and so a higher impedance. This is how we ran this speaker, as the power amplifier used to drive it was a very heavy duty (3kW+ @ 1 Ohm) PowerBass XA3000D. This meant the amplifier was ‘seeing’ a 6 Ohm load and so would be less likely to harm the woofer. (or so I hoped! more in the editor review.)
This is a very serious piece of equipment and weighs in at a fat 12.8 kilos (28lbs). There are dual bottom spiders (the lower suspension element of a speaker cone, often corrugated doped Linen cloth) which helps linearity under heavy drive and is a feature of high power speakers. Also the voice coil tinsel wires (those that join the speaker wire connection points to the coil itself inside the speaker) are woven into the top spider. This is to stop them flapping around under heavy drive and breaking.
– Frequency response: 20Hz to 800Hz
– Power Handling: 700w RMS (3kW max)
– Carbon/glass fibre cone
– Die cast aluminium chassis
– Large rubber top gasket
– Dual 3 Ohm voice coils with ‘Smart Switching’ jumper system for series, parallel or bi-amplified use
– Gold plated 4mm binding post terminals
– Voice Coil Diameter: 3 inch (75mm)
– Mounting depth 211mm
– Supplied with large ‘Parker’ type screws for fixing, bottom gasketing, a rubber top gasket and badges to apply after installation
– 4,080 Gram magnet
– Efficiency: 91dB 1w/1M
– Fms: 35.8Hz
– Qes: 0.598
– Qms: 4.403
– Qts: 0.526
– Vas: 29.11 Litres
Review by Adam Rayner
A beast of a subwoofer for a mainstream Japanese brand, this is a flagship product. A full thousand watts is what it says it’ll eat in the blurb but the rating is more accurately stated at seven hundred RMS in the specs. This is still a very heavy duty item. It has the loveliest of cones and looks as though it is only made of CF but in fact has some glass fibre in there too which saves major cost without detracting hugely from the performance of such a product.
It has a clever system of connecting the voice coils using the gold plated binding posts, a gold plated jumper piece fitted to the terminal system that you remove if you want to use the speaker with series rather than parallel hook-up and a slider that is used to set which fuses do what. With a cunning dual 3 Ohm voice coil configuration, this can thus look like a relatively easy to run 6 Ohms or else a lower than 2 Ohms (1.5) for massive suck of watts from an amp that does low impedance loads. It can of course be used as two separate coils bi-amped.
It is gorgeously built and presented in pretty packaging, with plenty of bits to help you fit it, including a template and some very heavy duty woodscrews and a large rubbery gasket that you fit once installed and then stick the supplied separate Kenwood logo badges to. Very nice.
I confess that when I first hooked this up, it was a bit of a worry as I used a super posh headunit with no watts in its insides so I couldn’t really monitor the music signal very well. I connected it up, and turned it up. It got plenty loud and I turned it up some more. There was a ‘burp’ sound and it all went quiet. It turned out I had been a bit over enthusiastic and had vaporised one of the fuse elements. It was a five ampere fuse!
All was removed, checked on the meter and the run up again. The sound output was capable of shaking the floor in my wee house’s test area and I felt the very floorboards shake as the box was on its back so the woofer’s moving mass was literally wobbling my home. It can go loud and deep and although doesn’t do the mad end SQ fancy footwork stuff of being able to follow the tiniest nuances of bass melodies, it will be a serious underpinning for a Kenwood enthusiast who wants to compete with his friends’ exotics. I will confess I found the switch and fuse system a little confusing as the ‘switch’ is just a slider and is used to choose which pair of fuse jumper connectors are in place. But the system works well once grasped.
There seems to be a healthy excursion of the cone, with plenty of in and out travel. This woofer moves air. The only thing that concerns me slightly is that three thousand watt rating of peak power handling. I confess again that after all the worry of the start of the test I had the thing running happily and did wick up the power somewhat. The PowerBass XA3000D amp is rated as 1200 watts into four ohms, so at six (as hooked up here) should have been about right for the subwoofer. Thing is, after a bit of enthusiastic bass I experienced another silence. Sick with worry for the voice coils, I disconnected and took a bleepy continuity meter to the thing. The terminals registered an open circuit on one coil and not the other but yet when applied to the tinsel wires, was a continuous circuit. Therefore I managed to barbecue the terminal switching system without harming the coils. So in the death although I thought it clever and perhaps a bit tricky to fathom for the hard of thinking, I do feel this system is an unnecessary frill and a simple pair of dual terminals with instructions or even supplied widgets to connect to them would have been better. Almost certainly not a problem if you are using it with caution but in my job I kind of have to ‘Do a Jeremy’ (Clarkson) to do you readers justice. This time it went pop in my face. I do hope Kenwood will understand.
Sound Quality 8.0
Build Quality 8.0
Power Handling 6.0
Efficiency 9.0
Value For Money 7.0
Overall rating 7.6