KX Audio KX12 & KX1.5

The speaker components used in the KX range are all specifically engineered to suit the model in question, and make use of the latest in neodymium magnet technology to reduce weight and maximise power handling and acoustic output. The 12-inch driver is equipped with a 2.5-inch voice coil and an epoxy-reinforced cone, and uses what KX Audio call ‘inside outside’ technology, which refers to the coil windings being wound on both sides of the former. Frequency response of the LF section is quoted in the specifications as going down to a respectable 58Hz at the -3dB point, and the internal crossover point is set at 1.3kHz, which is low enough to direct more of the critical vocal frequencies to the HF section and thus control (and project) them using the HF driver and horn design. One of the KX12’s claims to fame is the use of a medium-format compression driver — in this case using a 1.4-inch exit with a 2.5-inch diaphragm — which I think is a real improvement on the more common one-inch exit drivers used in many two-way speakers and offers a useful increase in projection and power handling. The upper frequency response goes to 18kHz (again using the -3dB point) and the horn coverage is 80 x 40 degrees, which is usefully horizontally wide and vertically narrow enough to focus more of the output energy where it is needed, ie. where the audience is and not into the roof.

Onboard power, processing and protection are all integrated within a single module recessed into the rear of the cabinet. The huge advantage of these all-in-one active speakers is that all the components from input signal to acoustic output are correctly matched, and all the parts within the system are designed to obtain the best sounding and best protected results. Setting up is nothing more complicated than plugging in an XLR cable and switching on, but of course a mains power feed has to be run to each cab in the system, and you have to be a bit more careful in protecting the speakers from moisture and ensuring adequate ventilation. There isn’t much to see on the control panel — there’s an input XLR connector and a direct-link male XLR output for feeding on to other speakers; as it’s a true hard-wired link, it doesn’t matter if the KX12 is switched on or off and is therefore ‘fail safe’ in case, for example, any single KX12 unit had its power accidentally disconnected during a performance. The only controls, apart from the on/off switch, are a 90Hz filter switch, which reduces unwanted low frequencies when using the KX12 as a monitor or for speech-only applications, and a rotary level control that provides 6dB above and below the centre 0dB setting — note that it’s not a traditional volume control in that it doesn’t turn the signal all the way off. This level control was actually one of the first things I noticed when I took the speaker out of its shipping box. It’s a small, rather delicate-looking thing, which looks very vulnerable to accidental knocks from other gear or mishandling, especially as the control panel isn’t very deeply recessed and the knob isn’t really protected at all. It’s also the first thing Paul (bass player with Hair Of The Dog, and also my chief crewman) noticed, with a comment of, “These are nice... Ooh, that’s not going to last long is it?” For install and personal (careful) use, you’d probably be alright, but as hire stock I’d expect these cabs to come back knobless before long, and this is something that needs looking at. A pair of colour-changing LEDs tells you all you need to know about the operating conditions (on, limit, audio present, thermal), and that’s just about it. There’s an IEC power outlet next to the mains in connector — very handy when connecting additional speakers, and something you don’t always see on MI gear.

One thing that is noticeably absent from the rear panel is a heat sink — or rather, the cooling fins normally associated with one. The KX12 rear panel itself acts as a heat sink, but the designers have opted for a fan-cooled arrangement that does away with the need for external fins or extrusions. The fan speed is controlled not only by internal amplifier temperature (to be expected), but also by the audio signal level (clever), which should ensure that the temperature stays well within operating conditions when being driven hard. The no-fins approach has two other advantages that I can see: it makes no difference whether this speaker is used upright or sideways, and it doesn’t bite.

To accompany the KX12 speakers I had a pair of KX1.5 subs, which use a 500W high-current switching amp coupled to a cellulose-coned neodymium 15-inch driver with a three-inch voice coil. Like their full-range relations, they are well finished in durable black over solid 18mm ply, and again the side handles are very well designed and best placed for good balance. The subs weigh only 37kg each, and are very easy to handle — although easier with two people, I did load them a couple of times by myself, and managed them without any trouble. My previous comment about the vulnerability of the level control applies equally to the KX1.5, but this would be my only issue with the design. Most of the functionality on the control panel is the same as described for the KX12, but the KX1.5 is designed to be used either on its own with two mid/tops, or as part of a pair (ie. one sub each side). The KX1.5 has two main input sections, which, if both used, sum the input signals together and feed the internal sub amp, and then the left/right signals can be taken from the (hard-linked) full-range outputs or via the high-pass outputs, which are internally crossed over at 125Hz.

Although the venue was of modest size, it was definitely in the ‘loud’ category, and the guy who runs the installed disco setup has a habit of playing music in the interval at (what he considers to be) at least/slightly above the level that the live band have just achieved. I’ve come across this many times over the years, and whereas I used to be fairly paranoid about it I now find it only mildly irritating when I want to rest my ears in between sets. Anyway, I was looking forward to having a decent reserve of power in hand, and we decided to put everything through the PA apart from kit overheads. I used one sub per side, and their small footprint was a bonus given the somewhat restricted floor space. A pair of adjustable standard mounting poles was used for the KX12s, which I set at around a foot above head height. I used the high-pass outputs from each sub to feed the KX12s, and I left the 90Hz monitor filter switched in, although it wasn’t necessary. Connecting up the main system took about five minutes, and that included running the mains supplies to each side — the high-efficiency amps don’t draw all that much current, and are very kind to the supply at power-up (and there’s no switch-on noise that I could detect), so everything was running from a single (suitably-protected) power outlet. When we had persuaded the resident guy to turn the house system off, I played a few CD tracks just to get the feel of the KX gear, and from the amount of level coming from the system with virtually no VU LEDs showing, I thought we might be in for a good night.

My main impression of the KX speakers was one of clarity and strength; there was no getting away from that vocal sound, or that massive kick, and I just felt that I could have thrown almost anything at this little rig and it would have handled it. After the show, packing up was quick and easy, and the band even paid me with a smile — always a good sign, that!