Review

Vortex Complete Review - Sound & Image Magazine - Australia

01 Sep 2009

When you’re watching a movie with surround sound, there is an obvious and important need for centrally-positioned speech to be clear and powerfully projected. Loud effects crossing the stereo soundstage will sweep through the centre channel, so that needs to be a good match for the main front speakers. Yet in many surround speaker systems, the centre channel is outweighed and out powered by the rest of the system.

With its Vortex centre channel loudspeaker, South Australian loudspeaker maker Krix has changed all that.

Equipment

For one thing, it weighs in at 24kg – that’s more than two of the three floorstanding models it offers as ‘complementary’ models. And the Vortex centre speaker is large. Very large. It measures a full 725mm wide, 230mm tall and 383mm deep.

It provides, according to Krix, and internal volume of 42 litres, which is nearly as much as that of Krix’s highly regarded Harmonix floorstanding stereo loudspeakers, the top of that complementary range.

The similarities don’t end there, for the Vortex shares essentially the same set of drivers as the Harmonix. This is a four-driver three-way loudspeaker. Treble above 2.1kHz is handled by a 28mm soft-dome tweeter which is ferro fluid cooled and sports a neodymium magnet.

Immediately below that in centre position, and responsible for handling the frequencies between 340Hz and 2100Hz, is a 130mm cone driver. This has a 26mm voice coil, an aluminium coil former for improved power handling, and a copper shorting ring to limit excessive driver excursion.

Then for bass, there are two 165mm polypropylene cone drivers. They have a 33mm voice coil over a heat-carrying aluminium former, a ventilated spider (the springy part behind the cone that brings it back into place), and an aluminium flux stabilisation ring.

The speaker is biwirable, with proper gold-plated binding posts, and is bass reflex loaded, with the ports firing to the front. Krix rates the impedance of the Vortex at four ohms, its sensitivity at 91dB, its power handling at up to 10W and its ‘in room’ frequency range at 35Hz – 20,000Hz.

Price varies with finish – black vinyl, Atlantic Jarrah vinyl or American Cherry vinyl have recommended retail price of $1095. Otherwise, with the Black Ash timber veneer, Atlantic Jarrah timber veneer or American Cherry timber veneer, it is $1195.00.

Performance

Centre-channel loudspeakers are normally placed sideways, not so much for performance reasons but due to crowding at the front of the room. It has to fit with your TV or some other display device.

Most horizontally-located centre speakers have a problem: they suffer from left-right dispersion problems in the upper midrange. The reason is that they have a tweeter in the middle, and then two bass/midrange drivers producing frequencies up to a couple of thousand hertz on either side of it. But if you are offset to either the left or the right, then the path-length of the sound from the two drivers to your ears differs. In their upper ranges – at 2000Hz the wavelength is about 17cm – so you get an uneven interference between the two drivers.

With a single high-powered midrange driver handling down to 340Hz (wavelength: one metre), there is no such problem. We took turns with several dialogue-heavy film clips, sitting in different seats on our viewing couch, and then moving further to the sides, and the character of the voices produced by the Vortex remained perfectly steady, regardless of the position.

Just as importantly, the sound was very precise and tonally neutral. While clearly this speaker would be ideal for use with other Krix speakers, if you already have some high quality front speakers – especially if they have a flat frequency response – and need a high-quality centre channel to go with them, the Vortex is unlikely to let you down.

As to robustness, we have one DVD Audio disc that is particularly troubling to centre-channel speakers. It is Emerson, Lake and Palmer’s Brain Salad Surgery, and mastering engineers, perhaps in the pay of some loudspeaker repair company, mixed the centre channel with prodigious levels of deep bass rather than hiving it off to the LFE channel. Quite competent centre-channel speakers have problems with this track, because even with an 80Hz crossover, enough of this deep bass can make it through to bottom their cones!

So we set the Vortex to ‘Large’ with our home theatre receiver to ensure it received all the bass, spun up the ELP disc, advanced the volume control to a ridiculous level, and waited to see what would happen.

What happened was a musical performance with tightly controlled and remarkably deep bass. Not as deep as with proper set-up (we suggest setting a crossover of 50Hz for the truly deep bass to go to a subwoofer that can reproduce it with greater impact), but it coped wonderfully. That is indeed impressive.

Conclusion

If you have Krix speakers, then this is definitely the centre channel for you. But even if you have another brand of speakers and want to upgrade your centre channel, the Krix Vortex is worth an audition. The question is likely not to be whether it is good enough for your system, but whether your other speakers are good enough for it…

- Sound & Image Magazine - Australia , Stephen Dawson

Back to previous page