Reflexion Filters – Independent Tests

Reflexion filters, the curved screens intended to shield a vocal microphone from reflected reverberations in a room and thus “dry up” the signal are sprouting everywhere these days.  A studio I hired recently had one set up despite the live room being designed by a respected acoustician.  The original idea came from Chinese firm SE Electronics in the form of their Reflexion Filter a curved metal screen sandwiched together with other layers and lined with absorbent foam.  The sales pitch was that it would create a magic forcefield around your microphone excluding all unwanted reverb, flutter echoes and subsonic noise making it sound like you were in a vocal booth.  Well, not quite but as an easy solution to the problem of recording in undesirable spaces it caught a wave.  Sales were so good that in no time at all knock-offs of various price and quality flooded the market and anyone considering such a device was spoilt for choice.

The theory of the filter has led to some (probably deliberate) confusion.  They work principally by absorbing some of the direct sound from your gob on it’s way out into the room.  It then deflects and re-absorbs reflected sound TO A LESSER DEGREE.  The cumulative effect is to adjust the ratio of direct to indirect sound in your singer’s favour and render the vocal “drier”.  So the filter is much less effective at attenuating unwanted sound coming inside from out, though it does do that to a degree.  This is why it is only worth considering in tandem with some room treatment and if the room is ghastly it won’t help much. It also achieves it’s work at the cost of colouring your signal with close reflections from its own structure.  These will generally be fairly benign, but you would want to minimize them nonetheless.

Until recently there was not an independent reliable test of the claims SE and its competitors have made for their products – Sound On Sound to the rescue.  Using an anechoic chamber to test a selection of screens, the magazine provided a buyers guide.  The screens were rated for attenuation of room echo, attenuation of external sound and colouration of sound.  The results were intriguing; the original filter scored well, showing SE were wise to copyright it’s specific design.  Their uprated and expensive successor “Space” (a hefty £300) was better but not outstandingly so.  The humble Auralex Mudguard (£75) which features a moulded plastic shell lined with foam was the dark horse, coming within shouting distance of the SE product’s performance at a remarkably low price.  There were some other interesting findings but you should buy the mag to find out.  These filters are not without their uses but it was instructive to see what they are really made of performance wise.  And remember, room treatment ends with one not starts.

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