sE Electronics - Reflexion Filter

Highlights

• Isolate and capture better vocal recordings in less-than-ideal environments
• Carefully tested to maximize absorption while leaving the microphone's polar pattern unaffected
• Securely clamps to any microphone stand
• Great for recording vocals in the control room, the tour bus, or even just home studios with no acoustic treatment

General Information

"Every studio should have an sE Reflexion Filter. It's great for isolating sound and it's perfect for on the road."
- Stevie Wonder

What is the Reflexion Filter?
The Reflexion Filter is basically a portable device for recording live sound sources with reduced room ambience. It is an advanced composite wall which is positioned behind any microphone by means of a variable position stand clamp assembly which ships with the product. The main function is to help obtain a dry vocal or instrument recording. This is especially useful in studios without proper acoustic treatment, but can also be used to help record takes in control rooms, where the performer also has to operate the recording device, or in rehearsal studios to reduce ambient noise.

The Technical Bit
The Reflexion Filter has 6 main layers. Firstly, a strong layer of punched Aluminum which allows sound waves to pass through it, diffused, to a layer of absorptive wool. The sound waves then hit a layer of Aluminum foil which helps dissipate energy and break up the lower frequency wave-forms, and from here they hit an air space kept open by rods passing through the various layers. The air gap acts as an acoustic barrier. The sound waves then pass to a further layer of wool and then through an outer, punched, Aluminum wall which further serve to absorb then diffuse the remaining acoustic energy.

How does it work?
The various layers both absorb and diffuse the sound waves hitting them, so progressively less of the original source acoustic energy passes through each layer. This reduces the amount of energy hitting un-treated walls and other surfaces so there is less of the original source reflected back as unwanted room ambience to the mic. The Reflexion Filter also helps prevent any reflected sound reaching the back and sides of the mic. Its shape and size have been carefully tested to maximize absorption while keeping �coloration� down to only around 1dB, and leaving the microphone�s polar pattern unaffected.

The Results
'Independent test results from the Tongji University Audio Lab in Shanghai show audio image colouration with and without the sE Reflexion Filter. The tests (carried out by China's leading Acoustic Engineering University completely independently) clearly show extremely low levels of coloration when using a microphone with the Reflexion Filter while recording (20Hz to 20KHz).

This was one of the greatest challenges in designing the RF. Other companies have now started to try and copy our designs (without breaking the patents which are what make the Reflexion Filter actually work!), but fail to achieve such good results because the designs are too simplistic.

The RF comprises several layers of Aluminium and patented acoustic fibreboard separated by acoustically isolating air gaps... and therefore manages to remove large amounts of room ambience with a very compact design. The whole idea was to make the unit as effective as possible, but in the smallest space... otherwise what would be the point... you may as well treat a wall behind the mic.

The shape of the RF is also critical to the design as it randomises any Reflections back from the surface of the filter. Products which are semicircular (without the flat diffuser panels the RF has) will concentrate any inconsistently reflected frequencies onto the mic... the worst possible scenario.

Another very poor design though is a simple 'V' shape behind the mic. This creates one of the worst coloration problems you can manage to achieve when recording audio. Think about problems of Bass Accumulation in room corners... the bass is accentuated worst in 90 degree corners, so any baffle placed behind a mic which is this shape creates huge coloration problems in bass frequencies. This also adversely affects higher harmonic frequencies because of the massive energy in bass frequencies exciting these higher harmonics. A simple flat panel on a wall positioned behind the mic is a much better solution, as it does not create coloration, but still limits at least some of the early reflections in the room.

+- read more >

Related Categories