Jecklin Disc, Baffled stereo

 
recording tips

Apologies for the lack of new material but the mobile and the studio are so busy at the moment that weve just not had time to put any new stuff up. We have some great new sessions waiting to go up and a sneak preview of a fantastic new compresser but thats all to come!!!!! In the meantime have a read about the first in our series of great mics under £100

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Recording Bass Guitar
Recording Acoustic Guitar
Recording Acoustic Part 2
Recording Nylon strung
Choosing microphones
Stereo 1: XY coincident
Stereo 2: Blumlein Pair
Stereo 3: Middle-Side
Stereo 6: Binaural

Baffled stereo recording

Baffled stereo is a generic term for a number of different stereo techniques which use an acoustic baffle in between a pair of matched microphones to enhance the channel separation of the stereo signals. You can use a baffle in all the main stereo set ups, in spaced or A-B stereo, ORTF, DIN or NOS stereo, and the shadow effect from the baffle has a marked effect on the attenuation of off-axis sound sources, enhancing the channel separation. A number of baffles are available commercially made from an acoustic absorbent and non-reflective material but the most well known is the Jecklin Disc developed by the Swiss sound engineer Jürg Jecklin. The disk is basically a circular central plate about 10 mm thick, covered on both sides with thick foam intended to suppress high frequencies and various materials have been tried as coverings for the disk most noticably lambs wool. Two mics (ideally small diaphragm omni condensers) are mounted, one on each side of the disc, with their capsules 165 mm apart which is calculated to give the correct delay time difference between the two channels. How the disc works is that as the frequency increases, the two microphones are more and more separated. Below around 200 Hz, the two microphones record the same but frequencies above this are attenuated by the acoustic muffling of the disc resulting in a frequency response difference of the two channels depending on the angle of impact of the sound. In addition, there is also a sound diffraction around the disc rim which is dependent on frequency and angle.
I have never used a disc though I have come across a number of mobile recording outfits using home made versions of the disc with a pair of very high quality small diaphrgm omnis like Earthworks. I have also seen versions of the disc sprouting a hemispherical lump on each side which is obviously begining to look very much like a dummy head/Binaural setup and it does generally seem to be a great area for home made experimentation. So if you have any experience with a disc get in touch. There is a full technical breakdown of the Jecklin disc on the Josephson microphones website.

September 2008) The Hebden Sound omnis have become the mic set up of choice for me when recording a choir and while I still haven't had the opportunity to compare them to the more established small diaphragm omnis like the DPA range I am completely sold on these mics. They have performed faultlessly for the last year and have given my mobile recordings a sense of space that coincident pairs or even single fixed piont stereo mics like the mighty Soundfield can't achieve. I have recently come across a very nice Jecklin disc and I plan to try out the Hebdens with the disc on an up coming session. Watch this space!!! JR

 

 

 

Recording


 
 
Microphones and recording 2008. Jecklin Disc, Baffled stereo Microphones