Small technical backgrounder this time.

When recording stereo it is essential to have equal gain settings for the microphones at the risk of the stereo image shifting to either left or right. More gain on the right mic channel will shift the image to the right and the other way around. Equal gain settings are especially important in XY, ORTF or any other spaced or coincident microphone positioning.

With mid-side recording the gain setting for the mid and side channels allow you control the stereo spread. More gain on the side channel compared to mid will widen the stereo image. More gain on the mid channel will narrow the image. Ultimately, no gain on the side channel will leave you with a centered mono signal from the mid mic.

Reading gain or trim pot settings is easy enough but you usually end up with differences in signal strength if you don’t take into account microphone sensitivity even with an equal gain setting on your recorder or mixer. Unless you have a matched pair, microphones have different sensitivity characteristics.

A typical MS setup is the Sennheiser MKH60/ MKH30 microphone pair.

The MKH60 has a sensitivity of 40mV/Pa, the MKH30 has 25mV/Pa. With equal gain you will end up with a much stronger mid signal and consequently a narrow stereo image.

The calculation to compensate for sensitivity is as follows:

±dB = 20 x log(MmV/SmV)

where

MmV = sensitivity of the mid mic in mV/Pa
SmV = sensitivity of the side mic in mV/Pa

In our example we need 4.1dB more gain on the side channel compared to the mid channel to get equal signal strength on both of the recorded channels.

This is easy to realize on mixers such as the Sound Devices 302. With MS stereo linking set trim pots allow you to set gain for the mid and side channels separately. The input 2 fader controls the overall gain for the pair.

Just posted an excerpt of the field recordings I did in North India earlier this year. Using SoundCloud for the first time for this.

Recorded with a Sennheiser MKH8020/ MKH30 MS stereo microphone configuration to a Sound Devices 702 recorder. MS converted to AB stereo at the recorder stage.

SoundCloud uploads are transcoded to 128 kbps mp3 format for streaming. That’s still twice as good as MySpace.

As anyone familiar with processing audio on a computer will testify there are hundreds of plug-ins available for any application. Searching the KVR site for an EQ for OS X based applications gives you a choice of 141 different plug-ins. For the Windows platform you will find 226. And that’s just for EQ.

Without any exception these plug-ins were engineered with music in mind and that makes life for the field recordist slightly more difficult. While the Abbey Road TG12413 compressor/ limiter plug-in is a brilliant piece of software that does wonders on a drum kit, few field recordists will find a use for it. Vintage style EQ plug-ins can bring excessive coloration to a recording. Many plug-in developers will advertise the ‘warmth’ their processors will bring to your recorded material but that does not interest me, and I suspect most field recordists,  at all. What I am looking for is audio processors that keep the recorded material intact. No added warmth required, not looking for increased presence or transients adjustment to obtain better attack.

My search for the ideal field recording plug-in pack is an on-going thing but here is the result so-far:

EQ: Waves Q10 Paragraphic equalizer, DDMF LP10 Mastering Equalizer

Dynamics: Flux Pure Compressor II, PSP Xenon Limiter

Channel strip: Waves Audio Track

Audio restoration: iZotope RX

Analysis: RNDigital Labs Inspector XL

UK based band A Dancing Beggar are releasing their second album called ‘What We Left Behind’ on iTunes today. The album features samples of recordings of mine. A big thanks for that. I can only hope the recordings helped in the inspiration process.

Go check these guys out:

http://www.myspace.com/adancingbeggar

Soundwalkers, a film by Lisbon, Portugal based video director and sound researcher Raquel Castro after having been available on VIMEO has seen its release on DVD format.

The documentary film captures the importance of sound in the environments we live in and the way people interact with these sounds. Above all it is a film about hearing, listening, perception and reaction and it does a brilliant job at it.

Raquel used some of my field recording work in the film. I met Raquel at Chris Watson’s Sound Recording course hosted by Wildeye in Norfolk, 2007. A few scenes of that course are in the film. I like the shot where the microphones are facing the sea. Waves in the background they stand as devices out to try and get a glimpse of the sounds that live in that particular place by the sea at that particular time.

Check it out on VIMEO here: http://vimeo.com/1737899

It appears to me that field recordists and phonographers are the only remaining people in the audio industry who still care about having dynamic content in their material.

The battle for the consumers money has resulted in increasingly loud music. Louder is better. Louder means more money in the bank.

Louder however also means boring song material and fatiguing music because dynamics and clarity have disappeared in the process of compressing and limiting the sound material to maximum loudness. It is not uncommon for CD’s today to peak at full scale almost throughout their entire length.

This stands in sharp contrast to the dynamics of sound in the natural world. Quiet and very quiet sounds exist alongside louder sounds. Consider a forest at dawn in spring or a tropical rain forest after a thunder storm. Quietly falling drops of water, the rustling of the foliage, birds in the trees vocalizing their songs and insects humming above the flowers, some rolling thunder in the distance. Imagine how this would sound if everything was compressed to equal loudness and normalized to peak level.

Sound artists and more so field recordists and phonographers are trying to capture the world of natural sound dynamics.

Beginning of next month I will be going on a recording trip to Corbett National Park in North India. On the trip also will be Chris Watson.

Corbett is situated in the foothills of the Himalaya mountains in the Nainital and Pauri Garhwal districts of Uttaranchal at altitudes ranging from 400m to 1100m. The forests, jungles and grasslands feature some of the richest wildlife in the Indian sub-continent.

Mammals are typically Rhesus Macaques, Langurs, Leopards, Jungle Cat, Leopard Cat, Fishing Cat, Dhole, Jackals, Red Fox, Sloth Bear and the Black Bear. Near to 600 species of birds can be observed and reptiles are typically the Gharial Crocodile, the Muggar (Marsh Crocodile) but also the Indian Python, Viper and the King Cobra.

This will be a unique opportunity once again to work with Chris and learn from the master in wildlife recording.

My recording kit so far looks like this:

Sound Devices 702 recorder
Sennheiser MKH 8020/ MKH 30 mid side kit
DPA 4060 spaced omni kit

This is slowly becoming a series.  I posted a recording to Freesound where I am testing the new Sennheiser MKH 8020 omnidirectional microphone as the mid microphone with my MKH 30 as the side mic.

The low end response of the MKH 8020 is very very impressive.  It is more sensitive than the MKH 20 omni (31mV/Pa compared to 25mV/Pa) and adds a few dB to the high end response. Beyond 20 kHz the frequency response goes all the way up to 60 kHz. It’s also very small: diameter 1.9 cm, length 7.4 cm. The pair fitted in my size 3 Rycote windjammer.

Better low end response is what you expect from an omnidirectional microphone as I explained in earlier posts but the MKH 8020 is in a league of it’s own. So, curiosity put to the test I set out in Brussels city center. The “carbon chorus” of the city never fails you if you are looking for those low frequencies. With so much low end energy setting levels proved a bit of a challenge. Dynamic bandwith gets eaten fast and limiters kicked in often.

The sample on Freesound is a recording of the air vent of an airco system. A giant outlet of 2 by 5 meter or so. That night it all came together. Traffic, airplanes, the airco system everything in perfect harmony.

Hear the recording here: Air,

or jump to the Drones Sample pack.

If you have the time and you if you’re in the neighborhood, go check out the excellent Happy New Ears festival for New Music held in Kortijk, Belgium from September 13 through September 28.

The Festival features some of the most important new music composers, sound artists and performers from around the world. 

Happy New Ears have set up a collaboration with  Freesound. For the Omni sound installation for children (and adults alike) several Freesound contributers, myself included, have submitted sound material. Go create and have a good time.

www.happynewears.be

Going to Italy next month travelling through Tuscany and then setting up near the small town of Gubbio. I was there last year. So being more familiar with the surroundings should make things easier. 

Being mobile and travelling light is not exactly compatible with trying to make as high as possible quality recordings. The stereo rig will be a Sennheiser mid-side setup but I also plan to do as much hydrophone recordings as possible. Part of the trip will be following the River Arno upstream out of Florence. Let’s see how that goes.  Pelican cases to the rescue.

Gear:

Sennheiser MKH 60
Sennheiser MKH 30
DPA 4060
Aquarian Audio H2a-XLR hydrophone
Sound Devices 302 field mixer
Nagra ARES-PII+ recorder

The DPA’s will find their place in Chris Watson’s tried and tested sonic coathanger setup. One of the things I learned when we were with him last December.

The Nagra continues to amaze me. No other recorder delivers such high quality in so small a package. You can put it in the inside pocket of your jacket. 2-track only but such great preamps, phantom power and 24 bit resolution.