Velkommen til Lydhjørnet!

Mitt navn er Robin Bjerke. Jeg er en freelance Studiotekniker og studioprodusent ve Urban Sound Studios i Oslo ( Her skriver jeg ned mine tanker om det å jobbe i et studio, forskjellige mikrofonteknikker og hva jeg mener om dem. Først og fremst vil jeg atdette skal bli et sted man kan ta nytte av om man er glad i lydteknikk og musikkproduksjon. Ingenting er fastsatt, det finns ingen regler. Som Joe Meek sa: If it sounds right, it is right.

My name is Robin Bjerke. I am a freelance studioproducer and engineer based at Urban Sound Studios i Oslo, Norway ( I'll be writing down my thoughts about working in a commercial studio, different studio techniques and other useful tips. Most importantly, I want this to be a resource to you people out there that love sound technology and music production. Nothing is set in stone, there are noe rules. In the words of Joe Meek: If it sounds right, it is right.

mandag 14. desember 2009

Recording tools: The Microphone

As with any other process, the tools used are all important, but if I had to decide which tool was the most important (a futile act, seeing as all the components need eachother to function) it would have to be the microphone.

Microphones are the physical "ears" of the recording session. Their purpose is to transate the physical sound waves from the air, into an electrical signal that can then be recorded. Sound is actually the movement of air molecules, or rather the movement of regions of denser and less dense particles. When a 1kHz tone is heard, you eardrum is actually picking up density changes in the air inside the ear, oscillating at 1000 times per second.

A microphone works in a similar fashion. Just as the ear drum vibrates with the air and transfers this energy into nerve impulses, the membrane of a microphone vibrates and translates this energy into electrical impulses.

There are three major types of microphone:

Dynamic microphones are by far the cheapest and most common microphones, especially in project studios and on the stage. These microphones consist of a membrane with a coil of wire attached on one side. In the center of this coil there is a stationary magnet.

Now, when the soundwaves hit the membrane they casue it to vibrate. The vibrations are the same as found in the soundwave. Physics tell us that when a coil of wire moves within a magnetic feild a current in the wire is induced, proportional to the movement. When the membrane moves, the wire moves and a current is induced. now, due to the membrane vibrating in the same way as the soundwaves, the induced current will also be proportional to the soundwaves, with voltage changes representing the wave. Positive voltage peaks are the same as wave peaks, while negative voltages are the same as troughs.Dynamics are good because they are cheap to make. They are also robust which means you can easily put them in more dangerous places, like a kick drum or the top of a snare drum. One of the problems with them is their relatively low sensitivety, seeing as the membrane and the coil are slightly heavy and therefore heavy to move. This also means that they often have a reduced responce in the high frequency bands. Common dynamic microphones are f.eks. the Shure SM57, SM58 and SM7B. Or the Sennheiser MD421's.

Condenser Microphones use a slightly different princial, though the basics are the same.

A condenser microphone uses a condenser, two plates of metal with a gap between them. A current is passed from one plate to the other, and the gap between them has a resistance, which affects the voltage of the current. When the soundwaves hit one of these plates it vibrates (in the same way as the membrane on the dynamic), thus changing the distance between the plates and therefore changing the resistance. The Resistance changes affect the voltage of the signal proportionally to the vibrations of the membrane.Condenser microphones require a current to work, and this current is usually provided by the preamp on either the desk or the interface. Most condenser microphones operate on a 48V current. The current is led through the same cable as the sound signal, so on condensers it is not the overall signal which is recorded, but rather the difference in Voltages from 48V. These differences are proportional to the soundwave and can therefore be recorded.

Condenser Microphones are a tad more expensive to manufacture than dynamics. You can however pick one up for around 2000kr (350USD norwegian prices) new at a store that are acceptable. The good thing with condensers is that their membrane is very light. This means they have an extended frequency pickup range and also react faster to changes in volume (transients.) These characteristics make them the microphone of choice for vocals, overheads on drums and acoustic instruments. In professional studios there are often more condenser microphones than there are dynamics, for this very reason.

The last type of microphone are called Ribbon Microphones. These microphones use a strip of very thin metal that vibrates within a magnetic feild. They are not as commonly used as condensers and dynamics due to their high pricetag and vulnerable ribbon. Ribbons also usually have a diminished pickup of the higher frequencies, usually dipping off at 16kHz. They do however excell at giving the source a very warm and mellow, natural sound amking them a good choice for strings, choirs and very often guitar amps. They are often very good on kick drums, but caution has to be made when placing them. Try to angle them at 45 degrees to the membrane of the drum (meaning pointing at the top of the drum with front angled down). This positioning makes sure the pressure from the air rolls off along the length of the ribbon without stretching or braking it.

As allways, leave a comment if you have any questions. I will be writing a post on common microphones, and microphone characteristics soon. Stay tuned!

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