Blumlein Stereo Microphone Technique
The Blumlein stereo microphone technique is named after Alan Dower Blumlein, who patented this approach in 1931. Blumlein stereo miking involves placing two figure-8 microphones at right angles to one another with the diaphragms as close together as possible. The two microphones are mounted on separate stands, one above the other. The following illustration shows this technique.
The advantage of this technique is that the figure-8 mics pick up signals from both the front and back. This produces a natural sound. You also don’t have to contend with proximity effects (enhanced bass response due to being close to the sound source) because figure-8 mics don’t produce these effects. Here are some suggestions for when you should use this technique:
The room sound is important. Because the Blumlein technique uses figure-8 mics that can pick up the sound on the other side of the mics than your instruments, you end up recording quite a bit of room sound with your instruments. This is one of the reasons that this technique sounds as good as it does, but your room must add to the quality of your sound, not hinder it.
Find the best place in the room. Take some time to find the best place to put the mics. The placement may not be in the center of the room or the front of the band. Instead, it may be off to one side or closer to the back or front.
This advice holds true for all miking, but with the Blumlein technique (or when using omnidirectional mics with the other techniques), correct mic placement can make the difference between a decent recording and a truly awesome one.
Get a sturdy stand that can handle both mics. Using two stands to hold both mics makes moving them around (to find the sweet spot in the room) a real pain in the you-know-what. You can easily find mic-stand adapters that hold both mics. These can be an invaluable investment.