Originally Posted by Omega
LFF, I would be interested to hear more about how you do a good passive stereo recording with modest equipment, and I'm sure there are other interested readers too. Personally, I'm familiar with binaural sound to the extent that I have made my own HRTF's and learned that recordings made with someone else's weird pinna are not optimal to my ears...but the dummy heads are pretty good. What natural stereo recording methods do you prefer? Anything a recording newbie could manage with a decent microphone (or two)?
It's really not a huge science really. Passive stereo recording essentially requires no work during the recording, thus making it "passive". All the real work and critical decisions are done during warm-up and mainly requires finding the right position for your set-up followed by proper level calibration for the microphones. After that, just press record and relax.
As I said before, the critical decisions in recording with two microphones is 1) What method to use and 2) the placement of the microphones.
Adding in pinna complicates the problem unless the pinna is an "averaged" pinna since all of our pinna are different. If the pinna are not averaged, some people will hear amazingly accurate reproduction through headphones and others will be less than pleased. Moreover, the recording is only compatible with headphones.
While I do LOVE a proper dummy head recording, approaching a recording without using pinna, makes it headphone compatible and speaker compatible. Some recordings without pinna can sound eerily close to "being there" on headphones while remaining completely compatible with speakers. Hence, pinna-less techniques are my favorite.
I have 3 microphone sets which I use the most and are my absolute favorite natural stereo recording techniques. They tend to produce accurate recordings with great dynamic range and require little or no post processing. They sound great on speakers and headphones as well.
1. I have a hand held holophonic microphone.
2. A body and head holophonic microphone.
3. A matched pair of holographic microphones.
1 & 2 are essentially the same thing with different configurations and measurements. They produce recordings which are similar to a dummy heads and remain speaker compatible. A professional holophonic microphone can range from $400 to $9,000 or more. The quality varies but you can make a DIY version for well under $100 if you get creative and do your research. Matched microphone elements are preferred but not always used.
Examples of holophonic recordings (numbers correspond to above mic sets):
NOTE: Both of these clips have full dynamic range so turn up your volume!!!
1. http://www.sendspace.com/file/65zlxf (band located to the far left with me recording about 10 feet away - raw)
2. http://www.sendspace.com/file/tsrqt5 (recorded in front of the band, three feet away - raw)
Holographic microphones are more expensive ranging from $1,000 to $10,000 per microphone and you must have a matched pair. These produce amazing results on speakers. The recordings are realistic and stereo imaging is natural and precise. The result on headphones is also great but gives a slightly less "you are there" feeling, although it is still very impressive. You can DIY a pair but it's more expensive than a holophonic microphone. I have done only a few recordings using mine and all were in less than ideal conditions but the recordings are amazing. I love these microphones because they can usually record from 1Hz to 30kHz relatively flat and some can go well beyond 30kHz as well. Not that we can hear it, but it's cool to know it captures that information as well.
Example of holographic recording:
3. http://www.sendspace.com/file/scvpe3 (not done by me - with EQ and some compression)
As you can tell, both produce different results, although admittedly, you have to hear the same performance recorded by all microphones at the same time to really tell the difference.
Other favorite methods are Blumlein, Jecklin Disc, X/Y and Decca Tree methods.
Blumlein involves placing two figure 8 microphones at 90 degrees from each other and placing the set 45 degrees from the subject being recorded. This method produces very sharp and very accurate stereo imaging. It has been used for a number of famous recordings and tends to provide a wonderful recording on speakers and headphones. Chesky uses this method a lot for recording (even overdubs). If you are looking for some cheap but great microphones to use for this technique, try these:
Jecklin Disc recordings places two omnidirectional microphones, spaced about 8 inches apart, with a baffle in between the spaced microphones. The baffle acts like a human head of sorts providing a time delay of certain frequencies which in turn provides an accurate stereo image.
You can DIY the Jecklin disc or baffle and use these inexpensive mics:
X/Y involves using a coincident pair of cardioid microphones which are positioned so that their capsules are as close to each other as possible with an angle between the capsules of 90 and 135 degrees. The greater the angle, the wider the stereo imaging. Directional, cardioid microphones are used because they are the most sensitive to sound coming from directly in front of the capsules and are less sensitive to off-axis sound. However, I have also heard recordings done this way with omnidirectional microphones that sounded great.
If you want omni mics, see the above recommendation for cheap ones. If you want to use cardioid microphones, these are some good and cheap ones:
Decca Tree methods actually involves using 3 microphones but I really like this method for recording classical music. It's not really a natural stereo method so I won't go into it much but it is still considered a minimalist microphone technique. Many old RCA Living Stereo recordings and all Mercury Living Presence Stereo Recordings used only 3 microphones.
Hope that helps! I think natural stereo recording is really more of an art than science but it's an art we all know. Nature gave us two ears and we can hear perfectly well with two ears. Doesn't it follow logically that two microphones could do the same?
Edited by LFF - 7/16/10 at 11:14pm