Stereo Recording Techniques for Omnidirectional Microphones

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I currently use the Blumlein or ORTF microphone configurations and I'm looking for a more accurate sound. From what I've read, I think I can get that sound with real omnidirectional microphones, but my experiments, using the multipattern AKG 414s switched to omni and placed in many configurations (on one stand), have yielded vague images and less excitement than ORTF. Hence, I have a couple of specific questions, Mr. Boyk, if you please.

Firstly, are my omni experiments useless because the large diaphrams behave so differently than say, the Earthworks QTC1?

Secondly, the string quartet I plan to record will be playing in a marble atrium with large tapestries and considerable HVAC with 160 people or so in attendance. I am only able to place one stand and it can only go in one place (next to an indoor tree). I will have the C414s in Blumlein or ORTF going directly to CDR, and would like to purchase and have on the same stand an omni pair going directly to DAT. I ask if there is an omni configuration that can be used with the microphones in such close proximity? It seems that I need something to "separate" the two mics - maybe that disc technique I've read about? Unfortunately, I won't have any time to experiment on the night - I'm just going to have to hope for the best. I have plenty of time to plan and experiment beforehand in my living room.

In addition, could you please advise on general techniques for using omnidirectional microphones for stereo recordings without such restrictions. Subjects range from outdoor rock concerts to string players and singers in my living room.

Thanks very much and I sure have enjoyed reading about the Magnesaurus - makes me regret some

-- Michael Macaulay (mjmacaulay@iname.com), January 03, 2000

Answers

I started recording for "commercial" release (as well as recording concerts) in 1979 under my label "Direct-to-Tape Recordings" (also called DTR) after many years of concert recording. I have always used cardiod mics and only within the last ten years did I experiment with omnis, with much less than satisfactory results.

However, I have always believed that recording with two (and only two) mics results in a more accurate representation of the sound of a performance. Multitrack recording is fraught with problems and doesn't capture the ensemble and "soul" of a performance (if, indeed, there ever was a performance--all musicians playing together--of the music being recorded). More information about my recording philosophy can be found at my web site: http://www.dtrmusic.com

About two years ago I tried omnis again, this time by purchasing the Earthworks QTC1MP (matched pair). Since then, I have been using the (omnidirectional) QTC1MP mics with the Earthworks LAB102 for stereo recording as a replacement for cardiod Schoeps mics with a custom preamp. The sound is much better than the Schoeps because it is even smoother, flatter, more open, and has significantly better impulse response. Since the Schoeps are much smoother and more musical than AKG414s, the result is a major improvement in the sound.

I also questioned in my mind how well the stereo image would be captured with omnis using the two mic technique I use, but, at least with the Earthworks, I am a true believer. Here's how I record with both cardiods and the Earthworks omnis:

One stand with an Atlas T-mount, which is a horizontal bar that mounts on top of the mic stand and provides mounting for two mics, separated by about 15" (I've never measured it, thus the "about"). Normally I point the mics towards the outer edges of the performing group.

The only difference in using the omnis was that the mics are set up closer than with the cardiods. Note that when I say "closer", I still mean at a distance from the performing group. Even with a chamber group I was probably about 5-7 feet from the from of the group.

The proof is in the results. If you want to hear the difference, purchase a copy of DTR9803, "The Philadelphia Connection", since one of the works was recorded with a pair of cardiod Schoeps mics and the remaining works were recorded with the Earthworks QTC1MP using the same stand, Atlas T-mount, but just placed closer than the Schoeps. The program notes identify which mics were used for which work. Another DTR recording which I think is the best piano recording I have ever made (and many years ago I made one which is praised even today as sounding "like a real piano") is DTR9807, "An American Journey". This was made with the Earthworks QTC1MP mics.

--Bob Sellman

-- Bob Sellman (bob@dtrmusic.com), January 09, 2000.


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