Center Ambient array/technique; it's all new to me.
I had a problem where a pianist had the choice to either use a lame piano or an electronic kepboard and opted for the keyboard. I was asked to record this performance which was in a church to raise funds for an overseas charity. I agreed but worried about how to make it "not mono." The sound was coming from an ordinary speaker; distinctly mono. Norsehorse came to the rescue with the suggestion that I use a "Center Ambient" method, new to me. Simply put it invlolved gaff taping an omni mic under the keyboard with the mic diaphragm about halfway between the center and edge of the speaker. The trick is with the second mic. It too is an omni, and was about six feet from the keyboard, further back on the stage and about four feet up.
I recorded the two tracks and approximately the same level. Following Norsehorse's instructions I used the omni under the keyboard as the center channel, duped the other omni, the "ambient" mic so I had two, panned one hard left, the other hard right and flipped the phase on the right channel.
When played back the two channels indicate in the level meter they are unique and separate, the Vectorscope in SAM shows a solid stereo image and when the track is played it sounds stereo. And like MS it sounds fine in mono as then just the center omni is heard.
At tip of the hat to Norsehorse for 1) knowing and 2) sharing. This is what makes GS Remote a great forum. And the artist was quite pleased, too. And she raised more money than she expected. No, the album will not be released to BMG. But I have uploaded a short track so those who do not know about this can hear how it sounds.
So this second mic is 6' behind the mistress? (and 4' up).
(Further back on the stage could be in any direction relative to the keyboard, You know how pesky computer/IT people are, Sandy!)
And I suppose the keyboard is one of them that have a speaker underneath facing the player?
(Just getting more details, I might need this once!).
Paul, In reviewing Christian's instructions the trick is to not be too close to the C mic as that will pull the image, he says. I offered a meter and then he cautioned me about being too close with the possible problem outlined above. I do not believe that the distance is really critical and a couple of meters is probably a safe distance almost always. Play with it. I had originally planned on using the DS 60 and an omni but opted for a pair of 4006 TL's at the last moment. Christian does not think the mics are critical. It is just that there be a second fake figure 8 channel and that it be a safe distance from the center channel mic. Too close and, as IBM says in these matters, "Results are unpredictable." I bet you have seen that in a manual once or twice.
Actual positions: keyboard stage right facing stage left. C mic under keyboard taped to bottom in front of speaker which faces the floor. Second mic, A mic, in front of the keyboard ~0.25 meters and two meters to the left of the keyboard. Ça va?
It is a great trick to know and Norsehorse was a saint to share it.
Last edited by boojum; 7th January 2013 at 09:48 AM..
David, thanks for the help. Count on you to have the technical underpinning to all of this. Norsehorse will be posting a more thorough presentation than what I did. He has the background, too, to understand the technical part of this.
As for the code, I haven't read code since '99 and am not eager to start again. Those "C like" languages never interested me much. Either high level (COBOL) or low level (Assembler) did it for me and my Assembler was neglected and used only for ugly dumps. I don't need no steenking code.