Center Ambient array/technique; it's all new to me.
Old 7th January 2013
  #1
Lives for gear
 
boojum's Avatar
 

Thread Starter
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.

Cheers
Attached Files
File Type: mp3 01 CA.mp3 (3.05 MB, 46 views)
Old 7th January 2013
  #2
Gear addict
 
Bibster's Avatar
 

Quote:
Originally Posted by boojum View Post
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.
Chèr Boojum,

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!).

Thanks,

Paul
Old 7th January 2013
  #3
Lives for gear
 
boojum's Avatar
 

Thread Starter
Quote:
Originally Posted by Bibster View Post
Chèr Boojum,

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!).

Thanks,

Paul

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.

Cheers

Last edited by boojum; 7th January 2013 at 08:48 AM.. Reason: afterthought
Old 8th January 2013
  #4
Lives for gear
 
David Rick's Avatar
 

This is an "acoustic version" of the pseudo-stereo network known to many old-timers. In this case, the delay line consists of the distance between the close and far microphones.

If you're not familiar with pseudo-stereo networks, here's a nice summary -- ignore the code and look at the block diagrams!

An interesting distinction from the "electronic" version is that any hall ambiance captured by the far mic is out of phase in L/R and will be steered to the rear in certain surround decoders.

David L. Rick
Seventh String Recording
Old 8th January 2013
  #5
Lives for gear
 
boojum's Avatar
 

Thread Starter
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.
Old 8th January 2013
  #6
Lives for gear
 
Tommy-boy's Avatar
 

Neat trick. Definitely sounds better than just mono.
Old 8th January 2013
  #7
Gear interested
 

yeah,Norsehorse will be posting a more thorough presentation than what I did. He has the background, thank you
Topic:
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Similar Threads
Thread
Thread Starter / Forum
Replies
Stress Man / So much gear, so little time!
62
Slim ManDjango / Electronic Music Instruments & Electronic Music Production
27
mic anon / So much gear, so little time!
24

Forum Jump
 
Register FAQ Search Today's Posts Mark Forums Read

SEO by vBSEO ©2011, Crawlability, Inc.