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Entry level microphone cancellation hardware solution? Ribbon Microphones
Old 10th April 2019
  #1
Here for the gear
 

Entry level microphone cancellation hardware solution?

Hi,
I'm in a live sound situation where I have a set of speakers playing sound (just your regular 5.1 PC speakers) and a microphone (a typical PC headset). I'd like to prevent the microphone from picking up what the speakers are playing. This cannot be done in post (I would know how to do that), because it's for live communication. The speakers never play sound coming from the mic - so there is no feedback, this is about removing background sound. I know the theory behind this, but I am not well versed in hardware, especially something relatively inexpensive. I'd be really happy if someone could point me in the right direction.

My experience would suggest that you'd run all the 5.1 signals and the mic signal through the hardware solution, and calibrate it once (similar to ARC) to let it know what the impulse response would be between each of the speakers, and the microphone. (of course moving the head would change the response, but likely less than is important). Then the hardware would subtract the speaker sound, convolved with the measured response, from the microphone sound, estimating the amplitude of the signal being subtracted by using the least squares method (i.e. change the amplitude of what you're subtracting until the least volume sound is left). If anyone knows of a practical available solution, please let me know.

Please let me know if this is not the right place to post on this forum. I read GS often but I post here very rarely.
Old 10th April 2019
  #2
Lives for gear
Perhaps a similar (omni) mic attached to the headset mic's mounting gooseneck but reversed in phase could partially cancel out the 5.1 audio, when summed with the headset mic output ?
Old 10th April 2019
  #3
Lives for gear
 

no way this will work! - well, it might work (to some degree) but only if you're playing test tones at a fixed level, but certainly not with music, not outside of your studio, not with any audience...
Old 10th April 2019
  #4
Here for the gear
 

Quote:
Originally Posted by deedeeyeah View Post
no way this will work! - well, it might work (to some degree) but only if you're playing test tones at a fixed level, but certainly not with music, not outside of your studio, not with any audience...
Hi!

Which post are you replying to?

Thanks!

There's no audience here, btw. I am in a quiet room.
Old 10th April 2019
  #5
Lives for gear
Clearly it worked in the 70's at concerts (see Joni's end to end guitar mic in the pic, 'though not the double vocal mic, I suspect one was for PA and the other for recording) ....but as Lou Reed said "those were different times"

Phase Cancellation to Prevent Feedback
Ozzy & Plant with 2 mics taped together.
double vocal mics in the 70s ???

"Heil also had a unique technique to handle the feedback problems; a small second microphone taped behind each main microphone. He stated "We would run the microphones out of phase from the monitors, something that nobody had been doing yet. Since they were out of phase with the microphones and the FOH system, anything that leaked in from the monitors would be canceled out. As a result, we could get these things incredibly loud before they would feed back. That's one of the things that Jerry Garcia really loved."

The show was a success, and the Grateful Dead asked Heil, his crew, and his sound system to join them on the road. Heil's setup would later become a template for the modern concert touring sound system"​

YouTube


It could cost you very little or nothing to experiment....
Attached Thumbnails
Entry level microphone cancellation hardware solution?-joni-mitchell-isle-wight.jpg   Entry level microphone cancellation hardware solution?-g-dead-wall-sound.jpg  

Last edited by studer58; 10th April 2019 at 02:47 AM..
Old 10th April 2019
  #6
Gear Guru
 
jwh1192's Avatar
the two mics were because they did not have proper Splitters .... so one for PA and one for Recording .... or am i crazy !! and i agree with DeeDeeYeah .. unless it is fixed positions you will never cancel out all the signal .. so, yes he did reply to the correct Thread !! cheers john
Old 10th April 2019
  #7
Lives for gear
Partial cancellation (and hence some reduction in intrusion of unwanted background sound) is perhaps the best that can be attained....but that may be sufficient for the OP...who probably isn't working at Grateful Dead/Wall of Sound levels anyway....
Check out those 3 GS links in post #5 ....
Old 10th April 2019
  #8
Here for the gear
 

Hi, partial cancellation would be great as well, but bear in mind i'm using 5.1 here, so the monitors aren't exactly in front of me, or behind me, or some specific direction.
Old 10th April 2019
  #9
Lives for gear
Quote:
Originally Posted by cheater View Post
Hi, partial cancellation would be great as well, but bear in mind i'm using 5.1 here, so the monitors aren't exactly in front of me, or behind me, or some specific direction.
Is your headset mic omni or cardioid/hyper-cardioid) ? That will determine how directional it is with regard to surrounding noise sensitivity. If it's a small mic and low cost, it's probably an omni electret element...and you could simply try a cheap lavalier omni lapel mic for the experiments I'm recommending. The omni will largely pick up sound in a spherical pattern so all the 5.1 speakers would be equally represented in the sound it picks up (and cancels with) ?

Another option to try would be a boundary layer or PZM mic, which creates a very big path length difference between the direct sound of your voice vs the incredibly small 'bounce' reflection path of your voice off the boundary plate. Perhaps that woulld cancel more effectively with your headset mic ?
Old 10th April 2019
  #10
Gear Head
 

Have you tried simply keeping the headset mic close to your mouth for a good signal-to-noise ratio, and applying a noise gate? Plenty of inexpensive hardware solutions of that sort.

I realise this isn't the more sophisticated processing you have in mind but, depending on your purposes, it might well be adequate.
Old 10th April 2019
  #11
Gear Maniac
 

I would get a Coles lipmic, works for sports commentators. Searching Ebay would get you more towards 'entry level'..
Or a plain old 58: Youtube - Comparison between Coles & Shure
coleselectroacoustics.com - 4104 Commentators Microphone
Old 10th April 2019
  #12
Gear Guru
 
jwh1192's Avatar
Quote:
Originally Posted by Newmann View Post
I would get a Coles lipmic, works for sports commentators. Searching Ebay would get you more towards 'entry level'..
Or a plain old 58: Youtube - Comparison between Coles & Shure
coleselectroacoustics.com - 4104 Commentators Microphone
forgot about these .. i used one ONCE at a Celeb Oscar After Party .. Chantal from ABC was our commentator ... i mean it was wall to wall people and they were yelling drunk and happy ... and we did her standup VO right in the corner of the room .. you will need to put your Mouth Right against this microphone to get the advantages of what it does .. !! it works but not very convienient like aheadset mic .. just my .02
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