Microphone Feedback: Difference between revisions

Line 1:

Proper Gain Staging is essential to avoiding feedback. Please take 2 minutes to review this short video. Although this is based on the Classic and Model I, the principles are generally applicable.

== Gain Staging ==

Line 10:

Line 12:

* If you are using vocal effects like reverb, chorus or delay, turn them off until you can get sufficient [[Gain Before Feedback|gain before feedback]] to get performance level volume. Then add the effects back into the signal chain (one at a time) so you can be aware of the individual impacts that each effect is having on feedback.

* Get close to the microphone. No other technique has a big an impact on feedback. Each halving of distance is approximately another 6 dB of gain before feedback. This means that the difference between working a microphone at 2 inches, and 1/4 inch is ~~18dB!~~

* Get close to the microphone. No other technique has a big an impact on feedback. Each halving of distance is approximately another 6 dB of [[gain before feedback]]. This means that the difference between working a microphone at 2 inches, and 1/4 inch is 18 dB, which is more than twice as loud.

[[Image:Ferrin_eat_mic.jpg]]

[[Image:Ferrin_eat_mic.jpg|Charlie Ferrin at Bose: Nov. 9, 2007]]

* Use a directional microphone. Hypercardioid is better than cardioid, which is ~~way~~ better than omnidirectional. All sound waves impinging on the microphone from a direction other than the intended signal is "noise" and will lower the threshold of feedback.

* Use a directional microphone. Hypercardioid is better than cardioid, which is better than omnidirectional. All sound waves impinging on the microphone from a direction other than the intended signal is "noise" and will lower the threshold of feedback.

* Use as few open microphones as possible. When a microphone is not in use, turn it off.

* Use as few open microphones as possible. When a microphone is not in use, if possible, turn it off.

* When stand mounting a directional microphone, tilt the microphone up ten or twenty degrees off the horizon so that it is less sensitive to direct sound from the speakers.

Line 26:

Line 28:

[stopped editing here]

~~== Notes from {{Bose}} ==~~

~~=== My vocal microphone keeps encountering feedback. Is there anything I can do to stop it? ===~~

From the Official Product Troubleshooting Page <ref>[http://www.bose.com/controller?event=VIEW_STATIC_PAGE_EVENT&url=/musicians/support/troubleshooting.jsp&ck=0#feedback Official Product Troubleshooting Pages]</ref>.

* Orient the microphone so that it is not pointing directly at your Cylindrical Radiator™ loudspeaker. It’s best when your system is not directly behind you- give greater than 5 feet distance between you and your system.

* Try using a “close-miking” technique to increase the gain at the microphone and to reduce unwanted stage sound.

* Use the HIGH tone control knob for the microphone channel carefully. Feedback could occur when this is set too high.

* Upgrade your power stand to newer software that offer a high gain preset. see: Software Upgrading (This covers firmware update and Version 2.0 [[Presets/Model I and Classic|Presets]])

* If using a vocal effects processor, make sure that it is not contributing to the feedback problem.

* If stand -mounting a directional microphone, tilt the microphone up ten or twenty degrees off the horizon so that it is less sensitive to direct sound from the speakers.

* Try a different microphone such as a directional mic. Hypercardioid microphones work well with the system.

~~=== How do I control feedback that I may get when using microphones? ===~~

From the Official Product FAQs <ref>[http://www.bose.com/controller?event=VIEW_STATIC_PAGE_EVENT&url=/musicians/support/product_faqs.jsp&ck=0#question40 Official Product FAQs]</ref>.

Techniques that control feedback with a conventional system help with the Personalized Amplification System™ approach also.

~~== Microphone on a Stand ==~~

~~Here's a sketch of setting up a microphone on stand.~~

== Other general notes ==

* All players should be playing / singing through the L1™ System closest to them

* Every doubling of distance between the microphone and the singer reduces gain-before-feedback by a factor of 4. The difference between 1/2 inch and an inch can be significant.

* Wherever possible "acoustic" instruments should use pickups instead of microphones. This is important because many players find it a struggle to keep a consistent and close distance between the microphone and their instrument. Also, an instrument can be a source of feedback as it resonates with the amplified sound.

* Another (low priority) design guide-line could be to keep open microphones as far apart as possible. Neighboring systems with open microphones can mutually decrease gain-before-feedback

@@ Line 1: / Line 1: @@
 Proper Gain Staging is essential to avoiding feedback. Please take 2 minutes to review this short video. Although this is based on the Classic and Model I, the principles are generally applicable.
 == Gain Staging ==
@@ Line 10: / Line 12: @@
 * If you are using vocal effects like reverb, chorus or delay, turn them off until you can get sufficient [[Gain Before Feedback|gain before feedback]] to get performance level volume. Then add the effects back into the signal chain (one at a time) so you can be aware of the individual impacts that each effect is having on feedback.
-* Get close to the microphone. No other technique has a big an impact on feedback. Each halving of distance is approximately another 6 dB of gain before feedback. This means that the difference between working a microphone at 2 inches, and 1/4 inch is 18dB!
+* Get close to the microphone. No other technique has a big an impact on feedback. Each halving of distance is approximately another 6 dB of [[gain before feedback]]. This means that the difference between working a microphone at 2 inches, and 1/4 inch is 18 dB, which is more than twice as loud.
-[[Image:Ferrin_eat_mic.jpg]]
+[[Image:Ferrin_eat_mic.jpg|Charlie Ferrin at Bose: Nov. 9, 2007]]
-* Use a directional microphone. Hypercardioid is better than cardioid, which is way better than omnidirectional. All sound waves impinging on the microphone from a direction other than the intended signal is "noise" and will lower the threshold of feedback.
+* Use a directional microphone. Hypercardioid is better than cardioid, which is better than omnidirectional. All sound waves impinging on the microphone from a direction other than the intended signal is "noise" and will lower the threshold of feedback.
-* Use as few open microphones as possible. When a microphone is not in use, turn it off.
+* Use as few open microphones as possible. When a microphone is not in use, if possible, turn it off.
 * When stand mounting a directional microphone, tilt the microphone up ten or twenty degrees off the horizon so that it is less sensitive to direct sound from the speakers.
@@ Line 26: / Line 28: @@
 [stopped editing here]
-== Notes from {{Bose}} ==
-=== My vocal microphone keeps encountering feedback. Is there anything I can do to stop it? ===
-From  the Official Product Troubleshooting Page <!-- TODO fix this link --><ref>[http://www.bose.com/controller?event=VIEW_STATIC_PAGE_EVENT&url=/musicians/support/troubleshooting.jsp&ck=0#feedback  Official Product Troubleshooting Pages]</ref>.
-* Orient the microphone so that it is not pointing directly at your Cylindrical Radiator™ loudspeaker. It’s best when your system is not directly behind you- give greater than 5 feet distance between you and your system.
-* Try using a “close-miking” technique to increase the gain at the microphone and to reduce unwanted stage sound.
-* Use the HIGH tone control knob for the microphone channel carefully. Feedback could occur when this is set too high.
 * Upgrade your power stand to newer software that offer a high gain preset. see: Software Upgrading (This covers firmware update and Version 2.0 [[Presets/Model I and Classic|Presets]])
-* If using a vocal effects processor, make sure that it is not contributing to the feedback problem.
-* If stand -mounting a directional microphone, tilt the microphone up ten or twenty degrees off the horizon so that it is less sensitive to direct sound from the speakers.
-* Try a different microphone such as a directional mic. Hypercardioid microphones work well with the system.
-=== How do I control feedback that I may get when using microphones? ===
 From  the Official Product FAQs <ref>[http://www.bose.com/controller?event=VIEW_STATIC_PAGE_EVENT&url=/musicians/support/product_faqs.jsp&ck=0#question40 Official Product FAQs]</ref>.
 Techniques that control feedback with a conventional system help with the Personalized Amplification System™ approach also.
-== Microphone on a Stand ==
-Here's a sketch of setting up a microphone on stand.
 == Other general notes ==
 * All players should be playing / singing through the L1™ System closest to them
-* Every doubling of distance between the microphone and the singer reduces gain-before-feedback by a factor of 4. The difference between 1/2 inch and an inch can be significant.
 * Wherever possible "acoustic" instruments should use pickups instead of microphones.   This is important because many players find it a struggle to keep a consistent and close distance between the microphone and their instrument. Also, an instrument can be a source of feedback as it resonates with the amplified sound.
 * Another (low priority) design guide-line could be to keep open microphones as far apart as possible. Neighboring systems with open microphones can mutually decrease gain-before-feedback