Feedback and how to minimize it

The Merriam-Webster definition of feedback as is follows; “a rumbling, whining, or whistling sound resulting from an amplified or broadcast signal (such as music or speech) that has been returned as input and retransmitted”. So for us it occurs when the audio from the speaker is picked up by the microphone and returned to the amplifier, it is an acoustic problem. Feedback has been a problem ever since amplifiers have been around and engineers (way smarter than us pedal builders) have worked hard to find a solution but no solution exists to this day. What we have are tools and techniques to reduce feedback. Let’s discuss these.

• Decoupling, moving the microphone away from the amplifier, turning down the volume control on the microphone when not in use, proper cupping technique, repositioning yourself and improving cupping technique.
• Modifying the amplifier to reduce pre amp gain. When this is done properly, you will be operating in the upper three fourths of the volume control where it is more linear, feedback can still occur but it is more manageable. Ultimately your amplifiers output volume is not much higher but you do gain some volume.
• Equalization, you can notch out the offending frequency with an equalizer or by reducing treble. This is very effective as long as you do not try to increase volume after notching because if you continue to increase the volume, the feedback will return but at a different frequency, notch the new frequency and increase the volume and guess what? The feedback returns but at a new frequency and so on.
• Use a more directional microphone.

Nothing new here, same ol’, same ol’. Unfortunately there is no magic box that truly eliminates feedback without effecting tone. But maybe we can put some tools together and really put the squeeze on feedback and maybe some tonal loss is acceptable in exchange for more volume. Let’s check it out.

• Kinder Anti-Feedback, in my opinion is the best tool available to harp players, however it does affect tone. How it affects tone is subjective, some like it and some don’t.
• Processors like the Behringer Feedback Destroyer are great, it will search out the up to 24 offending frequencies and notch them out. But remember, as I stated earlier the more you increase your volume the more frequencies are notched out, the more tone loss you will have.
• Noise gates are very effective but the more you turn your volume up, the more you have to decrease the sensitivity of the pedal and you will lose some attack on notes that is noticeable when playing softly.
• Any device that lowers the level entering the amplifier, this counteracts the excessive pre amp gain in guitar amplifiers.
• Eliminate the amplifier and go straight to the PA 

I feel the best and most effective is to use as many of the following as possible. And, remember that even with all of the tools there will still be limits, limits as to how much you are willing to have your tone affected and how much volume you can achieve

before feedback once again rears it’s ugly head.

• Proper microphone handling technique
• Directional microphone
• Noise gate
• Go straight to the PA
• Something to cut treble or notch out frequencies
• Something to pad down the signal entering the amplifier

The choice of which product(s) to use is yours and yours alone, money is tight these days so plan out a good strategy and work it to perfection.

My name is Randy Landry, I am an electronic technician by trade. I own and operate Lone Wolf Blues Company, where we make effect pedals and amplifiers for harp players.