Abstract: There are styles of music that rely on the amplification of a harmonica by utilizing a microphone and an amplifier. When a harmonica needs to be amplified to a level where an audience can hear, audible feedback typically occurs due to the interaction of the microphone properties with the high amplification level. This audible feedback forces the artist to maintain a lower volume level and therefore a lower projection of sound. There have been attempts to reduce feedback in the past through the use of resistor and capacitor networks, however, these attempts altered the normal sound of the amplifier which in most cases is not a positive consequence and frowned on by musicians. The Squeal Killer is the first feedback reduction device that utilizes a 12at7 vacuum tube and when used with a microphone and amplifier, significantly reduces feedback and allows the musician to obtain higher volume levels.

Abstract: There are styles of music that rely on the amplification of a harmonica by utilizing a microphone and an amplifier. When a harmonica needs to be amplified to a level where an audience can hear, audible feedback typically occurs due to the interaction of the microphone properties with the high amplification level. This audible feedback forces the artist to maintain a lower volume level and therefore a lower projection of sound. There have been attempts to reduce feedback in the past through the use of resistor and capacitor networks, however, these attempts altered the normal sound of the amplifier which in most cases is not a positive consequence and frowned on by musicians. The Squeal Killer is the first feedback reduction device that utilizes a 12at7 vacuum tube and when used with a microphone and amplifier, significantly reduces feedback and allows the musician to obtain higher volume levels.