[Harp-L] re:Kinder anti Feedback and bass harp? Electronics guys please help!

[joe.mahan@xxxxxxxxxxx]

Michael: 
The Kinder design is a well-kept secret, so I can only speculate. 
For starters, it is extremely unlikely that you will "blow up" any line-level device like the AFB+ just due to the low frequency input from the bass. It is possible to damage the power amps and speakers if low-frequency feedback runs away for a sustained period, so stay near the volume control as you experiment. 

It is somewhat likely that the AFB+ has a high-pass filter to cut off the bass notes that do not exist in the normal range for ten-hole harps. Feedback grows in unused gain, so eliminating unused frequencies from the signal is a good first step to reducing feedback. Just as we know to turn down the treble to reduce "squeal", cutting the low bass will reduce"growl"-often without affecting the tone as much as the treble cut does. (In normal harp range) With the bass, of course, you will affect the tone with any low frequency, and that gets to my point: 

You probably won't blow things up, but it might not sound so great either. If you need to boost the bass to compensate for any cut that might be built into the AFB+, you will likely lose that component of the anti-feedback solution. 

If you have a friend with a signal generator and an oscilloscope (or AC voltmeter) you can check the frequency response of the AFB+ easily enough. 

Let us know how it goes... 

Joe