[Harp-L] New Backless and Backless + Feedback Suppresor Pedals

[Ronnie Schreiber]

Based on an anti-feedback circuit that I found on a vintage PA 
amplifier, I've been developing the Backless and Backless Plus feedback 
suppressor pedals for harmonica. At their heart is an adjustable notch 
filter, with a side circuit that still allows critical high-mids to pass 
through so things still sound natural. I'm still fine tuning the layouts 
and working on the graphics but the electronics are buttoned down and 
production ready.
If you're looking for a good, basic anti-feedback device, the Backless 
should be a great choice. It has an adjustable single band filter that 
works in the range of the most common frequencies that cause feedback. 
It runs on common 9V negative-pin power supplies and is wired for 
true-bypass when switched off. For high impedance microphones. Inputs 
and outputs are standard 1/4" jacks.
For even more control, and use with both high and low impedance 
microphones, the Backless Plus has three individually switchable and 
adjustable bands of feedback control, plus a switchable noise suppressor 
circuit, using ISP Technologies' sophisticated Decimator downward 
expander. Unlike conventional noise-gates, which use an arbitrary dB 
level to cut off sound and can sound unnatural, the Decimator circuit 
closely tracks the musical signal for more natural sustain and decay. 
With true-bypass wiring, you have the choice of operating either the 
filters or noise suppressor, or both. 9V, negative pin power supply needed.
The Backless Plus has a 1/4" TS jack for high impedance microphones like 
the Green Bullet as well as 1/4" TRS and female XLR jacks for low 
impedance microphones like the Shure SM57 and SM58.
I'm aiming for a target price of $125 for the basic Backless and $250 
for the Backless Plus.
Let me know what you think.