I have an SWR bass amp that lacks a high pass filter in it's design, this can lead to the amp running out of power with infrasonic signals. There are a few options out there for off the shelf pedals or utility boxes but none in the DIY board world that I have found so far. The commercial HPF products out there have a tunable High Pass Filter with a range from 20Hz up to around 200Hz with a 12 dB/octave roll off. I've seen references to SWR amps that did have HPF in the design have it set at 45 Hz rolling off at 18 dB/octave. For my application I'd desire a simpler board that could be either build into an enclosure or a board that could be built into my amp (though I recognize that's a more limited application for any potential board).
Products out there that I'm aware of include the Broughton HPF and the fDeck HPF-Pre.
Products out there that I'm aware of include the Broughton HPF and the fDeck HPF-Pre.