Variable High Pass Filter

[Paul Kincaid]

Here is a simple custom pedal made as a secret Santa gift. I plan on elaborating to make a bandpass pedal in the future.

[Brian Evans]

Can you elaborate a bit on what and why? Frequency, slope of the filter curve, type of notch planned for the bandpass, active or passive? What do you use it for, what is the "effect"?

Brian

[Dan Smith]

Yes Paul,
Please elucidate!
Dan

[Jason Rodgers]

Oh man, I've resisted the urge to go down the custom effects pedal rabbit hole for so long....... keep it away, keep it away..... but, you know..... tell us more about it.

[Paul Kincaid]

This one has a few potential uses. It's a simple passive filter to roll lows off with a corner frequency between 50 and 150 hz. with a slope around 20db/octave.

A low setting, around 50-75 hz, keeps the signal from being muddy and keeps equipment from trying to reproduce unnecessary frequencies. Even bass instruments can benefit from a low frequency high pass.

Turn it up to 100-125 and it will reduce acoustic guitar body resonance feedback, thumps, and make more low end room for the kick and bass in the mix.

At 150 it can make an electric guitar cut through without competing with the vocals.

The toggle switch changes between true bypass and mute; true bypass seems self explanatory, while the mute function is for a specific purpose. With people that play multiple instruments or only play on some songs, it allows a simple way to keep quiet while they unplug or put their guitar on a stand.

The bandpass filter I plan to make will add a low pass after the high pass, with a frequency range of around 3.5k to 14k. It will be switchable between low pass, high pass, or bandpass. I will likely make the high pass range go a little lower, around 25 hz.

[Dan Smith]

Thanks Paul!

[Jason Rodgers]

Is there anything like this on the market in a stomp-box unit (not just rack-mountable)?

[Brian Evans]

The tone control on most guitars is a passive low pass filter, in essence. The tone control on my old Epiphone is, if I understand it correctly, both a high and low pass filter, it is straight through in the middle setting, high pass on the "brilliant" setting and low pass on the "Mellow" setting. Of course the notch frequency is not adjustable and that is what gives this the flexibility. Nice idea, I like it.

Brian

[David King]

Back in the 80's I had a TC Electronic dual band parametric filter pedal with high pass and low pass filter as well. 10 knobs in all and with a signal to noise ratio of 110 dB. I strapped 4 9V batteries to the back of it in series to get a bit more headroom. It had a 48V phantom power input too. Of course someone swiped it during an extended studio gig and I've never seen another one. I'd picked it up in Denmark.