The Broughton Audio Low + High Pass Filter is a pedal that combines a low pass filter, a high pass filter and a clean gain stage in one enclosure. It is aimed at players who want to shape the extremes of their tone: rolling off sub-bass rumble with the high pass filter, taming harsh top end with the low pass filter, and adding up to 20 dB of clean boost on top. RockBoard's PedalPedia lists the circuit type as analog1.
The controls: LPF, HPF and gain
The pedal has three knobs, each covering a specific job:
| Control | What it does | Range |
|---|---|---|
| LPF | Sets the low pass filter cutoff frequency | 20 kHz down to 330 Hz, continuously variable2 |
| HPF | Sets the high pass filter cutoff frequency | 25 Hz to 190 Hz, continuously variable2 |
| Gain | Clean gain stage | Unity gain to +20 dB2 |
Both filters have a 12 dB per octave slope: the high pass filter is a 12 dB per octave low frequency filter, and the low pass filter is a 12 dB per octave high frequency filter2. In practice, that means each knob removes a defined slice of the frequency spectrum on either side of the cutoff point, which is a common approach for cleaning up a bass signal, tightening an overdriven amp's low end, or softening a piezo pickup's brittle top.
Power and connections
The pedal can be powered by a 9V battery or a DC power supply, though the supply is not included. It accepts 9 to 24 volts through a standard Boss style connector with center negative polarity, and the current draw is approximately 10 mA2.
The DC power supply is not included with the pedal. The wide 9 to 24 volt input means most standard pedalboard supplies will work, but the connector must be center negative2.
The stock input impedance is 1M ohm, and the output impedance is 100 ohms. Broughton Audio states that the device will work with active or passive instruments, as well as with other devices such as pedals, preamps or effects loops2.
Acoustic pickups and custom options
For players with acoustic instruments, Broughton Audio offers a custom option: if an acoustic pickup requires a specialized input impedance, the request can be written in the notes during checkout and the maker will accommodate it at no extra cost2. That makes the pedal a candidate for taming a piezo pickup's low-end boom and top-end quack, since the HPF range of 25 Hz to 190 Hz covers the usual problem frequencies2.
Bypass options
The Low + High Pass Filter comes standard with a true bypass switch. It can also be upgraded to a soft touch relay based bypass system for an extra $20; the soft touch switch does not have a mechanical click when stomped2. Players who record or play quiet material sometimes prefer a relay bypass for that reason.
Related Broughton filter pedals
Broughton Audio builds several pedals around filtering. If a single high pass filter is all that is needed, the Broughton Audio High Pass Filter and the Broughton Audio Always On High Pass Filter cover that ground, while the Broughton Audio Low Pass Filter handles the top end alone. The Broughton Audio State Variable Filter, the Broughton Audio Filter FX Loop and the Broughton Audio Broughton Resonant Filter Equalizer take filtering in other directions. For more on the category, see Filter Pedals.
Questions
Is the Broughton Audio Low + High Pass Filter analog or digital?
It is an analog pedal. RockBoard's PedalPedia lists the circuit type as analog, and the pedal's controls are straightforward analog filter and gain stages rather than digital processing.
Is the Broughton Low + High Pass Filter true bypass?
Yes. The pedal comes standard with a true bypass switch. Broughton Audio also offers an optional upgrade to a soft touch relay based bypass system for an extra $20; the soft touch switch has no mechanical click when stomped.
What is the filter slope of the Broughton Low + High Pass Filter?
Both filters are 12 dB per octave. The high pass filter is a 12 dB per octave low frequency filter, and the low pass filter is a 12 dB per octave high frequency filter.
Does the Broughton Low + High Pass Filter work with acoustic pickups?
The stock input impedance is 1M ohm, and the pedal works with active or passive instruments as well as other devices such as pedals, preamps or effects loops. If an acoustic pickup requires a specialized input impedance, Broughton Audio will accommodate the request at no extra cost if it is written in the notes during checkout.
How much current does the Broughton Low + High Pass Filter draw?
The current draw is approximately 10 mA, according to Broughton Audio's product page.
Sources (2)
- Low + High Pass Filter by Broughton Audio, RockBoard (rockboard.de PedalPedia), 2026
- Low + High Pass Filter, Broughton Audio
