The Maxon AF-9 Auto Filter is a Maxon envelope filter pedal, currently around $270. Close alternatives include the Emma DiscomBOBulator and the Musitronics Mu-Tron III. It pairs well with the Fender Deluxe Reverb and the Fender Bassman Combo Amp.
Maxon AF-9 Auto Filter
Maxon · pedal
The Maxon AF-9 Auto Filter is an analog envelope filter that opens and closes an optical photocoupler filter in response to pick attack, producing the warm, vowel-like, liquid and shimmering sweep associated with vintage units like the Mu-Tron III. It offers low-pass, band-pass, and high-pass filter modes with switchable direction, plus threshold and peak controls that shape how quickly and how far the filter sweeps. Two selectable frequency ranges let it track both guitar and bass cleanly. It is closely associated with funk and soul playing, where its liquid, three-dimensional quacking response reacts directly to how hard notes are picked, and it remains a favored alternative to pricier vintage envelope filters for players chasing that vowel-like auto-wah character.
- filter
- bass
- peak
- frequency
- envelope
- vintage
- optical
- analog
Price updated Aug 27, 2026
Genres the Maxon AF-9 Auto Filter is commonly used in
- Funk
- Alternative Rock
- Metal
- Soul
- Experimental
cited
Inferred from shared tonal signals, not a stated genre tag. - Rock
cited
Inferred from shared tonal signals, not a stated genre tag.
Amps that pair well with the Maxon AF-9 Auto Filter
Pedals that stack with the Maxon AF-9 Auto Filter
MXR Distortion+
MXR
10% matchWhat MXR Distortion+ brings here leans toward compressed — that's worth building a pairing around
Beetronics Swarm
Beetronics
10% matchBeetronics Swarm leans toward fuzzy, and that's a real, usable character to pair with
Roland SDE-3000D
Roland
6% matchRun Roland SDE-3000D after Maxon AF-9 Auto Filter in the signal chain, clear of Maxon AF-9 Auto Filter's own gain stage — goes in the amp's FX loop (or last, into a clean amp)
Walrus Audio Mako D1 High-Fidelity Stereo Delay V1
Walrus Audio
6% matchRun Walrus Audio Mako D1 High-Fidelity Stereo Delay V1 after Maxon AF-9 Auto Filter in the signal chain, clear of Maxon AF-9 Auto Filter's own gain stage — goes in the amp's FX loop (or last, into a clean amp)
Cheaper alternatives
Electro-Harmonix Riddle Q Balls
Electro-Harmonix
71% similarityShared character: soul, peak, sensitivity
Electro-Harmonix Doctor Q
Electro-Harmonix
70% similarityShared character: soul, sensitivity, pick_attack
Carl Martin Ottawa Vintage Optical Envelope Auto-Wah/Envelope Filter
Carl Martin
70% similarityShared character: soul, sensitivity, pedal
Dunlop Cry Baby
Dunlop
69% similarityShared character: peak, natural_resonance, pedal
Carl Martin Ottawa
Carl Martin
69% similarityShared character: soul, sensitivity, natural_resonance
Fender Pour Over Envelope Filter
Fender
69% similarityShared character: soul, sensitivity, signal
Similar charactersee all similar tone character →
Emma DiscomBOBulator
pedal
75% similarityShared character: controls, soul, sensitivity
Musitronics Mu-Tron III
Musitronics
70% similarity“associated with vintage units like the Mu-Tron III”
Ashdown Type 23 Three Band Filter
Ashdown
70% similarityShared character: soul, live_performances, sensitivity
Subdecay Proteus MKII Sample
Subdecay
96% similaritysimilar tone character
Aitone AT-08
Aitone
96% similaritysimilar tone character
Vox V863CA Auto Wah
Vox
96% similaritysimilar tone character
See all alternatives to the Maxon AF-9 Auto Filter (cheaper + boutique) →
Questions people ask
What are good alternatives to the Maxon AF-9 Auto Filter?+
The closest matches in character are the Emma DiscomBOBulator, the Musitronics Mu-Tron III, the Ashdown Type 23 Three Band Filter. Budget picks: Electro-Harmonix Riddle Q Balls, Electro-Harmonix Doctor Q, Carl Martin Ottawa Vintage Optical Envelope Auto-Wah/Envelope Filter.
What pairs well with the Maxon AF-9 Auto Filter?+
Strong matches from rig and tone-complementarity evidence: Fender Deluxe Reverb, Fender Bassman Combo Amp, MXR Distortion+ — What Fender Deluxe Reverb brings here leans toward spring — that's worth building a pairing around.
How much does the Maxon AF-9 Auto Filter cost?+
Around $270 (live listing price, updated Aug 27, 2026).