Filter / Wah (Optical envelope filter) · $299
The Maxon AF-9 Auto Filter is an analog optical envelope filter pedal based on the Photocoupler-based envelope filter with HP/BP/LP modes, up/down sweep and high/low range (Mu-Tron III style), with Sens. and Peak sliders; Filter (HP/BP/LP), Drive (Up/Down), Range (High/Low) controls, made in Japan. From $299.
| Category | Filter / Wah (Optical envelope filter) |
| Circuit / based on | Photocoupler-based envelope filter with HP/BP/LP modes, up/down sweep and high/low range (Mu-Tron III style) |
| Signal | Analog |
| Controls | Sens. and Peak sliders; Filter (HP/BP/LP), Drive (Up/Down), Range (High/Low) |
| Switches | Filter HP/BP/LP, Drive Up/Down, Range High/Low |
| Footswitches | 1 |
| Bypass | true bypass (Fujisoku 4PDT) |
| True bypass | Yes |
| I/O | 1 x 1/4" input, 1 x 1/4" output |
| Power | 9V DC |
| Power draw | 17 mA |
| Battery power | Yes |
| Enclosure | Nine Series |
| Dimensions | 74 x 124 x 54 mm (W x D x H) |
| Weight | 580 g (incl. battery) |
| Country of manufacture | Japan |
Closest matches from other makers, by spec and circuit.