Electro Harmonix Doctor Q Envelope Follower from 1976

Great sounding filter.

This pedal has been fulling tested and works as it should with no issues. No box

The Electro-Harmonix Doctor Q is a vintage, analog envelope follower introduced around 1976–1977, designed to produce percussive, "wah-like" funk tones. Known as a simpler alternative to the Mu-Tron III, it features a single "Range" knob and a "Bass" switch to toggle between a bandpass filter (guitar) and low-pass filter (bass). These units are sought-after for their 70s analog character, often requiring 9V battery power or a 3.5mm adapter.

Key Information on Vintage Doctor Q:

• Release Date: First manufactured around 1976–1977.
• Controls: One knob (Range/Sensitivity) and one Bass switch.
• Function: An envelope follower that reacts to picking dynamics, producing sounds described as "ow" and "wow".
• Filter Type: Primarily acts as a bandpass filter, but the "Bass" mode switches it to a low-pass filter.
• Power: Originally designed for 9V batteries, often using 3.5mm (1/8") jacks in early versions.
• Sound Characteristics: Often described as having a "gritty," raw, and 70s-style funk tone, sometimes regarded as a "niche" or "ugly duckling" pedal due to its intense, unbuffered, and sometimes erratic response to dynamics.
• Reissues: Modern versions (like the Nano Doctor Q) are also available, which are much smaller but aim for the same classic sound.

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