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This EXH Doctor Q is in fantastic condition and comes with a 9V power adapter. It is missing one of the rubber feet.

A Classic Envelope Filter

Pedals like Doctor Q are a bit of a curiosity within the vintage market.
Built at a time when the battle between the wah-wah and the envelope filter was still going, it’s a great example of a good effect that has more or less fallen by the way-side in recent years.
That’s not to say you won’t find auto-wah pedals on the market. Pedals like Boss AW-3 – a basic auto-wah with little to no bells or whistles – are decent enough, but at the same time, they’re not particularly special.

When you get right down to it, modern auto-wahs tend to be a pretty vanilla take on this effect. Yes, they’ll give you an auto-wah of sorts, but they won’t do anything all that special with it.