1st issue, all original 90s Q-Tron; plays & powers perfectly. Excellent filter for any signal, exceptional on bass with super fat low pass tones. This early version has the diffused/softer LEDS, not as annoyingly blinky as the later watercolor era. Always on power LED. I've had this a loooong time and its beaten a Guapo sized plethora of other killer filters. I powered it by Cioks Dc7 outlet and its perfect. Pedal only. Ships fast. Thanks for stopping by-

From EHX:
"Mike Matthews, founder of Electro-Harmonix, and Mike Biegel, designer of the Mutron III, have together created the first all new Electro-Harmonix product in 15 years: The Q-Tron envelope controlled filter. This new effect uses the same opto-electronic design of the Mutron-III and has an increased frequency response and an improved signal-to-noise ratio. Has all Mutron-III features plus switchable Boost and Filter Mix mode.

There are seven onboard controls :

1. Drive Switch (up/down) - selects direction of filter sweep : up (wah) or down (ow).

2. Range Switch (Hi/Low) - Emphasizes vowel like sounds in low position, overtones in high position.

3. Gain Control (0-11) - Functions as both a volume control and a filter sensitivity control in boost mode. In normal mode it acts only as a filter sensitivity control, unlike the Mutron-III which also changes the unit's output volume.

4. Boost Switch (Normal/Boost modes) - Normal mode allows setting the Gain control without changing the output volume.

5. Peak Control (0-11) - Determines frequency peak of filter. Makes more "effected sound" when turned up more.

6. Mode switch (LP, BP, HP, MIX) - Select the frequency range for the filter to sweep. Low Pass is lows, Band Pass is midrange, High Pass is treble. MIX mode (new feature not on the Mutron-III) combines BP with dry unprocessed sound.

7. Bypass switch (in/out) - Turns effect on and off.

Features

Needs 24 volt AC adaptor (will not run on batteries).
True Bypass

POWER indicator LED
2 outputs - normal and effected outputs.
True bypass DPDT switching."