From the Heptode website: “The Virtuoso is a boutique recreation of the original Maestro* PS-1A Phase Shifter, as used in the 1970's by keyboardist John Paul Jones (Led Zeppelin) and guitarists Steve Howe (Yes) and Ernie Isley (Isley Brothers), among many others.” This pedal’s history should be enough for any phase shifter fan to pick one up. If you need more convincing, just take a look at its uncompromising simplicity and beautiful sound.
External Control: None
This is literally the easiest pedal possible to use. There are no knobs. Just three settings. Each has a footswitch. Simple.
Although it only does one thing, this pedal does it very well. You get three speeds. You may not tweak them.
Clarity of Effect: 4.5/5
Truly one of the better sounding phase shifters we have heard. The effect cuts though without compromising your tone. The virtuoso sounds as good as it is simple.
Live application: 3.5/5
This is a fantastic pedal if you want a no frills phase. It sounds great, and goes slow, medium, or fast. What else could you possibly need?
6-stage analog phase shifter
3 phase speeds (Slow, Medium, Fast)
Relay-based true bypass
Power: 9V battery (High quality alkaline battery included) or AC Adapter DC 9V (negative center pin, not included)
Current draw: 45 mA typical
Dimensions: 153 mm (W) x 88 mm (D) x 70 mm (H) / 6.0’’ (W) x 3.5’’ (D) x 2.7’’ (H)
Weight: 500 g / 17 oz
Product info from the Heptode website