This is a vintage 1970’s Dan Armstrong Purple Peaker electric guitar effects pedal. Considered the EQ pedal amongst the small effects line, the Purple Peaker offers a great treble boost option. In the “1” position, the Peaker introduces a 12 db peak centered at 4000 Hz which gives the instrument more “presence” or “bite”. In the “2” position it produces the same presence peak plus a 7 db peak at 200 Hz to give the instrument more bottom or “punch”. In the “Off’ position neither peak is produced, but the guitar’s signal is still improved, since the Peaker’s low impedance 200 ohm Output eliminates signal loss and hum pick-up, even with very long cables. The Purple Peaker makes weak-sounding instruments sound fuller, and full-sounding instruments sound super. It is also excellent for musicians who want to record themselves by plugging directly into a tape machine without going through an amp. The Purple Peaker has an Input Impedance of 100 k Ohms, and an excellent Signal-to-Noise ratio of 90 db.