Boss SP-1 Spectrum
the SP-1 is a parametric equalizer with one frequency band only. The spectrum knob sets the frequency range in the interval 500Hz to 5kHz. The balance knob sets the peak within the range. The SP-1 was more popular with keyboard players than with guitar players. Today it is one of the most sought after collectors items and a mint condition SP-1 doesn’t come cheap.
The first models featured the clear plastic switch and immediate LED as well as the silver thumb screw. The switch was later changed to black, the LED was made permanent and the black thumb screw was the last change made before it was discontinued 1981.
- Controls: Balance, Spectrum
- Connectors: Input, Output, AC Adaptor
- Current Draw: 23mA
- Weight: 410g (15 oz.)
- Input Impedance: 1 Mohm
- Output Impedance: 1 kohm
- Residual Noise Level: less than -98dBm (IHF-A)
- Recommended Load Impedance: More than 10kOhm
- Recommended AC Adaptor: ACA Series
- Black – Made In Japan
The SP-1 was sold from November 1977 to November 1981.