Ovation Preamps

OP20 Preamp Complete Set

Ovation’s popular OP-20 preamp features 3-band EQ with a bypass switch, a Pre-Shape tone enhancement circuit, and a battery status light. Equipped with an easy-to-read LED array, the onboard chromatic tuner works for standard, open, or altered tunings, and can be calibrated to non-standard reference pitches.

How the OP-20 works:

  1. VOLUME: Adjusts the overall output level of the preamp.
  2. BASS: Increases or reduces low frequency content of the guitar's electrical signal.
  3. MID: Controls the amount of a broad range of frequencies in the middle of the sound spectrum of the guitar.
  4. TREBLE: Increases or reduces the high frequency content of the guitar's electrical signal.
  5. EQ IN/OUT: Engages or bypasses the EQ controls.
  6. PRESHAPE: Engages or bypasses a fixed tone enhancement circuit.
  7. MID SHIFT: Moves the center frequency of the midrange control.
  8. TUNE/CAL: This switch turns on the built-in tuner for approximately 60 seconds. Press a second time while playing a note and this pitch will become the calibration point for operation (handy when tuning to an “out-of tune” instrument). During the tuning operation the guitar output will be muted. If you finish tuning prior to the 60 second timer returning the tuner to idle (and un-mute), you may press this button again to manually return the preamp to normal operation.
  9. TUNER LEDs: These LEDs indicate the note being played and whether it’s sharp or flat. Tune string up or down until the LED lights.
  10. BAT: When steadily illuminated, indicates that the battery is low and should be changed soon. Also intermittently flashes when plug is inserted into jack to confirm normal operation.
  11. RELEASE: Pressing this button will release the module from its receptacle. Use this button to access to the battery compartment.
  12. MODULE: The preamp is housed within this module and mates to the receptacle mounted in the body. Remove this module to gain access to the battery compartment. See the illustration below for instructions on replacing the battery.


  • Battery Voltage: 9VDC
  • Idle Current: 5.1mA
  • Sleep Current: 40µA
  • Battery Low On: 6.7VDC
  • Max. Output @ 1kHz: 6VP-P
  • THD @ 1VP-P Input: <0.1%
  • S/N Ratio: >92dB
  • Frequency Response (-3dB): 50Hz-90kHz
  • Preshape EQ: -6dB@500Hz
  • Bass EQ Response: ±9dB@60Hz
  • Mid EQ Response: ±10dB@600Hz
  • Mid Shift Response: n/a
  • Treble Response: ±12dB@10kHz
  • Tuner Accuracy: n/a
  • Tuner Auto-Off: n/a


Model Name: OP20 Preamp Complete Set
Series: Ovation Preamps
Color: N/A