Ovation Preamps
OP-40 Preamp

OP-40 Preamp Complete Set

Ovation’s OP-40 preamp leaves other electronics in the dust. It features 3-band EQ with a bypass switch, a Mid-Shift control for selecting a midrange center frequency of either 400 Hz or 900 Hz, a Pre-Shape circuit for boosting bass and treble response while cutting rumble-prone frequencies below 40 Hz, and a battery status light. An ultra-steep sweepable notch filter lets you surgically cut feedback without affecting the guitar’s overall tone. 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 it Works:

  1. VOLUME: Adjusts the overall output level of the preamp.
  2. BASS: Adds or subtracts the low frequency content of the signal.
  3. MID: Controls the amount of a broad range of frequencies in the middle of the sound spectrum of the guitar.
  4. MID1: Controls the amount of power in lower middle frequencies.
  5. MID2: Controls the amount of power in upper middle frequencies.
  6. TREBLE: Adds or subtracts the high frequency content of the signal.
  7. EQ IN/OUT: Engages or bypasses the EQ controls.
  8. PRESHAPE: Engages or bypasses a fixed tone enhancement circuit.
  9. MID SHIFT: Moves the center frequency of the midrange control.
  10. NOTCH SW: Enables or disables the Notch Filter (see 11).
  11. NOTCH POT: This control is used to tune a very sharp and deep filter designed to reduce feedback when using high-gain amplification. At a high volume level, your guitar may “feedback” causing a low, steady tone to come from your speakers. With the notch filter
  12. 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.
  13. 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.
  14. 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.
  15. RELEASE: Pressing this button will release the module from its receptacle. Use this button to access to the battery compartment.
  16. 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: 6mA
  • Sleep Current: 40A
  • Battery Low On: 6.7VDC
  • Max. Output @ 1kHz: 6VP-P
  • THD @ 1VP-P Input: <0.2%
  • S/N Ratio: >95dB
  • Frequency Response (-3dB): 27Hz-90kHz
  • Preshape EQ: +3dB@70Hz -6dB@500Hz +3dB@9kHz
  • Bass EQ Response: ±11dB@84Hz
  • Mid EQ Response: ±6dB@900Hz
  • Mid Shift Response: ±6dB@400Hz
  • Mid 1 Response: n/a
  • Mid 2 Response: n/a
  • Treble Response: ±12dB@8.4kHz
  • Notch Range: 24-264Hz
  • Notch Depth: -32dB
  • Tuner Accuracy: <1 cent
  • Tuner Auto-Off: 1 minute


Model Name: OP-40 Preamp Complete Set
Series: Ovation Preamps
Color: N/A