Ovation OP-24Plus User manual

ment of your guitar. The battery will fit only one way to assure
correct polarity. Plugging a 1/4” shielded guitar cable into the jack
on the guitar activates the electronics in your guitar. Please note
that the tuner will operate without "plugging in." After connecting
the guitar, plug into a PA or acoustic guitar amp for best results.
Controls
Pleasereferagaintofigures1+2tohelpyourselfassociatecontrol
names with their functions.
Volume
This slide control allows you to set the output level of the preamp.
Moving the slider toward the top increases the output level. The
OP-24Plus/OP-24Plus C can output a very potent signal, so be
careful not to "overdrive" your amp or mixer. If you notice any
unwanted signal coloration, just reduce the output level of the
guitar with this control.
Battery Low
This indicator performs two functions. First, when you plug in a
cable to the output jack, it will flash briefly to indicate that a
batteryispresent. If noflashisevident,your battery is eitherdead
or not installed. Secondly, this indicator will illuminate (and stay
on) if the voltage of the battery installed in the guitar dips below
about 7 volts. Replace the battery as soon as possible. With aver-
age use, expect 100 hours of operation per battery.
EQ Controls
TheEQ section allowsyou to accentor attenuate certainfrequency
bandswithin the guitar’saudio spectrum. When all of thecontrols
are in the center (detent) position, signals pass through the circuit
unaltered.Raising an EQ knob abovethe center position increases
the energy contained within that spectrum. Likewise, moving the
controlbelow the center position decreases the signals withinthat
band.
The OP-24Plus and OP-24Plus C preamp offers ±12dB control
simultaneouslyover three discreteranges of theguitar’ssonic spec-
trum. In addition, with the Mid-Shift switch, you can change the
center frequency of the Mid EQ control by roughly one octave.
TheLow EQ control allows you to increase or reducethesound in
the bass region. Raise this control above the center position to
add fullness or bottom to your sound. De-emphasizing this band
results in a lighter, less ponderous sound quality.
The High EQ control performs similarly to the “Low” control ex-
cept that its effect shapes the high frequency, or treble band. In-
crease this control for bright or airy sounds, or decrease for darker
or round tonalities.
Much like the High and Low controls, the Mid-band control adds
coloration to one of two user-selectable midrange frequencies.
With the Mid-Shift switch in the 400Hz position (down), the mid
EQ iseffective controlling “nasal” tonequalities while in the1KHz
position, the mid control can add punch in upper mids or help
"round off" the attack present in this frequency spectrum.
Introduction
Congratulations and thank you for selecting an Ovation Acoustic/
Electric guitar equipped with the OP-24Plus or OP-24Plus C
preamp. Please read this brief manual thoroughly to insure you
get the best performance from your new Ovation.
TheOvation OP-24Plus/OP-24PlusCpreamps accessawide range
of "studio-quality" contemporary acoustic/electric guitar sounds
offering a player tremendous control and sonic flexibility. The cir-
cuitry is exceptionally quiet and adds no unwanted coloration. In
addition, the OP-24E features a built-in chromatic tuner.
Referringto fig. 1 or fig.2, you’llsee the layoutand nomenclature
associated with the control features of these units.
Preamp Features & Functions
Thepreamp's audio circuitry is whisper quietwith very low distor-
tion (see specifications table). Tone control is greatly enhanced
with a "three-and-a-half" (we'll talk about that later) band graphic
equalizer. Moreover,youcanconnectyourguitartoawiderange
ofaudio amplification andrecordingequipment with thepreamp's
standard 1/4” Hi-Z, unbalanced phone jack output.
Connections
Neartheendpinofaguitar featuring these preamps, you’llnotice
a 1/4” phone jack. This jack provides the signal from the preamp
to any of a number of audio devices... mixers, effects, amps.
The Hi-Z Connection
To connectyour guitar to any high impedance (Hi-Z) acoustic gui-
tar amp or mixer, use a standard, shielded, 1/4” guitar cable in-
serted into the 1/4” jack on the guitar. The preamp will drive most
audio equipment with rated inputs down to about 1000 Ohms
(this mean you can connect to almost anything). If you have a
battery installed in the guitar, you’re ready to play.
Operation
Make sure a fresh 9V battery is installed into the battery compart-
Figure 2
Figure 1

OP-24Plus®
OP-24Plus C®
Acoustic/Electric Guitar Preamps
Owner's Manual
Ovation Instruments
Division Of Kaman Music Corporation
37 Greenwoods Road
New Hartford, CT 06057
www.kamanmusic.com Printed In U.S.A.
990153-C
Specifications: OP24Plus
Current Draw: 5mA @ 9VDC
Flat Ref. Level: -7.5dB
Freq. Response: 20Hz-20KHz (±0.5dB)
Signal to Noise:
EQbypass - 91dB
EQ in w/flat setting: - 89dB
EQ in w/max High: - 84dB
EQ Response:
Low: ±13dB @ 80Hz
Mid: ±12dB@ 400Hz
±6dB @ 1KHz (shift)
High ±12dB@ 10KHz
Output: Max. Level @ 10K Ohm: 4Vp-p
1.4VRMS
THD: < .28% @ 500mV input
Tuner "On" Time: 30 Seconds
Low Battery "ON" voltage: 7.7V
EQ In/Out
This push-button enables you to engage or defeat the EQ section.
When the switch is in the depressed position, the EQ is active.
Mid-Shift
As discussed above, this switch allows you select the cen-
ter of the frequency band in which you would like the Mid
control to operate.
Pre-Shape
By engaging this control (switch in the "down" position), you
add a fixed EQ curve on the sound from the pickup. Technically
speaking, when the pre-shape circuit is in operation, the bass
and treble frequencies are enhanced while at the same time,
mid range response is attenuated. This pre-emphasis can be
used alone, or with any other EQ settings you "dial in" with the
three EQ controls.
Tuner (OP24 Plus C only)
Pushing the tuner buttonactivatesthe built-in tuner. When turned
on, the green "OK" LED flashes. Playing a note on your guitar will
illuminate a "note" LED on the bottom row which indicates the
name of the note played. If this note is a sharp (or flat) the LED on
the far right will also light. In addition to these LEDs, one of the
three indicators in the row above will turn on. If the note you're
playing is substantially flat, the left LED will glow brightly and, as
you tune the string sharper, this "flat" LED will get dimmer and
finally shut off as the "OK" LED lights to indicate that the pitch
you're playing is in tune. Likewise, if you're playing a note that is
sharper than the correct pitch, the "Sharp" LED will light. Tuning
the string lower will cause this LED to dim and finally yield to the
"OK"LED.
It is not usual to perform the tuning procedure on all strings more
thanonce toget yourinstrumenttuned correctly,especiallyif you're
using new strings. Although there is a built-in auto-off feature for
the tuner circuit, to conserve battery power, it's a good idea to
push the tuner button again to manually turn off the circuit when
you're done tuning.
Specifications: OP24Plus C
Current Draw: 6mA @ 9VDC Tuner Off
10.8mA Tuner On Max.
0.4uAOff
Flat Ref. Level: -7.5dB
Freq. Response: 20Hz-20KHz(±0.5dB)
Signal to Noise: EQbypass - 91dB
EQ in w/flat setting: - 89dB
EQ in w/max High: - 84dB
EQ Response: Low: ±10dB@ 134Hz
Mid: ±12dB@ 400Hz
±7dB @ 880Hz (shift)
High ±10dB@ 10KHz
Output: Max. Level @ 10K Ohm: 4Vp-p
1.4VRMS
THD: < .28% @ 500mV input
TunerAccuracy: <.1%
Low Battery "ON": 7.7V