K&K Sound ULTRAPURE User manual

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ULTRAPURE PREAMP
Overview photo: UltraPure Mini System, installed in a steel string flattop guitar
Package Contents
•Pure Pickup, with accessories & manual
•UltraPure preamp with battery clip cable
•Battery bag
•Allen wrench
•Output cable with endpin jack
•3 cable clamps with adhesive backing: 1 big, 2
small
•Cable tie
You Need
•9-volt battery
•Any materials required for the pickup
installation (see Pure Pickup manual)
UNPLUG THE CABLE FROM THE ENDPIN JACK TO
SWITCH OFF THE BATTERY. USE A SHIELDED
STANDARD MONO ¼” GUITAR CABLE ONLY.
This sound hole mounted UltraPure Preamp features
the same EQ and phase switch circuitry as our Pure
XLR Preamp, without the XLR output and with
components that are optimized for longer battery
life. It has a ¼” endpin jack line output.
Features
•Volume control slider
•Proprietary K&K 3-band EQ with +/-20dB Bass,
Mid and Treble controls
•K&K’s extra wide band midrange filter,
especially geared towards acoustic guitar
•Phase switch: flips the phase 180 degrees if
pressed in
•Low battery indication light: comes on at about
6.5-volt operating voltage. There will be at least
3-4 hours playing time left.
•Adjustable input gain: a small blue trim pot on
the bottom of the preamp

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Installation Procedure
1. Hold the UltraPure preamp in the guitar in its
desired position to check the fit. Note that
different guitars have different soundhole
bracing and in some models it may be a tight fit.
In very few cases the bracing might be arranged
so it would not allow for this type preamp, but
this is extremely rare.
2. Install the transducers and drill the endpin hole
following the manual for the pickup installation.
3. Apply a strip of masking tape to the edge of the
soundhole on the guitar, hold the preamp in
place and mark the position of the lower edge of
the preamp’s mounting bracket with a pencil on
the masking tape (the piece with the red tape).
4. Unscrew the 2 screws that hold the mounting
bracket to the preamp. The nuts have been
secured to prevent falling out.
5. Make sure the area in the guitar where the
mounting bracket will be installed, is perfectly
clean.
6. Remove the red protective foil from the
mounting bracket, align it with the pencil mark
you did in step 3.
7. Press the mounting bracket onto the wood at its
desired position. Make sure not to distort the
mounting bracket’s natural form when you stick
it onto the guitar! Press the bracket tightly
against the guitar top over its entire length to
ensure good bonding. Note: The tape will take
24 hours until the final bonding strength is
reached, but it will hold sufficiently immediately.
8. Plug the pickup plug (2.5mm smaller diameter
plug) into the input of the ultrapure preamp. It is
located on the square gray metal box in the rear
of the preamp.
9. Establish a precisely fitting length of the endpin
jack cable by making a loop in it, about where
the cable meets the waist of the guitar (see
overview photo, p. 1). Secure this loop with the
supplied cable tie and cut off the excess of the
cable tie.
10. Plug the 3.5mm plug of the endpin jack cable
into the 3.5mm output jack on the back of the
preamp.

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11. Attach the preamp to the mounting bracket with
the 2 screws that you removed in step 4. Start
with the screw on the neck end of the preamp.
This is the narrower end with less tape. Be
gentle to avoid stressing the fresh hold of the
tape while doing this.
12. Plug the pickup into the RCA connector on the
preamp’s input cable and stick the RCA
connection either to the side or to the bottom of
the guitar with the supplied self-adhesive Velcro
material. Secure the pickup cables with the
smaller metal clip and the output/endpin cable
with the bigger clip as shown in overview photo
on page 1.
13. Install the endpin jack according to the pickup
manual.
14. Stick the supplied rectangular Velcro piece to
the neck block for the battery bag (see overview
photo, p. 1).
15. Connect the battery clip to a new 9-volt battery
(not supplied) and put it into the battery bag.
16. Stick the battery bag to the Velcro on the neck
block (see overview photo, p. 1).
Adjustable Input Gain Control
This is a small blue trim pot that is located on the
bottom side of the preamp circuit board. It is factory
set to the middle position.
To access this trim pot you have to remove the 2
Allen screws, separate the preamp from the
mounting bracket (as described in point 4) and take
it out of the guitar.
This control sets the amount of pre-amplification and
allows using the UltraPure Preamp with a large
variety of pickup systems, including non K&K
systems. You can lower (turn counterclockwise) or
raise (turn clockwise) the input gain if necessary.
Gain and volume both have an effect on the output
volume of the preamp, but they accomplish different
tasks. The gain (also called input gain or sensitivity
control) is located at the INPUT of the circuit. It sets
the amount of pre-amplification before the signal
enters the EQ section. The volume control is located
at the OUTPUT (the very end of the circuit) and
simply allows you to adjust the volume.
To get the best performance out of the UltraPure
Preamp,the input gain can be set to fit the
instrument you are using. An instrument with a high
output signal will require less gain than one with a
weaker output. The gain is factory set to a “happy
medium” position that will most likely be just fine if
you use the Pure Pickup. Too much input gain will
distort the sound when you strike the guitar hard,
too little input will raise the noise floor of your
amplification system.
Phase Switch
Phase switches are usually marketed as a feedback-
controlling device, but they accomplish more than
just that. Phase determines at what point in time a
sound wave has it’s peak or bottom.
This picture shows two simple (identical)
sine waves, but the wave on the bottom
(2) is inverted in respect to the wave on
top (1). Interestingly enough, if these 2
waves were played back simultaneously,
they would cancel each other out and no
sound be heard. Amplification systems and effect
pedals may or may not invert the phase with
respect to the signal sent in.
Every acoustic instrument projects sound waves in a
certain phase. The phase that is projected from the
amplified speaker source needs to be "in phase"
(not inverted) with the acoustic instruments’ own
sound waves or the result will not be optimal. If the
amp projects the inverted phase, the acoustic
instrument will fight its own sound and balanced
tone cannot develop. Round and warm tone is only
achieved when acoustic and amplified sound
oscillate in the same phase.
The UltraPure’s phase switch allows for instant
correction of this problem. Play your instrument and
flip the phase switch back and fourth. You will
experience a fuller and warmer tone one way or the
other (in most cases it will be correct when the

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phase switch is not pressed in, but there are
exceptions!).
EQ Specifications
The Ultrapure Preamp features strong +/-20 db bass,
mid, and treble controls. The special super-wide-
band midrange filter is absolutely great in
combination with the Pure Pickup. The bass control
is set to roll of at 100Hz, the midrange at 1.5kHz with
extra large bandwidth and the treble are set at
10kHz. Input impedance is 1 meg. Output impedance
is 100 Ohm. Frequency response is 30 –20000 Hz.
We recommend pre-setting the 3-band EQ and
phase at sound check as the EQ knobs are
somewhat difficult to reach on the fly. When done
correctly, there should be no need to adjust during
the performance. If there is, we found it easiest to
turn the knobs with thumb and middle fingers,
encircling the strings.The volume slider is always
easily accessible.