Avedis Audio KeyPre KP6 User manual

KeyPre®
KP6 - Electronic Instrument Preamplifier
USER’S GUIDE
!
00dB
-10dB
Mute 32 dB
+10 dB
20
AVEDIS AUDIO
ELECTRONICS
0 0 00
-10dB
Mute 32dB
+10dB
20-10dB
Mute 32dB
+10dB
20
-10dB
Mute 32dB
+10dB
20-10dB
Mute 32dB
+10 dB
20
-10dB
Mute 32dB
10dB
20
+
+
+
+
+
1.1"
1.225"
12 ININ OUTIN ININ OUT OUT 345
6OUTOUTOUTIN
GROUND
LIFT
AC INPUT
100-240VAC
50/60 Hz
FUSE:
250V
T 1A
AVEDIS AUDIO ELECTRONICS, INC. Designed and manufactured in the U.S.A. Serial No.
USE ONLY WITH 250V FUSE
+
+
+
+
avedisaudio.com

KeyPre®
KP6 - Electronic Instrument Preamplifier
IMPORTANT SAFETY INSTRUCTIONS - READ FIRST…………………………….……2
INTRODUCTION………………….……………………………………………………………3
INSTALLATION……….………………………………………………………………………..3
AC CORD……………………………………………………………………….………………3
AC POWER SWITCH………………………………………………………….………………3
INPUT…………………………………………………………………………….……………..3
GAIN ………………………………………………………………………….………………4
OUTPUT………………………………………………………………………..……………….4
PHASE…………………………………………………………………………..………………4
METER……………………………………………………………………….…………………4
INPUT IMPEDANCE……………………………………………………….………………….5
MAXIMUM INPUT LEVEL…………………………………………….………………………5
GROUNDING…………………………………………………………………………………..5
FLOWCHART…………………………………………………………………………………..6
SPECIFICATIONS……………………………………………………………………………..7
WARRANTY INFORMATION …………………………………………………………..……8

IMPORTANT SAFETY INSTRUCTION – READ FIRST

Read Instruction: Retain these safety and operating instructions for future reference. Heed all warnings printed here and
on the equipment. Follow the operating instructions printed in this user guide.
Do Not Open: There are no user serviceable parts inside. Refer any service work to qualified technical personnel only.
Power sources: Connect the unit to mains power only of the type described in this user guide or marked on the rear
panel. For safety, the power source must provide a good ground connection.
Power cord: Use the power cord with sealed mains plug appropriate for your local main supply as provided with the
equipment. Route the power cord so that it is not likely to be walked on, stretched or pinched.
Non-Use Period: The power cord should be unplugged from the AC outlet when left unused for a long period of time.
Grounding: Do not defeat the grounding and polarization means of the power cord plug. Do not remove or tamper with
the ground connection on the power cord.
Ventilation: Do not obstruct the ventilation slots or position the unit where the air required for ventilation is impeded. If
the unit is to be operated in a rack, case or other furniture ensure that it is constructed to allow adequate ventilation.
Moisture: To reduce the risk of fire or electrical shock do not expose the unit to rain, moisture or use in damp or wet
conditions. Do not place container of liquid on it, which may spill into any openings.
Heat: Do not locate the unit in a place close to excessive heat or direct sunlight, as this could be a fire hazard. Locate the
unit away from any equipment, which produces heat such as: power supplies, power amplifiers and heaters.
Environment: Protect from excessive dirt, dust, heat, and vibration when operating and storing. Avoid tobacco ash, drink
spillage and smoke, especially that associated with smoke machines.
Handling: To prevent damage to the controls and cosmetics avoid rough handling and excessive vibration. Protect the
controls form damage during transit. Use adequate padding if you need to ship the unit. To avoid injury to yourself or
damage to the equipment take care when lifting, moving or carrying the unit.
Servicing: Switch off the equipment and unplug the power cord immediately if it is exposed to moisture, spilled liquid,
objects fallen into opening, the power cord or plug becomes damaged during a lightning storm or if smoke odor or noise is
noted. The user should not attempt to service or modify the unit unless qualified to do so and under the guidance of
Avedis Audio service personnel.
This symbol, whenever it appears, alerts you
to the presence of uninsulated dangerous
voltage inside the enclosure-voltage that may
be sufficient to constitute a risk of shock
This symbol, wherever it appears, alerts to important
operating and maintenance instructions in the
accompanying literature. Read manual.


2

Installation: Install the unit in accordance with the instruction printed in the user guide.
INTRODUCTION:
The KeyPre® was designed for professional keyboard, synthesizer, and drum machine users
who want the highest performance when recording their electronic instruments. The wide
range of different output levels, frequency response, and impedances from electronic
instruments makes it especially challenging for preamplifiers. Over two years have been
dedicated to research, test, and development in designing the KeyPre® and we are confident
it will improve your sound for both recording and live applications.
INSTALLATION:
It is recommended that the KeyPre® be located away from any strong electromagnetic
sources when racked. These sources can include power supplies, AC distributors and power
conditioners, digital clocks, power amplifiers, and other units that may throw off a field above
or below your rack mount equipment.
AC CORD:
The AC cord supplied with the KeyPre® is no ordinary cable. If you look closely, you will read
that it is SHIELDED. This means that the safety ground conductor covers the live and neutral
conductors along with a drain wire
This helps minimize noise by containing the electromagnetic field from coupling into nearby
enclosures, chassis, and cables, and should the be only AC cord to power up the KeyPre®.
AC POWER SWITCH:
This rocker switch turns the power on and off. Allow a minute or so to warm up the KeyPre’s
circuitry. The unit could also be switched off at the AC power source with a AC distribution
unit.
Save electricity - turn the unit off when not in use.
INPUT:
The KeyPre® provides both front and rear inputs. To use the front input, push the button
which turns the LED on to indicate the input for the front TRS.
This way, you could keep your most used or more permanently installed instruments
connected to the rear, and smaller pieces and more infrequently used instruments would
connect to the front, even leaving them in and only toggling the push button when needed.
3

Both front and rear inputs have a balanced TRS (tip/ring/sleeve) input, and designed so that it
could work with both balanced and unbalanced TS (tip/sleeve) instruments. Commonly,
balanced outputs could in the form of an TRS or XLR type connector, and unbalanced outputs
could have either 1/4” or RCA type connector. The advantage of having a balanced output
from your instrument is the immunity to interacting with nearby noise sources. This immunity
to noise is especially better with the input stage of the KeyPre® because it makes use of the
THAT Corp InGenius® input IC (integrated circuit), developed by Bill Whitlock, former
president of Jensen Transformers, to have transformer-like performance. Balanced audio’s
ability to reject noise is measured by common-mode rejection ratio, or CMRR, and at the
worst offending frequency of 60Hz, this rejection is a high 90 dB.
GAIN:
The gain control is a continuously variable starting at Mute up to 32 dB of gain.
Most electronic instruments have ample output and may not need much gain to get you up to
recording level for best signal to noise, although some need more gain and 32 dB should be
more than enough. You can start at the 0 dB mark, which keeps your level the same from,
input to output, which is also known as unity gain. From here you can adjust your level to
optimize it whether you are recording or using a live setup.
OUTPUT:
The outputs of the KeyPre® are transformer balanced using TRS connectors.
Because Jensen® transformers are used for balancing the output, we say this is a floating
balanced output. This means that you can unbalance the output of the KeyPre without
compromising level and headroom.
Usually the output becomes unbalanced if, for example, the KeyPre® was to connect directly
to effect processors and outboard gear with an unbalanced input. To get the most of the
balanced noise-cancelation affect, it is smart to only unbalance right at the input of the
unbalanced gear by using cables that are balanced 1/4” TRS on one side and TS unbalanced
on the other side with the Ring and the Sleeve connected only on the TS end.
PHASE:
The KeyPre® operates in true phase from the input to the output jack so that Tip is hot (+),
Ring is cold (-). In an unbalanced TS connection, Tip would still remain hot, but Ring would
connect to Sleeve and have a ground potential.
METER:
4

The 5-bar LED meter is connected to the output of the KeyPre® and starts to illuminate when
audio reaches 0 dBu level and each bar is lit with each additional 3 dB ending with +12 dBu
with the fifth bar.
Each channel meter has been individually calibrated at these default levels, and although we
found this to be most optimal, it is possible to customize them to your liking by means of an
internal trim pot.
Please contact us for technical support if you would like to change the default meter levels
yourself. Be sure to always disconnect the AC power before opening up the KeyPre and
follow good safety practices. If you don’t feel confident doing it, we can adjust it for you at no
extra charge.
INPUT IMPEDANCE:
In our research, we found that different electronic instruments have a wide range of output
impedances, from as low as 200 ohms to as high as 5k ohms. To load the instrument
properly, higher input impedance is needed but this should not be too low, such to “match” it,
and should not be too high, as with DI boxes. We must think of the imperfect world of audio
electronics - that ALL outputs of audio equipment don’t have steady output impedance to its
frequency response. This unsteadiness and tendency for the audio to weaken at some point
(higher output impedance) at the extremes of its frequency response limit is what engineer
types like to call a reactive output. If you couple a reactive output to a long cable, which will
also have an inherent capacitance between the conductors, you will have a tuned filter circuit.
The result is a roll off at some frequency either in the low frequencies, high frequencies, or
both depending on the output stage of the electronics instrument.
The KeyPre’s steady input impedance of 48k ohms means that it will provide a comfortable
load for any electronics instrument output, even if it’s as high as 5k ohms.
MAXIMUM INPUT LEVEL:
The maximum input level before clipping is +24dBu. This high headroom handling capability is
important so that even the highest output from your DAW should not be able to make the
input clip. The overall headroom in the output stage is even higher with +28dBu of level
handling.
GROUNDING:
The KeyPre® is equipped with the Xsolate® patented ground lift system located as a switch
at the rear of the unit. (Patent 9,054,463)
To reduce ground-induced noise, system safely isolates your ground connection at the
outputs only, since the Jensen transformer provides a balanced floating output and no ground
connection is needed.
5

Balanced systems only need a ground connection on one end only. This is called a telescope
ground where only the Tip and Ring are used in audio transmission, and the ground
connection on one end shields the cable.
6
1.1"
1.225"
12 IN
IN OUTIN ININ OUT OUT
345
6OUTOUT
OUTIN
GROUND
LIFT
AC INPUT
100-240VAC
50/60 Hz
FUSE:
250V
T 1A
AVEDIS AUDIO ELECTRONICS, INC. Designed and manufactured in the U.S.A.Serial No.
USE ONLY WITH 250V FUSE
+
+
+
+
Ingenius®
Input Stage Gain knob
Jensen
Output
Transformer
Internal
Gain TRS Balanced
Output
Discrete
amp
KeyPre®Flowchart
1
2
3
Meter
Internally adjustable
trim pot
1
2
3
Front TRS Input
Rear TRS Input
Input select pushbutton
1
2
3

Use the space above to note instruments on channels
KeyPre™ Specifications
Avedis Audio maintains a policy of constant product improvement. Avedis Audio reserves the
right to make changes in design or make additions to or improvements upon this product
without any obligation to install same on products previously manufactured. Therefore,
specifications are subject to change without notice.
7
Frequency Response
3Hz - 75kHz (-3dB)
Input Impedance
48k ohms
Maximum Input Level
+24dBu
Maximum Output Level
+28dBu
THD+N
0.015% @ 10dB Gain
CMRR
90 dB @ 60Hz
IMD
0.02% (400Hz, 4kHz)
Noise
-115dB (unfiltered, unweighted)
Dimensions
19”W x 1.75”H x 8”D
Weight
8 lbs (3.6kg)
Power requirements
100-240 VAC, 0.65A, 50/60Hz
Power consumption
18W

WARRANTY INFORMATION
Limited Warranty
Avedis Audio Electronics will provide warranty and service for this unit in accordance with the
following warrants:
Avedis Audio Electronics warrants to the original purchaser that this product and the
components thereof will be free from defects in workmanship and materials for a period of
three years from the date of purchase. Avedis Audio Electronics will, without charge, repair or
replace, at its option, defective product or component parts upon prepaid delivery to factory
service or authorized service center.
Exclusions:
This warranty does not apply in the event of misuse or abuse of the product or as a result of
unauthorized alterations or repairs. This warranty is void if the serial number is altered,
defaced, or removed.
Avedis Audio reserves the right to make changes in design or make additions to or
improvements upon this product without any obligation to install the same on products
previously manufactured.
Avedis Audio shall not be liable for any consequential damages, including without limitation
damages resulting from loss of use. Some states do not allow limitations of incidental or
consequential damages, so the above limitation or exclusion may not apply to you. This
warranty gives you specific rights and you may have other rights, which vary, from state to
state.
For units purchased outside the United States, an authorized distributor of Avedis Audio will
provide service.
8

9
www.avedisaudio.com
[email protected]
[phone]
© 2018 Avedis Audio Electronics, Inc.