Coda 07X User manual

OPERATION MANUAL
Preamplifier 07x
CARE & HANDLING
WARRANTY REGISTRATION
WARRANTY & DISCLAIMER
3
6
9
8
4
INSTALLATION CONNECTIONS
DETAILED INSTALLATION
DESIGN PHILOSOPHY
10
TECHNICAL DATA
2
INTRODUCTION
11
1
SAFETY PRECAUTIONS
2
INTRODUCTION
1
SAFETY PRECAUTIONS

!
CAUTION
CAUTION
WARNING
WARNING
1
SAFETY PRECAUTIONS
CAUTION -
-
-
-
-
CAUTION: TO PREVENT ELECTRIC
SHOCK, DO NOT REMOVE COVER.
NO USER SERVICEABLE PARTS
INSIDE, REFER SERVICING TO
QUALIFIED SERVICE PERSONNEL.
THIS SYMBOL IS TO ALERT YOU OF
THE PRESENCE OF UNINSULATED
DANGEROUS VOLTAGE WITHIN THE
UNIT'S ENCLOSURE THAT MAY BE OF
SUFFICIENT MAGNITUDE TO
CONSTITUTE A RISK OF ELECTRIC
SHOCK.
THIS SYMBOL IS INTENDED TO ALERT
YOU OF THE PRESENCE OF
IMPORTANT OPERATING AND
MAINTENANCE INSTRUCTIONS IN THE
LITERATURE ACCOMPANYING THE
UNIT.
WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO
NOT EXPOSE THIS UNIT TO RAIN OR
MOISTURE. TO AVOID ELECTRICAL SHOCK, DO
NOT OPEN THE UNIT. REFER SERVICING TO
QUALIFIED PERSONNEL.
Never install or remove the power cord from the chassis
unless it has been disconnected from the AC power source
first.
Never pull on the power cord when removing it from an AC
power source. Grasp it by the plug.
Do not leave the power cord connected to an AC power
source unless it is connected to the unit.
It is recommend that during extended periods of non-use
that the units power cord be unplugged from its AC power
source.
Route the AC power cord so that it will not be damaged or
walked on.
!

2
INTRODUCTION
This preamplifier is a precision device, designed in an effort to provide the listener with
unmatched sound quality, design, and construction. In order to operate your preamplifier
properly and to realize all of the capabilities of the 07X PREAMPLIFIER we recommend that
you read this entire manual carefully.

3
INSTALLATION CONNECTIONS
Illustrated below is the rear panel of the 07X. The connections are standard and typical of any
audio preamplifier. Any unknown features should be adequately explained by the function
descriptions on the following page.
Both sets of balanced receptacles on the left side are identical stereo outputs suitable for
connection to multiple amplifiers. The two sets of balanced receptacles on the right side are
separate input channels.
Make sure during installation that the AC power connections are interrupted to the
preamplifier and all other components are off. While the diagram may be self explanatory, we
strongly recommend that you read the front panel description on the following page for use
instructions.

4
DETAILED INSTALLATION
When adjusting individual channel level for balancing purposes, the display shows "actual"
decibel level. In other words, the default value of "0" on the LEFT or RIGHT channel mode,
shows that the channel is not attenuated. A value of "99" shows the channel is -99 db below
full volume.
FOR VOLUME ADJUSTMENT: The volume display shows "relative" volume level. When the
display reads "99" there is no decibel attenuation, "00" is the maximum decibel attenuation,
and level changes occur in 1dB increments.
3. The MONO button combines the left and right audio channels.
FOR BALANCE ADJUSTMENT: In the window next to the number display are three indicator
LEDs, MAIN, LEFT, and RIGHT. In the MAIN mode (blue LED) the display readout shows
volume level. In the LEFT mode (white LED) the display readout shows left balance level. In
the RIGHT mode (red LED) the display readout shows right balance level. In addition the
display will flash on and o when the volume is muted.
7. To adjust the GAIN of each input ( to match the levels of all the components in the system),
press and hold its selector button while you press the volume knob - then release them both.
The display will switch to "00" and the selected input light will flash.
5. Volume and balance setting is indicated by the decibel (dB) display.
4. The BYPASS button will cause the gain to drop to unity, bypassing the normal 12dB
standard gain of the 07x.
6. The VOLUME/BALANCE is controlled by the optical encoder control . Clockwise rotation
increases level, counter clockwise rotation decreases level. Left balance is selected by
pressing the knob once, and adjusting the level. Right balance is made by pressing the knob
again, and adjusting the level. Pressing the knob once again will bring it back to being a
volume control.
Turn the volume knob clockwise to raise the input gain up to +18db or turn counter clockwise
to reduce the input level up to -99 db (note that the signs "-"or "+" are not displayed).
To switch back to MAIN, press any button or the knob, or wait fifteen seconds.
2. The PROCESSOR button switches in an audio processor (surround sound, equalizer, etc.)
1. The first four buttons select the input source.

REMOTE OPERATION
The 07x can be operated by remote control. The MX-450 Learning Remote is
included with the amplifier. For instructions on using the MX-450 itself see the
on screen manual included in the remote.
5
DETAILED INSTALLATION

6
DESIGN PHILOSOPHY
Noise is kept low by multiple paralleling of input devices, careful selection of circuit
impedances, and pre-screening of devices. The Class A complimentary followers used to
drive the preamplifier output are of such speed, linearity, and low output impedance that no
feedback correction is required or used. The advantage of this is that the circuit's perfect
stability and transient response are preserved into a wide range of dicult and unpredictable
loads. Variation in sound, which could occur through interactions with interconnect cables and
other system elements are thus avoided.
They limit resolution because the most contacts available on rotary switches are thirty-one.
This requires two or three dB steps in order to get enough range out of the attenuator, which
isn't a fine enough resolution for most listeners. Switched attenuators also introduce switching
transients (a "click" or "pop") each time they change positions.
This noise comes from two sources. The first is mechanical noise from the switch itself as its
ball-detent mechanism moves from detent to detent. But a more troublesome source is the
voltage difference caused by the change in the musical waveform during the time it takes the
switch to move from one position to the next. The greater the voltage difference, the louder
the transient.
FETs are inherently transconductance devices, meaning that an input voltage controls an
output current. Unlike conventional transistors, FETs have extremely high input impedance
(about 10 meg ohm - similar to vacuum tubes). The FET "senses" the audio signal without
drawing current from the source. This eliminates complex interactions with the source, allows
maximum performance from each system element, and greatly reduces the chance of cable
characteristics altering the sound. The absence of input current in FETs allows high bias
currents for linearity and speed without sacricing DC parameters.
The circuitry used in the FET PREAMPLIFIER 07x is the result of an advanced and complete
design process combining innovation and prove fundamentals. This process avoids both the
limitations of total adherence to convention and the flaws resulting from inappropriate
applications of clever circuit gimmicks.
Impedance isolation and matching is derived from FETs. While careful design can yield good
results from any device type, FETs consistently have the edge in voltage gain, low noise, low
interaction, and interface applications.
Until recently, perfect volume controls (attenuators) did not exist. This is because
conventional stereo potentiometers have serious channel mistracking (20% typically),
become noisy with age, wear out, and have poor resolution of level - particularly when
operated by a motor as required for remote operation. In an attempt to solve these problems,
many manufacturers have been using "switched attenuators", which are discrete, resistor
ladders built on rotary switches. But while these eliminate channel mistracking, they introduce
new problems, including limited resolution, stepping transients, and cannot be operated
remotely. And they still wear out.

7
DESIGN PHILOSOPHY
1. Finishes - All exterior and interior metal parts are anodized. While paint may be more
impact resistant, the anodized surface is more resistant to solvents and prevents corrosion.
Moreover, the anodized parts' appearance can be enhanced by either graining or bead-
blasting the surface.
2. Circuit Board - Circuit boards are fiberglass epoxy with gold plating over a tin/nickel barrier.
This gold layer will not corrode, while the barrier plate prevents the gold from migrating to the
lower copper layer and detracting from its appearance.
5. Semiconductors - There are no integrated circuits (IC) to be found in the circuit path. Very
high quality dual FETs are the only source of voltage gain and were selected for their superb
noise performance and precision matching. The remaining semiconductors are also of very
high quality, each possessing parameters ideally suited for the specific application.
4. Capacitors - All capacitors are of high quality. The only electrolytics used are in the power
supply where large numbers provide enormous filtering capacitance for the supply.
6. Connectors - Coda employs a standard RCA configuration with a gold plated case. The
balanced connectors are Neutriks from Switzerland.
3. Resistors - All are high reliability metal film 1% resistors.
7. Wire - All signal wire has been eliminated whenever possible. Where wire is used, Coda
employs silver plated copper, 141 strand, 18 gauge wire with a silicone insulation.

8
TECHNICAL DATA
Frequency Response:
-3dB @ 5Hz to 200kHz
Distortion:
<.005% from 10Hz to 40kHz @ 5V peak into 600 ohms or higher, shunted by 1000pF or less.
Gain:
12dB plus 0-18dB variable per input in 1dB steps. Unity gain when Bypass feature is
enabled.
Maximum Output:
Regulated supply with shielded toroidal transformer and 19,800uF of low-ESR capacitance
and capacitors smoothing the regulator outputs.
50 Ohms non-reactive unbalanced
20 kOhms balanced or unbalanced
90dB @ 20kHz
Dimensions:
Power Consumption: 10 Watts
Output Impedance:
Width: 18” Faceplate, 17.0” Chassis
<110dBA referenced to 1V output
Power Supply Specifications:
Depth: 9.75” Overall
Crosstalk:
Weight: 14.0 lbs Shipping
Noise:
100 Ohms non-reactive balanced
Height: 2.5” Faceplate, 2.85” Overall
Input Impedance:
10V peak

9
CARE & HANDLING
When handling the unit, take care not to mar the aluminum. Aluminum is a medium hardness
metal and can be scratched by the harder tool steels.
Avoid exposing the unit to direct sunlight, and keep it away from sources of intense heat.
The interior of the unit requires no special care. If it becomes necessary to clean the exterior,
a simple dusting may be all that is required. If a cleaner is necessary, any dilute commercial
ammonia based product will be appropriate. NEVER use any abrasive rags, cleaners or
chemical solvents on Coda products.
Do not throw away the carton or associated packing material. They are ideal if you need to
pack the unit for moving and in the unlikely event that servicing is needed, they will be
necessary for safe shipment.
Be sure to provide adequate insurance when shipping.

10
WARRANTY & DISCLAIMER
I. Warranty - Any failure of the Coda product, hereafter known as the product or original
product, to operate or to meet specifications, applicable at time of manufacture, due to a
manufacturing defect or component failure, will be corrected by Coda Technologies without
charge for parts or labor, for a period of ten years from date of original purchase. Coda
Technologies will provide for surface transportation to and from the factory for a period of one
year from date of original purchase.
i. operation not in accordance with the instructions in this manual
iii. serial number defacement
III. Exclusion of Coverage - Coda Technologies is not obligated to service the product in
certain conditions, as according to the following subsections.
c. The product has been transported outside of the United States of America.
In these conditions any service will be made at Coda Technologies sole option.
b. The product has been transferred to a third party. This warranty is valid only for
the original purchaser of the product.
ii. abuse, tampering, modification or accident
II. Procedure - If the product should require service under warranty contact Coda
Technologies at the location on the back cover of this manual for shipping instructions.
Products purchased outside of the United States will be covered by the warranty conditions
extended by the importing distributor which may differ from those given above.
a. The product has been damaged through:
This warranty gives you specific legal rights. You may have other rights which vary from state
to state.
IV. Total Loss and Replacement - If the product is submitted for service due to a severe
malfunction which has caused damage sufficient enough to make a repair attempt infeasible,
the product will be replaced with another unit of equal or superior specifications. Coda
Technologies product line is frequently updated and changed, and the specific model and
version of the original product may be discontinued at any time without notice. In this case no
guarantees are made that the replacement unit will be visually similar to the original product.
Disclaimer - Coda Technologies cannot be held responsible for any damage caused by their
products, including but not limited to:
c. Damage caused by defects in design, construction or component quality.
VI. Unnecessary Service - In all conditions, if the product is submitted for service and found
to be operated without fault and within specifications, shipping charges will be billed to the
customer.
b. Damage caused by connecting a load to a Coda Technologies product having
an improper impedance as described in the products manual.
V. Subjective Differences - No guarantee is made that the product will perform to any
specifications that cannot be measured and confirmed with precision audio analysis
equipment. Coda Technologies is only obligated to make repairs which will bring the product
into compliance with the specifications stated in this manual.
a. Damage to speakers caused by failure of a Coda Technologies product to mute
or disable itself as expected or described in its manual.

11
WARRANTY REGISTRATION
It is recommended that you retain a copy of this form for your own records. Coda
Technologies’ address and fax number are located on the back of this manual.
Fill in this registration sheet and fax or mail it to Coda Technologies to ensure you are in our
warranty system. This will facilitate warranty service should it become necessary.
MODEL DESIGNATION:
DATE OF PURCHASE:
PLACE OF PURCHASE
SERIAL NUMBER:
NOTES:
Phone:
Name:
OWNER INFORMATION
Address:
City: State: Zip:
Phone:
Address:
City: State: Zip:
Name:

12
WARRANTY REGISTRATION
It is recommended that you retain a copy of this form for your own records. Coda
Technologies’ address and fax number are located on the back of this manual.
Fill in this registration sheet and fax or mail it to Coda Technologies to ensure you are in our
warranty system. This will facilitate warranty service should it become necessary.
SERIAL NUMBER:
DATE OF PURCHASE:
PLACE OF PURCHASE
Name:
Address:
OWNER INFORMATION
MODEL DESIGNATION:
Phone:
Name:
City: State: Zip:
City: State: Zip:
Phone:
Address:
NOTES:

SACRAMENTO, CA 95826 USA
7850 CUCAMONGA AVENUE #34
email us at [email protected]
phone fax [phone] +01 916.455.3653
on the web at CODA.CC