RTZ 9762A User manual

RTZ Professional Audio, LLC
Atlanta, GA USA
http://www.rtzaudio.com
COPYRIGHT © 2014, RTZ PROFESSIONAL AUDIO, LLC REV-A.03
05/12/2014
9762A
LEGENDS 500
MICROPHONE PREAMPLIFIER
Owner’s Manual
RTZ PROFESSIONAL AUDIO

TABLE OF CONTENTS
1WELCOME!............................................................................................................................. 3
2OVERVIEW ............................................................................................................................. 3
3INSTALLATION AND CONNECTIONS.................................................................................. 4
3.1 ENVIRONMENTAL CONSIDERATIONS.................................................................................... 4
3.2 CLEANING THE UNIT........................................................................................................... 4
3.3 MODULE CONNECTIONS..................................................................................................... 5
5FRONT PANEL CONTROLS.................................................................................................. 8
5.1 +48V PHANTOM POWER ENABLE ....................................................................................... 9
5.2 +48V POWER STATUS INDICATOR...................................................................................... 9
5.3 OVERLOAD SIGNAL (OL) INDICATOR................................................................................... 9
5.4 GAIN SELECT SWITCH........................................................................................................ 9
5.5 SIGNAL PRESENT (SP) INDICATOR...................................................................................... 9
5.6 DIRECT INSTRUMENT (DI) SOURCE SELECT........................................................................ 9
5.7 LOW-Z MICROPHONE IMPEDANCE SELECT.......................................................................... 9
5.8 LINE OUTPUT POLARITY INVERT SELECT........................................................................... 10
5.9 100 HZ HIGH PASS FILTER ENABLE.................................................................................. 10
5.10 LINE OUTPUT VU METER INDICATOR................................................................................ 10
5.11 DIRECT INPUT (DI) -UNBALANCED.................................................................................... 10
5.12 OUTPUT LEVEL CONTROL ................................................................................................ 10
6OPERATION ......................................................................................................................... 11
6.1 GAIN AND LEVEL ADJUSTMENTS....................................................................................... 11
6.2 USING THE DI INPUT ........................................................................................................ 11
6.3 POLARITY AND IMPEDANCE SELECTION............................................................................. 12
6.4 USING 48V PHANTOM POWER.......................................................................................... 12
6.5 LINE OUTPUT TRANSFORMER TERMINATION...................................................................... 12
7HARDWARE CONFIGURATION FEATURES..................................................................... 13
7.1 PHANTOM POWER ENABLE SWITCH (S1) .......................................................................... 13
7.2 LINE OUTPUT TRANSFORMER STRAPPING (JP2) ............................................................... 13
7.3 LINE OUTPUT TRANSFORMER TERMINATION (JP1)............................................................ 14
7.4 48V LED CONFIGURATION OPTIONS (JP3)....................................................................... 14
8SPECIFICATIONS ................................................................................................................ 16
9LIMITED WARRANTY.......................................................................................................... 17

9762A –Preamplifier Owner’s Manual
Page 3
RTZ Professional Audio
1 Welcome!
Thank you for purchasing your new Model 9762A Legends 500 Series
microphone preamplifier! Before operating or installing the unit, please
read this manual thoroughly and retain it for future reference. Additional
copies of this manual are available upon request or from our website at
http://www.rtzaudio.com.
All units are carefully packed to endure the rigors of shipping and
handling. However, please inspect all contents and packaging
immediately upon receipt. Please report any problems to us immediately.
In the event of damage, retain all shipping and packaging materials for
shipper damage claims inspection.
The 9762A is designed to deliver a lifetime of musical pleasure and
trouble free operation. If you experience any problems or difficulties,
please contact us directly. Do not attempt to modify, alter or repair the
unit yourself. Each unit has been carefully tested and calibrated for
proper operation. Any unauthorized modifications may destroy the unit or
severely degrade performance and void the warranty.
2 Overview
The 9762 preamplifier is designed to emulate the vintage 1970s large
format consoles (i.e. Neve 1073 Series) yet provide a more open and
detailed sound by using modern components and transformers. We use
a super high quality input transformer (manufactured by Lars Lundahl of
Sweden) with excellent sonic performance. This transformer is
considered by many to be one of the world’s finest input transformers.
The preamp gain blocks and gain structure have been carefully
optimized to match the input transformer impedance characteristics as
closely as possible. This combination of classic circuitry and a modern
input transformer allows the 9762 to deliver a classic super fat sound
with the benefit of increased high-end openness and clarity.
The standard unit contains a single channel of high gain amplification
capable of providing up to 75 dB of gain. The microphone input and line
output signals are fully transformer balanced and isolated. The (DI)
instrument input is unbalanced. Standard features include +48V
Phantom power, polarity (phase) reverse, DI input source select,
microphone impedance select and HPF (high pass filter) options. The
9762A is a high performance preamplifier designed for the popular 500
Series modular rack style format. It is well suited for professional
recording, sound reinforcement, broadcast or any application where a
high quality preamplifier is required.

9762A –Preamplifier Owner’s Manual
Page 4
RTZ Professional Audio
3 Installation and Connections
The 9762A is designed for standard API™ 500 Series compatible
modular rack systems. Ideally, the rack should be mounted where cool
air flows across the rack and modules. Do not obstruct the flow of air
around and across or through the preamplifier module or rack. In tight
equipment enclosures, consider placing a ventilated rack panel between
racks to allow increased airflow. Do not place the rack or module unit
near strong magnetic fields and noise sources such as power amplifiers,
console power supplies, transformers, motors, florescent lighting,
computers, etc.
3.1 Environmental Considerations
The 9762A is designed to operate reliably over a wide range of ambient
temperatures. Always provide proper ventilation to avoid overheating
conditions. This extends component life and provides maximum
operational stability of the circuits. Ideally, the 500-series mainframe
housing the module should be mounted in a rack where cool air flows
around all sides of the rack and unit.
The 9762A is fully transformer isolated to help reduce interference and
hum from outside sources. However, the unit should not be placed near
strong magnetic fields or noise sources such as power amplifiers, power
supplies, transformers, motors, florescent lighting, computers, etc.
Mount the power supply away from the module rack or other audio gear
to avoid magnetic field radiation. This is especially true of the line output
transformer (or output transformers in any other modules, RTZ or not)
3.2 Cleaning the Unit
The 9762A is painted with a durable epoxy paint, but always use care
not to scratch the finish or metal. Do not use harsh cleaners or chemicals
to clean the unit or knobs. Use alcohol or a mild window glass cleaner
with a cotton ball the clean the control surfaces. Do not spray any
cleaners on the PCB or faceplate to avoid seepage into the unit and or
possible damage to the PCB or components.
WARNING
NEVER INSERT THE 9762A MODULE INTO A RACK WITH POWER
APPLIED; DOING SO WILL LIKELY DAMAGE THE MODULE AND
VOID THE WARRANTY. NONE OF THE 500-SERIES RACKS ARE
DESIGNED TO ALLOW HOT-SWAPPING MODULES. DOING SO
COULD DAMAGE THE MODULE BEING INSTALLED, AND/OR
OTHER MODULES ALREADY INSTALLED, AND/OR THE RACK
ITSELF. TO AVOID DAMAGE, ALWAYS POWER THE RACK DOWN
WHEN INSTALLING ANY MODULE.

9762A –Preamplifier Owner’s Manual
Page 5
RTZ Professional Audio
3.3 Module Connections
Install the module in a 500 rack (always with the rack powered down)
and verify that the XLR input and output cables are connected properly.
In some cases you may wish to lift the ground wire from pin 1 of the
output signal XLR cable to “float” the ground and create a “telescopic
shield”. This method provides full ground loop isolation since the 9762A
is fully transformer isolated.
The 9762A is designed for balanced mode operation as typically found in
professional studio installations. While it can be wired for unbalanced
operation, we highly recommend using balanced mode operation for
reduced hum and interference. If you must wire the unit for unbalanced
operation, keep the cables as short as possible. Connect pin-3 of the
rack output signal connector to ground for unbalanced operation. Note:
the transformer coupled output means that you MUST connect pin 3 to
ground for unbalanced operation. It’s best to carry pin-3 all the way to the
unbalanced input and ground it there.
Power up the rack after all the I/O cables and connections are properly
established. The 9762A VU and signal LED’s should illuminate when the
rack is powered up. If the LED’s fail to illuminate, check that your
mainframe has the correct +/- 16V power and that no fuses are blown.
Table 1: Edge Finger Pin Definitions
Pin#
Description
1
CHASSIS GROUND
2
OUTPUT '+' (+4 dBm)
3
N/C
4
OUTPUT -' (+4 dBm)
5
AUDIO GROUND
6
N/C
7
N/C
8
INPUT '-' (+4 dBm)
9
N/C
10
INPUT '+' (+4 dBm)
11
N/C
12
+16 VOLTS DC
13
POWER GROUND
14
-16 VOLTS DC
15
+48 VOLTS DC

9762A –Preamplifier Owner’s Manual
Page 6
RTZ Professional Audio
4 Design Features
The 9762A has been designed and built with great attention to detail. In
particular, the input transformer and gain switching network have been
painstakingly matched and optimized to present the proper load
impedance to the microphone transformer (and hence, the microphone)
at all gain settings. This refinement, combined with a super high quality
input transformer, gives the 9762A a more detailed sound when
compared to vintage units.
The module’s PCB carrier and faceplate are made of heavy gauge steel
for extra strength and maximum magnetic shielding. The PCB is a four
layer design with full ground plane shielding to serve as a signal
reference plane internally for maximum signal isolation and ground
shielding.
4.1 Input Stages
The input transformers are optimized for 200-Ohm impedance
microphones or other devices having 200-Ohm source impedance. The
LO-Z impedance select switch configures the transformer input for either
50-Ohm (LO-Z) or 200-Ohm source impedance. Keep in mind that the
impedance select switching is accomplished by configuring the input
transformer primary wiring as either a series or parallel circuit, which
affects the transformer’s turns ratio. By nature, the impedance switching
affects the signal level by roughly 6 dB when switching impedances.
Miniature sealed gold contact relays are used for all audio switching
functions and maximum reliability.
A separate high impedance FET buffer stage is used in the instrument
direct input (DI) stage. The FET input buffer stage serves as a high
impedance conversion stage designed to prevent loading of the
instrument pickups. The DI switch allows manual selection of the DI or
microphone input source. Additionally, the DI select switch may also
serve as a channel mute switch when the DI or microphone input is not
in use.
4.2 Phantom Power
The phantom power switching circuitry uses a smooth power ramping
design to help reduce pops and clicks during switching. The phantom
voltage ramps up quickly when enabled and ramps down quickly when
disabled. Phantom power may also be completely disabled via DIP
switch S1 located on the lower PCB near the edge fingers. Phantom
power is fully protected against continuous shorting via each channel’s
current limiting resistors.
4.3 Gain Blocks and Metering
The 9762 provides up to 75 dB maximum gain using a dual gain block
type design. Gain is selectable from –20 dB to -75 dB in 5 dB increments
via the twelve position rotary switch. At higher gain settings (above -50
dB), a second gain block is inserted into the signal path for additional
gain and increased headroom. The input signal stages are designed for
maximum headroom throughout the audio path at any gain setting.

9762A –Preamplifier Owner’s Manual
Page 7
RTZ Professional Audio
The SP (signal present) and OL (overload) LED’s provide input stage
signal monitoring. In normal use the OL should not light to prevent signal
distortion. The signal quality degrades rather quickly once the OL
threshold is reached. The SP and OL LED’s monitor channel activity and
clipping for the signal source currently selected by the DI switch.
The eight LED VU meter monitors the master output level from the line
amplifier stage. The first LED lights at around –20 dB with subsequent
steps at –10 dB, –6 dB, –3 dB, 0 dB, +3 dB, +10 dB and +18 dB. The
master LEVEL control is used to trim the output level using the VU meter
as a level reference.
4.4 Line Amplifier Stage
The line amplifier stage input level is controlled by the master LEVEL
control. The LEVEL control acts as a channel fader to trim the line
amplifier output as needed. In general, the LEVEL control should be set
to the maximum position (fully CW) and the input GAIN control is then
adjusted to obtain the desired output signal level. If the output signal is
slightly “hot”, use the LEVEL control to trim the output level back to
obtain the desired output signal level.
In situations where distortion or warmth is desired, the input GAIN setting
may be set “hot” and the output LEVEL control is used to trim the output
back to a suitable level. Use care with this technique to avoid overdriving
the input stage excessively as the signal becomes very ugly sounding at
extremes. Also, keep in mind the line amplifier stage is capable of
delivering very large output level swings (around 40V peak-to-peak!);
excessive signal levels could damage the input stages of gear being
driven by the 9762.

9762A –Preamplifier Owner’s Manual
Page 8
RTZ Professional Audio
5 Front Panel Controls
1. +48V Phantom Power Enable
2. +48V Power Status Indicator
3. Signal Overload (OL) Indicator
4. Gain Select Switch
5. Signal Present (SP) Indicator
6. Direct Input (DI) Source Select
7. Low-Z Microphone Impedance Select
8. Line Output Polarity Invert Select
9. 100 Hz High Pass Filter Enable
10. Line Output VU Meter Indicator
11.Direct Input - Unbalanced
12. Output Level Control

9762A –Preamplifier Owner’s Manual
Page 9
RTZ Professional Audio
5.1 +48V Phantom Power Enable
This switch enables +48V phantom microphone power on the rear
microphone input connector. The LED next to the switch lights when
phantom power is active. The +48V switch controls circuitry that ramps
the 48V power up or down gradually to reduce unwanted bangs or pops
in the audio signal.
5.2 +48V Power Status Indicator
This LED indicates when phantom power is active. Note that the
hardware switch S1 on the lower PCB near the edge fingers can be used
to completely disable phantom power to the microphone; this feature is
useful to protect ribbon microphones when used with the 9762A.
5.3 Overload Signal (OL) Indicator
This LED indicates signal overload/clipping conditions at the input gain
block stages. In normal use the LED should not light or flicker. Reduce
the input GAIN switch to lower the input gain and avoid clipping.
5.4 Gain Select Switch
The rotary gain switch has twelve positions that select the input
sensitivity in 5 dB increments from -20 dB to –75 dB for a maximum gain
of 75 dB. The unit is set to maximum gain in the fully CW position.
Always start at the lowest gain setting and increase the gain to obtain the
desired output level.
5.5 Signal Present (SP) Indicator
The SP LED indicates signal activity on the microphone input. The
detector is sourced from the gain blocks prior to the line amplifier and
output LEVEL control. This LED lights at around -30 dBu (referenced to
775 mV) to indicate activity.
5.6 Direct Instrument (DI) Source Select
The DI switch selects the preamp input signal from either the unbalanced
DI input jack or the balanced Microphone Input connector on the rear
panel. The DI input jack is selected in the depressed position; otherwise
the balanced XLR microphone input connector is selected. Note that the
DI switch may also serve as a “MUTE” switch when only one input
source is being used.
5.7 Low-Z Microphone Impedance Select
This switch configures the input transformer for Low-Z impedance mode.
The input transformer and circuitry is optimized for 50-Ohm microphones
or other devices having 50-Ohm source impedance. In the non-
depressed state the input transformer is configured for 200-Ohm source
impedance. Note that the input signal level varies by approximately 6 dB
when the switch is operated. Adjust the gain switch to compensate for
the level change and to avoid masking the tonal differences between
impedance settings when changing impedances.

9762A –Preamplifier Owner’s Manual
Page 10
RTZ Professional Audio
5.8 Line Output Polarity Invert Select
This switch inverts the line output polarity (phase) in the depressed
position. Normally the unit will be used with polarity in the non-inverted
state, however you may use this switch to reverse the polarity if needed.
5.9 100 Hz High Pass Filter Enable
This switch enables the 100 Hz high pass filter (HPF). The HPF is 3dB
down at 100 Hz and attenuates signals below this at a rate of 12 dB per
octave. The HPF is useful to cut unwanted low frequency signals when
less low frequency content is desired.
5.10 Line Output VU Meter Indicator
The eight LED’s provide output VU Meter level indication sourced from
the line output amplifier at +18, +10, +3, 0, -3, -6, -10 and –20 dB. The
“0” LED indicates 0 dB output level referenced to +4 dBm.
5.11 Direct Input (DI) - Unbalanced
The Direct Input is designed for use with instrument sources and is
buffered by a Hi-Z FET stage to avoid instrument pickup loading. The
input connector accepts standard ¼“ Phone Plugs in either TS (Mono –
TIP, SLEEVE) or TRS (Stereo –TIP, RING, SLEEVE). Note that when
TRS connectors are used, the RING and SLEEVE are both referenced to
ground internally. The DI input may also be used as an unbalanced
direct input, however, line level +4 dBu signal levels will most likely result
in distortion. In this case, the signal level should be reduced from the
source.
5.12 Output Level Control
The output level control acts as a master fader to facilitate fine trimming
of the output signal level from –90 to 0 dB as required. In normal
operation this control should be set to maximum level (fully CW position)
and then trimmed back as needed to obtain the desired output signal
level.

9762A –Preamplifier Owner’s Manual
Page 11
RTZ Professional Audio
6 Operation
The 9762A is designed for convenience and ease of use. In general you
should experiment with a variety of microphones, placements and
settings to achieve best results. The 9762A works well with all types of
balanced microphones (dynamic and condenser) and is exceptionally
suited for use with ribbon type microphones.
The preamplifier may be located in the studio control room or in the
recording room itself. Ideally there should be a minimum of additional
cables, boxes or connectors between the unit and the microphones for
best results. The use of high-quality microphones and cables with gold
contacts are highly recommended.
6.1 Gain and Level Adjustments
In normal use the output LEVEL control should be set to the maximum
position (fully CW). The LEVEL control acts as a master fader control for
overall output level adjustment. The line amplifier input stage is sourced
from the LEVEL control and provides up to 10 dB gain. Thus, the output
LEVEL control is used for any adjustment or trimming of the master
output level.
Typically the line output of the preamplifier directly feeds a track on a
recorder or other piece of inline gear. Always start with the lowest setting
on the GAIN switch (fully CCW in the –20 dB position) and increase the
sensitivity to obtain the desired record level. If the output level is slightly
higher than desired, trim the output level back using the LEVEL control.
The SP signal present indicator lights to indicate signal activity. Under
normal operation, the OL overload indicator should not light for the most
accurate results. Any clipping of the input stages will result in distortion. If
clipping occurs, reduce the input GAIN sensitivity switch to an acceptable
level. The output VU meter allows monitoring the output signal level
while adjusting the GAIN and LEVEL controls.
6.2 Using the DI Input
Recall the DI source select switch selects the front panel instrument
input jack in the depressed state. The DI input is primarily designed for
use with electric guitar, bass or similar instruments. The DI input may
also be used with other sources such as electronic keyboards if the
source’s output signal level is kept to a reasonably low level. However,
line level signals of +4 dBm or greater will most likely result in distortion.
The DI input is NOT a line input.
The DI switch also serves as a mute switch when only one input source
is being used (either the DI input jack or the microphone input). For
instance, if you are only using the microphone input and no cable is
plugged into the DI instrument input, press the DI switch to mute the
microphone input. The DI switch was added for this purpose rather than
automatic DI jack insert switching.

9762A –Preamplifier Owner’s Manual
Page 12
RTZ Professional Audio
6.3 Polarity and Impedance Selection
The POL polarity switch inverts the polarity (or phase) of the line output
transformer. When the POL switch is depressed a relay inverts the line
output transformer polarity. In most situations the polarity will be used in
normal phase with the POL switch in the non-depressed state.
Low impedance microphone operation is enabled when the LO-Z
impedance switch is in the depressed state. In most cases low
impedance is desired for 50-Ohm impedance microphones. Most modern
microphones expect a bridging load and the 9762’s input circuitry
accommodates this when the impedance switch is OUT.
Experiment with the LO-Z feature using a variety of microphones to
obtain the best sound and tonal qualities. Note that the signal level is
affected by roughly 5-6 dB when switching ratios. Adjust the GAIN switch
to compensate for the level change and to avoid masking tonal changes
as compared to the signal level change.
6.4 Using 48V Phantom Power
Notice the 48V LED gradually lights or dims when power is applied or
removed. Special ramping circuitry ramps the voltage up and down when
power is applied or removed to reduce large pops or bangs in the signal
output. Allow a second or two for the phantom power to reach full voltage
when enabled.
The phantom circuitry is protected against shorts for extended durations
and provides up to 14 mA of current for each channel. However, you
should always ensure the microphone or other phantom powered device
is working properly when using phantom power. Improper use of
phantom power may damage some microphones or other devices
connected to the microphone input that are not intended for use in the
presence of phantom power.
6.5 Line Output Transformer Termination
Jumper JP1 (see the Hardware Configuration Features section) on the
lower PCB is used to enable or select the termination resistor on the line
output transformer secondaries. In most situations termination should be
enabled to assure the flattest frequency response. However, you may
also disable termination to affect the sound in different ways depending
on the source impedance. In many cases removing termination adds a
slight amount of “air” to the signal due to the gentle HF rise property of
the output transformer when operating un-terminated.

9762A –Preamplifier Owner’s Manual
Page 13
RTZ Professional Audio
7 Hardware Configuration Features
The 9762A is equipped with a of number hardware configuration features
that may be controlled via jumpers and a DIP switch. The phantom
power feed may be completely disabled and disconnected from the
microphone input signal lines if desired. Configuration options are also
available for the output transformer impedance strapping and
termination.
7.1 Phantom Power Enable Switch (S1)
DIP switch S1 (see Figure 1) allows disabling all phantom power from
the balanced microphone input lines. No phantom power can be applied
to the microphone when this switch is disabled regardless of the +48V
switch setting on the front panel. Although the +48V LED will continue to
glow when the front panel +48V switch is enabled, no power flows to the
microphone if S1 is on the OFF position.
Note that switch S1 is provided to ensure that phantom power can never
be applied to a microphone by the preamp. Since certain types of
microphones (ribbon, etc.) may be damaged by the application of
phantom power, the 48V enable switch allows you to dedicate the
preamp for use with microphones that can’t tolerate phantom power.
7.2 Line Output Transformer Strapping (JP2)
The line output transformer has dual secondaries that can be configured
in series or parallel mode via JP2 (see Figure 1). The table below shows
the jumper settings for both strapping modes available. Note you should
also change the termination select jumper JP1 to match line impedance
strapping configuration for best frequency response.
Table 2 –JP2 Output Transformer Strapping
Impedance
Jumper Settings
HI-Z (1.2KΩ)
Jumper Pins 1+3
LO-Z (600Ω)
Jumper Pins 1+2 and 3+4

9762A –Preamplifier Owner’s Manual
Page 14
RTZ Professional Audio
7.3 Line Output Transformer Termination (JP1)
Jumper JP1 (see Figure 1) allows selecting the transformer termination
resistor to either 1.5K or 600 ohms. Note that the termination resistor
should be set to match the line out transformer secondary strapping
configuration as listed in Table 2.
Figure 1 –48V Enable Switch and Transformer Jumpers
7.4 48V LED Configuration Options (JP3)
The 48V phantom LED may be configured to indicate the presence of
phantom power in two modes. The use of external microphone splitter
transformers (mainly in live sound) opens up the possibility that phantom
power may be “back fed” into another preamp via the splitter transformer.
If another preamplifier is connected to the splitter and is supplying
phantom 48V, then the other preamplifier could see 48V applied to its
input from the other preamp on the splitter as well.
Table 3 - 48V LED Indicator Configuration Jumper

9762A –Preamplifier Owner’s Manual
Page 15
RTZ Professional Audio
Jumper JP3 allows for three configuration options for the +48V LED on
the front panel as shown in the following table.
Table 4 –JP3 Front Panel 48V LED Configuration Options
Mode
JP3
Description
Auto
1 & 2
48V LED glows if the +48V phantom power
switch is enabled or the unit if being “back fed”
48V from another microphone input source
through a microphone splitter or other external
source.
ON
2 & 3
The 48V LED only lights if the +48V phantom
power switch is enabled. The LED will not light
even if the unit is being “back fed” phantom
power into the microphone input from another
source.
OFF
(none)
The 48V will never light regardless of whether or
not phantom is being applied internally or
externally.
The 9762A ships with the 48V LED configured for “Auto” (pins 1 & 2)
mode as the default mode operation. This is the preferred mode of
operation in most cases and the 48V LED will indicate the presence of
phantom power either internally by 9762A or externally from another
source.
Note that you can completely disable the phantom power and LED via
JP3 and the S1 DIP switch. The 48V LED can be disabled via JP3 and
the power can be disabled via S1 such that all phantom power and
features are disabled. Thus, the preamp can never apply phantom power
to a microphone and the 48V LED and front panel switch are effectively
disabled. These features allow you to dedicate the preamp module for
use with non-phantom microphones if desired.
When S1 is used to defeat the possibility of phantom powering, it also
disconnects the phantom feed resistors from the input wiring, resulting in
the highest possible input impedance at the microphone input. This is the
preferable way to use the preamp with ribbon microphones, however you
may need the ability to use the 9762A with either type, in which case
leaving S1 set for phantom powering is the proper option.
S1 is mounted somewhat internally to the module, and is not really
meant to have its setting changed frequently. This causes wear to the
edge connector contacts, which was not meant for frequent mate/unmate
cycles.

9762A –Preamplifier Owner’s Manual
Page 16
RTZ Professional Audio
8 Specifications
Recommended Source Impedance.....................200Ω balanced
Recommended 9762A Load:...............................Low-Z (600Ω)
Maximum Input Level.......................................... 0 dBu
Output Level........................................................+27 dBu Maximum
Maximum Gain.................................................... 75 dB
Frequency Response..........................................20 Hz to 50 kHz ±1.5dB
Output Distortion (THD+n)...................................1% THD, 22kHz B/W
Low-Z mode, 150-Ohms source, 27 dBu
Input Sensitivity...................................................–75 dBu to –20 dBu for +4 dBu output
Input Referred Noise...........................................-106dBu Unweighted Noise, Lo Z Mode
22kHz Bandwidth
Power Requirements...........................................+/-16 VDC, 120mA
Temperature Range............................................ 10 C to 50 C
Shipping Weight.................................................. Approximately 2 lbs
Dimensions .........................................................5.25” (H) x 1.5”(W) x 5.6”(L)

Page 17
RTZ Professional Audio
9 LIMITED WARRANTY
RTZ Audio warrants this product to be free of defects in material and workmanship for a period of
5 years to the original owner. This warranty is enforceable by the original purchaser and is
transferable to a subsequent single owner via resale by the current owner. The current owner
must provide positive dated proof of the original purchase in the form of the original sales receipt,
original canceled check, or other form of positive original proof.
To request warranty service, the owner must call or contact RTZ Audio in writing to obtain a
return authorization and instructions concerning shipment. All authorized returns must be sent to
RTZ Audio postage prepaid, insured and properly packaged. We recommend using a shipping
method that provides delivery tracking. All warranty service returns must include positive proof of
purchase, such as a copy of the sales invoice, from the original sale.
During the warranty period RTZ Audio shall, at its sole and absolute option, either repair or
replace free of charge any product that proves to be defective upon inspection by RTZ Audio or
an authorized repair representative.
This warranty does not cover claims for damage due to abuse, neglect, alteration or attempted
repair by unauthorized personnel and is limited to failures arising during normal use that are due
to defects in material or workmanship in the product.
IN NO EVENT WILL RTZ AUDIO BE LIABLE FOR INCIDENTAL, CONSEQUENTIAL OR
OTHER DAMAGES RESULTING FROM THE BREACH OF ANY EXPRESS OR IMPLIED
WARRANTY, INCLUDING AMONG OTHER THINGS, DAMAGE TO PROPERTY, DAMAGE
BASED ON INCONVENIENCE OR ON LOSS OF USE OF THE PRODUCT, AND, TO THE
EXTENT PERMITTED BY LAW, DAMAGES FOR PERSONAL INJURY. Some states do not
allow the exclusion of limitation of incidental or consequential damages, so the above limitation or
exclusion may not apply to you.
This warranty gives you specific legal rights, and you may also have other rights, which vary from
state to state. This warranty only applies to products sold and used in the United States of
America. For warranty information in all other countries, please contact RTZ Audio directly.
RTZ PROFESSIONAL AUDIO, LLC
ALPHARETTA, GA USA
TEL [phone]
http://www.rtzaudio.com