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THETA DIGITAL
CORPORATION
Citadel
Owner’s Manual
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PREFACE
CONGRATULATIONS
You have just acquired one of the most advanced and versatile components for the amplification of audio ever
to have been developed.
IMPORTANT
Save all packaging in a dry place away from fire hazards. Your Citadel is a precision electronic instrument and
should be properly packaged any time shipment is made. In the unlikely event that you have to return your
Citadel to the factory or dealer for service or updating, the original packaging will best protect the unit from
shipping damage.
In order to achieve the fullest flexibility and enjoyment from your Citadel, we at Theta recommend that you
read this manual in full before connecting the unit to your audio system.
Note: It is imperative that the Citadel be operated in a well-ventilated environment and that the immediate
external temperature be maintained as specified. External cooling fans may be required in some cases. Do
not stack any equipment directly above, below or to the immediate sides of the Citadel to protect it from
overheating, as well as to protect the continued functionality of equipment near and around it.
Warning: The Citadel is a balanced bridge amplifier, thus the negative speaker terminal is NOT
cannot be connected to a system ground or a loudspeaker system with a common ground. Consult your
speaker manufacturer to ensure that any speaker in your system that will be connected to the Citadel does
have internal circuitry with a common ground.
NOT
WARNING: When connecting the speaker wire to the Delrin output connector, using the hex tool provided –
DO NOT OVER TIGHTEN. There is a lot of surface area in the Delrin connector to create a complete
connection with a minimum of torque applied. OVER TIGHTENING WILL ULTIMATELY BREAK THE
DELRIN CONNECTOR, WHICH WILL NOT BE COVERED UNDER WARRANTY.
WARNING
United States law prohibits disposition of these commodities to Libya, Laos, North Korea, Cambodia or Cuba
unless otherwise authorized by the United States.
2001 Theta Digital Corporation. All rights reserved.
Written and Illustrated by Glenn Buckley.
This manual is also available for download as a PDF file at Theta Digital’s website. http://www.thetadigital.com
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or
mechanical, for any purpose, without the express written permission of Theta Digital Corporation.
a ground, and
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The lightning flash with arrowhead symbol, within an equilateral
triangle, is intended to alert the user to the presence of uninsulated
“dangerous voltage” within the product’s enclosure that may be of
significant magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert
the user to the presence of important operating and maintenance
(servicing) instructions in the literature accompanying the product.
WARNING
TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,
DO NOT EXPOSE THIS PRODUCT TO RAIN OR MOISTURE
CAUTION: TO PREVENT ELECTRIC SHOCK, DO NOT USE THE AC (POLARIZED) PLUG WITH AN
EXTENSION CORD, RECEPTACLE OR OTHER OUTLET UNLESS THE BLADES CAN BE FULLY
INSERTED TO PREVENT BLADE EXPOSURE.
Extension cords are not recommended for use with this product.
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Citadel Identification Record
This information is for your records and for future identification of the Citadel. Please take a moment to fill
out all pertinent data now, and as upgrades and/or options are installed. Whenever upgrades, inquiries
and/or changes are requested, the serial number will be required.
SERIAL NUMBER
DATE PURCHASED
DEALER’S NAME
DEALER’S ADDRESS/PHONE
INSTALLED CARDS/OPTIONS
(Date of installation)
(Date of installation)
(Date of installation)
(Date of installation)
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SAFETY PRECAUTIONS
Please carefully read each item of the operating instructions and safety precautions before installing and
using this product. Use extra care to follow the warnings written on the product itself and/or in the operating
instructions. Keep the operating instructions and safety precautions for future reference.
CAUTION: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT REMOVE ANY OF THE COVER
PANELS.
NO USER-SERVICEABLE PARTS INSIDE. REFER ALL SERVICING TO QUALIFIED SERVICE
PERSONNEL ONLY.
TO PREVENT FIRE OR SHOCK HAZARD, DO NOT ALLOW LIQUIDS TO SPILL OR OBJECTS TO FALL
INTO ANY OPENINGS OF THE PRODUCT.
THIS UNIT IS SUPPLIED WITH TWO 3 PIN GROUNDED AC PLUGS. ALWAYS INSERT THE AC PLUGS
INTO GROUNDED OUTLETS. DO NOT REMOVE THE GROUND PINS OR DISABLE THE GROUNDS
FOR ANY PURPOSE.
BEFORE MAKING ANY CONNECTIONS TO THE CITADEL, FIRST TURN OFF THE POWER AND THEN
DISCONNECT THE AC POWER CORDS.
WHEN INSTALLING THE CITADEL IN YOUR SYSTEM, MAKE CERTAIN TO ALLOW A MINIMUM OF 6
INCHES OF VENTILATION ON TOP AND ON EACH SIDE OF THE UNIT. IMPROPER VENTILATION OF
THE UNIT MAY CAUSE OVERHEATING, WHICH MAY DAMAGE THE UNIT AND CAUSE A FIRE.
PLACE THE UNIT ON A SOLID SURFACE ONLY. I.E. NOT ON CARPET, ETC.
DO NOT PLACE THE CITADEL NEAR HEAT SOURCES SUCH AS DIRECT SUNLIGHT, STOVES, HEAT
REGISTERS, RADIATORS OR OTHER HEAT PRODUCING EQUIPMENT.
TO PREVENT DAMAGE TO THE ANALOG OUTPUT CIRCUITRY, BE CERTAIN NOT TO SHORT THE
OUTPUT SIGNAL TO GROUND. ENSURE THAT YOUR AUDIO OUTPUT CABLES DO NOT HAVE ANY
INTERNAL SHORTS BEFORE CONNECTING THEM TO THE CITADEL.
IF REPLACEMENT OF THE AC LINE FUSE AND/OR ANY INTERNAL FUSE BECOMES NECESSARY,
REPLACE ONLY WITH SAME VALUE AND TYPE OF FUSE. NEVER BYPASS THE FUSE.
IF THE AC CORD(S) BECOME DAMAGED, DO NOT USE IT/THEM. IMMEDIATELY REPLACE IT/THEM
WITH NEW ONES OF THE SAME OR BETTER RATING.
IT IS IMPERATIVE THAT THE CITADEL BE OPERATED IN A WELL VENTILATED ENVIRONMENT AND
THE IMMEDIATE EXTERNAL TEMPERATURE BE MAINTAINED AS SPECIFIED. EXTERNAL COOLING
FANS MAY BE REQUIRED IN SOME CASES. DO NOT STACK ANY EQUIPMENT DIRECTLY ABOVE,
BELOW OR TO THE IMMEDIATE SIDES OF THE CITADEL AS TO PROTECT IT FROM OVERHEATING,
AS WELL AS THE CONTINUED FUNCTIONALITY OF ANY EQUIPMENT NEAR AND AROUND IT.
THE CITADEL IS A BALANCED BRIDGE AMPLIFIER, THUS THE NEGATIVE SPEAKER TERMINAL IS
NOT A GROUND, AND CANNOT BE CONNECTED TO A SYSTEM GROUND OR LOUDSPEAKER
SYSTEM WITH A COMMON GROUND. CONSULT YOUR SPEAKER MANUFACTURER TO ENSURE
THAT ANY SPEAKER IN YOUR SYSTEM THAT WILL BE CONNECTED TO THE CITADEL DOES NOT
HAVE INTERNAL CIRCUITRY WITH A COMMON GROUND.
AFTER MARKET and THIRD PARTY MODIFICATIONS
Please note that any after market and/or third party modifications will void the warranty. In the case of
changing the feet on a unit, in order to prevent any damage (which will also not be covered under warranty),
please verify that the screws being used to secure non-Theta feet do not screw any deeper into the chassis
than the original ones. The original screw is 1/4-20 by 1/2 and goes into the chassis 1/8 inch.
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Table of Contents
PREFACE............................................................................................................................. i
WARNING ...................................................................................................................................................... ii
Citadel Identification Record ..........................................................................................................................iii
SAFETY PRECAUTIONS ............................................................................................................................. iv
INTRODUCTION ................................................................................................................. 1
Getting to know your Citadel .......................................................................................................................... 1
Burn-In Time................................................................................................................................................... 1
Reference Manual Conventions ..................................................................................................................... 1
IMPORTANT NOTICE.................................................................................................................................... 2
Citadel Block Diagram.................................................................................................................................... 3
Front Panel Layout ......................................................................................................................................... 4
Rear Panel Layout.......................................................................................................................................... 6
OPERATION .......................................................................................................................7
Connecting the Citadel ................................................................................................................................... 7
Setup and Operation ...................................................................................................................................... 7
Remote Triggers............................................................................................................................................. 7
RS232............................................................................................................................................................. 8
Appendix A Troubleshooting Guide ......................................................................................................... 9
Appendix B Wiring Diagram ................................................................................................................... 10
Appendix C RS232 Protocol................................................................................................................... 11
RS232 Jumper Settings...................................................................................................... 14
Appendix D Specifications...................................................................................................................... 15
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INTRODUCTION
Getting to know your Citadel
This Citadel has been put through a rigorous and unique testing procedure that ensures that it will last for
many years with minimal service requirements. This procedure includes the following:
• All assembled circuit boards are given a thorough visual inspection and are then tested in a bench-
reference Citadel.
• The tested, assembled circuit boards are then installed in a new Citadel and the whole unit is tested
for every function and parameter.
• The unit is put on a burn-in torture rack to test for any possible component failures.
• It is then tested on an audio analyzer for all pertinent parameters.
• The unit has all remaining chassis components installed and then undergoes a complete visual
inspection, which assures that all Citadels meet visual specifications.
• The Citadel then undergoes a critical listening and functional test.
The front panel of the Citadel is manufactured in two versions – a left and a right, as shown in figure 3. A left
version has the tower on the right side of the faceplate and is intended to be placed on the left side of the
room. Visa versa for the right.
Burn-In Time
This unit has a break in period of about 1 week during which continuous improvement in sound quality will be
observed. It is recommended that music be played continuously through the unit during this time to expedite
the break in period.
Reference Manual Conventions
For clarity purposes, references to buttons and LED’s will be shown in bold capital letters.
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IMPORTANT NOTICE
I. It is imperative that the Citadel be connected to a ground via its two three wire AC power cords. It is
important that the AC power outlet, which the Citadel is plugged into, is actually grounded. Failure to
do so will severely compromise the performance, reliability and safety of use of the Citadel.
II. Ventilation is an important issue when placing the Citadel in a system. Make certain that the Citadel
is placed in a well-ventilated area or rack unit. Heat must be dissipated and cool air must be allowed
to enter the Citadel.
III. Please take note that some powerline conditioners defeat the AC power ground on their outlets. If
the intention is to plug the Citadel into a line conditioner, check with your dealer to make certain that
the particular conditioner that is intended for use DOES NOT DEFEAT THE AC GROUND on its AC
outlets. Only the highest powered line conditioners should be considered for use with the Citadel.
Otherwise, the amplifier’s power output may be compromised.
IV. DO NOT remove any cover panels from the Citadel, as there are no user serviceable components
inside. Refer servicing and updating to qualified service personnel only.
V. Endcaps (NOT shorting plugs) on the unused RCA inputs will improve the sound quality and may
reduce the susceptibility to RF induced anomalies.
VI. It is imperative that the Citadel be operated in a well ventilated environment and the immediate
external temperature be maintained as specified in Appendix D of this manual. External cooling fans
may be required in some cases. Do not stack any equipment directly above, below or to the sides of
the Citadel as to protect it from overheating, as well as the continued functionality of any equipment
near and around it.
VII. Each channel is a balanced bridge amplifier, thus the negative speaker terminal is NOT a ground,
and cannot be connected to a ground or a loudspeaker system with a common ground. Consult your
speaker manufacturer to ensure that any speaker in your system that will be connected to the Citadel
does NOT
have internal circuitry with a common ground.
VIII. WARNING: When connecting the speaker wire to the Delrin output connector, using the hex tool
provided – DO NOT OVER TIGHTEN. There is a lot of surface area in the Delrin connector to create
a complete connection with a slightly firm torque applied. OVER TIGHTENING WILL ULTIMATELY
BREAK THE DELRIN CONNECTOR, WHICH WILL NOT BE COVERED UNDER WARRANTY.
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Figure 1 - Block Diagram (Citadel showing one output module)
Citadel Block Diagram
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Front Panel Layout
Figure 2 - Front Panel Layout of a LEFT Citadel
1.
STANDBY
MAIN POWER
front panel Theta logo button to exit the
standby mode. The Citadel will come out of
standby.
2.
STANDBY
power amplifier is in
the amplifier is active.
3.
THERMAL
Citadel’s amplifier module temperature rises
above the maximum operating temperature
and puts the Citadel into standby.
4.
DIG IN/LOCK LED
internal DAC is installed, this LED will
illuminate red. When a valid digital signal is
present at it’s input, it will illuminate orange.
When Analog is selected, it will illuminate
green.
5.
ANA/DIG INPUT
an analog or digital input. This button has no
effect if a DAC board is not installed.
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button. After the rear panel
switch is turned on press the
LED. Illuminates red when the
STANDBY
LED. Illuminates when the
. When the optional
button. Selects between
, green when
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Figure 3 - Front Panel of a LEFT and RIGHT Citadel
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