Ovation 1721 User manual

Ovation High Fidelity User Manual
Engineered for Art™

Model 1721 Stereo Power Amplifier Owner’s Manual
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O V A T I O N
H I G H F I D E L I T Y
Engineered for Art™
Model 1721 240 Watt Stereo Power Amplifier User Manual
May 2017 rev 1.0

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Welcome to Ovation High Fidelity.
Thank you for purchasing this Ovation High Fidelity product. We have taken
every care in the design, engineering and manufacture to ensure the highest
levels of craftsmanship and quality so that you will have many years of trouble
free operation and musical enjoyment.
Proof of Purchase
Should the item be returned under warranty, proof of purchase will be required.
Therefore, you must keep the original purchase receipt. We suggest you staple
this into the rear inside cover of this user manual and retain it in a safe place
after reading it. We always include a hardcopy of the purchase invoice with
every shipment.
Product Usage Declaration
This product is designed for use in a domestic hi-fi system driving loudspeakers
with a rated impedance of 8 Ω.
Warranty: -
•This product is warranted free of manufacturing defects for a period of five
years from date of purchase.
•This warranty excludes cases where the product is abused, or used for
purposes other than which it was intended, or modified in anyway
whatsoever
•The warranty is not transferable
•Remote controls are warranted for a period of one year from date of
purchase. The warranty does not cover damage due to battery leakage or
battery replacement
•The costs of sending the product back to the company under warranty, and
its subsequent return, are for the account of the purchaser

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Returns Policy/30 Day Money Back Guarantee
Should you not be 100% satisfied with your product for any reason, you may
return it within 30 days from date of purchase for a full refund, provided:-
•The product is returned packed in the original packaging
•The product is not damaged in anyway whatsoever either electrically
or cosmetically
•The company reserves the right to deduct from the refund any costs
required to make good any damage to products returned by
customers.
•The costs of returning the product back to the company under the 30-
day money back guarantee are for the account of the purchaser.
The Ovation High Fidelity Company reserves the right to modify and/or make
technical and/or design changes to the design of its products without
obligation to prior purchasers

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Unpacking Your New Product
Do not damage the carton, associated packaging materials or any
documentation. Retain these items in a safe, dry place until after your
30 day money-back guarantee has expired.
Check that you have the following items in the carton once opened: -
•Model 1721 Power Amplifier Unit
•IEC mains lead with appropriate mains plug for your region
•User manual (this document)
•Registration warranty card
Where to Locate Your New Model 1721 Stereo Power Amplifier
Locate your Power Amplifier in a well-ventilated area away from sources of
heat, dust and humidity and direct sunlight. You should position the product
alongside your preamplifier. We do not recommend that you stack high
fidelity components on top of one another as this could interfere with
ventilation.
You may not place any Ovation High Fidelity product directly on a
carpet as this will obstruct airflow and will lead to overheating.
This amplifier will run warm to the touch –this is quite normal.
Make sure when locating the product, that no liquids or any other foreign
objects can enter the unit through the ventilation holes.
Keep this equipment out of the reach of children.

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Warning!
Ovation High Fidelity products contain no user serviceable parts.
There are lethal mains voltages present inside the unit.
DO NOT open the product under any circumstances - If faulty, refer it
back to Ovation High Fidelity if still within the warranty period or to a
qualified, authorized service engineer if not.
This product must be Earthed (Grounded) when in use. Use the
supplied country specific mains cable to ensure this.
Never use an ‘Earth Lifter’ (‘Ground Lifter’) or any similar device that
interferes with the electrical safety of this product
If you are not going to be using your equipment for any length of time –e.g.
going away on vacation - it is advisable to unplug it from the mains.
Cleaning your Ovation High Fidelity Product
1. Unplug the unit from the mains supply
2. Use a soft, slightly damp cloth or chamois leather wipe to clean the
unit.
3. Use a dry, lint free cloth to wipe the unit down after step 2 is
completed
4. Never use any abrasive cleaning agent to clean the unit –e.g. Cif,
Vim, CLR or Softscrub
5. Never use furniture polish or similar oil based agents to clean your
unit
6. Never use any solvent based cleaner like petroleum (i.e. gasoline),
turpentine, benzene, methylated spirits or similar

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Model 1721 Front Panel
Model 1721 Rear Panel Key
The figure above identifies the key components on the Model 1721 power
amplifier rear panel.

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Connecting a Preamplifier to the Model 1721 Stereo Power Amplifier
The figure above shows how to connect your Model 1721 power amplifier to
your preamplifier.
Note that you do not need to connect both the single ended and the
balanced interconnects –you only need to connect the single ended inputs
or the balanced inputs.
We recommend where possible, you use balanced interconnects for best
performance.
Always make sure that you have the ‘Input Select’ switch on the rear panel
in the correct position –depressed for balanced inputs and out for single
ended (aka unbalanced) inputs.
We recommend the Ovation High Fidelity Model 1501 High Resolution
Stereo Preamplifier for use with the Model 1721 Power Amplifier.
Connecting Loudspeakers to Your Model 1721 Stereo Power Amplifier
Your Model 1721 Power Amplifier is designed for operation with 8 Ωrated
loudspeakers. You should only connect 1 pair of speakers to your amplifier
for best performance. Note that during the short power-up and power down
periods, the loudspeakers are automatically disconnected from the amplifier.
Balanced
Input
Connections
Unbalanced
Input
Connection

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Powering ON and OFF
To power up the amplifier, depress the black pushbutton located in the
center of the front panel. The GREEN indicator LED beneath the pushbutton
switch will flash twice per second for 5 seconds. You will hear a click after
3 seconds or so - this is the in-rush power limiting bypass relay energizing.
After a further second or two, the amplifier output will engage, allowing
sound to come from the loudspeakers. The front panel GREEN LED will
remain ON.
To power down, simply press and release the push button again. The power
in-rush relay will click as it de-energizes; the amplifier will disengage the
loudspeakers and the GREEN indicator LED will slowly extinguish over the
course of about 60 seconds.
Front Panel LED Status Indicator
The status of your amplifier can be determined from the front panel LED as
detailed in the table below:-
Front Panel LED Indication
Amplifier Status
OFF
Amplifier is powered OFF
GREEN and flashing twice
per second
Amplifier is in power-up cycle which lasts for 5 seconds
GREEN ON (i.e. not flashing)
Amplifier is powered up and loudspeakers are connected
to the output
GREEN but then flashing
RED intermittently on loud
music
Amplifier output is clipping i.e. overloading –reduce the
volume
RED and flashing at 1 Hz
The amplifier is too HOT and may automatically
disconnect the loudspeakers if you continue to play the
music too loudly or do not dramatically improve the
amplifier ventilation. Do not use your amplifier on a
carpet as this block the underside ventilation holes and
can lead to overheating
RED and ON continuously
The amplifier has automatically disconnected the
loudspeakers either due to over-temperature, overcurrent
or a DC output offset fault
Table 1 –Status Indication
Your amplifier is equipped with sophisticated protection functions that
include DC offset detection to protect your speakers, output short
circuit/overcurrent protection and overtemperature protection. If any of these
protection features are activated, the unit will automatically disconnect the
loudspeakers.
See the next page for additional details on the protection features

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About the Protection Features on Your Amplifier
Overcurrent Protection. If the load impedance of the speakers drops
significantly below 2 Ωwhen the amplifier is sustaining full output power or
the connection from the amplifier to a loudspeaker experiences a short
circuit, the amplifier output stage protection circuit will activate. This will
instantly disconnect the loudspeakers from the amplifier to protect it and the
speakers from damage. The LED on the front panel will remain illuminated
RED if this happens.
The amplifier will have to be powered OFF for at least 3 to 5 minutes before
it will power up normally again.
Note that if the cause of the problem is a short circuit in your loudspeaker
connection, the amplifier will shut down again when re-applying power. You
should therefore always check carefully to ensure you do not have a short
circuit in your loudspeaker connection after a shutdown.
Overtemperature Protection. If the amplifier heatsink temperature exceeds
65  C (this is too hot to touch, but in normal operation it is highly unlikely to get
this hot), the front panel LED will flash RED twice per second while above this
temperature.
If you do not reduce the volume, or allow the amplifier to cool and the
temperature continues to rise, it will disconnect the loudspeakers at 70  C. The
loudspeakers will not be re-connected until the temperature of the heatsinks
drops below 63  C. Do not locate your amplifier directly on a carpet when in use.
This blocks the ventilation holes and severely restricts airflow through the
amplifier which can lead to overheating.
DC (Direct current) Offset Protection. If the amplifier develops an internal
fault, and outputs DC to the loudspeakers, the internal protection circuit will
immediately disconnect the loudspeakers and the front panel LED will
illuminate RED and remain ON. The loudspeakers will remain disconnected
until the DC offset ceases. If the LED remains illuminated and RED even
after powering down and then up again, you should get in touch with Ovation
High Fidelity through the ‘Contact’page on our website.
Attention: Playing music at excessive volume levels can damage your
hearing.

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Replacing the Fuses on your Model 1721 Power Amplifier
In the unlikely event that the mains fuse on your unit should blow, you should
check the following carefully before replacing it: -
1. You are using the correct mains voltage. The mains voltage for your
product is permanently set at the factory at the time of shipping and
shown on the rear panel bottom left hand side of the unit.
2. On power amplifier products, make sure the speaker outputs are not
shorted in any way.
3. Make sure the mains power at the wall socket is not inadvertently
switched OFF.
4. If your unit still does not operate, you need to replace the fuse as
detailed below
Important! Always unplug the unit from the mains
before attempting to replace the fuse!
Use a flat bladed screw driver and gently lever open the fuse drawer
Replace the Model 1721 fuse with the ratings as indicated below
Mains Voltage
Fuse Rating
Remarks
100 VAC to 130
VAC
15A T
slow acting ‘T’ fuse
200 VAC to 240
VAC
8A T
slow acting ‘T’ fuse
Firmly push the drawer closed, after which you can reconnect the unit to the
mains and then apply power.
Do not use fuses marked FF, F or M as these are fast/medium acting and
will likely blow when you power the amplifier up. Only use ‘T’ fuses.
If the fuse immediately blows again, refer your unit to a qualified repair
technician, or if still under warranty, contact the factory via the ‘Contact’
page at www.ovationhifidelity.com
Never use fuses rated higher than shown in the table above on your
Model 1721. Equipment fuses are designed and rated to prevent fire
hazard and are a legal requirement in all countries.

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How to Use the Trigger Input Facility
On the rear panel, a ‘Trigger’input is provided. This allows the amplifier to
be powered up or down remotely from a preamplifier or a system controller
equipped with a 12V trigger output.
Important Note: The front panel power switch takes precedence over the
Trigger input. In other words, if the front panel power switch is depressed
(i.e, power ON), the trigger input will be overridden and the amplifier will
remain ON for as long as the switch is depressed. Therefore, when using
the trigger input, always ensure the front panel switch is OFF i.e. not
depressed.
The Trigger input uses a standard 3.5mm mono or stereo jack plug. The
diagram below shows the polarity connections.
The maximum trigger voltage may not exceed 15 Volts and must not drop
below 10 Volts during normal operation. The total current drawn by the
trigger circuit in the amplifier is typically 35mA and will not exceed 40mA at
12V.
+12V switched
from Trigger
controller
+12V switched
from Trigger
controller
+12V
0V
+12V
0V
3.5 mm Stereo Phono Jack Plug
3.5 mm Mono Phono Jack Plug

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Trouble Shooting –Model 1721 Preamplifier
Problem
Likely Cause
Action
Unit will not power up with
the front panel POWER
switch in the depressed
position. The front panel
Power LED is not
illuminating
No AC mains power is
coming to the unit
Check that the wall socket is
switched ON and is providing power.
You could for example plug another
appliance like a lampshade into the
same socket to verify this
If still not working, check that the
mains cable plug (UK only) fuse is
intact
If the wall socket is ON and the
power cable fuse is intact, check the
Model 1721 mains fuse –see
Page 10
There is no sound coming
from the system but the
power LED is illuminated
GREEN on the front panel
Speakers are not
connected to the amplifier
or not connected correctly
Check the speaker connections and
make sure they are connected at
both the amplifier and the speaker
side. Always observe the correct
polarity of the connections
If above is ok but there is
still no input signal from the
preamplifier
Make sure the interconnect cable
from the preamplifier is in place and
an active source signal isselected on
the preamplifier
The LED is illuminated RED
The amplifier protection
scheme has triggered
See Table 1 on Page 8 –The
amplifier has overheated, there is a
speaker short circuit/overcurrent
condition or an output DC Offset
fault. See Table 1 on Page 8
The LED is flashing RED
once per second
The Amplifier is too hot
Reduce the volume and/or improver
the ventilation around the amplifier.
See Table 1
The LED is GREEN, but
flashes RED intermittently
The amplifier is being
overdriven and is clipping
Reduce the volume. See Table 1 on
Page 8
The sound coming from the
loudspeaker lacks bass and
the stereo sound
stage/image seems to
wander
Speaker phasing is
incorrect and/or
interconnect plugs are not
seated properly
Ensure that the speaker wire
connection polarity is correct –see
Page 7 for details on how to connect
the speakers
Make sure all interconnect plugs are
fully seated into their respective
sockets
There is a hum coming from
the loudspeakers
Interconnect cable is faulty
or is not properly seated in
its associated receptacle
Check all interconnects - they must
to be fully seated in their associated
receptacles to prevent hum
If the problem is not due to the
above, check that the interconnect
cable is not faulty. On the amplifier
input, swap the left and right
channels. If the problem moves to
the other channel, the fault is with the
interconnect cable, or the source i.e.
the problem is not with the Model
1721 Power Amplifier
If your unit is still not working correctly, kindly contact Ovation
High Fidelity via the ‘Contact’ page at www.ovationhifidelity.com

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Specifications
Model 1721 Stereo Power Amplifier
General Description
240 Watt RMS, wide bandwidth, ultra-low distortion Current Mode Topology (CMT) power amplifier equipped with non-
invasive over-current and DC Offset protection. Power up/Power down muting utilizing solid state loudspeaker relay and in-
rush current limiting during mains power-up. Balanced or single ended input selected via a push button on the amplifier’s
rear panel.
Inputs 1 pair unbalanced (i.e. single ended) via RCA phono receptacles (Zin = 10k Ω) and 1 pair
XLR balanced input (Zin = 10 k Ω); Input selection is via pushbutton located on amplifier rear
panel
Input sensitivity For rated output power: 1V for single ended inputs; 0.5V for balanced inputs
Output Power 240 W RMS into 8 Ω20 Hz to 20 kHz; 400 W RMS into 4 Ω20 Hz to 20 kHz; Peak I2R Power
1200 W single channel driven (t ≤ 50ms)
Rise time Large signal: <500 ns rise and fall time 120 V pk~pk 10% to 90% into 8 Ω; small signal rise
time ≤ 100 ns 2 V peak into 8 Ω
Slew Rate ~250 V/µs positive and negative
Frequency Response 20 Hz to 20 kHz +0 dB -0.1 dB 1 W into 8 Ω
2 Hz to 250 kHz +0 dB -3dB into 1 W 8 Ω
Intrinsic response (front end low pass filter disabled) 2 Hz to 700 kHz -3dB 1W into 8 Ω
Distortion ≤30 parts per million (0.03%) at all frequencies and power levels up to rated output into 8 Ω
≤5 parts per million (0.0005%) 20 Hz to 20 kHz 1 V into 8 Ω
Signal to Noise Ratio Better than -100 dB ref 1 V output; ~120 dB ref max output voltage swing into 8 Ohms
Damping Factor approx. 200 at 1kHz into 8 Ω
Operating voltages 110-130 VAC or 220 to 260 VAC; factory set at time of order
Trigger Input +12V at 35 mA typical; 40 mA at 12 V maximum. Trigger voltage not to exceed 15 V
Max Power consumption 1200VA at 240VAC or 110 VAC ; Mains Voltage is set at time or ordering and cannot be
changed by the user
Weight 24 Kgs (unit only); 30 kg when packed for shipping
Dimensions Unit only: 450mm (W) x 450mm (D) x 130mm (H)
Packed for Shipping: 700mm (W) x 700mm (W) x 250mm (H)
Operating Temperature -10 ºC to +45 ºC non-condensing
The Ovation High Fidelity Company Limited
Norfolk, England
www.ovationhifidelity.com
™

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Glossary –Some General Terms
AC
Alternating Current –the type of electricity supply used in normal house wiring and to power consumer appliances like
TV’s, washing machines and high fidelity systems
A-D or A/D
Analog to Digital –an electronic technique whereby an analog signal is sampled at short, regular intervals and the sampled
value converted into a representative numeric value that is stored in computer memory, CD or some other mass storage
media
Analog Signal
A voltage or current signal that varies continuously with time. Examples are the pickup signal froma turntable, or the output
signal from a microphone. All natural world signals are analog.
Balanced Audio Signals
A method whereby audio is transferred between equipment using two connections without reference to ground, making it
highly immune to ground loop induced hum and extraneous noise pickup. Uses XLR connectors. See also Unbalanced or
single-ended audio signals below
Bipolar Transistor
A three-terminal semiconductor amplifying device
CMT or CFA
Current Mode Topology –a type of audio amplifier wherein the peak current into the main amplifier stage is determined
directly by the output voltage and the gain setting resistor. Also known as CFA (Current Feedback Amplifier)
D-A or D/A
Digital to Analog –the technique of converting digitally stored samples into a continuous analog signal. See A-D above
Damping factor
A measure of an amplifiers load impedance divided by its output impedance. Higher figures are deemed better. In a modern
amplifier, any figure above 50 should be considered adequate and above 100 excellent
DC
Direct Current. Examples would be the type of electric current supplied by a battery
dB
Abbreviation for Decibel - a logarithmic measure of an analog signal with respect to a reference, or expressed as the
difference between two signals. 20 dB = 10x and 40 dB = 100x while 100 dB = 100 000x. By way of an example, if the S/N
of a preamplifier is -100 dBV, it means that the noise is 100 000 times lower than 1V –i.e. 10 millionths of a Volt. In this
case, the ‘V’ in dBV refers to the reference which is 1V and is a standard measure used in audio
Digital Audio Signal
An audio analog signal is sampled at discrete time intervals by an A-D and theresultant samples converted to anumerically
representative value. An example is a CD, where the original analog signal (e.g. the voice of a singer) is sampled 44100
times a second and each sample converted to a 16 bit digital representation. See also A-D
Digital signal
A binary coded numerical value represented by 0’s and 1’s where the ‘0’ value corresponds to 0V and the ‘1’ corresponds
to 3.3V, 5V or some other non-zero voltage. Digital signals are either parallel or serial format. Examples of digital signals
would be the co-ax output from a CD drive (serial digital signal), or the data on an Ethernet cable used in communications
(also a serial digital signal)
Distortion and Noise
The presence in any electrical audio signal of unintended harmonics and/or noise. Reducing distortion and noise are key
goals in any equipment that reproduces audio signals
EMI or Electro-Magnetic
Interference
Noise and/or extraneous signal introduced into a system through magnetic or capacitive coupling mechanisms. Filtering,
bandwidth limiting and careful design and equipment layout can reduce the effects orders of magnitude below human
hearing threshold, and/or render it of no consequence to the correct operation of the equipment.
EQ or Equalization
A technique whereby an electrical signal which is intentionally or unintentionally altered from the original, is corrected.
Examples would be RIAA (intentionally altered during the disc cutting process) or room EQ whereby acoustic imperfections
of the environment are corrected
Frequency Response or
Bandwidth
The extent of frequencies an amplifier or transducer (e.g. a microphone or a loudspeaker) can reproduce to within a
specified range. Human hearing covers 20Hz to 20 kHz. Audio amplifiers typically cover at least 5 Hz to 100 kHz (-3 dB) to
ensure a flat response to within 0.2dB across the human hearing range of 20 Hz to 20 kHz
Input Sensitivity
The level of input signal required to produce a given output from a preamplifier or a power amplifier.
IR Remote
Infra-red Remote control
JFET
Junction Field Effect Transistor –a three terminal semiconductor amplifying device that somewhat emulates vacuum tube
triodes in its performance characteristics.
Ω
Ωis the unit of electrical resistance. Most loudspeakers are rated at 8 Ω
Output Power
Measured in Watts, the amount of electrical power that can be delivered into a loudspeaker load by an amplifier. Always
quoted into a known resistive load –usually 4 or 8 Ω
Phono socket
The small round sockets –usually grouped in Left (WHITE) and Right (RED) pairs on the rear side of audio equipment.
Also referred to as ‘RCA Phono’ sockets
RC5 IR
The protocol by which commands from the remote are encoded and transmitted via infra-red to the receiving equipment
which then executes them. Invented by Philips in the 1970’s and now one amongst 4 or 5 industry standards
RIAA
Recording Industry Association of America –The association that standardized the LP/vinyl playback equalization curve in
the early 1960’s that is still the standard for LP/vinyl today
Signal to noise ratio (SNR)
A measure of the amount of noise in a system against the nominal output signal of that system. In modern equipment, any
figure lower than -90 dBV should be considered excellent
Slew Rate or S/R
The fastest rate of output voltage change that an amplifier can sustain. A typical design goal for an audio amplifier is 1V/us
per volt of output swing. For a 100 Watt amplifier, this corresponds to a minimum figure of about 40V/us
Small signal rise time
A measure of the speed (i.e. rate of change) of an amplifier or preamplifier when dealing with low level signals in the 1-2
Volt range. Small signal rise time and slew rate (S/R) are not equivalent measures
Unbalanced or single-ended
audio signals
With this type of interconnection, audio is transferred between equipment using a ground connection and a signal
connection. It is more common than balanced audio signals due to its lower implementation cost, but much more
susceptible to noise pick-up
VMT or VFA
Voltage Mode Topology –a type of amplifier wherein the peak current into the main gain stage is limited to that of the input
stage ‘Long Tail Pair’ (LTP) current source. Also known as VFA (Voltage Feedback Amplifier)
XLR
The standard interconnect format for balanced audio signals

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Owners Information
Date Purchased: ____________________________________
Dealer (if Applicable): ________________________________
Warranty Registration Date: ___________________________
Serial Number: _____________________________________

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The Ovation High Fidelity Company
Norfolk, England
www.ovationhifidelity.com