JEFF ROWLAND 312 User manual

OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

© Jeff Rowland design gRoup 2007. all Rights ReseRved.
TABLE OF CONTENTS
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER
    
   
   
    
 
  
  
  
 
  
  

PO BOX 7231, COLORADO SPRINGS, COLORADO 80933 USA E-mAIL: [e-mail] www.jEffROwLAND.COm TELEPHONE [phone]

If you have any additional questions
regarding the installation or operation
of the Model 312 Stereo Amplifier, please
contact your authorized Jeff Rowland
Design Group dealer or check the Jeff
Rowland Design Group web site at
www.jeffrowland.com.
Enjoy the music!
Jeff Rowland
President,
Jeff Rowland Design Group
the operational features will allow you
to gain the maximum performance and
ease of use for which this amplifier was
designed. Please note that your Model 312
Stereo Amplifier serial number begins
with the letter “T”. This serial number is
located on the rear panel of the chassis.
Please include this number with any corre-
spondence regarding your Model 312
Stereo Amplifier. It has been my joy to
create an audio component of enduring
value that reflects the highest ideals of
musical and artistic expression. It is my
hope that these qualities will enrich your
experience and pride of ownership.
Welcome to the Jeff Rowland Design
Group “family” and congratulations on your
purchase of what is unquestionably one
of the world’s finest amplifiers. With its
combination of features such as precision
electronic circuitry, exceptional
efficiency,
and accurately machined chassis compo-
nents throughout, your
Model 312 Stereo
Amplifier will offer you many years of musi-
cally satisfying enjoyment.
Please take a few minutes to read the
remainder of this Owner’s Manual before
proceeding with the installation of the
amplifier. A thorough understanding of
INTRODUCTION
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

© Jeff Rowland design gRoup 2007. all Rights ReseRved.

• XLR input connectors for balanced
system conguration.
• RCA input connectors for unbalanced
system congurations.
•
Dual Speaker Output Terminals on each
channel for bi-wiring applications.
• User selectable switching between
balanced and unbalanced connections.
• Transformer coupled inputs provide
universal compatibility with other
components and eliminate ground
loop noise and EMI.
• High efciency ICEpower® power
conversion technology generates high
output power with very little heat.
• Fully-balanced topology implemented
in both input and output circuitry.
• Power Factor Correction (PFC) in
power supply reduces AC line har-
monic noise pollution and increases
AC line power utilization to 99%.
• Proprietary switch-mode power
supply technology ensures
consistent performance under
all operating conditions.
• 12V remote ON/OFF remote power
switching via 1/8” jack on rear panel.
• Standby power mode reduces
warm-up time.
• CE approved speaker output terminals
require no tools for secure, low resis-
tance connections.
• Fail-safe operation provided by
user-resetable thermal circuit breaker
located on rear panel.
• Quiet, transient-free operation
during power ON/OFF and input
conguration switching.
• Selectable overall gain of 26 or 32 dB.
• Ultra-low resonance, structurally
rigid chassis, precision-machined
from a solid block of aircraft grade
6061-T6 aluminum.
• 3-point self-leveling chassis support.
PRODUCT FEATURES
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

PO BOX 7231, COLORADO SPRINGS, COLORADO 80933 USA E-mAIL: [e-mail] www.jEffROwLAND.COm TELEPHONE [phone]

Ensure that all of the auxiliary components listed below are enclosed within the shipping carton and
accessory box. Refer to the illustrations and verify that the proper components are included.

WARRANTY REGISTRATION
 
OWNER’S MAN UAL MODEL 312 STEREO A MPLIFIER

PACKAGE CONTENTS
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

© Jeff Rowland design gRoup 2007. all Rights ReseRved.

Inspect the shipping container for damage. If any portion of the shipping container, packing material,
amplifier, or accessories are damaged or missing, notify your dealer and the shipper (if a claim is
to be made) immediately.


Your Model 312 Stereo Amplifier has undergone extensive performance evaluations, listening tests,
quality control inspections, and a minimum 72 hour burn-in period prior to shipment and should
therefore be in perfect operating condition upon delivery. If the amplifier does not operate correctly,
please notify your dealer immediately.
We strongly suggest that you save all of the packing materials. If the amplifier is returned to your
dealer or JRDG, the original packing materials must be used for shipment to avoid possible damage.
Neither JRDG nor the shipper can be held responsible for damages incurred during transit if the
original factory packing is not used. All factory returns require that JRDG issue a Return Authorization
(RA) number prior to shipment.
      
The Model 312 is a large and heavy
amplifier. Due caution should be taken
when unpacking and installing the
amplifier to avoid injury or damage to
the amplifier. The Model 312 should
be unpacked by at least two people,
however it is possible for one person to
unpack the amplifier safely. There should
be a portion of carpet or soft, padded
cloth to stand the amplifier on when
unpacking it from the shipping box.
INITIAL INSPECTION
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

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
All JRDG products are designed to provide a lifetime of enjoyment
and listening pleasure. The Model 312 Stereo
Amplifier is uniquely
constructed from precision-machined 6061-T6 aluminum sub-
assem-
blies, configured and dimensioned to maximize chassis strength and
reduce vibration. Constrained mode damping materials have also
been applied in several areas to further reduce chassis resonance.
The chassis is sealed to prevent dust from
entering the interior and
should never need interior cleaning during the lifetime of the product.
All internal circuitry is maintenance-free such that no adjustments of
any kind are necessary over the lifetime of the product. If the amplifier
is ever in need of service, updating, or upgrading, it should only be
returned to an authorized repair facility or technician for servicing.
The front panel of the unit is precision-machined in a unique process
that incorporates a diamond tipped cutting tool. This process was refined
over many years to produce an attractive and unique appearance.
Because the surface is not finished in the typical fashion of most
audio and video equipment, there are a few rules that must be kept
in mind when cleaning the equipment.
• Please allow the front panel, which is coated with an automotive-grade polyure-
thane nish, to cure for 6 months before attempting to clean it.
This will prevent
small scratches from marring the surface before the surface coating has had a
chance to harden completely.
• The front panel of the unit should never be cleaned with anything other than a very
soft cotton cloth and plain water or ne oil-based furniture polish. Because of the
ne nish of the front panel, use of any other cleaning agent may permanently
scratch the nish.
• The top cover, sides and bottom are protected by a durable black anodized nish
and can be cleaned with a soft cotton cloth (such as an optical lens cleaning cloth
or ne furniture polishing rag) dampened with plain water. Water should be applied
directly to the cloth and not the chassis. A very mild plastic or glass cleaner that
does not contain ammonia may also be used. If a mark has been left on the
chassis,
do not use any type of abrasive or chemical cleaner to remove the mark.
Maintenance & cleaning
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

© Jeff Rowland design gRoup 2007. all Rights ReseRved.

Protection SyStemS
If you have any questions about the care or cleaning of your Model
312 Stereo Amplifier, please contact your dealer or the JRDG factory
before attempting to clean the chassis. The use of a cleanser or
abrasive to clean the chassis that has not been approved by the
factory will almost certainly damage the finish and will not be
covered under warranty.
NOTE: Cleaner/polish should be applied directly to the cloth and not the chassis.
The Model 312 Stereo Amplifier is equipped with internal fuses for
protection against excessive AC current draw; however, since no
protection circuitry or system can completely protect a product from
every electrical hazard, certain precautions should be observed. In
the event
of severe voltage hazards such as lightning or when the
amplifier
will not be used for extended periods of time, the amplifier
should be unplugged from the AC mains to avoid potential damage
to the internal circuitry. All other audio/video system components
should also be disconnected from AC mains power as hazardous
voltages can easily travel throughout an interconnected system.

PO BOX 7231, COLORADO SPRINGS, COLORADO 80933 USA E-mAIL: [e-mail] www.jEffROwLAND.COm TELEPHONE [phone]

Locate the amplifier as close as possible to its final installation point.
Allow access to the rear panel for making connections.
The Model 312 Stereo Power Amplifier is extremely efficient and
convection cooled, eliminating the need for fans or forced-air cooling.
Multiple chassis can be stacked vertically, facilitating an upward flow of
warm air currents throughout the vertical heatsink areas. This upward
flow must not be blocked or recirculated around the chassis if proper
cooling is to be maintained.
Typical installations allow the amplifier to be rigidly coupled to a
support structure or floor via optional spiked coupling supports that
are available separately from JRDG. In carpeted installations, these
supports provide excellent anchoring from the amplifier chassis to the
rigid floor or sub-floor below. If there is concern about damage to the
structure or floor’s finish, a coin can be placed beneath each spiked
coupling support. In installations where the resonant properties of the
supporting structure are poor or unknown, the amplifier chassis can be
loosely coupled to the supporting structure via the supplied compliant
isolation interface pads. This will help to attenuate the transfer of vibration
or resonant energy from the support structure to the amplifier chassis.
InstallatIon, Use & care
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER
RISK OF ELECTRICAL SHOCK!
WARNING: Do not attempt to access the interior of the MODEL
312 STEREO AMPLIFIER
by removing the top or bottom cover.
Doing so will void your warranty and could expose you to
dangerous, potentially lethal electrical voltages.

© Jeff Rowland design gRoup 2007. all Rights ReseRved.

• Do not expose the amplier to
rain, moisture, or excessively
damp conditions.
• The Model 312 Stereo Amplier
must not be modied in any way,
other than according to ofcial
service bulletins from JRDG.
Otherwise, the factory warranty
will be immediately voided.
• The Model 312 Stereo Power
Amplier
can be operated at a
nominal 100, 120,
220, or 240
volts AC. The amplier must be
congured for the correct AC input
voltage before operation or serious
damage will result.
• Be sure the amplier is unplugged
from the AC mains wall plug (front
panel indicator light OFF) before
connecting or disconnecting any
loudspeaker or interconnect cables.
• When operating the Model 312, a
properly grounded AC receptacle
should be used. A potential shock
hazard may result if the supplied
3-wire, grounded AC cable ground
terminal is defeated or lifted or
the unit is connected to a 2-wire
ungrounded AC outlet.
• The output terminals or loudspeaker
cables should never be shorted to
each other or to any chassis surface.
Shorting of the outputs may result in
damage to the output section of the
amplier.
• The Model 312 is designed to per-
form
optimally with no adjustments
or
maintenance for the lifetime of the
product. Do not attempt to open the
bottom cover of the amplier and
refer all service issues to qualied
personnel. The voltages inside the
Model 312 can be hazardous.
The JRDG Model 312 Stereo
Amplifier has been designed to
operate at the highest level of
efficiency and performance in
any normal operating situation;
however, there are a few impor-
tant use and care principles
that must be kept in mind when
operating the amplifier.

PO BOX 7231, COLORADO SPRINGS, COLORADO 80933 USA E-mAIL: [e-mail] www.jEffROwLAND.COm TELEPHONE [phone]

1
2 F ED ED
A AB BC C
signal & power connections
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

© Jeff Rowland design gRoup 2007. all Rights ReseRved.

Before attempting any system interconnection, please familiarize yourself
with the front panel control of the Model 312 Stereo Power Amplifier.
(1) FRONT PANEL STANDBY/POWER BUTTON: Press this button to
operate the amplifier. Press again to place the amplifier in Standby mode.
(2) FRONT PANEL STANDBY/POWER INDICATOR: This small, blue
light will illuminate when the amplifier is operational. When the light is not
illuminated, all amplifier inputs are muted and internal circuitry reverts to
power-saving (Standby) mode.
NOTE: All ON/OFF power switching should be initiated ONLY with this button. The amplier
should not be disconnected from AC power without rst placing the amplier in Standby mode.
When connecting or disconnecting speaker or interconnect cables, the
amplifier should be placed in Standby mode (blue POWER INDICATOR
LED on the front panel OFF) or the AC mains power plug should be
removed from the amplifier.
(A) BALANCED INPUTS: If you are using balanced XLR interconnects
from your preamplifier or source component, position the INPUT
SELECT switches (B) to BALANCED INPUT.
(C) UNBALANCED INPUTS: If you are using unbalanced RCA intercon-
nects,
position the INPUT SELECT switches to UNBALANCED INPUT.
Connect the corresponding interconnect cables to either the BALANCED
INPUTS (A) or UNBALANCED INPUTS (C) on each channel. Both RCA
and XLR inputs cannot be used for the same channel simultaneously.
For example, an unbalanced output connection from a surround
processor and a balanced output connection from a CD player cannot
both be connected to the same channel at the same time.
A slight
mechanical click may be heard when the balanced XLR inter-
connect cables are correctly installed and locked. The unlocking tab
(located
on the input connector and labeled “PUSH”) must be pressed
to
disconnect the XLR interconnect cable from the amplifier.

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
(D & E) LOUDSPEAKER OUTPUT: Unscrew the knob that secures
the speaker output connectors on both the LEFT SPEAKER OUTPUT
(E) and the RIGHT SPEAKER OUTPUT (D) and pull the securing block
out far enough to allow access to the binding posts. Install the positive
(usually red) loudspeaker cable spade terminal to the positive (+)
binding post and the negative spade terminal to the negative (–) binding
post on both the LEFT and RIGHT CHANNEL. Secure the loudspeaker
connections by tightening the knob securely with your fingers.
The Model 312 will only accept spade terminations for loudspeaker
cables. Banana plugs or bare wire connections can be used but require
an optional clamp available from your JRDG Dealer.
The Model 312 has two pairs of binding posts per channel to facilitate
bi-wiring. Both sets of binding posts are active and connected in parallel
with no difference in signal quality. If your loudspeakers are capable of
bi-wiring and you wish to do so, remove the jumpers connecting the two
sets of binding posts together on your loudspeakers. Connect one pair
of binding posts from each channel to the high frequency terminals of
your loudspeakers and one pair from each channel to the low frequency
terminals of your loudspeakers.
signal & power ConneCtions
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER
WARNING: Both positive and negative outputs are electrically active with respect to
chassis
and/or system ground potential. Therefore, this amplier cannot be used
in certain loudspeaker switching congurations, such as those used in retail demonstrations.
Failure to avoid these precautions may short the outputs to ground and can result in damage
to the amplier and will void the warranty.
Certain subwoofer speakers which derive signals
from amplier outputs will require additional circuitry to properly isolate the amplier output.
Please contact JRDG before connecting these types of subwoofers.

© Jeff Rowland design gRoup 2007. all Rights ReseRved.

NOTE: Due to the exceptionally low power consumption rating of the Model 312, it is
recommended that the unit not be disconnected from AC mains unless the amplier is to be
moved or reinstalled in another location. It is recommended that the amplier be placed in
Standby mode rather than disconnected from the AC mains power when the amplier is not
in use.
WARNING: If the unit is plugged into a voltage different from the range listed on the back
panel, serious damage to internal circuitry will result and will void the warranty.
STEP 1: Verify that the VOLTS AC input identified on the rear panel
near the AC input socket is the same as the AC mains voltage
in your area. If the voltage does not match, DO NOT CONNECT THE
AMPLIFIER TO AC POWER and contact your dealer immediately.
STEP 2: Verify that the AC MAINS circuit breaker is closed (no white
area visible on breaker).
STEP 3: Install the AC Power Cable between the amplifier and your AC
mains outlet.
STEP 4: Connect the 12V Remote ON/OFF Mini-plug Connector if required.
(F) 12V REMOTE TRIGGER: A 1/8” (3.5 mm) mini-plug connector is
provided on the rear panel of the Model 312 for remotely switching the
amplifier between Operational and Standby modes. When connected
to another component with the proper circuitry, the amplifier standby
function can be turned ON and OFF remotely in a custom installation,
theater, or automated system setup. (See FIGURE 1)
FIGURE 1: Detail of 12V remote trigger and mini-plug connector
requirements
NOTE: Please be aware that the remote feature simply places the
amplier in standby mode and does not disconnect the unit from
power or AC mains.
NOTE: The amplier must be placed in Standby mode with the
front panel button before the 12V remote trigger function can be
activated.
Constant 3v To 15v DC Signal
(12VDC Typical) (tip)
Ground (sleeve)

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
Output Power, Continuous RMS watts, both channels driven 500 watts @ 8 ohms, 1000 watts @ 4 ohms per channel
Frequency Response 5 Hz – 45 kHz, -3 dB @ 8 ohms
Peak Output Current 40 amps
Dynamic Range 120 dBa
Load Impedance Range 2 ohms – 16 ohms
Input Impedance 40k ohms
THD + Noise, 0.1 watts – 500 watts, 4 ohms < 0.1%, Typically .01% @ 1 kHz
CCIF Intermodulation Distortion, 19/20 kHz < .002%
Damping Factor @ 1 kHz > 1000
Overall Gain (Balanced or Unbalanced) Selectable Internal Jumper, 26 or 32 dB
Common Mode Rejection Ratio > 90 dB, 20 Hz – 20 kHz
Absolute Phase Non-inverting, Pin 2 Positive
Inputs 2 Balanced (XLR), 2 Unbalanced (RCA) (user selectable)
Outputs 2 pair Parallel Binding Posts per channel
Power Consumption Idle – 35 watts, Maximum – 2000 watts
Amplifier Weight
70 lbs. / 32 kg
Amplifier Shipping Weight 83 lbs. / 38 kg
Overall Amplifier Dimensions (H) x (W) x (D) 10.5” x 15.5” x 18.3”
267mm x 394mm x 465mm
SPECIFICATIONS
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

© Jeff Rowland design gRoup 2007. all Rights ReseRved.






DIMENSIONS
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

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
RISK OF ELECTRICAL SHOCK!
WARNING: The instructions in this section are
meant for qualied JRDG service per sonnel
only; however, if you as an end user choose to attempt
these adjustments yourself, JRDG cannot be held
liable for any damage that may occur to your Model
312 Stereo Amplier because of your actions. Further,
accessing the interior of your Model 312 by removing
the bottom cover can expose you to dangerous, poten-
tially lethal
electrical voltages. Thus, JRDG cannot be
held liable for any injury you may sustain
should you
undertake any of these adjustments yourself.
OVERALL GAIN ADjUSTMENT
By removing the top cover the overall gain of the Model 312 Stereo Power
Amplifier can be adjusted to either 26 dB or 32 dB via jumpers located on
the rear panel circuit board inside the amplifier. The default setting from the
factory is 26 dB, which is adequate for the majority of applications. There is
no sonic difference between the two settings.
Because of the potentially dangerous voltages inside of the chassis, it is recommended
that you contact your dealer for information regarding the overall gain setting adjustments.
NOTE: Do not attempt to remove the top cover to adjust the overall gain without explicit instruc-
tions from your dealer or JRDG.
optional adjustments
OWNER’S MANUAL MODEL 312 STEREO AMPLIFIER

PO BOX 7231, COLORADO SPRINGS, COLORADO 80933 USA E-mAIL: [e-mail] www.jEffROwLAND.COm TELEPHONE [phone]