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Model 6
Mono Power Amplifier
Owner’s Manual
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Introduction
W
elcome to the Jeff Rowland Design Group “family” and congratulations on your purchase of the Model 6 Amplifiers. þ
These mono Amplifiers are unquestionably considered to be one of the finest in their class. þ With the combination of
industrial-grade active and passive devices, precision electronic circuitry and accurately machined chassis components
throughout, your Model 6 Mono Amplifiers will offer you many years of musically satisfying enjoyment.
þ Please take a
few moments to read the remainder of this Owner’s Manual.
þ A thorough understanding of the operational features
will allow you to gain the maximum performance and ease of use for which these Amplifiers were designed.
þ Please
note that your Model 6 Mono Amplifiers are marked with serial numbers beginning with the letter A.
þ These numbers
are recorded below and are also located on the rear panel of each chassis.
þ Please include these numbers with any
correspondence regarding your Model 6 Amplifiers.
þ It has been my joy to create audio components of enduring
value which will reflect a higher ideal of musical and artistic expression.
þ It is my hope that these qualities will enrich
your experience of ownership.
Enjoy the music!
Jeff Rowland
President
þ Jeff Rowland Design Group, Inc.
2911 North Prospect Street
Colorado Springs, CO 80907
Phone: 719/473-1181
Fax: 719/633-4158
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Product Features
þ XLR Balanced Input jacks for balanced (Differential Mode™) system
configurations
þ XLR to RCA Input adapters included
þ User-selectable overall gain of 26 or 32 dB
þ User-selectable input impedance of 18kΩ (HI) or 600Ω (LO)
þ All internal signal circuitry is totally isolated from chassis and system
ground potentials to eliminate noisy ground loops and to provide
extreme immunity from RF interference
þ Optional remote (wired or wireless power ON/OFF switching)
þ Automatic temperature stabilizing circuitry maintains constant
operating temperature
þ Standby power condition reduces warm-up time
þ Fail-safe operation provided by user-resetable AC circuit breaker
located on rear panel
þ Quiet, transient-free operation during power and function mode
switching
þ Automatic input muting under anomalous input or output operating
conditions
þ Balanced Differential Mode™ circuit topology implemented from input
to output
þ Plug-in modules, containing critical electronic circuitry, enhance
thermal stability, mechanical integrity and serviceability
þ Low-resonance, structurally integrated chassis of precision machined
aluminum alloy components.
Introduction / Product Features
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Contents
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Initial Inspection
I
nspect the shipping containers for damage. If the shipping containers,
packing material, Amplifiers or accessories are damaged or missing, notify
your dealer and the shipper (if a claim is to be made). Note: Many shippers
require notification and an inspection within twenty-four (24) hours of
delivery to ascertain the nature of damages incurred.
Each of your Model 6 Amplifiers has undergone extensive performance
evaluations, listening tests, quality control inspections and a minimum
seventy-two (72) hour burn-in period prior to shipment and should be in a
perfect operational condition upon receipt. If the Amplifiers do not operate
correctly, please notify your dealer immediately.
We strongly suggest that you save all packing materials. If the Amplifiers are
returned to your dealer or Jeff Rowland Design Group, the original packing
materials must be used for shipment. Neither Jeff Rowland Design Group
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 a
Return Authorization number be issued by Jeff Rowland Design Group prior
to shipment.
Contents
E
nsure that all of the auxiliary components listed below are enclosed
within the accessory box. Refer to the diagrams illustrated above and
verify the components included.
1 Two (2) AC power cables
2 Two (2) XLR/RCA adapters
3 Eight (8) spiked coupling interface supports
4 Eight (8) compliant isolation interface supports
5 One (1) speaker terminal hand wrench (7/16 inch)
6 One (1) warranty card (in some countries warranties are provided by
the respective importer)
Initial Inspection / Contents
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Front & Rear Panel Function Controls
A
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1
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Front & Rear Panel Function Controls
Before attempting any system interconnection, please familiarize yourself
with the front and rear panel controls of the Model 6 Amplifiers. The
descriptions below refer to the numbers associated with the features in the
diagram above.
Front Panel
A
FRONT PANEL STANDBY/POWER button: Press to operate Amplifier in
standby mode. This button will illuminate when the Amplifier is
operational. When the button is not illuminated, all Amplifier inputs are
muted and internal circuitry is reverted to power-saving (standby) mode.
Note: All ON/OFF power switching should be initiated ONLY with this
button. Anomalous operating conditions will automatically switch the
Amplifier off (no illumination) and will prevent the Amplifier from being
switched back on again until such a condition is eliminated.
Rear Panel
(Note: The switches described below can be switched, if desired, while
the Amplifier is operational and playing music.)
1 INPUT IMPEDANCE switch: This switch selects between a high
(18KΩ) or low (600Ω) input impedance.
2 OVERALL GAIN switch: This switch selects between a high (32 dB)
or normal (26 dB) overall gain structure of the Amplifier.
Front & Rear Panel Function Controls
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2
1
3
Rear Panel Power Connections
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Installation
L
ocate the Amplifiers as close as possible to their final installation point.
Allow access to the rear panels for making connections.
Each Model 6 Amplifier is convection cooled, eliminating the need for fan
or forced air cooling. When operating, the chassis should have at least two
(2) inches of air space around the heatsink areas. Both right and left
channel chassis can be stacked vertically thus facilitating an upward flow of
warm air currents throughout the vertical heatsink fin areas. This upward
flow must not be impeded or recirculated around the chassis if proper
cooling is to be maintained.
Supplied with your Model 6 Amplifiers are two different support systems.
An assessment of the supporting structure should be made to determine
the proper system for the Amplifiers. Both spiked and compliant interface
supports can be easily installed within the indentations on each of the four
chassis pods located underneath the corners of each chassis. These system
options permit the coupling or decoupling of the Amplifier chassis to the
supporting structure.
As a general rule, most installations allow each Amplifier chassis to be
rigidly coupled to the supporting structure via the spiked coupling interface
supports. In carpeted installations, these supports provide excellent
coupling from the Amplifier chassis to the rigid supporting structure below.
In installations where the integrity of the supporting structure is poor, the
Amplifier chassis can be loosely coupled to the supporting structure via the
compliant isolation interface supports. This will help attenuate the transfer
of spurious energy from the supporting structure into the Amplifier chassis.
Note: Another installation option, when incorporating the Battery Power
Source, utilizes its chassis as a stable, high mass structural support for the
Amplifier chassis. In this configuration, the Battery Power Source chassis is
rigidly coupled to the supporting structure via the spiked coupling interface
supports and the Amplifier is placed directly above the Battery Power
Source and isolated via the compliant isolation interface supports.
If desired, a coin may be placed directly under the point of the spiked
coupling support to prevent damage to various surfaces (i.e. hardwood
floors).
Rear Panel Power Connections
Important: Please strictly follow the steps in order as outlined below
before operating your Model 6 Amplifiers.
1 Verify that the supplied connector jumpers and covers are installed
correctly to the JUMPER/BPS-6 CONNECTOR on each Amplifier. These
connector jumpers can serve as an interlock to prevent unauthorized
operation of the Amplifiers when not in place. When using the
companion BPS-6 (Battery Power Source), these connector jumpers
must be removed and the BPS-6 DC power cables must be installed in
their place.
2 Verify that the VOLTS 50/60 Hz INPUT identified on each rear panel
corresponds to the AC mains voltage of your service area.
3 Install the AC power cable between the Amplifier and an active AC
mains outlet.
Installation / Rear Panel Power Connections
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1
Signal Connections
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3
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Signal Connections
T
he Model 6 Amplifiers offer unprecedented compatibility with associated
audio components. When connecting or disconnecting speaker or
interconnect cables, it is only necessary that the FRONT PANEL
STANDBY/POWER buttons be pressed to switch the Amplifiers to standby
mode. The button will not be illuminated in this mode.
1 When installing the interconnect cables, a slight click may be heard
when the XLR interconnect plugs are installed correctly and latched.
The latch (located on the input connector and labeled PUSH) must be
pressed to remove the XLR interconnect cable.
2 When using RCA unbalanced interconnects from your preamplifier or
other source component, install the supplied XLR/RCA adapters into
the XLR input connector on each Amplifier. The Amplifiers will still
operate in the fully balanced (Differential Mode™) configuration.
3 Unscrew the positive and negative OUTPUT connectors and install the
positive and negative loudspeaker cable spade terminals respectively
to each Amplifier OUTPUT. Red is normally positive; black is normally
negative. ALWAYS USE THE SUPPLIED SPEAKER TERMINAL HAND
WRENCH WHEN CONNECTING OR DISCONNECTING LOUDSPEAKER
CABLES. DO NOT OVERTIGHTEN THESE TERMINALS.
WARNING: Both positive and negative OUTPUTS of both
channels are electrically active with respect to chassis and/or system ground
potential. It is important that both of these outputs are electrically isolated
from system ground potential. This precludes the use of these Amplifiers in
certain loudspeaker switching configurations (sometimes used in retail
demonstrations) and testing or servicing situations where either positive or
negative outputs can be connected to ground potentials. Failure to observe
these precautions may result in damage to the Amplifiers and may void your
warranty. Consult the factory first if the Amplifiers are to be used under
these conditions.
Remote
4
A REMOTE connector (DIN 5-pin) is provided on the rear panel of each
Amplifier for remotely switching the Amplifier between operational and
standby modes. The pin connections on this connector parallel the
electrical contacts of the FRONT PANEL STANDBY/POWER button and
lamp. An optional wired remote switch or infrared wireless remote
sensor can be plugged into the REMOTE connector to facilitate this
function. Contact your dealer or Jeff Rowland Design Group for further
information and availability of this feature.
Signal Connections
!
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Operation
A
fter following the procedures outlined in the Installation/Rear Panel
Power Connections and Signal Connections sections, the Amplifiers can be
turned on by pressing the FRONT PANEL STANDBY/POWER buttons. Allow
approximately twenty (20) minutes for each Amplifier to reach operating
temperature and maximum performance potential. A short warm-up time is
dependent upon each Amplifier being plugged in to an active AC mains
power source for at least two hours prior to activating the FRONT PANEL
STANDBY/POWER buttons. Therefore, it is recommended that each
Amplifier be continuously connected to an active AC mains power source.
If you desire to disconnect the AC mains for an extended period of time,
simply disconnect the AC power cable from the wall outlet and reconnect
upon your return. Slight transients may be heard in the loudspeakers during
the AC mains connect/disconnect transitions.
Your new Model 6 Amplifiers will require an initial break-in period of at
least eighty (80) hours before maximum performance can be expected.
Efficient break-in procedures require the Amplifiers to be fully operational
(playing music). Continuous and noticeable performance improvements will
occur during subsequent months of operation.
To achieve the maximum performance for which these Amplifiers were
designed, it is recommended that balanced signal source (INPUT) and LOW
INPUT IMPEDANCE options are used. This condition requires that the
driving source component (preamplifier) is equipped with balanced
outputs and sufficient output current to properly drive the inputs of the
Model 6 Amplifiers when the LOW INPUT IMPEDANCE option is selected.
Most high-quality solid state preamplifiers can satisfy these conditions, and
best results are obtained when the output impedance of the preamplifier
(600Ω balanced) matches the input impedance of the power Amplifier
(600Ω balanced). When the impedances are matched, maximum signal
power transfer and signal fidelity are achieved in addition to the advantage
of utilization of long lengths (10 meters and greater) of interconnect
between components with no sonic degradation. However, there will be a
6 dB decrease in volume relative to a mismatched condition (low driving
source impedance driving high load (Amplifier input) impedance).
If there is any doubt as to the compatibility of the above mentioned
components, then HIGH INPUT IMPEDANCE should be selected. Since the
electrical performance of the Model 6 is not changed when selecting
different INPUT IMPEDANCE options, apparent differences in sonic quality
can be attributed to mismatched impedances.
Due to different sensitivities of associated equipment used with the Model 6
Amplifiers, the OVERALL GAIN switch can be used to optimize the total
gain structure of the entire system. This allows the volume control of your
preamp to be used in an ideal mid-range position.
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Performance Specifications
Output Power
Continuous RMS watts
@ 8 ohms 150 watts
@ 4 ohms 250 watts
Power Bandwidth 0.5 Hz to 160 kHz, -3 dB
Slew Rate 80 volts per microsecond
THD and Noise Less than 0.05% at rated power
Damping Factor Greater than 100, 20 Hz to 20 kHz, 8 ohms
Output Current 35 amps continuous, 50 amps peak
Overall Gain
& Sensitivity
User selectable on rear panel
(1 watt, 8 ohms) 26 dB or 32 dB; 141 mV or 71 mV
Input Impedance User selectable on rear panel
Unbalanced 18k or 600 ohms
Balanced 18k or 600 ohms
Common Mode
Rejection Ratio
Greater than 60 dB, 20 Hz to 20 kHz
Power Consumption 25 watts standby; 225 watts operating, idle;
400 watts per Amplifier maximum
Inputs
Unbalanced With supplied XLR/RCA adapter
Balanced XLR connector
Outputs 1 pair binding posts
Dimensions 17.5 in. W x 14.25 in. D x 5.25 in. H
44.5 cm W x 36.2 cm D x 13.3 cm H
Shipping Dimensions 24 in. W x 20 in. D x 12 in. H
61 cm W x 50.8 cm D x 30.5 cm H
Weight 45 lbs. (20.5 kg)
Shipping Weight 71 lbs. (32.0 kg)
Because Jeff Rowland Design Group is constantly analyzing new
design improvements, we reserve the right to change or modify product
specifications without notice or obligation.
Operation / Specifications
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Basic Troubleshooting
A
summary of fault conditions, their causes and remedies, are listed below.
The Model 6 Amplifiers can produce high power levels which, without well designed protection circuitry, could damage loudspeakers. Therefore, most fault
conditions which may occur during use will be indicated by the Model 6 reverting to a standby condition.
JRDG = Jeff Rowland Design Group, Inc.
Condition
FRONT PANEL STANDBY/POWER button lamp
does not illuminate after pressing, although the
Amplifier operates normally.
FRONT PANEL STANDBY/POWER button lamp
does not illuminate after pressing, and Amplifier
does not operate normally.
FRONT PANEL STANDBY/POWER button reverts
to standby condition during listening but can be
returned to operational condition.
Cause
Light bulb defective.
Incorrect power connections or AC MAINS
CIRCUIT BREAKER on Amplifier rear panel is
tripped.
Abnormal operation of Model 6 Amplifier internal
circuitry.
Excessive sub-sonic signals produced by source
components.
Severe clipping of Amplifier circuitry under
intermittent overload conditions.
Remedy
Remove STANDBY/POWER button from front panel
and replace bulb located under button. Use
replacement bulb kit and instructions supplied by
JRDG.
Review Installation/Rear Panel Power Connections
section. Reset CIRCUIT BREAKER on Amplifier rear
panel.
Consult dealer or JRDG.
Repair or replace source component (preamplifier).
Identify and correct abnormal conditions such as low
frequency rumble and/or acoustic feedback caused
by phono playback components (if applicable).
Reduce volume slightly or use higher efficiency
loudspeakers.
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Condition
FRONT PANEL STANDBY/POWER button
illuminates normally but Amplifier does not
operate or warm up to normal operating
temperature.
AC MAINS CIRCUIT BREAKER (rear panel)
switches off or will not remain on.
50/60 Hz hum noise in loudspeakers.
High frequency, random or scratching noise in
loudspeakers.
Cause
Internal DC fuses defective.
AC mains service voltage too high for Amplifier.
Sensitive source component(s) located too close to
Amplifier.
Unstable conditions created by excessive
capacitance in loudspeaker cables.
Remedy
Consult dealer or JRDG.
Reconfigure Amplifier to proper AC mains voltage
operation. Consult dealer or JRDG.
Reorient or increase distance between source
component and Amplifier.
Insert compensation network on Amplifier
OUTPUT connector(s) (available from JRDG).
Basic Troubleshooting
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If you have any additional questions regarding installation or operation,
please contact your authorized Jeff Rowland Design Group Dealer.
JEFF ROWLAND
DESIGN GROUP
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