Jeff Rowland Design Group Stereo Amplifier Model 2 User Manual

JEFF ROWLAND  
D E S I G N G R O U P  
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Introduction  
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Jeff Rowland Design Group, Inc.  
2911 North Prospect Street  
Colorado Springs, CO 80907  
Phone: 719/473-1181  
Welcome to the Jeff Rowland Design Group “family” and congratulations on your purchase of what is unquestionably  
one of the world’s finest audio power amplifiers.  
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With its combination of industrial grade active and passive devices,  
precision electronic circuitry and accurately machined chassis components throughout, your Model 2 Amplifier will offer  
you many years of musically satisfying enjoyment.  
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Please take a few moments to read the remainder of this Owner’s  
Fax: 719/633-4158  
Manual.  
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A thorough understanding of 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 2 Stereo Amplifier serial number begins  
with the letter A.  
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This number is recorded below and is also located on the rear panel of the chassis.  
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Please  
include this number with any correspondence regarding your Model 2 Amplifier.  
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It has been my joy to create an  
audio component of enduring value which will reflect a higher ideal of musical and artistic expression.  
that these qualities will enrich your experience of ownership.  
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It is my hope  
Enjoy the music!  
Jeff Rowland  
President  
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Product Features  
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Quiet, transient-free operation during power and function mode  
switching  
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XLR Balanced Input jacks for balanced (Differential Mode™) system  
configurations  
Automatic input muting under anomalous input or output operating  
conditions  
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XLR to RCA Input adapters included  
User-selectable overall gain of 26 or 32 dB  
User-selectable input impedance of 36k(HI) or 600(LO)  
Balanced Differential Mode™ circuit topology implemented from input  
to output  
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  
Plug-in modules, containing critical electronic circuitry, enhance  
thermal stability, mechanical integrity and serviceability  
Low-resonance, structurally integrated chassis of precision machined  
aluminum alloy components.  
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Optional remote (wired or wireless power ON/OFF switching)  
Automatic temperature stabilizing circuitry maintains constant  
operating temperature  
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Standby power condition reduces warm-up time  
Fail-safe operation provided by user-resetable AC circuit breaker  
located on rear panel  
Introduction / Product Features  
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Contents  
1
6
4
2
5
3
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Initial Inspection  
Contents  
Inspect the shipping container for damage. If 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). Note: Many shippers  
require notification and an inspection within twenty-four (24) hours of  
delivery to ascertain the nature of damages incurred.  
Ensure 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 AC power cable  
Your Model 2 Amplifier 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 Amplifier does not operate correctly, please  
notify your dealer immediately.  
2 Two (2) XLR/RCA adapters  
3 Four (4) spiked coupling interface supports  
4 Four (4) compliant isolation interface supports  
5 One (1) speaker terminal hand wrench (7/16 inch)  
We strongly suggest that you save all packing materials. If the Amplifier is  
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.  
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  
2
A
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 2 Amplifier. 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  
(36K) or low (600) 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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Rear Panel Power Connections  
2
1
3
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Installation  
Rear Panel Power Connections  
Locate the Amplifier as close as possible to its final installation point.  
Important: Please strictly follow the steps in order as outlined below  
before operating your Model 2 Amplifier.  
Allow access to the rear panel for making connections.  
The Model 2 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. Multiple 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.  
1 Verify that the supplied connector jumper and cover are installed  
correctly to the JUMPER/BPS-2 CONNECTOR. This connector jumper  
can serve as an interlock to prevent unauthorized operation of the  
amplifier when not in place. When using the companion BPS-2  
(Battery Power Source), this connector jumper must be removed and  
the BPS-2 DC power cable must be installed in its place.  
2 Verify that the VOLTS 50/60 Hz INPUT identified on the rear panel  
Supplied with your Model 2 Amplifier are two different support systems.  
An assessment of the supporting structure should be made to determine the  
proper system for the Amplifier. 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 the chassis. These system  
options permit the coupling or decoupling of the Amplifier chassis to the  
supporting structure.  
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.  
As a general rule, most installations allow the 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 optional 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).  
Installation / Rear Panel Power Connections  
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Signal Connections  
1
4
2
3
3
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Signal Connections  
The Model 2 amplifier offers unprecedented compatibility with associated  
audio components. When connecting or disconnecting speaker or  
interconnect cables, it is only necessary that the FRONT PANEL STANDBY/  
POWER button be pressed to switch the amplifier to standby mode. The  
button will not be illuminated in this mode.  
Remote  
4 A REMOTE connector (DIN 5-pin) is provided on the rear panel 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.  
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  
both XLR input connectors. The Amplifier will still operate in the fully  
balanced (Differential Mode™) configuration.  
3 Unscrew RIGHT CHANNEL OUTPUT and LEFT CHANNEL OUTPUT  
connectors and install the positive and negative loudspeaker cable  
spade terminals to the respective 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 this  
Amplifier 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 Amplifier  
and may void your warranty. Consult the factory first if the Amplifier is to  
be used under these conditions.  
Signal Connections  
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Operation  
To achieve the maximum performance for which this Amplifier was 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 input of the Model 2 when the LOW  
INPUT IMPEDANCE option is selected. Most high-quality solid state pream-  
plifiers can satisfy these conditions, and best results are obtained when the  
output impedance of the preamplifier (600balanced) matches the input  
impedance of the power Amplifier (600balanced). 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).  
After following the procedures outlined in the Installation/Rear Panel  
Power Connections and Signal Connections sections, the Amplifier can be  
turned on by pressing the FRONT PANEL STANDBY/POWER button. Allow  
approximately twenty (20) minutes for the amplifier to reach operating  
temperature and maximum performance potential. A short warm-up time is  
dependent upon the amplifier being plugged in to an active AC mains  
power source for at least two hours prior to activating the FRONT PANEL  
STANDBY/POWER button. Therefore, it is recommended that the 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 2 Amplifier 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 Amplifier to be fully operational (playing  
music). Continuous and noticeable performance improvements will occur  
during subsequent months of operation.  
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 2 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 2,  
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  
Power Consumption 25 watts standby; 175 watts operating, idle;  
Continuous RMS watts  
400 watts maximum  
@ 8 ohms  
@ 4 ohms  
75 watts  
150 watts  
Inputs  
Unbalanced  
Balanced  
User selectable on rear panel  
With supplied XLR/RCA adapter  
2 XLR connectors  
Power Bandwidth 0.1 Hz to 160 kHz, -3 dB  
Slew Rate  
80 volts per microsecond  
Outputs  
1 pair binding posts per channel  
THD and Noise  
Damping Factor  
Output Current  
Less than 0.05% at rated power  
Greater than 100, 20 Hz to 20 kHz, 8 ohms  
20 amps continuous, 35 amps peak  
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  
Overall Gain  
& Sensitivity  
(1 watt, 8 ohms)  
Weight  
47 lbs. (21.5 kg)  
75 lbs. (34.0 kg)  
User selectable on rear panel  
26 dB or 32 dB; 141 mV or 71 mV  
Shipping Weight  
Input Impedance  
Unbalanced  
User selectable on rear panel  
36k or 600 ohms  
Balanced  
36k or 600 ohms  
Common Mode  
Rejection Ratio  
Greater than 60 dB, 20 Hz to 20 kHz  
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  
Asummary of fault conditions, their causes and remedies, are listed below.  
The Model 2 Amplifier 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 2 reverting to a standby condition.  
JRDG = Jeff Rowland Design Group, Inc.  
Condition  
Cause  
Remedy  
FRONT PANEL STANDBY/POWER button lamp  
does not illuminate after pressing, although the  
Amplifier operates normally.  
Light bulb defective.  
Remove STANDBY/POWER button from front panel  
and replace bulb located under button. Use  
replacement bulb kit and instructions supplied by  
JRDG.  
FRONT PANEL STANDBY/POWER button lamp  
does not illuminate after pressing, and Amplifier  
does not operate normally.  
Incorrect power connections or AC MAINS  
CIRCUIT BREAKER on Amplifier rear panel is  
tripped.  
Review Installation/Rear Panel Power Connections  
section. Reset CIRCUIT BREAKER on amplifier rear  
panel.  
Abnormal operation of Model 2 Amplifier internal  
circuitry.  
Consult dealer or JRDG.  
FRONT PANEL STANDBY/POWER button reverts  
to standby condition during listening but can be  
returned to operational condition.  
Excessive sub-sonic signals produced by source  
components.  
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).  
Severe clipping of Amplifier circuitry under  
intermittent overload conditions.  
Reduce volume slightly or use higher efficiency  
loudspeakers.  
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Condition  
Cause  
Remedy  
FRONT PANEL STANDBY/POWER button  
illuminates normally but RIGHT, LEFT or both  
Amplifier CHANNELS do no operate or warm up  
to normal operating temperature.  
Internal DC fuses defective.  
Consult dealer or JRDG.  
AC MAINS CIRCUIT BREAKER (rear panel)  
switches off or will not remain on.  
AC mains service voltage too high for Amplifier.  
Reconfigure Amplifier to proper AC mains voltage  
operation. Consult dealer or JRDG.  
50/60 Hz hum noise in loudspeakers.  
Sensitive source component(s) located too close to  
Amplifier.  
Reorient or increase distance between source  
component and Amplifier.  
High frequency, random or scratching noise in  
loudspeakers.  
Unstable conditions created by excessive  
capacitance in loudspeaker cables.  
Insert compensation network on Amplifier  
OUTPUT connector(s) (available from JRDG).  
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Basic Troubleshooting  
If you have any additional questions regarding installation or operation,  
please contact your authorized Jeff Rowland Design Group Dealer.  
JEFF ROWLAND  
D
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