JEFF ROWLAND 3 Manuel utilisateur
MODEL 3 MONO AMPLIFIER
OWNER’S MANUAL
TABLE OF CONTENTS
Introduction
Features
Unpacking Instructions
Installation
* Space requirements
* A.C. connections
Input Impedance Selection
Adjustable Gain
Signal Connections
* Single-ended input configuration
* Differential mode input configuration
Basic Troubleshooting
Technical Specifications
Introduction
Congratulations on your purchase of the Jeff Rowland Design Group Model 3 Mono
amplifier.
Please take a few moments to read this owners manual. Contrary to popular belief, there
is actually quite a bit of useful information in an owners manual. The Model 3 offers
tremendous interconnection flexibility regardless of the preamp used. A thorough
understanding of your amplifier now can save you a lot of anxiety later.
Features
• Lack of overall or nested negative feedback eliminates time domain distortion.
• Proprietary distortion canceling techniques minimize amplitude related distortions.
• Each transistor individually tested and matched for optimum operating
characteristics.
• Constant output impedance is maintained over the entire audio range, allowing for
universal compatibility with associated equipment.
• The large number of high-speed bipolar output transistors provides uncompromising
reliability and eliminates the need for electronic protection circuitry.
• A single voltage amplification stage utilizes field effect transistors (operating in
transconductance mode), which increases low-level signal recognition.
• The absence of capacitors, inductors, fuses and protection circuitry throughout the
signal path eliminates the adverse effects of these devices.
• A specially designed toroidal power transformer is supported by the substantial
output stage capability.
• All critical circuitry is encapsulated in a thermally-conductive epoxy to ensure
excellent thermal stability, mechanical integrity and to facilitate ease of service.
Unpacking Instructions
In the shipping crate you will find:
--AC Power Cord
--Various Fuses
--XLR Shorting Plugs
--Performance Certificate
--Warranty Card (This form must be completed and returned to JEFF ROWLAND
DESIGN GROUP [or its authorized distributor if outside the U.S.A.] within 14
days of purchase. Not only will your amplifier be registered, but you will, in the
future, be informed of new products and services.
We strongly suggest that you save all packing materials
The amp can be lifted out of its crate while still wrapped in the plastic bag and
surrounded by the protective foam.
Installation
Locate the amplifier as close as possible to its final installation point. Allow access to the
back panel for making connections.
All Jeff Rowland Design Group products are convection cooled, eliminating the need for a
fan. When operating, the amp should have at least 2 inches of space on all sides. It is
acceptable to stack the amplifiers only if fresh air is allowed to circulate around them.
When the amp is in position, the power cord should be inserted first at the inlet on the
amplifier back panel, then connected to an appropriate power source. The amplifier is
equipped with a "stand-by" power switch, located and identified on the rear panel, as
well as an illuminated power push button switch on the front panel. The stand-by power
switch should be turned on initially after plugging in the AC power cord. The amplifier
will now be in stand-by mode, indicated by a dimly lit front panel button. The rear panel
switch should be left on at all times, maintaining stable operating parameters and
thereby improving performance, reliability and longevity. Power consumption in stand-by
mode is less than 25 watts, providing low-cost operation.
Pressing the dimly lit push button will switch the amplifier on for normal operation. Note
that the lamp intensity will increase and a faint "click" will be heard. All subsequent on-
off cycles should be initiated by the front panel switch.
If the front panel switch does not light, the amplifier does not power up or a fuse blows,
disconnect AC power, refer to the troubleshooting section of this manual or contact your
dealer.
Input Impedance Selection
Your amplifier is provided with user-adjustable input impedance. A four (4) position
D.I.P. switch for each channel is located and clearly marked on the back panel. Jeff
Rowland Design Group has chosen 3 values of input impedance to cover the majority of
applications. If you want to change your input impedance, please turn off the front panel
power before doing so. Selecting from the switch codes shown below will provide the
specific input impedance desired by the user.
The "low" setting is for use with most direct-coupled solid-state preamplifiers such as
those made by Jeff Rowland Design Group; the "medium" setting is for use with most
solid-state, hybrid and some tube preamplifiers; the "high" setting is for use with most
tube preamplifiers. We have provided these different settings so that you may find which
one provides the best sonic results in your system. Your amp comes set from the factory
at the "medium" (20 k ohms) adjustment.
Adjustable Gain
The overall gain structure of your Model 3 amplifier can be adjusted to one of four
different values, 20, 26, 29.5 or 32 dB. (Your amp comes set from the factory at the 26
dB adjustment.) The Model 3 can thus be used with dissimilar-gain preamplifiers, as well
as with a wide variety of analog and digital sources (since many digital sources [compact
disc players, digital to analog converters] have high output voltages relative to tuners,
tape decks, etc.). This feature allows the volume control of your preamp to be used in its
optimum position. It also permits you to tailor the gain structure for use with high or
low-efficiency speakers.
The gain switches are located on the underside of the plug-in modules and should only
be adjusted by your Jeff Rowland Design Group dealer. Incorrect installation of these
modules will result in damage to the amplifier circuitry which cannot be covered under
warranty.
Signal Connections
The amplifiers from JEFF ROWLAND DESIGN GROUP offer unprecedented compatibility
with associated equipment. In all cases turn the front panel power off before
connecting or disconnecting signal wires. "Hot patching" is not recommended.
A series of descriptions follows to explain the hookup schemes most commonly utilized
in home stereo applications. For a more thorough understanding of the terms used in
this section, please read the enclosed paper on differential mode technology.
The back panel of the amplifier is clearly marked with the following:
• paralleled right and left channel outputs
• remote power switch connector
• right and left channel inputs (single-ended non-inverting, single-ended inverting and
differential inputs)
• right and left channel input impedance adjust
• AC power switch
• AC power connector
• AC line fuse
Operation with a single-ended output preamplifier
For standard operation, insert the interconnect cables from your preamp to the non-
inverting RCA inputs. Insert shorting plugs into each of the inverting RCA inputs. If you
desire inverted operation, reverse the above procedure. Either of the two paralleled
outputs can be used, or all four if you are bi-wiring your speakers.
Operation with a balanced output preamplifier
Insert the output of your preamplifier into either the differential XLR input or both the
single-ended inverting and non-inverting RCA inputs. You can then utilize either of the
two paralleled outputs, or all four if you are bi-wiring your speakers.
Basic Troubleshooting
If your amplifier does not turn on:
1. Make sure the power cord is connected to both the inlet at the back of the amp and
an appropriate AC power source.
2. Check the power supply fuses located next to the AC inlet; there are two fuses--one is
a spare.
If your amplifier shuts down after being turned on, with or without the presence of
signal:
1. Check the rail fuses; on the Model 3, these are located on the inside of the amp
adjacent to the encapsulated transformer. A fuse can often look good even if it is
actually bad. If possible, check the fuses with a meter.
2. If the fuses are good, disconnect the inputs from the amp and see if it will power up
again. Your amplifier will generally only shut down if it senses DC, thus protecting your
speakers. Certain associated equipment can occasionally pass DC.
If the above suggestions do not work or you are having other problems,
please contact your Jeff Rowland Design Group dealer.
Technical Specifications
Output power
100 watts RMS continuous, 8 ohms
200 watts RMS continuous, 4 ohms
320 watts RMS continuous, 2 ohms
Power Bandwidth 0.15 Hz to 175 kHz, -3 dB
Slew Rate 45 volts per microsecond
THD and Noise Less than .03%, 1 kHz, 8 ohms, 20 watts
Less than .08%, 1 kHz, 8 ohms, 100 watts
Damping Factor Greater than 120, 20 Hz to 20 kHz, 8 ohms
Greater than 80, 100 kHz, 8 ohms
Output Current 32 amps peak, continuous
80 amps peak, 0.1 ohm, 20 msec, 1 kHz
Overall Gain Selectable: 20, 26, 29.5, 32 dB
Sensitivity 136 mV, 1 watt, 8 ohms
Input Impedance Selectable: 100k, 20k, 600 ohms
Power Requirements 100V-240V
Dimensions 19 in. W x 8.75 in. H x 24 in. D
48 cm W x 22 cm H x 61 cm D
Ce manuel convient aux modèles suivants
1
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