User manual JEFF ROWLAND MODEL 3

[. . . ] 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 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 onoff 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. 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. [. . . ] Check the rail fuses; on the Model 3, these are located on the inside of the amp adjacent to the encapsulated transformer. 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. If the above suggestions do not work or you are having other problems, please contact your Jeff Rowland Design Group dealer. [. . . ]