User manual JEFF ROWLAND MODEL 1

[. . . ] · 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. [. . . ] 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 1 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 5 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 Stereo operation with a single-ended output preamplifier For standard operation, insert the interconnect cables from your preamp to the noninverting RCA inputs. Insert shorting plugs into each of the inverting RCA inputs. [. . . ] 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 1, 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. [. . . ]