User's Manual

Loud howl, squeal, or whistle.

•The Tape Monitor switch is engaged while microphones (in the same room as the speakers) are connected to a tape deck for recording.

•Put the cat out.

Solo voices, or instruments sound thin, shrill or distorted.

•Phono cartridge is wired out of phase.

Hum

Under normal operating conditions you hear very little hum originating in the circuitry of the Classic. There is one exception to this rule: If you have a high-gain power amplifier and unusually sensitive (i.e. efficient) loud- speakers, normal listening levels will involve using abnormally low output levels from the preamp, and those small signals might then pick a bit of hum or hiss in the preamp’s circuits. In this case the solution is to turn down the power amplifier’s level controls if it has them, or consider having its gain reduced by the manufacturer. Contact Sunfire Technical Services for further information.

Except for the condition described above, audible hum will nearly always be found to be due to problems external to the Classic — usually in the signal source, i.e. the turntable or tape deck. Many turntables, for example, have a hum field in the vicinity of the platter due to the turntable’s motor or internal power transformer which is acceptably low with moving-magnet cartridges but audibly bothersome with moving-coil cartridges. If your turntable has a non-polarized AC plug, you can experiment with reversing it to see which orientation of the plug minimizes the audible hum. The hum may also vary with the location and orientation of the turntable with respect to AC wiring in the walls, making it necessary to move the turntable to another part of the room.

Turntables and tape decks are sensitive to the external hum fields created by many power amplifiers, and sometimes to the hum fields of other house appliances (such as a refrigerator on the other side of the wall). It is important that signal cables in general, and the turntable signal leads in particular, should not run close to and parallel with AC power cords, nor close to a power transformer or motor (including that in the base of the turntable).

As a test, you might try and disconnect all cables which come from outside the room, such as cable TV, satellite TV, or roof top antennas. Make sure that they are disconnected where they first enter the room, so they are making no connection to your VCR, TV, or any other component. If you find that noise goes away when a cable TV line is disconnected, then you will need a “ground- loop isolator.” This is an inexpensive device fitted in line with the coaxial cable feed.

If the hum persists, disconnect all the source components one at a time from the back of the preamplifier and you may identify the problem.

In many cases, hum may be eliminated by reversing the Classic’s (unpolarized) AC power plug in the wall socket. In others it can be minimized by connecting a heavy stranded wire from the preamplifier’s ground post to a true earth ground — which may turn out to be any, all, or none of the following: the third (round) hole in an electrical wall socket in modern U.S. homes, a steam radiator, or a cold water pipe. However, if your power amplifier employs a three-wire power cord, the stereo system may already be grounded through that, in which case another grounded wire from the preamp may create a “ground loop” and make the hum worse. As for the various components within the stereo system, they are mutually grounded via the shields of the signal cables and should not be interconnected with additional grounding wires, for the same reason (except, of course, the turntable; whose grounding wire usually (but not always) should be connected to the preamplifier’s ground post).

20Troubleshooting