Conrad-Johnson Premier 18LS line preamplifier Page 2
The front panel is divided into two main sections. Moving from left to right, the product's name occupies a small section, separated from the rest by a curved indentation that sweeps from top to bottom. The controls sit on the other side of this curve. Two portholes include numeric displays of the left- and right-channel output levels; the dark circle below is the infrared receiver for the remote. Farther left are two rows of five LEDs each: above are indicators for the selection of Phono/Aux 2, Tuner, CD, Video, and Aux 2; below are Source, EPL (external processor loop), Theater, Stnby, and Mute. Farther to the right are two rows of three buttons each: above are Mute, Level Down, and Level Up; below are Source, EPL, and Theater.
The 18LS lets you select one of two external processors, as the remote clearly shows. Pressing EPL 1 toggles between the source and the output of a processor, though the 18LS controls the volume level in either position. EPL 2/Theater, however, sets the 18LS to unity gain, so the level of the front speakers can be set by the processor. This makes it simple to incorporate the 18LS into a high-quality home-theater system without compromising its two-channel performance.
Looking at the rear panel, there are inputs for Phono/Aux 1, Tuner, CD, Video, and Aux 2. These are electrically equivalent: the load they present to the source varies with the volume-control setting, but in no case does it drop below 12k ohms. Farther to the left are inputs and outputs for EPL 1, for connecting a surround-sound processor to a high-quality two-channel system. Next are inputs and outputs for Thtr/EPL, which allow for matrix processing of selected two-channel sources. Then come Main Out 1 and 2, to be connected to the inputs of a power amplifier or an electronic crossover. There are no balanced XLR connectors.
Conrad-Johnson supplies the buyer of an 18LS with a 10-page manual that describes the model's basic operation. There is no table of contents or index, but I particularly missed any control or connector diagrams. An owner might not miss such diagrams—the rear-panel arrangements are among the "set and forget" operations that need to be done only once—but they can be of great help to a reviewer in the repeated pluggings and unpluggings of connectors during reviews.
The 18LS's quality of internal components is superb, with polypropylene and polystyrene capacitors used in the audio circuitry. The power supply's polypropylene capacitors are bypassed with small polystyrene caps. The audio circuits and their related power supplies use precision low-inductance, laser-trimmed metal-foil resistors from Vishay. The same resistors are used in the level control; the level is set by selecting combinations among an array of these resistors. Loudness and balance can be adjusted precisely in 99 steps of approximately 0.7dB each.
My moderately damped, 5400-cubic-foot, rectangular living room has a 12' semi-cathedral ceiling. I did most of my listening in the nearfield of my Quad ESL-989 loudspeakers, which were 63" from the rear wall and 36" from the side walls, sitting on a circular area rug. Imaging and soundstaging were best when the speakers and my chair described an 8' equilateral triangle, measured from the centers of the Quads' panels.
The Premier 18LS's lack of balanced outputs ruled out the use of my Krell FPB 600c power amplifier, so I mainly used a Mark Levinson No.334. Later, I tried the Bryston 14B-SST and Conrad-Johnson MV2500 amps.
In my system, the amplifier and preamplifier are 10' apart, so I had to use long runs of single-ended interconnects: Mark Levinson HFC (with Camac connectors), Coincident CST Interface, and Ultralink Performance Audio. To reduce hum and interference, I crimped the ground shields of the cables' RCA plugs to make a snug fit on the power amplifier's single-ended jacks, and kept the cables as far as possible from power supplies and AC transformers. All in all, because of the long runs required, I would have preferred using balanced interconnects.