Preamp/Processors

The above chart shows the frequency response of the left (aqua), center (green), LFE (red), and left surround (purple) channels at the preamp outputs of the Dolby Digital decoder. The left channel measures -0.00 decibels at 20 hertz and -0.18 dB at 20 kilohertz. The center channel measures -0.00 dB at 20 Hz and -0.22 dB at 20 kHz, and the left surround channel measures -0.00 dB at 20 Hz and -0.22 dB at 20 kHz. The LFE channel, normalized to the level at 40 Hz, is +0.13 dB at 20 Hz, reaches the upper -3dB point at 96 Hz, and reaches the upper -6dB point at 116 Hz.

The analog frequency response measures -0.01 dB at 20 Hz and -0.18 dB at 20 kHz. Looking at a broader bandwidth, the response measures -0.04 dB at 10 Hz and -1.11 dB at 50 kHz. The analog THD+N is less than 0.014% at 1 kHz with a 100-millivolt input and the volume control set to 35. Crosstalk with a 100-mV input was -81.38 dB left to right and -82.68 dB right to left. The signal-to-noise ratio with a 100-mV input from 10 Hz to 24 kHz with "A" weighting was -95.65 dBrA.—AJ

HT Labs Measures: Krell Showcase 7 Amplifier

This graph shows that the Showcase 7's left amplifier channel, with two channels driving 8-ohm loads, reaches 0.1% distortion at 140.4 watts and 1% distortion at 161.3 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 201.7 watts and 1% distortion at 266.9 watts. An input level of 141.5 millivolts was required to produce an output of 2.83 volts into an 8-ohm load, indicating an overall gain of 26.02 decibels using the RCA input. When using the XLR input, a level of 141.2 mV was required to produce an output of 2.83 volts into an 8-ohm load, indicating an overall gain of 26.04 dB. With six channels driven into 8-ohm loads, the amp reaches 0.1% distortion at 105.7 watts and 1% distortion at 136.9 watts.

The amplifier's frequency response measures +0.03 dB at 20 hertz and -0.21 dB at 20 kilohertz. Looking at a broader bandwidth, the response measures +0.02 dB at 10 Hz and -1.25 dB at 50 kHz. THD+N from the amplifier was less than 0.061% at 1 kHz when driving 2.83 volts into an 8-ohm load using the RCA input. When using the XLR input under the same conditions, THD+N was less than 0.050%. Crosstalk at 1 kHz driving 2.83 volts into an 8-ohm load was -92.19 dB left to right and -105.81 dB right to left. The signal-to-noise ratio with 2.83 volts driving an 8-ohm load from 10 Hz to 24 kHz with "A" weighting was -96.47 dBrA using the RCA input and -115.73 using the XLR input.—AJ