THX ULTRA: Episode 2 HT Labs Measures
This graph shows that the VSX-49TX's left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1% distortion at 160.4 watts and 1% distortion at 182.7 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 245.5 watts and 1% distortion at 277.3 watts. With six channels driving 8-ohm loads, the amplifier reaches 0.1% distortion at 124.5 watts and 1% distortion at 139.4 watts.
The analog frequency response was +/-0.10 decibels from 20 hertz to 20 kilohertz. The response dropped to -0.31 dB at 10 Hz and -0.38 dB at 50 kHz. THD+N from the amplifier was less than 0.005% at 1 kHz when driving 2.83 volts into an 8-ohm load. Crosstalk at 1 kHz driving 2.83 volts into an 8-ohm load was -85.93 dB left to right and -85.76 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 -106.76 dBrA.
From the Dolby Digital input to the loudspeaker output, the left, center, and surround channels are all flat, +/-0.11 dB from 20 Hz to 20 kHz. From the Dolby Digital input to the line-level output, the LFE channel is +0.01 dB at 20 Hz when referenced to the level at 40 Hz and reaches the upper 3-dB down point at 117 Hz and the upper 6-dB down point at 125 Hz.—AJ
HT Labs Measures: Snell THX Ultra 2 Speaker System
This graph shows the quasi-anechoic (employing close-miking of all woofers) frequency response of the XA1900THX satellite (purple trace), ICS Sub24 subwoofer (blue trace), and AMC900dp surround (red trace). All passive loudspeakers were measured at a distance of 1 meter with a 2.83-volt input and scaled for display purposes.
On-axis response of the XA1900THX measures +1.72/-2.53 decibels from 200 hertz to 10 kilohertz. An average of axial and (+/-15 degree) horizontal responses measures +1.10/-2.59 dB from 200 Hz to 10 kHz. The -3dB point is at 71 Hz, and the -6dB point is at 56 Hz. Impedance reaches a minimum of 1.74 ohms at 299 Hz and a phase angle of -49.74 degrees at 66 Hz. Sensitivity averages 92 dB from 500 Hz to 2 kHz.
Averaged response of the AMC900dp measures +3.10/-4.41 dB from 200 Hz to 10 kHz. The -3dB point is at 63 Hz, and the -6dB point is at 55 Hz. Impedance reaches a minimum of 4.71 ohms at 6.7 kHz and a phase angle of -48.53 degrees at 82 Hz. Sensitivity averages 85 dB from 500 Hz to 2 kHz.
Close-miked response of the ICS Sub24, normalized to the average level from 40 to 80 Hz, indicates that the lower -3dB point is at 27 Hz and the -6dB point is at 24 Hz. The upper -3dB point is at 129 Hz with the crossover control set to maximum.—AJ