February 2002Tenor Audio 75 Wi Mono Amplifiers: Measurements
All amplifier measurements are performed independently by BHK Labs. Please click to learn more about how we test amplifiers there. All measurement data and graphical information displayed below are the property of SoundStage! and Schneider Publishing Inc. Reproduction in any format is not permitted.
The Tenor 75 Wi appears to be a robust, well-designed output-transformerless power amplifier. Ironically, many of its characteristics, like distortion and output impedance, are typical of good tube amplifiers having output transformers. As can be seen in Chart 1, frequency response is wide, with a -3dB high-frequency point in excess of 200kHz. There is some small rise at very low frequencies. This very-low-frequency rise has effects on the low-frequency damping factor characteristic, as can seen in Chart 4. Output impedance is fairly low, meaning that the frequency response delivered to a connected speaker will be affected minimally. The response with the NHT dummy speaker load was within about +/- 0.5dB. Chart 2 shows that output power at clipping is fairly constant at 70-80W with loads over a 4-16-ohm range. Harmonic distortion is reasonably low and stays below 1% for an 8-ohm load to better than 80W output. Harmonic distortion increases only moderately with frequency, as shown in Chart 3. As predicted from Chart 1, output impedance is fairly low, and this translates to a damping factor of over 10 over most of the audio frequency range. Finally, in Chart 5, the harmonic-distortion residual spectrum shows the AC-line harmonics to be reasonably low and the signal-distortion components are dominantly second and third harmonic.
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