Inconsistency in Yamaha RX-V1 Receiver Test
A CLARIFICATION REGARDING RECEIVER TEST REPORTS : IN THE MAY 2000 SOUND & VISION MAGAZINE
Originally published July 2000
The May 2000 issue of Sound & Vision included test reports on two high-end receivers: the Yamaha RX-V1 by Daniel Kumin and the Denon AVR-4800 by David Ranada.
It was brought to our attention that there has been some confusion over the performance of these receivers because our reviewers used different test procedures to measure two of the parameters, which appear under the Dolby Digital (AC-3) Performance heading: Output at clipping (five channels driven) and Subwoofer distortion.
In the case of the Output at clipping test, the Yamaha RX-V1 receiver was plugged directly into the (A.C.) wall outlet. The power-line was not stabilized, so when all five channels were driven hard the voltage may have dropped to as low as 108 volts, resulting in a low wattage measurement. In contrast, when the Denon AVR-4800 receiver was tested, power-line voltage was monitored during testing to make sure that it did not deviate by more than 1% from 120 volts. Given this inconsistency in the testing procedure, it is unfair to directly compare the measured power outputs of the Yamaha and Denon : receivers.
In the Subwoofer distortion test, Mr. Kumin used test tones from the Dolby Labs test DVD, while Mr. Ranada used a new set of test tones he generated using a Dolby Digital encoding program. When the Yamaha RX-V1 was remeasured using the same test tones Mr. Ranada used, its subwoofer-output distortion was very low and close to what we had reported for the Denon AVR-4800.
In the July/August 2000 issue, the inconsistency in the Subwoofer distortion results for the two receivers is explained in both the "Feedback" department and in Mr. Ranada's "Tech Talk" column. The discrepancy in the Output at clipping power tests was not addressed in the July/August issue only because we had already gone to press when the discrepancy was discovered.
We apologize for any confusion that these inconsistencies may have caused.
Editor in Chief
We appreciate HT Mag's honesty in recognizing the faulty test data taken on the RX-V1. I was suspicious when I viewed the Denon AVR-4800 power results surpassing that of the RX-V1. I knew this was not possible as the RX-V1 has a much more robust power supply section and heatsink area.
It would be interesting to rerun these tests under the same test criteria. It would be more "real world" if they tested these units with a 120Vrms 15A source without boosting AC voltage when load current increases. People do not have this luxury in their homes.
HT Mag may also wish to include BODE plots of the two amplifiers under full power. Many lesser design amps tend to suffer from bandwidth limitations when driven harder. This will demonstrate the robustness of the feedback, power supply, and quality of output devices utilized.
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