Perreaux R200i integrated amplifier Manufacturer's Comment
Editor: Thank you to Michael Fremer and John Atkinson for taking the time to review the Perreaux R200i in June 2003. It is refreshing to feel that the unit has been subjected to a reasonable level of scrutiny by your publication, and as such it is proper that our company be given the opportunity to respond:
Regarding the channel naming, to ease confusion in future, we will consider changing the rear-panel transfer. In the interim, we will consider changes to the product manual.
The Audio Physic Avanti III is rated at a nominal 4 ohms impedance. We have not seen how the impedance of this speaker varies over frequency, but, at face value, would agree with Michael in saying that the R200i would easily drive a wide variety of loudspeakers, including the Avanti III. Indeed, John Atkinson warns about using the R200i with "speakers that dip below 4 ohms for much of the audioband." This observation was made from the power output at 2 ohms, and, I feel, is not entirely accurate. It would, in our opinion, be a more accurate statement if it were to say "speakers that dip close to 2 ohms for much of the audioband"—which, in effect, is saying "speakers rated at ~2 ohms nominal impedance."
With respect to John Atkinson's comments on our 1.5dB-resolution volume control bordering on being too coarse, we respond by saying that 3dB is the theoretical minimum change distinguishable by the human ear (footnote 1). A 2dB change should not be audible, and steps of 1.5dB should provide a comfortable safety margin.
The reason the heatsink temperature showed so much of a difference could possibly be due to the temperature-measuring sensor not resetting properly, or it may have been damaged. In the first instance, disconnecting the R200i from mains power, then reconnecting, would fix the problem. If the temperature device was damaged, then the only way to fix the problem is to replace the device. There is certainly no way the heatsinks would have had that much heat difference, and this would have been apparent by touching them. It appears that the incident cleared itself, as readings of both channels were taken and recorded in the measurement section.
When JA measured the R200i's 8 ohm rated output, comments were made that the amplifier displayed "Over Current Left—Over Current Right" when full power was reached at 8 ohms (268Wpc), and that "it attenuated its output in a rather arbitrary manner." This is incorrect. The message would have read "L Clipping—R Clipping," which means that the algorithm to control clipping is working, hence the "wiggly trace." What the R200i's internal algorithm does is drop the output by ~2dB, then step it back up to the set level. If clipping is detected again, then the level will be dropped ~2dB from this point, and so on and so on, until the set output volume level is reached and clipping is no longer detected. Usually, the user will see the message and decrease the volume accordingly. If the message goes unnoticed (eg, party scenario), the speakers will be totally free from harm and the output will sound relatively unaffected. This feature has been specifically designed to protect speakers from DC output due to clipping, which is detrimental to speaker longevity.—Martin van Rooyen, Managing Director, Perreaux Industries
Footnote 1: With respect to Martin van Rooyen, this is incorrect. The audibility of a volume change will depend on the bandwidth covered. A change in level of just 0.5dB is audible in blind comparisons if it covers the entire audioband.—John Atkinson