FOLLOW-UP
AYRE ACOUSTICS EX-8 2.0 INTEGRATED AMPLIFIER
When I examined the Ayre Acoustics EX-8 2.0’s performance on the test bench, to accompany Ken Micallef’s review in the November 2021 issue, the two channels behaved somewhat differently. The right channel’s output impedance was higher than that of the left—0.525 ohm vs 0.35 ohm, which resulted in a level imbalance of 0.2dB into 8 ohms—and while the distortion was predominantly third-harmonic in the left channel, it was predominantly second-harmonic in the right channel.
Ayre Vice President & CTO Ariel Brown emailed me after he had seen the preprint of the review; manufacturers are always sent a copy of the review so that they may correct any factual errors and write a Manufacturer’s Comment. He was puzzled by the differences in the behavior of the channels and conjectured that one of the pairs of complementary output devices in the right channel was effectively out of the circuit and not contributing as it should, perhaps due to a cold solder joint. Ayre tests its products with an Audio Precision analyzer before they leave the factory, so why would there be a cold solder joint with the review sample, especially as Ken Micallef had been impressed with its sound quality?
It appeared that the review sample had suffered some kind of shock in transit from Ken Micallef’s place to mine—the top panel was dented—and that shock may well have caused a marginal solder joint to open. Ariel Brown shipped a new sample of the EX-8 2.0 to me for measurement. The original sample’s serial number was 27G-0103; the new sample’s was 27C-0002.
As before, I measured the new sample with my Audio Precision SYS2722 system (see the January 2008 As We See It). The voltage gain, input impedance, maximum power, and signal/noise ratios were all identical to those of the original sample, but the frequency responses of the channels now matched much more closely (fig.1). To calculate an amplifier’s output impedance, by ±0.25dB (fig.1, gray trace).
