Onkyo Integra A-8067 Integrated Amplifier Review

Onkyo’S A-8067 integrated stereo amplifier, which replaces the A-8017 in the Integra line, delivers slightly higher power, with significantly improved dynamic headroom and performance with difficult loads, for a price $ 15 lower. The A-8067’s power rating is 80 watts per channel into 8-ohm loads, or 135 watts into 4 ohms, from 20 to 20,000 Hz with no more than 0.015 percent total harmonic distortion. For a moderately priced integrated amplifier, it has unusually good dynamic power ratings (based on the EIA’s dynamic-headroom test standard) of 135 watts, 205 watts, and 295 watts per channel into load impedances of 8, 4, and 2 ohms, respectively. The improved performance of the A-8067 compared with the A-8017 primarily results from its larger power transformer and from doubling the number of output transistors.

Other features of the A-8067 include Onkyo’s “Real Phase” power supply and a dual record-output selector system, which provides independent source selection for two tape decks in addition to the regular program-source selector. If two tape decks are used, this feature permits recording, say, a phonograph record on one deck and a CD on the other deck while listening to a tuner through the speakers or headphones. Alternatively, if a signal-processing accessory, such as an equalizer, dynamic expander, or noise reducer, is connected into one of the tape loops instead of a tape deck, it can be used to modify the program being heard without affecting the signal being recorded.

The Real Phase power supply, also featured on some other Onkyo amplifiers, is designed to minimize fluctuations in power-supply capacitor-charging currents while amplifying low-frequency signals (principally in the range from 50 to 60 Hz, where speaker resonances can cause large phase angles between the amplifier’s voltage and current output). According to Onkyo, this effect causes “ripples” or fluctuations in the power-supply charging currents that can be imposed on the d.c. operating voltages or induce spurious signals into the low-level amplifier stages. To avoid this effect, Onkyo added a second power transformer, which supplies the charging currents needed to compensate for these extra demands and results in a more uniform power-supply output and a full power reserve for the lowest frequencies.

The overall “beefing up” of the A-8067 has resulted in an amplifier with a current-delivering capacity unheard of only a few years ago in its price class—and still quite unusual. This makes the A-8067 suitable for driving some of the low-impedance, high-quality speakers that have previously been fully usable only with much larger and more expensive amplifiers.

The Onkyo A-8067 is relatively large and heavy for its power ratings and price. Measuring 17-1/8 inches wide, 15-3/8 inches deep, and 5-5/8 inches high, it weighs 26-1/2 pounds. Price: $400.

Lab Tests

Because of its large size and mass relative to its power rating, the Onkyo A-8067 became only moderately warm over the internal heat sink fins during the hour of preconditioning at one-third rated power. In fact, at no time during our tests or use of the amplifier did any part of its exterior become uncomfortable to the touch.

With both channels driving 8-ohm loads at 1,000 Hz, the output clipped at 98 watts for a clipping headroom of 0.88 dB. With 4-ohm loads, the output at clipping was 144 watts per channel, and with 2-ohm loads it was an impressive 200 watts per channel. With the 20-mil-lisecond tone bursts (twice per second) of the EIA dynamic-power test, the respective clipping power outputs were 138, 242, and 352 watts per channel into loads of 8, 4, and 2 ohms. Each of these measurements surpassed the ratings.

The 1,000-Hz harmonic distortion with 8-ohm loads fell from 0.015 percent at 1 watt to less than 0.002 percent between 30 and 90 watts. Driving 4 ohms, the amplifier’s distortion curve was similar, dropping from 0.02 percent at 1 watt to 0.0025 percent at 120 watts. With 2 ohms the range was from 0.028 percent at 1 watt to 0.0034 percent at 150 watts. The distortion was unusually independent of frequency, remaining between 0.002 and 0.005 percent from 20 to 20,000 Hz at the rated 80 watts into 8 ohms and also at half power. At one-tenth the rated power, the shape of the curve was the same but the distortion readings were between 0.0055 and 0.0085 percent.

The frequency response with the tone controls at their center (DEFEAT) settings was ruler-flat, varying less than the width of the ink trace on our pen recorder (less than 0.1 dB overall) from 20 to 20,000 Hz. The tone controls had shelved characteristics, affecting bass response below 300 Hz and the treble above 3,000 Hz. The maximum range was an adequate + 8 dB at the frequency extremes. The loudness contour boosted both low and high frequencies as the volume-control setting was reduced but had a maximum boost range of only 5 dB. The range from 1,000 to 3,500 was essentially unaffected, and the overall effect was pleasing and free of unnatural effects.

The subsonic- filter began to roll off response below 100 Hz, and it was down 3 dB at 27 Hz. The RIAA phono equalization was extremely accurate, varying less than the tolerance of our inverse-RIAA network or the width of the recorder pen trace. The overall response variation of perhaps 0.1 dB was unique in our experience.

Comments

Because of the great similarity in performance and features among most comparably priced audio products, we were unprepared to find so many points of superiority in a $400 integrated amplifier. Frankly, the Onkyo A-8067 was a surprise to us, one of those occasional “finds” that prevent our work from becoming humdrum. Its superiority did not lie in any special sound quality, although it certainly sounded as smooth and quiet as any amplifier we have ever used. Amplifiers tend to sound pretty much alike, and any departure from the norm is more likely to reflect a flaw than a virtue.

The characteristic of the A-8067 that impressed us most was its excellence in so many areas of performance. It is exceedingly rare for an amplifier to have nearly constant (and low) distortion over the full audio frequency range and at widely divergent power levels. Usually the distortion rises considerably at one or both of the frequency extremes or varies substantially with frequency.

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