Grundig Fine Arts A-903 Stereo Amplifier Review

Fine Arts high-fidelity products manufactured by Grundig, a long-established West German manufacturer, have recently been introduced into this country. The Fine Arts A-903 is an integrated amplifier rated for 100 watts per channel into 8-ohm loads. It has a protection system that safeguards it against short-circuits, overloads, DC components in the outputs, and excessive heat.

The A-903 is a solidly built amplifier whose principal front-panel controls are a large volume knob and a number of flush-mounted, flat pushbuttons to select the program source. Other buttons connect one or both pairs of speaker outputs, bypass the tone controls, and activate the loudness-compensation circuit. Small amber lights above or next to the buttons indicate when they are active, and the volume knob carries a light that serves as an index marker. The power switch has a red pilot light above it. There is a headphone jack and four gold-plated phono jacks for the inputs and outputs of a tape deck (duplicated on the rear).

A section of the panel below the input selectors hinges down to reveal four small knobs and a pushbutton. The knobs for the bass and treble tone controls and the balance control are center-detented. The remaining knob, marked level, operates a six-position switch to adjust the overall amplifier gain from +6 to — 9 dB (relative to the normal “zero” setting) in 3-dB steps. Its principal function is to adjust the degree of loudness compensation at a preferred listening level. The pushbutton parallels the signal channels for mono inputs.

The rear apron of the A-903 contains two pairs of insulated speaker connectors, which accept stripped wire ends but not banana plugs or similar connectors, and phono, CD, tuner, video/TV, and tape-monitor input jacks. The monitor input is used with a three-head tape deck in order to monitor the recording from the tape. There are two sets of regular tape input/output jacks, one of them wired in parallel with the front-panel jacks. A small screwdriver adjustment varies the phono-input sensitivity.

The Fine Arts A-903 measures 18-3/4 inches wide, including its removable decorative end plates, 13 inches deep, and 4-1/2 inches high. It weighs 24 pounds. Price: $899.

Lab Tests

Although the top of the A-903 became quite warm during its hour of preconditioning at one-third rated power and subsequent high-power testing, it was never too hot to touch. The output power at clipping into 8-ohm loads was 122 watts per channel, increasing to 170 watts with 4-ohm loads. The protection circuit shut off the amplifier when it was driving 2 ohms at an output of 175 watts, although the waveform had not yet clipped visibly. During our slew-factor measurement, the amplifier shut down at 50 kHz, corresponding to a slew factor of 2.5. Dynamic power readings were respectively 150, 242, and 196 watts into 8, 4, and 2 ohms.

The total harmonic distortion (THD) plus noise at 1,000 Hz into 8 ohms decreased from 0.085 percent at 1 watt to a minimum of 0.01 percent at 100 watts. Into 4 ohms, the distortion ranged from 0.1 percent at 1 watt to a minimum of 0.021 percent at 40 watts and 0.035 percent at 140 watts. The 2-ohm distortion readings were roughly similar, reaching their minimum of 0.011 percent at 100 watts. Driving 8 ohms, the amplifier’s distortion was relatively constant with frequency and power, with typical readings of 0.01 percent or so, a minimum of 0.005 percent at 1,000 Hz and 50 watts, and a maximum of 0.0148 percent at 20,000 Hz and 10 watts.

The input sensitivity (through the CD input) for a 1-watt output was 108 millivolts (mv), with an A-weighted noise level of —89.5 dB referred to 1 watt. Using the factory setting of the phono-input sensitivity control, 0.25 mv was required for a 1-watt output, and the noise level was —69 dB. The phono input overloaded at 71 to 76 mv through the middle- and high-frequency range and at 110 mv at 20 Hz. The sensitivity adjustment had a considerable range, from 0.94 to 0.062 mv, with corresponding overload limits (at 1,000 Hz) of 500 and 19 mv. The phono-input termination measured 49,000 ohms in parallel with 100 picofarads.

The tone-control characteristics were conventional, with a maximum range of about ± 15 dB at the frequency extremes. The range from 500 to 1,500 Hz was unaffected by the controls. The frequency response (CD input) with the tone controls centered was slightly different between channels but varied only about 1 dB overall. With the defeat (bypass) switch engaged, the amplifier’s response was an impressive ± 0.03 dB from 20 to 20,000 Hz.

The loudness compensation boosted both lows and highs, by as much as 15 and 5 dB, respectively, as the volume was lowered. The level switch, as rated, shifted the amplifier gain in 3-dB steps from + 6 to —9 dB. The RIAA phono-equalization error was +0.2, —0.7 dB from 35 to 20,000 Hz and —3.5 dB at 20 Hz.

Comments

The Fine Arts A-903 had the look, feel, and sound of a fine audio product. For the most part, it appeared to be a perfectly conventional integrated amplifier with obvious control functions that could be understood without reference to the instruction manual. The manual, incidentally, was both clear and comprehensive.

The input selectors operated quietly, positively, and with little pressure. They were free of audible switching transients. The phono-level adjustment in the rear, intended for matching the phono volume to that of other sources such as a CD player or tuner, also permits optimizing the amplifier’s noise and overload margin for any moving-magnet cartridge, regardless of its output. The volume control, which operated with a silky smoothness, had a tapered characteristic that simplified precise, noncritical volume adjustment. The only change, though a minor one, that we would like to see would be in the speaker-output terminals. Binding posts on 3/4-inch centers, able to accept single or dual banana plugs, would be a welcome convenience.

The A-903’s protection system was exceptionally effective. Apparently with little or no conventional current limiting, it cuts off the outputs by a relay before the transistors can be damaged by an overload, and they recover automatically a second or two after the overload is removed. We must admit to a few worried minutes when the amplifier shut off entirely (including all front-panel lighting) during 2-ohm high-power testing. But about 45 minutes later, after the power transformer cooled down, it returned to life none the worse for its experience.

Removing the top cover of the A-903 should dispel any lingering doubts about its credentials. The mechanical assembly, the neatly cabled and dressed wiring, and the generally professional appearance were completely consistent with its image and performance. Noting the statement on the rear of the amplifier that it was built for Grundig in Portugal, we began to wonder how many other high-quality electronic products come from Portugal. Is this small country about to become the Korea of Europe? The Grundig Fine Arts A-903 is a fine piece of work in any case.

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