Stereo Amplifier

Review: Audiolab 8000A Stereo Amplifier

Examination of the current 8000A reveals that there have been a number of detail improvements and modifications over the years although few of them would be obvious 10 a prospective owner. The major visible alteration is the addition of a further line input; the possible inputs now number six, labeled respectively, CD, Video, Phono, Tuner, Tape 1 and Tape 2. The third of these, Phono, can offer two alternatives, for low output moving-coil cartridges or standard magnetics. Selection of these is decided by a red push-switch protruding through the rear panel adjacent to the two pairs of phono input sockets provided (both types of cartridge can be left plugged in if one has two separate turntables) and a couple of red LEDs at the front remind you of your choice. The first pair of pointer knobs on the front left of the panel have the input designations listed between them; the left knob selects which source is passed for amplification, that to the right decides which is sent to the three pairs of record outlets. The adjacent central pair of pointer knobs is continuously variable bass and treble adjustments and are provided with mid-point detents and calibration in decibels, ± 3 and 6 at the frequency extremes of 20 and 20kHz. They are thus very mild in their range and operation. Set between them is a push-bar switch which can be used to bypass the tone control circuit entirely but such was the accuracy of the miniature variable controls and their centre-stop that neither measurement or sound gave any clue as to whether tone correction was engaged or not. A further detente control provides balance adjustment, a large circular knob operates the high grade Noble volume control, another pair of bar switches energize a second pair of loudspeaker connections and the main power On/Off; between them is a headphones socket, which, with arguable logic, mutes both sets of loudspeakers. At the rear is a fused IEC power connector, four pairs of 4mm centered terminals for loudspeaker leads, 24 pairs of gold-plated phono sockets and a pickup arm grounding terminal. In case any astute reader is wondering where a surplus two pairs of phono sockets might apply, they provide for preamplifier output and power amplifier input and, as supplied, are linked internally.

The circuit of the 8000A is designed around discrete components and so several dozen little black transistors and their accompanying hordes of feed and coupling resistors and capacitors give the single large epoxy glass printed circuit board a very busy look. However, it is all skillfully laid out (the work of those computers again) and the high count of bits and pieces has been accommodated without loss of serviceability. There is little internal wiring apart from a 25-way printed ribbon carrying the inputs to the front selector switches. This presses against the top cover which must add to the input capacity but I am sure they will have allowed for that! At rear right is a fat 250VA toroidal power transformer with a pair of 10,000 μF Elna reservoir capacitors alongside. Line voltage is ±42 volts. Adjacent is a squarish heatsink sandwiched between ventilation slots in the top and bottom cover plates; extension fins carry the complementary pairs of Sanken 2SA1216/2SC2922 power transistors with their drivers separately sinked to hefty aluminium mounts. The casework of aluminium and steel is very substantial and neatly folded to provide a box of above average strength. At 445mm it is slightly wider than the 430mm norm which most equipment conforms to. The overall presentation, although not obviously dated, is perhaps a trifle heavy by modern standards and was to set the pattern for the rest of their products. However, its appearance is far removed from the blatant ugliness displayed by much of that which arrive s from overseas.

How it performed

On test the 8000A clearly showed its pedigree, exceeding the specification in most respects. Slightly more powerful than the original, my sample provided 64 watts at the onset of clipping into 8 ohm resistive loads, both channels driven. I was slightly perturbed by a small oscillatory burst to be seen on a 1kHz sine-wave when naughtily driven beyond clipping as such things are notoriously destructive of tweeters, although I found nothing of that magnitude; repeating the exercise at 10kHz caused a sudden squaring of the output signal. Moral: don't push the 8000A into deliberate overload. Used normally and with due discretion this proved to be an excellent piece of equipment of very high quality, exhibiting anonymous neutrality with all types of programme. The tone controls were nicely judged to correct minor imperfections in either the room situation or in source discrepancies. The phono inputs, particularly the moving-coil, were judged to be well above average, a description which fits the 8000A admirably. It may well go on to collect future awards and it will certainly continue to carry our recommendation as long as it is in production.