|Scott 299-D stereo integrated amplifier|
COMMENT: The Scott 299D is the highest-powered and most versatile integrated stereo amplifier offered by this manufacturer, and the latest in a long line of reliable performers in the "double nine" series which dates back to the highly regarded Model 99 of pre-stereo days. The present model is distinguished by high, clean power across the audio band, rugged construction, and a galaxy of control features that should satisfy the operational needs of any stereo installation.
The amplifier's main front panel operating controls are (from left to right) a five-position input selector switch (microphone, tape head, magnetic phono, tuner, and extra); a seven-position function selector switch (left balance, right balance, monophonic, stereo, reverse stereo, left input, and right input); dual concentric bass controls operating independently on each channel; similar treble controls; a channel balance control; and a gain control. Slide switches along the top of the front panel are used to choose between either of two pickups (or a pickup and tape head input), to switch in the tape monitor function, to cut in the rumble or scratch filters, to silence the speakers (when using headphones), to turn on the AC power, and to introduce the loudness compensation. The front panel also has a low-impedance stereo headphone jack as well as three pilot lights to signify different modes of operation as chosen on the function selector switch.
The rear of the chassis contains eight sets of stereo signal input jacks, plus a stereo pair for feeding signals to a tape recorder, and a "derived centre channel" output for driving a mono basic amplifier. Left and right speaker outputs are provided in impedances of 4, 8, and 16 ohms. A "powered centre channel" connection also is provided, by means of which a third speaker may be driven directly from the 299D without a separate mono amplifier. A speaker-phasing switch, two AC convenience outlets (one switched, the other unswitched), a fuse holder, and power cord complete the rear complement.
The circuitry of the 299D is well designed and thoughtfully arranged. For instance, the preamp section actually incorporates the equivalent of a "pre-preamp" to accommodate signals from the lowest-output pickups and tape heads as well as from more conventional low-level sources, without the danger of insufficient gain for the former or of overloading the circuits with the latter. The tubes in the preamp section are heated by DC voltage in the interest of low hum. The power amplifier section employs negative feedback, and has provisions for setting the bias and balance of each pair of output tubes, although these adjustments are made at the factory and are not intended for use by the amplifier's owner.
In tests conducted at United States Testing Company, Inc., the 299D proved to be a reliable; clean performer that met its important specifications and remained stable under all conditions of loading. The manufacturer's rating of the amplifier by the IHF music power method corresponds roughly to the sine-wave power figures measured in the lab. Harmonic distortion was well within the limits specified. IM distortion—although somewhat high at the higher power levels—fell below the specified value at normal, average listening levels. The frequency response of the 299D was uniform across the audio range, and down by 3 db at 60 kc and at 17 cps. The low-frequency attenuation is deliberate and, according to the manufacturer, is designed to avoid the wasting of power in the bass as well as to prevent overload in the circuits from subsonic frequencies. The tilt in the 50-cps square-wave response reflects this attenuation; the 10-kc square-wave response shows good transient characteristics with very little "ringing." Equalization, for both RIAA (disc) and NAB (tape head playback) characteristics, is good; the amplifier's tone control and filter characteristics are well suited from a musical standpoint for their intended purposes.
Using and listening to the Scott 299D is a gratifying
experience. The number of controls and features may stagger the audio
novice at first, but there is a logic to their being made available and
to their placement on the panel. One can ignore many of them, or use them
to regulate the most complex three-channel stereo system, complete with
tape decks, recorders, auxiliary program sources, extension speakers,
and private headphones. The intricacies and versatility of this instrument,
by the way, are thoroughly explained in a well-organized instruction manual
that presumes no previous technical training on the part of the owner.
The "sound" of the 299D—driving a variety of speaker types—places
it among the better integrated amplifiers now available. It is a fine
piece of equipment in its size and power class, and one that can serve
very nicely as the centre of a' high quality home music system.