Review

Kenwood-Trio Model 600 Amplifier Review

Ranking amongst the most expensive integrated amplifiers in this book, it has quite a few good but also some very bad points.

Amongst these is the appalling power bandwidth which was as bad as only 2kHz when working into 4 ohm loads, and only 3.5kHz into 8 ohm loads. Another matter was that intermodulation distortion at half power was poor at 10kHz and rose sharply as the frequency was increased until the amplifier tripped around 15kHz.

Whilst the measured harmonic distortion was reasonably low, the distortion products consisted of crossover spikes which tend to be subjectively objectionable, and also the intermodulation performance at 1W is bettered by many amplifiers.

So far as the output load is concerned the amplifier was quite happy working into 4 ohms, but one channel gave up the ghost when loaded into 2 ohms. There are three loudspeaker outputs. If only individual loudspeakers or one pair in series is selected, 4 ohm speakers should be adequate.

In addition to the loudspeaker outputs, there is a headphone jack, and the output level and impedance here were most sensible, with the output noise performance of Kenwood-Trio Model 600 being far better than average. Similarly the noise performance of the two phono inputs was good, with the auxiliary, tape and tuner noise being respectable.

One phono input has three switchable impedances of 28/49/95k ohms which is a good selection, whilst the other phono input has a front panel pre-set sensitivity control which covered the range 2.8 to 5.5mV with a good associated input clipping level of 224 to 460mV. The sensitivities and clipping levels of the other inputs were good, but the tape input’s shunt capacity was too high at 430pF and likely to lead to loss of high frequencies with some tape recorders.

Both tape inputs are provided with DIN compatible connections as well as phono sockets, and tape switching is by two three position controls, allowing versatile monitoring and dubbing.

The only remaining signal connection is the provision of pre-amplifier output and power amplifier input sockets for connecting equalizers etc. If required, these sockets can be separated by a rear panel switch.

Concentric controls are used for the volume and balance controls, both of which had an excellent performance, the volume control being a fine stepped attenuator type which works in conjunction with a three position attenuator switch which provides an extra 15 or 30dB attenuation after the volume control.

An unusual feature is that concentric controls are also used for the treble and bass tone controls, so that the tonal balance can be changed between channels, the tone controls being stepped controls with realistic 2dB steps at 100Hz and 10kHz. Both tone controls have a choice of turnover frequency, 150Hz or 400Hz in the bass and 800Hz or 6kHz in the treble. In addition there is a presence switch which gives a broad spectrum boost of 7dB centered on either 800Hz or 3kHz, and it was felt that this boost was subjectively excessive. Finally there is the four position loudness control which applies a varying amount of bass boost, and the high and low pass filters of the 12dB per octave type with "3dB points at 40Hz and 7kHz, the former being good but the latter too fierce subjectively.

Whilst the Kenwood-Trio Model 600 is well made with many good features, it is severely let down by its power performance related to distortion, and thus cannot be recommended.

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