Pioneer SA-6500 II Amplifier Review

Rated at a conservative 30W per channel into either 4 ohm or 8 ohm loudspeakers, and having all that is required of a basic amplifier, the Pioneer SA-6500 II offers good performance.

As is to be seen from the adjacent table, the power output available into half the rated load of 4 ohms (ie 2 ohms) is exceptionally good, and whilst the power bandwidth varied a little between the channels, it was entirely satisfactory.

The noise performance so far as the inputs are concerned was unusually good, as was the measured output noise. But, subjectively there was mild hum at the output, and this might be annoying particularly when listening with headphones, as it was present at all volume control settings.

Terminals are fitted for two sets of loudspeakers, there being a front panel switch for selecting either or both sets of loudspeakers and also having an ‘off’ position for headphone listening via the front panel headphone jack. Provision is made for two tape recorders with one interface having a DIN compatible connector in addition to the phono sockets used for all other inputs.

Separate toggle switches permit tape monitoring with either tape unit, but no tape dubbing facility is fitted. Subjective assessment of the crosstalk at the tape monitor switches and also between input sources showed that there was minimal interference between sources.

The basic inputs consist of magnetic phono, tuner and auxiliary inputs which are selected by a rotary switch on the front panel. All these inputs and also the tape unit connections had sensible impedances and overload margins together with adequate sensitivities.

Further facilities include tone controls and a tone control defeat switch. Both the treble and the bass tone controls are eleven-position controls, but as the manufacturers have had the sense to limit the available range of correction to that which is reasonable in practice, the increments between the tone control positions are adequately small.

Having given credit where credit is due, examination of the overall frequency response shows that it extends to very low frequencies but rolls off at the high frequency end just above 20kHz. As no filters are fitted it would have been only reasonable to restrict the low frequency response, particularly with the phono input where unwanted low frequency response is a menace.

The volume control is an analog control having a good law and not exhibiting any unbalance between channels, with the balance control itself being of the full range type but also being well conceived such that the law about the mid-position made balance correction very easy.

The final amplifier control is the loudness control which affected a relatively mild boost to both the treble and the bass. Unfortunately this control did introduce significant unbalance into the amplifier, so that it was necessary to re-adjust the balance after the loudness control had been operated if perfect amplifier balance was to be retained.

However, the degree of unbalance introduced would probably not be noticed by many people on stereo programme material.

The overall subjective impression of the Pioneer SA-6500 II amplifier was good and driving it into overload did not have any particularly distressing effects. Finally, other than the standard of soldering at the DIN connector, the standard of construction was excellent with a clean component layout with proper identifications and good access for servicing.

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