Fisher X101-C stereo integrated amplifier (1961)
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Vintage test report


Taken from 'The Gramophone' October 1965

The latest and rather novel manifestation of the interest which leading American high fidelity manufacturers are showing in the British market will not have escaped readers of our advertisement pages. Fisher, like many others, have had no difficulty in establishing a good foothold in Europe and one can point to at least two factors which have undoubtedly helped them; first the lack of strong competition from native manufacturers and secondly the very large numbers of American Servicemen, plus Diplomatic and other Staffs, who have brought over such equipment and acted as unofficial demonstrators and salesmen.

In Britain the introduction has not been so easy, for dollars have been tight and the price, until now, quite uncompetitive with the very good products which our own makers can provide. Consequently the average tide of commerce with visiting Americans has, to our advantage, been outgoing. Of all the factors limiting British acceptance, Fisher have decided that the most telling is price. To overcome this they are reversing a system used by Quad for different reasons during the last two years in the USA; they are supplying a limited number of selected dealers in this country directly by air from the U.S. and are providing those dealers with a stock of spares based on experience of past needs. Because of the very large world market they command and their low mass-production unit costs, it is possible by the elimination of all shippers, distributors and other middlemen, to put in a price which rivals any similar product of British origin.

Two of the many Fisher models have been chosen to open the 1965 British campaign, the X-I00-A, a twin 17-Watt design and the more powerful X-101-C, which forms the subject of this report. The latter has several features that might be thought to have a particular appeal to users on this side of the Atlantic, where the typical amplifier owner is known to exhibit more devotion to the music than the means of reproducing it. Logically, but almost uniquely for an American design, the choice of input source is by push-button so that one does not have to pass through several unwanted positions before arriving at the one desired. In similar vein the usual profusion of projecting knobs and controls has been avoided by placing most of them in a recess under the black cover which forms the lower half of the control panel; this cover is normally held in place by a button latch taking the form of the Fisher trademark. The remainder of the control panel is a gold anodised aluminium extrusion; the push buttons are dark red and the control knobs brown with gilt centres.

Inputs selected by the push buttons are as follows: TAPE HEAD, PHONO, TUNER, AUX, TAPE PLAY; and there are accompanying pairs of sockets on the rear, plus a pair for recording and a second attenuated pair for use with high output pickup cartridges. It is a pity that the desired simplification is rather spoilt in the case of the first two buttons, for one of the switches under the panel is marked EQUALISATION and has TAPE and PHONO positions; this switch decides the compensation (RIAA for disc and NAB for tape) which is applied on both the first two button positions. To most British users this will be no snag, for they are unlikely to use the direct tape head connection and so the first button can conveniently be used for a separate magnetic pickup if required and the equalisation switch left permanently in the phono position. No provision is made for ceramic cartridges, and the radio and auxiliary connections require a higher signal than many British designs.

The only two knobs on the panel are a MODE switch, with MONO, STEREO and REVERSE positions (do we really need to reverse channels these days?) and a combined On/Off switch VOLUME control. A switch under the flap labelled LOUDNESS CONTOUR gives a substantial (15dB) bass lift at lower volume settings, for those who like the effect. Also on the panel are a tiny green jewel, illuminated when the power is on, and a stereo headphone socket. In the recess are two other slide switches, apart from the two already mentioned; one brings in the HIGH FILTER and the other is the TAPE MONITOR. Here again there is a minor departure from usual practice: as the filter is in an early part of the circuit, before the record outlets, it therefore operates on record but not on replay, unless the monitor switch is turned off and the tape play button pressed instead; just a little awkward until one gets used to it and then one can, if required, use the filter twice, during both record and play.

Four undercover knob controls remain and one of these is unusual, an OUTPUT SELECTOR. Due to an unconventional output connection it is possible to connect a third central loudspeaker and feed it with a part of the power of both amplifiers; this switch brings such a central speaker and/or the headphones into circuit as required. BASS and TREBLE controls are continuously variable and of the twin, clutch-coupled type which I have described in past reports and there is also a BALANCE control of the sort which reduces the output of each channel to zero. Legends for the 'under the hatch' controls are printed on the inside of the flap so that one does not have to peer inside the compartment.

The chassis layout conforms to typical American design, large but shallow with a raised frontal section covering the back of the panel controls. Immediately behind are the early stage valves, then the large output transformers and towards the rear the power output valves; connections on the rear flange include a pair of flat pin AC outlets. Layout underneath is open and point-to-point with a minimum of tag strips. Six 'packaged electronic circuits' (PECs) contain thirty-six components and help reduce the complexity. Each channel uses six triodes (three of ECC83) and two 7591 output tetrodes, a physically small but electrically hefty beam power valve not usual in this country. The first feedback pair, with switched equalisation, is used only for tape head and pickup. Other signals are fed straight into the third triode, an anode follower with the filter optionally switched into the feedback path. The signal from this stage goes through a link provided so that a Fisher Spacexpander (reverberation unit) can be added and also the tape monitor switch, before feeding the passive tone controls and another triode. Then it goes via volume/loudness and balance controls into the main amplifier consisting of triode amplifier, 'top and tail' phase splitter and output pair, running as straight tetrodes, grid biased; there is 22dB of negative feedback.

Power supply arrangements are quite up to date and use a pair of silicon rectifiers in a voltage doubler configuration, giving a very stable, large current supply for the Class A output valves. The heaters of the four early stage valves are connected in series with the output valve cathodes and thus receive a hum free DC supply. Three pre-set controls are provided to set the output valve bias and to adjust the balance of the drive from each phase splitter. The output transformers have taps for 4, 8 and 16 Ohm loads and, to provide the centre speaker feed, an unorthodox earthing arrangement is adopted, the 4 Ohm taps being connected to chassis so that the common tap of amplifier A and 16 Ohm tap of amplifier B then provide the necessary sum signal. This simple idea provides a mono signal for the centre speaker, with negligible blending of the signals sent to the left and right speakers, no loss of damping factor due to series connection of the common speaker, and no extra components.

Both to the ear and to measuring instruments this is an outstanding amplifier and the repetitive way in which the latter threw up results that exactly fitted the makers’ specification was quite exceptional. One can have every confidence that all models will be within the same 1dB or so which represents the limits of tolerance of good production technique. There is little point in publishing measurements that repeat those in the specification, but I can add a few that are not mentioned: the only deviation was in the filter which had its 3dB point at 6.5 Kc/s and not 5.5. Kc/s. From each channel separately 32 Watts continuous were available, falling to 25 Watts at 20 c/s and 28 Kc/s: 28 Watts were available from each channel when both were driven. Distortion at low signal levels and mid-frequencies was extremely low, about 0.03%. Square waves were accurately reproduced with a very slight overshoot that appeared to be due to stray capacity coupling in the loudness contour switch: it was quite innocuous. The range of tone controls, which is only specified overall, was Bass at 50 c/s + 13 to -11dB, Treble at 10 Kc/s +10 to - 11dB. Stability was excellent and it was impossible to produce oscillation with any load. Particularly notable are the very high and quite genuine signal to noise figures, giving a very silent background under all practical conditions.

To the ear this is a full-bodied, clean sounding amplifier and it joins the select group which all sound the same because they are all nearly perfect. It has some unusual features not found elsewhere and offers more power than most. At the price it really does represent excellent value for money and taking this into account it can be considered to be the best integrated amplifier available here at the present time.

[Note by P.W. The X-101 was one of the amplifiers on the main production lines when I visited the Fisher Amplifier plant in Pennsylvania. I was most impressed by the inspection arrangements to ensure consistency in the models coming off each line. Not only are there checks at the completion of each stage along the line and a very thorough examination with elaborate testing instruments at the end of the line; there is also a subsequent super-inspection of 10% and if a single amplifier of any one batch is found faulty the whole lot goes back and a rocket goes along the line. Geoffrey Horn's confident surmise in his penultimate paragraph is thus fully endorsed.]