Fisher Model X-100 Stereo Master Control Amplifier
This is an early 1960's Fisher Model X-100 Stereo Master Control Amplifier that uses vacuum tubes.
The unit has a metal case as opposed to a wooded case. The unit has
two magnetic phono inputs, two auxiliary inputs, and one tuner input. The magnetic
phono inputs have a switchable equilization - one setting is for phono, and the
other is for tape. These inputs have independent left and right level controls. The
two auxiliary inputs and the tuner input do not have level controls.
The unit also has a tape monitor input and provisions to output audio to a tape
recorder. Also included are high and low filters, treble and bass controls,
and a loudness contour control. Also included is a volume, balance and a center speaker
on/off control. Although the left/right channel treble and bass controls are ganged,
the treble and bass can be independently adjusted for each channel.
Another feature is a mode control rotary switch. This switch selects
monaural phono, reverse, stereo, channel A, or channel B. This switch allows you
to reverse left and right, or run channel A or channel B through both speakers.
The stereo position is the normal mode.
When I purchased the unit, it was quite dirty and I cleaned it up. Typical of most
vintage Fisher stereo systems, the on/off control was defective and someone
had removed the on/off control and soldered the wires together such that it is
always on. But the unit did work - for a short while. I discovered one weak 12AX7 tube
in the preamplifier and I simply exchanged it with one in the phono section to get
I had it playing for a while and then it blew the 3A fuse. The power transformer
develped a short circuit from the primary to the high voltage secondary. I removed
the transformer and took it apart to see if the short was simple, but I could not
fix the transformer. I purchased a Hammond Model 273BX transformer to replace the
original defective transformer. The Hammond transformer was too tall so I had
to lay it on its side. I had to make three aluminum brackets to fasten the new
transformer to the chassis. The picture below shows the new transformer installed.
The new Hammond transformer is on the left in the picture below.
The picture below shows the original transformer before I removed it.
The picture below shows the bottom of the chassis and the new transformer wired in on the lower left.
Below is a picture of rear of the unit with the case installed.
The unit works well now and has deep rich bass. It sounds really good.
The unit has eleven vacuum tubes. Many of the tubes are original Fisher tubes. If you
look closely, you can see the Fisher brand on the GZ34 rectifier tube next to the
transformer in the pictures above. Although the appearance of this unit is not
exceptional, it does not look bad. It has all of the gold knob caps that are
frequently missing. There are several blemeshes on the front panel, but the
photos make them look worse than they really are.
||AF Amp/Phase Inverter
|2 x ECC83 or 12AX7
||2 x ECC83 or 12AX7
||2 x 7247
||4 x EL84 or 6BQ5
||GZ34 or 5AR4