D.W. Fearn VT-4 Vacuum Tube LC Equalizer 23
6 .
M A I N T E N A N C E
The VT-4 is built with only the highest quality parts and will prove to be extremely reli-
able. Vacuum tubes and electrolytic capacitors, however, have a finite useful life and must
be replaced eventually.
Top Cover Removal
Removing the top cover allows access to the vacuum tubes. Phillips-head screws must
be removed. When replacing the cover, position it so that the slotted ventillation holes are
over the tubes (towards the back ).
Vacuum Tubes
Four 6N1P tubes are used in the VT-4. V101 and V201 are the input stage and V102
and V202 are the output stages. Tube life is difficult to predict, but it will probably be
measured in years. Catastrophic tube failure is rare with this type of device, but a gradual
increase in noise, microphonics, distortion, or a reduction in headroom, should indicate
the need for replacement. It is recommended that you periodically perform a quick noise
and distortion check on the VT-4 and compare the results to previous measurements.
Replacement tubes may be obtained from us (tested and graded for low-noise and micro-
phonics), or other suppliers.
