Vox BRIAN MAY SPECIAL VBM1 - Manual (Page 14)

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iv) PUSH-PULL OUTPUT STAGE. Again the original format was studied and
for the reasons outlined above has been changed to accommodate avail-
able technology:
a) Germanium PNP changed to Silicon PNP.
b) The output transformer has been changed to an electronic simulation.
v) The TONE circuit was not on the original Deacy amp. This has been added
to give more flexibility to the amp. It is placed after the distortion developing
original circuitry, and can be used to colour the sound from mellow “-” to
quite aggressive “+.” Its effect is inactive in the central, “off” position “0.”
vi) SPEAKER SYSTEM EMULATION. This circuit emulates the “miced” tonal
response of the original speaker system. The output of this is sent to both
the RECORDING/HEADPHONE OUTPUT jack, for direct connection into a
recording or PA system, and into the onboard 10-Watt POWER AMP sys-
tem.
vii) VOLUME controls the output volume of the POWER AMP.
viii) 10 WATT POWER AMP. This is a flat response amplifier and speaker sys-
tem, recreating the same signal that is sent to the recording/PA system.
ix) EXTERNAL LOUDSPEAKER JACK. This allows the monitor amp output to
be sent to an external speaker system (NOTE: using this mutes the internal
speaker). This can either be a full range monitor system or, if desired, a
guitar type cabinet. Both will work and give great results, but obviously their
inherent tonality will be somewhat different.
x) While the original Treble Booster and Deacy amp are both battery powered,
the VOX version is fitted with a mains power supply for practical reasons
(NOTE: the batteries do not last long!). This necessitated the design of the
“9 VOLT BATTERY SIMULATION” circuitry to mimic the unique characteris-
tics that are present in batteries.
xi) It should be noted that the signal circuitry uses a “phantom” ground; there-
fore ground loop problems when the amp is connected to other external
equipment should be non-existent.