Channel ii – top boost preamp, Input jack sockets, Volume control – Vox AC30HH User Manual
Page 5: Treble control, Bass control, Top cut, O/p mode switch, Power switch, Power light
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CHANNEL II – TOP BOOST PREAMP
6. INPUT JACK SOCKETS
Guitar input jacks into the Top Boost channel. These are wired in the traditional way that gives a
6dB difference in gain between them. The socket nearer the front of the amp is the higher gain,
the one nearest the rear of the chassis is 6dB quieter.
7. VOLUME CONTROL
Controls the volume level of the Top Boost channel.
8. TREBLE CONTROL
Part of the 1963 Top Boost circuit, and strangely enough; this controls the treble spectrum of the
channel!
9. BASS CONTROL
Again part of the 1963 Top Boost circuit—and by the way, controls the bass spectrum.
NOTE !
For newcomers to using a classic VOX, the Top Boost bass & treble controls are extremely
interactive and small adjustments can make quite a radical change to the tone, as both controls
have a big influence on how the mid-range reacts. Our suggestion is to start off with both the
Bass & Treble controls in the mid-way position, and experiment from there. And another thing,
maximum treble can be very, very bright!
10. TOP CUT
This is/was the original (and only!) tone control on the early VOX amps and works as part of the
power amp circuit by cutting the high frequency response.
Please remember that it works in reverse to how we would expect it to in the modern age—the
high end is cut as you turn the control up, i.e. maximum control rotation is maximum cut.
11. O/P MODE SWITCH
This switch changes the power output valves/tubes from Pentode Mode which is the normal
operating mode of the power amplifier to Triode Mode which will halve the power output and will
alter the tone to be somewhat smoother. So Pentode = full power = 15 watts (AC15 versions) or
30 watts (AC30 versions). Triode = half power = 7.5 watts (AC15 versions) or 15 watts (AC30
versions).
12. POWER SWITCH
Turns the applied input mains voltage ON/OFF.
13. POWER LIGHT
Illuminates red when the amp is switched on.
WARNING !
Please ensure that your amplifier is connected to the correct mains power voltage—please
check the rear panel rating plate. If in doubt consult dealer.
WARNING !
NEVER operate this amplifier without the loudspeaker load being connected. Serious damage
can occur otherwise.
WARNING !
This amplifier must always be earthed (grounded) to prevent the risk of electrical shock.