AC30 Top Boost Unit
Amplifier not included! 
The add-on Top Boost unit is an after-market module which can be fitted to early Non-TB Vox AC30′s to convert them to the later Top Boost specifications. Such units are popular with players who require tone controls and more gain from their early AC30′s.
The Top Boost module is fitted to the rear of the amplifier, a hole being cut in the back panel to allow the tone controls to show through. Note that some owners replace the rear panel to avoid having to modify the original.
A high-quality silver mica capacitor is used in the tone stack.
The unit is normally supplied without the ECC83 valve to allow the user to choose valve type.
Supplied with a circuit diagram, instructions and 100pF capacitor.
IMPORTANT NOTE: Valve amplifiers contain high voltages, this unit should only be installed by a qualified person.
Specifications:
Controls – Treble, Bass.
Control Panel – Engraved Traffolite.
Check out New York amp and guitar tech Lane Sparber’s excellent blog which covers fitting the VPW Top Boost kit: