New! The Ultimate GA15 Mod Kit – Legendary 18 Watt Version

 39,95 49,95

This brand new kit, a further development from our classic GA15 mod kit, will convert your Harley Benton® GA15 into that legendary British 18 Watt amp from the 1960s!
The only differences with its 1960s examples are solid state rectification, resulting in a a bit more power, and the absence of a tremolo circuit.
The kit further features added presence and negative feedback controls. The presence control can be effectively eliminated from the circuit by setting the negative feedback to zero, however.
Pretty amazing, if we dare to say so, considering the bargain-bin prices of a GA15 and this kit, versus the price of a reissue! If the mods are performed well, the GA15s annoying hum is eliminated too. Finally, we fixed some minor issues with previous versions of the kit, such as potmeter knobs that didn’t always fit the shafts of the potmeters.
This is a carefully selected set of electronic parts, high quality tone capacitors (Mallory 150s and Silver Mica type) included. It comes with an elaborate instruction manual with plenty of photographs. To view it, you might want to scroll a bit further down. By default, the 18 Watt instruction manual will be sent to you by email. A full-colour print-out is optional, against some extra cost.
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  • 100% tube-based signal path, identical to the legendary example! TL072 opamps and related components are removed from the circuit.
  • Hum-free operation: heater wiring is rerouted and a DC filament supply is introduced.
  • Four controls: volume, tone, presence, negative feedback (standard) or, optionally, five controls: volume, bass, treble, presence, negative feedback.
  • Inputs: one single input jack
  • Outputs: 4-8-16 Ohms speaker jacks (unchanged)
  • Power rating: 18-20W

Instruction Manual:

An elaborate instruction manual with plenty of photographs is part of “The Ultimate GA15 Mod Kit – Legendary 18 Watt Version”. It’s now available for consultation below (it may take a while to load…)


Disclaimer: We strongly recommend you to have a qualified amp technician modify your amp if you have not been trained to work with high voltages. A tube amplifier chassis contains lethal high voltages even when unplugged – sometimes over 500 volts DC! Cosmic Ampworks  assumes or undertakes NO LIABILITY for any damage suffered as a result of the use, misuse or reliance on the information and content in this manual. The modifications described in this manual do not necessarily comply with any electronic safety standards.
Legendary 18W manual

Additional information

Weight 0,35 kg
Dimensions 20 × 20 × 20 cm
Printed full-colour manual?

Send manual by email, Printed full-color manual included