The opportunity of restoring a pair of Quad II valve amplifiers and using these to drive successfully our updated transmission line Monitor Loudspeakers restored both confidence and interest in valve amplifiers despite their lack of power.
This has lead directly to the concept, design and development of the GVA-30 Monoblocks.
Knowing from earlier years that Beam Tetrodes such as the KT66 were good linear audio valves and that the use of Global Feedback was undesirable, determined a design constraint.
A considerable amount of research and development led us to request Martin Colloms, a highly respected Electro-acoustical Engineer, to provide us with an independent constructive criticism of the amplifiers. This enabled successful refinement of the design.
As a result of the assessment, changes were made to the output stage configuration resulting in the requirement for another valve. Optimisation of the power supply and introduction of a superior transformer also resulted.
Finally a change to modern KT88 valves and the output matching them to loudspeakers of 5 ohms impedance (4 to 8 ohms) provided the result that is now the GVA-30.
The chassis is superbly machined from a solid block of aluminium by a local company – Cranford Engineering.
The quality of build and selection of only the very best components (Eg:Mundorf Silver/Oil capacitors and Mills non-inductive resistors) will ensure a long life and enduring quality listening.
Gavin Ian Myers