copper_130 Watt Original Version

The first of this series were thirty-watt and pure class A, as reviewed in Hi Fi Choice in 1998 by Jason Kennedy. They used two kt88s and two 6sn7s in each channel, which were configured as follows; first stage directly coupled to a concertina phase splitter, capacitor coupled to a dedicated driver stage, capacitor coupled to the output stage. Overall feedback was applied, as well as local loops. Power supply HT was via two GZ34’s, and large choke for extra smoothing.

Read a full review here

 

 

copper 1

 

 

 

 

 

 

 

 

new_copper2b60 to 120 Watt Versions

These amps were quite a different breed from the latter. They had four kt88s and three 6sn7s in each channel (later versions had 2 6sn7s and one ecc34). The front-end circuitry was very similar to the 30-watt versions, but the output stage was grid biased and driven by cathode followers. They could be biased to give between 60 and 120 watts! Power supplies HT via solid state, capacitor, choke and capacitor. Time delay circuit for HT, approx. 40 seconds.

 

 

 

 

Copper 2

Some of the original Copper amps [including the one above] have now been brought up to the latest specifications, with larger mains transformers fitted, higher quality components including power supply, and bipass caps etc, and all versions are now fitted with the new’ and Excelent all-round performing Tungsol KT120 power valves, which means these amplifiers can now be set to give up to 50 watts [per channel] of pure class A power…