Tuesday, July 20, 2010

6AS7 SET amplifier

This very special, one of a kind, SET is based on the 6AS7 twin power triode. A two stage amplifier with a 12AX7 driver. Only two valves in the audio circuit and valve rectification. The rectifier valve is a rare JAN CBXL-5R4GY (brown base). The power valve is an English United Electric and driver valve, 12AX7 Australian made AWA.

Valve rectification and a reactor filtered power supply ensure true musicality. Combine this with an internal power filer, vibration isolated power tranni and OPTs. This makes a very quiet and dynamic amplifier.

There is no input capacitor. The critical inter-stage capacitor, joining the driver stage and power stage, is a large and expensive Jensen, pure copper, paper and oil type. Silver wire is use to bring the audio to the driver stage and component-2-component wiring is used throughout. No PCBs exist in this amp!

After much listening I am convinced this is the best amp I have ever built. Not only based on its detailed mid-range and extended highs but its deep and weighty bass. The volume of bass I was not expecting. The sound stage is deep and wide both behind and in front of the speakers. Sibilance is natural and sustain and reverb. extremely well rendered.

A lovely Mirbeu timber base (custom built especially for this amplifier) holds something very different. A blue top plate carries exquisite but bulky componentry. Though only a few watts, with the right speakers this simple amp will delight and surprise you. With a frequency range from 12hZ to 50,000hZ it is easy to understand why this amp sounds so good. And why the bass feels extended and full. I true audiophile SET amp.