Back to Blog


While I've been locked up in Sydney during COVID I decided to give this project an upgrade. It now has a new precision cut, folded, powder coated metal chassis with screen-printed fiberglass front and back panels. Not cheap but looks great. The new chassis also required a PC Board redesign.  It's come together so well I'm now confident to release it as a full kitset, with all parts except the valves and the 12V external power supply module. These parts are easily available from other suppli...

October 1, 2021


Its been about three years since the initial design now, and quite a few RedRoo amps have been constructed in that time.  All the amps that I know about have been great performers and 100% trouble-free. I had the chance to do some tests and voltage measurements on some that have had daily use, and they were all still spot-on. After embarking on what was basically a hobby project, I've decided to put the entire design and construction details up on this website as a free download, and to off...

April 12, 2021

Circlotron Amplifier

For years I've been mucking around with valve amplifiers, much to the amusement of my family and friends. My first attempt was a version of what's called the Murray amplifier; a 20 watt per channel design by Australian Cyril Murray in the 1960's, which used 6CM5 television line-output valves. I used PL509 valves for a bit more power. Cyril Murray went on to build amplifiers for the Sydney Opera House and his work was very well respected.  Later I made a 60 Watt 'circlotron' design using fou...

June 25, 2019 Posts 1-3 of 3 | Page

This product has been added to your cart