ax-Amplifier

The ax-Amp has been moved to the ‘Projects’ page – you can find a link to the shop for PCB’s in there.

Read more →

JLH 10 Watt Class A Amplifier

This is a copy of the original John Linsley-Hood article that appeared in Wireless World in 1969. This design, almost 50 years old, is still built in its hundreds all over the world.  A quick root around on the web will show numerous kits, many of quite acceptable quality, emanating from China and Hong Kong. […]

Read more →

Class A Buffering the Correct Way

Here’s a simple way to force an opamp output stage to run in class A when used with a discrete buffer output stage – it takes just 1 resistor to provide a near constant current source load. Operating the opamp (and the output buffer stage) in class A dramatically reduces harmonics on the power rail […]

Read more →

Stan Curtis 60W Class A Amplifier from ETI

Stan Curtis was involved in both engineering and management roles in companies like Quad, Cambridge, Rotel (a family owned Japanese brand) Mission and Lecson to name a few. He is primarily an audio business consultant and remains highly respected and a noted product designer within the sector in his own right. This is his 60 […]

Read more →

Hifisonix UBx Universal JFET Buffer

A while back, one of the diyAudio forum members who was building the nx-Amp (here’s the thread on DIYaudio.com) enquired about either reducing the amplifier’s overall gain, or providing a volume control facility. Since both the 15 W class A  sx-Amplifier and its bigger 100W sibling the nx-Amplifier, are Current Feedback Amplifiers, performance is quite […]

Read more →

OPEX-1: A Discrete OPAMP for Audio

This design showcases a discrete opamp for audio applications.  It features very low noise, low distortion and a class A output stage that will deliver 1ppm distortion into a 600 Ohm load at 12 V peak. OPEX-1-Discrete-Opamp

Read more →