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Tag: class A
The ax-Amplifier: A Very High-Performance 60W RMS Class A Amplifier featuring AFEC
Parts 1 and 2 of the ax-Amplifier were published in the April and May 2024 issues of US based audioXpress magazine. Part 1 – The ax-Amplifier Part 2 – The ax-Amplifier Click on the link to get the supplementary data (BOM etc) from audioXpress Click this link to order 2 off ax- Amplifier PCB’s https://hifisonix.com/shop/2-off-ax-amplifier-module-pcb/…
Hifisonix sx-Amplifier: A 15 W Class A Current Feedback Amplifier
Originally published in August 2012. Click here to order a set of DS THP PCBs for the sx-Amplifier from Jim’s Audio About 150 sx-Amplifier PCB sets have been sold, with most of those going on to be built. As you can read about in the PDF below, my class A journey started off after listening…
Hifisonix HPA-1 Class A Headphone Amplifier
The circuit combines a dual ultra-low distortion opamp, the LM4562 or OPA1642, with a class A discrete power output stage to deliver outstanding performance both measured, and sonically. The complete amplifier, including the opamps, runs in class A. Into 60 Ohm headphones and above, the HPA-1 remains fully in class A up to the rated…
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.…
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…
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…
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…
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