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Tag: Andrew Russell
CFA Diamond Buffer IPS: Does it Operate in Class B or class A?
There is a persistent assertion by small group of amplifier design practitioners that the diamond buffer input stage of CFA audio amplifier operates in class B (or AB) mode wherein there is a hard ‘handover’ between each half of the diamond buffer input stage as the input signal passes through 0V. The most recent claim…
Low Cost Isolation Amplifier for Industrial Applications
A Design Idea of mine that appeared in EDN around 2000. The article appeared with the title ‘Lost Cost . . . ‘ – seems someone got a bit mixed up. The idea has been referenced in a few papers on the web – always good to see! Low_cost_isolation_amplifier_suits_industrial_applications Here’s another one using a delta…
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
Solid State Relay with PCB Layout
A complete relay that is smaller than a Tyco RT series EMR Simple_solid_state_relay_Updated . This design uses a small double sided PCB and some SMD components. Here are the Gerber files SSLR. The recomended mosfets for this design are the PSMN4R3-100PS[1] for supply rails of up to +-50 V absolute maximum, and for supply rails of up…
Augmented Feedback Error Correction (AFEC)
AFEC is a simple technique that augments the feedback of an amplifier to dramatically improve the Large Signal Non-linearity (LSN) distortion performance by up to 20 dB across the audio band. Additionally, AFEC acts to remove any DC offsets and also improve PSRR significantly. Augmenting the feedback in a manner similar to that described in…
Output Coupling Inductors
Inductors on the output of an amplifer are used to isolate the amplifer from capacitive loads at HF and ensure stability. There has been quite some debate on DIYaudio.com as to whether they are audible, necessary, or just the result of designers being overly cautious. Some very well known designers in the field have decided against using…
Oscillation Sniffer
No ‘scope? This simple circuit can help you quickly see if you have any oscillation problems on your opamp or amplifer circuit. Note, its NOT designed to be connected to high impedance nodes. Oscillation Sniffer by Bonsai
12 point checklist for anyone using opamps in an audio design
Opamp User Guide V1.0.pdf
X-Altra Mini One Line Preamplifier
The X-Altra Mini One is a simple line preamplifer based on the National Semiconductor LM4562 (also known as the LME49720) that I built around 2008 and which served me well until about 2014 when it was replaced with newer more sophisticated designs. Nevertheless, this simple preamp sounded very good, and thanks to the LM4562 (which…