Review of Bob Cordell’s Book ‘Designing Audio Power Amplifiers’
in Power amplifiers, Technical
‘Designing Audio Power Amplifiers’ by Bob Cordell – Reviewed by Andrew C. Russell in 2011 Bob Cordell (on the right) pictured with Jan Didden, publisher of ‘Linear Audio’ After a 25 year hiatus from electronics, I returned about 6 years ago (i.e. 2005) to linear design not as a professional but as a hobbyist. Earlier […]
CFA Diamond Buffer IPS: Does it Operate in Class B or class A?
in Power amplifiers, Technical
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 […]
Barney Oliver: Crossover Distortion in Class B Audio Amplifiers
in Power amplifiers, Technical
This is the famous analysis of class B amplifier cross-over distortion by the then head of HP Reasearch Labs, Dr. Barney Oliver, published in the February 1971 edition of the HP Journal. The bias current Iq for a class B emitter follower amplifier is shown to be approximately Iq = .026/(Re+re+(rb/hFE)). In practice, – the […]
Stan Curtis 60W Class A Amplifier from ETI
in Power amplifiers, Technical
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 […]
Solid State Relay with PCB Layout
in Power amplifiers, Technical
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)
in Power amplifiers, Technical
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 […]