2A3 Push-pull amplifier, built in 2009, has proven itself to be an excellent performer. Compared with Single-Ended amps, I am happy about the additional watts and improved bass control.
The design of an amplifier is more important than parts quality – don’t waste $$ on expensive parts in a poor design.
However, I think it is worthwhile to spend some more time and $$ on this amp.
Real music has dynamics. Macro-dynamics – with unrestricted headroom in crescendoes. Micro-dynamics – with subtle low-level information.
Music should be reproduced also with a ‘time’ dimension. Not just tempo, but each sound accompanied by an harmonic ‘envelope’, where overtones are produced and decay naturally – providing a sense of ambience, dimension and space.
Diego Nardi published his φ42 (Phi 42) Phono Preamp in Sound Practices magazine, issue 14.
This is an all-tube (valve) circuit, designed without (global) negative feedback.
A Directly Heated Triode PP amp can combine the harmonic naturalness of triode amplification, with the lower output impedance & good LF control of Push-Pull amplification.
Further to the
JE Labs Linestage built in 2011…
A quick Frequency Response plot with 3V pk-pk sine input and 0.4V out (-17.5dB volume attenuation). Response from 20Hz – 20kHz is -1.2dB, -0.1dB, ref 1kHz. Not bad,
As Joseph Esmilla says, this was inspired by Bruce Berman’s Homebrew Type 76 Preamplifier described in Sound Practices #13.
In 1998 I built this line level preamplifier – the Diego Nardi 5687 ‘WOT’ (With Output Transformer) transformer-coupled linestage, as published in Sound Practices #10.