The Phædrus Audio PHAB is a recreation of the famous all valve (vacuum tube) mic' preamp's used to record The Beatles.
The PHAB is based around the fundamental building-brick of The Fabs' console: the Type 47 modular amplifiers.
The Phædrus Audio PHAB microphone preamplifier is essentially the front-end of a single-channel of the famous Stereosonic consoles, in which the modular-amplifier is combined with a rotary attenuator, switchable pad, high-pass filter and gain-switching circuitry.
Much more information is available on our Phædrus and the FABs..... The Beatles Recording Gear page.
Here's the circuit schematic of the PHAB microphone preamplifier....
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