The project is based on the Marantz MA-9S2 mono power amplifier. The MA-9S2 have two power amplifiers that are bridged to achieve a power output of 300 watts at 8Ω with a THD of 0.01%. The design adopts a Current Feedback Amplifier (CFA) topology. On this project only the front-end input stage of the MA-9S2 will be featured.
The MA-9S2 is using a proprietary Hyper Dynamic Amplifier Module (HDAM) to adjust the DC offset. However, in this project, DC offset correction will be achieved using a combination of manual trimming for the initial adjustment and an op-amp DC servo integrator for continuous dynamic correction to compensate for any drift or fluctuation.
Featured in this project is an LF411, a low-offset, low-drift JFET-input op-amp configured as a non-inverting integrator to continuously control the DC offset of the power amplifier.
How does the amplifier sound?
Listening to Fleetwood Mac's Rumors on vinyl at high volume level, delivered an enhanced audio experience—rich, dynamic, and impressively clean. The sound was full of depth and character, with a polished quality with hardly noticeable distortion or noise, offering a truly refined musical reality.
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