2225 PE01

Marantz 2225 Pre-Tone Amplifier PE-01 (pre-amp)

Overview

This project recreates (i.e., knocks off) the Marantz 2225 pre-tone amplifier (PE-01), as specified in the Marantz 2225L service manual, using modern and readily-available components. Our custom board is designed to function as a drop-in replacement for the original device. We selected components that meet or exceed the specifications from the service manual, which were experimentally verified by measuring values of components sourced from a vintage PE-01. When discrepancies were discovered between the service manual's component specifications and physical measurements of vintage components, we prioritized the physical measurements. The PCB layout was modified as necessary to accommodate the physical dimensions of our chosen components, and uses a four-layer PCB rather than the single layer of the original product. We used KiCad for design, and validated functionality via SPICE simulation prior to manufacturing. Quantitative characterization of the physical prototype is still in progress, but the initial subjective impression is that it sounds pretty good.

Components

The bill of materials/components list is here.

KiCad renders

Prototype board (V1.0, March 2023)

Original PCB

Schematic and Layout (from Marantz 2225L service manual)

Notes

• CE21 and CE22 should be 3.3µF, not 33µF as they're listed in the service manual.
• CE23 and CE24 are biopolar capacitors, which the service manual does not appear to indicate.
• The first prototype board substituted the specified 7.5K resistors RE13 and RE14 with 4.7K 1% components. The reason for the substitution was to mitigate clipping observed at higher volume levels (i.e., lower input attenuation) of aux input from a Macbook headphone jack, which was about 1.5VPP.