McINTOSH VACUUM TUBE AMPLIFIER RESTORATIONS

MC30 PAIR BEFORE AND AFTER

MC40 PAIR BEFORE AND AFTER

RESTORING A VINTAGE McINTOSH TUBE AMPLIFIER
The amplifier is broken down into its bits and pieces, the output and power supply transformers removed, inspected for lead damage and tested.  The tube sockets, phenolic circuit boards, potentiometers, terminal blocks, fuse holder, RCA inputs, switches and secondary power output jacks are removed and assessed for reuse.  Switches are dissembled and contacts cleaned and polished.  The rectifier/bias supply boards are stripped and reworked with new make components.  Power supply multi-section caps are replaced with new make parts, selenium rectifiers replaced with silicon-based circuits that provide the proper bias voltages.  Factory original Bumblebee and Black Beauty capacitors are replaced with top quality films.  Original tube sockets are ultrasonically cleaned, pins are reworked to eliminate excess solder, wire and loose strands.  The factory 2-conductor power cord is replaced with high quality, 3-conductor, cord with Earth prong lead bolted directly to the chassis.  If the top chassis cover is pitted or corroded replacements that are superior to the factory originals are available for most amplifier models.  For top chassis covers that are in good condition polishing using a range of diamond pastes improve the surface appearance without disturbing the silk screening.  The bottom chassis cover paint is removed to prepare the surface for fresh paint.  The cover is then cleaned, primed and painted using a satin black enamel followed by an oven bake to enhance durability.  The completed amplifier is bench tested for bandwidth, %THD v. voltage output and functionality.  After a 6 to 8h audition, the bottom cover is removed and the amplifier given a final visual inspection.

MC225

MC240

PERFORMANCE VERIFICATION INCLUDING BANDWIDTH, %THD AND NOISE CHARACTERIZATION

AMPLIFIER PHOTOGALLERY