MC3500 MKii

The McIntosh MC3500 MKii is a 350-watt vacuum tube amplifier based on the MC3500 originally used to power the sound system at Woodstock ’69 and other formative music events. This updated version draws on the original 1968-71 MC3500 while incorporating developments in vacuum tube amplifier design made since the 1960s.

The MC3500 Vacuum Tube Amplifier Mk II uses McIntosh’s proprietary Unity Coupled Circuit™ output transformer, along with an original transformer, to deliver its full 350 watts safely to virtually any speaker. Its fully balanced driver section contains three 12AX7A valves and one 12AT7, while 8 EL509S high-power output valves provide the output stage. These were selected for their similarity to the 6LQ6 ‘sweep tubes’ used in the original MC3500.

The valves sit behind the power and output transformers and are protected by a 12-gauge stainless steel wire cage. McIntosh Power Guard Screen Grid Sensor™ (SGS) technology helps prevent premature vacuum tube failure, while Sentry Monitor™ technology observes the output current to maintain operation within safe limits. Connections include balanced and unbalanced inputs, with patented gold-plated Solid Cinch™ speaker binding posts.

McIntosh has retained several practical details from the original amplifier. The MC3500 Mk II has 2 U-shaped side-rails wrapping around the top, back and bottom of each side. These provided strength and durability when the original amplifiers were used on the road. 4 black rubber bumpers on the rear of the rails allowed the amplifier to be stood upright temporarily during show setup, while helping to prevent parts extending from the rear from scraping against the floor.

The front panel is machined aluminium with a bead-blasted finish and gold anodising that emulates the original MC3500. A clear glass insert covers the output meter, while a black glass insert at the bottom houses the control knobs and illuminated lettering. The stainless steel chassis base has a polished mirror finish.

The larger output meter is centred on the front panel rather than offset to the left as on the original. It uses a variation of McIntosh’s DualView™ Power Output Meter design, with the top scale showing power output in watts and decibels and the bottom scale indicating amplifier warm-up time.

Handles follow the design of the original, with a more ergonomic form for moving the 121 lb. (54.9 kg) amplifier. The McIntosh MC3500 MKii reflects the appearance and practical construction of its predecessor while incorporating the company’s later amplifier technology.

McIntosh President Charlie Randall said, “At the 50th anniversary of Woodstock in 2019, there was a lot of buzz resurfacing about the McIntosh sound system. This enthusiasm was infectious and inspired me to get our engineering team together to redesign the amp that has obviously resonated with music fans as being a historically significant piece of audio gear.

“After over 2 years, we are really proud of the result. The MC3500 Mk II takes its inspiration from the original 1968-71 MC3500 and incorporates all the knowledge we have gained surrounding vacuum tube amplifier design since the 1960s.”