McIntosh ml-1 (1970)

Loudspeaker system designed to extend bass response to 20Hz when paired with a McIntosh equalizer

Overview

The McIntosh ML-1C is a loudspeaker system introduced in 1970 by McIntosh Laboratories. It was the company's first "mass" produced speaker model. Roger Russell designed it. The system is the ML-1C speaker plus the optional MQ101 environmental equalizer, and together they hold flat frequency response down to 20Hz within 1dB. The speakers were built to run with a McIntosh equalizer - either the MQ101 or the lower-cost MQ102 - because the full bass performance only shows up with equalization. Without one, the system lacks the deep bass it was designed to deliver.

Specifications

Design

The ML-1C design is covered by U.S. Patent 3,715,501. It is an acoustic suspension cabinet with one 12" woofer and one 8" midbass per cabinet. The 12" woofer has a barium ferrite magnet, an aluminum voice coil form, and 1" of total travel. The magnet structure weighs 15 pounds. The woofer is intentionally overdamped and rolls off starting at 150 Hz. The crossover network avoids electrolytic capacitors. Its supplementary design for modern driver replacements includes a 1.6 mH iron core inductor (L1) and a 2-ohm series resistor (R1). Original drivers are no longer available, and restoration typically uses Morel MDT40 and MDM 55 drivers as substitutes.

Context

McIntosh marketed the ML-1C on its ability to reproduce 20Hz bass, a claimed industry first at the time. The design needed the MQ101 or MQ102 equalizer for full performance, yet only about one in three buyers purchased one. The equalizers were sold separately, and McIntosh advised against using them with non-McIntosh speakers. A planned ML-1D version with indicator lights for clipping and blown fuses was scrapped. Some cabinets were already made with light cutouts, which were later covered by metal plates.

Market

Common failures include deteriorated foam surrounds on the woofer and midrange drivers, which means refoaming or full replacement. After approximately 50 years, tweeters and upper midrange drivers often have little or no life left. Direct replacement drivers are not available, so restoration depends on modern substitutes and custom crossover work.

eBay Listings

McINTOSH ML-1C / ML-10C GRILL CLIP/ RETAINER

$10.00

Pair of McIntosh ML-1C Speakers

$599

ML-1C ML-2C Vintage McIntosh Soft Dome Tweeter. Tested

$130

McINTOSH ML-1C 4-WAY CROSSOVER/ INPUT PLATE

$50.00

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Related Models

• McIntosh ml-2m (1980-1984)
• McIntosh ml-4c (1973-1975)
• McIntosh xl-1 (1980-1982)
• McIntosh ae2
• McIntosh ml-2 (1970-1972)