MCI JH-24
A 24-track machine that shrank the cabinet, not the capability - and became the workhorse of the American studio boom.
Overview
The JH-24 is a two-inch, 24-track analog tape recorder built by MCI in Fort Lauderdale, Florida. By the mid-1970s, MCI was the audio industry's only manufacturer of both professional multi-track recorders and recording consoles, and the JH-24 carried that reputation into studios across the country. The big engineering decision was size. MCI squeezed the 24-track into a cabinet just 31½ inches wide, down from the 47-inch cabinet of its predecessor. That made the JH-24 the company's first 24-track recorder to fit in a 16-track-size footprint, which mattered in any studio where floor space was already spoken for.
Owners report that the machine accommodates 14-inch reels, and MCI added handles and oversize casters to the cabinet, which made it more portable than a 24-track had any right to be. The company's own advertising framed the cabinet shrink as "a little revolutionary" — a bit of marketing that undersold how much studio logistics depended on getting a full 24-track into a room that could already barely hold a 16.
The JH-24 was also the flagship of MCI's transformerless push. Studio Sound (February 1981, p.53) reported that MCI was the first company to offer a totally transformerless system, with no head transformers in the tape machines and electronically balanced inputs and outputs throughout. Line transformers were optionally available. The JH-24 sat at the center of that product line alongside the JH-600 console series and the JH-110B.
Key Features
The JH-100 Transport
The JH-24 was built around the JH-100 tape transport, which replaced the earlier JH-10 transport across the JH-16, JH-8, and JH-24 recorders. The JH-100 brought a D.C. capstan servo drive with crystal-controlled fixed tape speeds of 15 and 30 ips, with 7.5 ips available. Speed stability was the point. MCI specified "piano proof" flutter, typically 0.04% at 15 ips DIN weighted and 0.06% at 15 ips DIN unweighted.
The transport also offered stable variable speed operation from the front panel for effects and speed corrections, plus wide-range external speed programming for inter-machine sync. That was useful for audio/video or audio/audio remote speed control. Full manual velocity programming was provided for cueing, editing, and special effects. The deck logic was fully "relay-less," built around TTL circuitry, which cut down on the mechanical wear points of relay-based transports.
Reel Tension Control
MCI's all-mode reel tension control system maintained constant tape tension and high speed accuracy anywhere in the reel, with consistent tape packing. The tape wound evenly whether the reel was fresh or nearly spent.
Mark II Auto Locator
The JH-24 shipped with MCI's "Mark II" auto locator, a full bidirectional unit with keyboard entry and real-time readout and operation. The locator used a controlled approach speed with no overshoot, so it landed on the target point cleanly rather than slamming past it and backing up.
24-Track Capability in a 16-Track Cabinet
The defining feature of the JH-24 was its size. MCI's own advertising noted that the cabinet had been slimmed from 47 inches to 31½ inches, making the JH-24 the company's first 24-track recorder in a 16-track-size cabinet. Buyers who didn't need all 24 tracks right away could purchase an 8- or 16-track configuration and add the rest later in the same cabinet.
Fingertip-Friendly Controls
MCI's field surveys found that most fingertips are rounded, not square, so the company replaced the square master status and record-ready buttons with rounded ones.
Historical Context
MCI announced the opening of expanded manufacturing facilities in Fort Lauderdale, Florida - a 20,000 square foot plant at 4007 N.E. 6th Avenue that consolidated the company's administrative, engineering, electronic manufacturing, and precision machine shop operations. The new plant expanded manufacturing capacity for the JH-16 and JH-24 multi-track recorders as well as the JH-416 stock console. G.C. "Jeep" Harned was company president at the time, and Claude J. Hill, Jr. was named Vice President of Marketing.
By 1980, MCI was marketing the JH-24 alongside the JH-600 Series automated recording and remixing consoles as a matched system. Recording Engineer (April 1980, p.28) called the pairing "The Differential Team," with the JH-600 available in factory-automated configurations with either a light meter panel (plasma display) or VU meter panel, or non-automated with VU meter panel, or non-automated with VU meter panel and VCA grouping.
By the early 1990s, the JH-24 was appearing regularly in the used-equipment columns of the trade press. A 1993 classified listing in Mix (October 1993, p.310) advertised an MCI JH-24 two-inch 24-track with Autolocator III, a two-inch 16-track head stack, extender cards, and manuals, described as being in very good condition.
Collectibility & Value
The JH-24 has settled into the same niche as most large-format analog multitracks. It is too big and too maintenance-hungry for casual collectors, but still wanted by working studios and dedicated hobbyists who want the sound of two-inch tape at 15 or 30 ips. A Boston-area broker listing in the early 1990s priced an MCI JH-24 at $16,000, and a later listing from the same broker showed $17,000.
Buyers should expect the usual realities of a machine this age. The transport is sturdy, but the electronics and mechanical assemblies need attention, and parts and service knowledge are increasingly specialized. The JH-100 transport's relay-less TTL logic is a long-term reliability advantage, but the capstan servo and tension system still need proper alignment and regular maintenance. Factor in the cost of a qualified tech. These are not machines you buy and simply plug in.
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