The wider family: MARK II, III and IV

This page is about the machines that are not mine.

The Mark I (Mini Pro) is where this site started, but you cannot read a forum thread or a marketplace listing about the MX-5050 without meeting the MARK machines — and their place in the family is the most consistently garbled thing written about the line. So here is the long version, with the evidence. If you only want to know where a silver-face deck sits, the generation table on the history page is the short answer.

Parallel to the B series, not later↑ TOP

MKIII and MKIV are not later generations than the B series — they are its contemporaries. The MARK line is Otari's second chassis: desk-top machines, and the wider tape formats the B-series uprights didn't cover. The two lines ran side by side, and each MARK model is a sibling of a B model, not a successor. Sequenced as a single ladder — Mark I, B, BII, BIII, then MKIII, MKIV — the line makes no sense, which is why so many accounts of it don't.

Otari says so in its own sales literature. A 1983 MX-5050B-II brochure introduces the B-II as "a member of the comprehensive Otari family of recorders which includes the 1/4″ two track MARK III/2, 1/4″ four track BQ-II, 1/2″ four track MARK III/4, and the 1/2″ eight track MARK III/8" — one family, listed together, in the same year. By 1991 the "MX-5050 Series Configurations" table sets MKIV-2, MKIV-2E, MKIV-4 and MKIV-8 (Desk Top) beside BQIII, BIII-F, BIII-2 and BIII-2E (Upright) — and gives every one of them the same capstan motor.

The service training binder on this site proves it at the parts level, which is the kind of evidence marketing copy can't fake. In its head-assembly guide, one head assembly — KH-41IA — serves "BII2, MKIII-2", and the audio PCB PB-16EB serves "BII, MKIII-2". Same heads, same audio board: a MKIII-2 is a BII in a different box.

The MARK II is older than the B↑ TOP

The MARK line starts earlier than the B series — a good deal earlier. Otari's own full-page ad in db, January 1978 lays the whole catalogue out in nine numbered photographs, and the Mark II-2 and Mark II-4 stand at numbers 5 and 6 — right beside the silver-face MX-5050-2S at number 1. There is no B in that ad, because the B didn't exist yet. Read the two entries together and the MARK II's whole character falls out:

1. MX-5050-2S Two-Channel Half-Track … • Optional dc capstan servo …

5. Mark II-2 Two-Channel Quarter-Inch All MX-5050 features plus: • Separate transport and electronics • 15 & 7½ ips • Variable speed (±7%) dc capstan servo.

"All MX-5050 features plus" — the MARK II is a first-generation machine in a desk-top box, with the electronics lifted out of the deck and the DC-servo capstan made standard while the plain 2S still sold it as an option. That is the same DC-servo story the history page tells — the servo was on the silver-face machine's options list from the very first ad in September 1974 — except that here it arrives first, and as standard.

Otari's own paperwork agrees: the factory maintenance manual for the MARK II covers "MODELS MX-5050 MKII-2, QXD, MKII-4 AND 8SD" — filed together with the QXD and 8SD, which are first-generation model codes. And it is not a separate book: a period copy of that manual is a catalogue-number OMM-1002E with "MKII-2" and "MKII-4" hand-lettered over the printed 2SD₂ and ½QXD on its cover — same catalogue number, same cover photograph, same pages inside as the QXD edition transcribed on this site. In the binder's head-assembly guide, MKII-2's assembly (KH-4F-A) carries erase head GH4E004 — the same erase head as the first-generation 2SD — where the BII/MKIII generation switched to GH4E082A. That head alone doesn't separate the Mark II from the B, either: the B-2HD's KH-4K-A stack is identical head for head (GH4E004, GH4R005, GH4P027, GH4P069). The MARK II sits on the old side of the BII/MKIII line, not apart from the B.

So the forum habit of writing "MkII" when you mean a BII isn't just loose, it is a different machine from a different era: the Mark II was announced for February 1977 availability, the BII, on sale by 1983. Both existed, and they are not even the same generation.

How the MARK line actually grew↑ TOP

Two details that a tidy generation table flattens out. The MARK III didn't arrive as a family — it grew backwards. The half-inch eight-track came first, in July 1981, as the replacement for the MX-5050-8D; the four-track followed in 1982; and the quarter-inch two-track — the BII's twin, the one that shares its heads and audio board — only in 1983, when the line was nearly a decade old.

Otari never printed a "Mark II-8", though its November 1976 Studio Sound advertisement captions an eight-channel "MX-5050-8SD MK-II". In 1978 the half-inch eight-channel machine was still the MX-5050-8D and the quarter-inch four-channel the QXHD; the MARK name only swallowed the wide formats at MARK III. That is the shape of the whole line: the MARK machines began as the desk-top answer to an upright machine, and grew into the wide-format answer to no machine at all.

None of which touches the first generation. Whichever way you cut the later line, the silver-face machine came first — and everything after it is a different box around a developing transport.

One thing the MARK machines will not tell you is their own name. Like every other MX-5050, their faceplates read a bare "MX-5050" — the MKIII and MKIV designations appear only on the rear plate. See the face badge.

Sources for this page↑ TOP

First generation and Mark II

db, January 1978 — the line-up ad that puts the Mark II-2 and Mark II-4 beside the silver-face MX-5050-2S, with no B anywhere in the catalogue. Mirrored in full on this site.

B-II, MARK III and later families

Otari's own brochure scan (PDF) — the 1983 B-II brochure naming the MARK III/2, BQ-II, MARK III/4 and MARK III/8 as one family with the B-II; the dedicated MARK III series brochure; the September 1979 MX-5050-B brochure still listing the Mark II-2 and Mark II-4; and the 1991 "MX-5050 Series Configurations" table setting the Desk Top MKIV models beside the Upright BIII models with a shared capstan motor.
Otari's MX-5050 MKIII-2 operation manual (PDF, Library of Congress) — the MARK III transport, in the factory's words.

Cross-family parts evidence

The service training binder transcribed on this site — Otari's own parts cross-reference, and the only source here that marketing copy cannot spin.

Dates come from the trade press: RE/P, June 1981 (the MARK III/8's announcement and July shipping date) and Billboard, 29 May 1982 (the MARK III/4 at AES Anaheim).

Have a MARK machine, a brochure, or a serial plate that adds to this? Corrections and additions are welcome — the MARK line is thinly documented, and this page is only as good as the paper behind it. The family reference pages are the counterpart to this narrative: one page per sibling, with the documents held and wanted for each, and how to contribute what you have.