QX / QXD / QXHD: the quarter-inch four-channel
¼″ quarter-track 4-channel
Designations
- MX-5050-QX
- MX-5050-QXH
- MX-5050-QXL
- MX-5050-QXD
- MX-5050-QXHD
What it is↑ TOP
The QX is the first generation's quarter-inch four-channel machine. It is on the panel photo of Otari's September 1975 tri-fold brochure, whose S/N table quotes it beside the two-channel machines (1975 brochure), and Audio's October 1976 directory lists its drive motor as DC servo alone where the two-channel machine lists both (Audio, October 1976). By 1978 the line-up ad calls it the QXHD, and the Mark II's maintenance manual title groups the QXD with the MKII-2, MKII-4 and 8SD — the four first-generation machines that shared a service book.
How to identify one↑ TOP
- Quarter-inch tape with a four-channel head block.
- The rear plate, not the faceplate: "QX", "QXD" or "QXHD". See the face badge.
- A DC-servo capstan — the 1976 directory lists no AC option for the QX.
Specifications↑ TOP
Not yet compiled beyond the drive-motor entry above. The 1975 brochure's specification page quotes the QX in its S/N table; read it on the brochure edition rather than trusting a figure copied here without its conditions.
Documents
Service training binder
Instruction and preventive maintenance manual (OIM-1004E)
Maintenance manual supplement (OMM-1002E)
Wanted
QXD maintenance manual (shared with the Mark II)
The QXD is named on the cover of "MODELS MX-5050 MKII-2, QXD, MKII-4 AND 8SD", the book it shares with the two desk-top MARK machines, and no scan of it has been located. Not to be confused with the two books above, which are first-generation too and name the QXD in different company: the 2SD₂, the ½QXD and the 8SD.
Have one? Here is how to contribute.
In the period press
- db, January 1978 — Otari's whole line on one page — and the proof that the MARK II shipped alongside the silver-face MX-5050-2S, with DC servo standard while the 2S still listed it as an option.
Sources↑ TOP
- Sales brochure, September 1975 — the QX on the panel photo and in the S/N table.
- Audio, October 1976 — the directory's drive-motor column.
- db, January 1978 — the QXHD in the line-up ad.
- The wider family — the shared maintenance manual title.
Have one, or paper for it?↑ TOP
Two factory books now cover this machine, both on the Manuals page: an instruction manual and its maintenance supplement, which name the QXD alongside the 2SD₂, the ½QXD and the 8SD. What is still missing is everything else. No brochure, no spec sheet, no photograph of a QXD's rear plate, and no scan of the later book that names the QXD beside the two desk-top MARK machines. An owner with any of those would fill most of this page. See how to contribute.