Mark II: specifications
These are Otari's preliminary November 1976 figures for the Mark II-2 and Mark II-4, from the paper S-114 specification sheet (page 2). The digital edition transcribes both pages; the document card provides the 600 and 1200 dpi scans. These are sales-sheet claims, not service acceptance limits. The 1978 db ad independently confirms the two formats, speed pair and standard DC servo.
Transport↑ TOP
| Parameter | Mark II-2 | Mark II-4 |
|---|---|---|
| Tape and channels | ¼″ (6.3 mm), two channels | ½″ (12.7 mm), four channels |
| Track width | 0.075″ (1.9 mm) | 0.075″ (1.9 mm) |
| Speeds | 15 and 7½ ips (38 and 19 cm/s) | Same |
| Maximum speed deviation | ±0.15% | Same |
| Rewind | Under 90 seconds for a 2500 ft reel | Same |
| Reels | 5″ and 7″ plastic, or 10½″ EIA/NAB | 10½″ NAB |
| Heads | Four stacks: ½-track erase, ¼-track reproduce, ½-track record, ½-track reproduce | Three four-track in-line stacks: erase, record, reproduce |
| Motors | DC-servo capstan, variable ±7%; two induction-torque reel motors | Same |
| Flutter and wow, NAB weighted | Under 0.05% at 15 ips; under 0.06% at 7½ ips | Sheet gives one speed table for both versions |
The sheet says the two-channel machine can replay quarter-track stereo tapes with its extra reproduce head. It does not say whether the DC-servo capstan drives the shaft directly or through a belt.
Electronics↑ TOP
The sheet gives one electronics specification for the two versions; it does not break these values out by channel count.
| Parameter | S-114, page 2 |
|---|---|
| Connectors | Line input/output: three-pin XLR; microphone: ¼″ phone jack |
| Line input | Minimum −15 dBm, unbalanced 50 kΩ; balanced 600 Ω with optional transformer |
| Microphone input | Minimum −70 dBm, unbalanced nominal 50 kΩ; balanced 150/250 Ω with optional in-line transformer |
| Line output | Variable or fixed; fixed +4 dBm or −10 dBm, rear-panel selectable; 600 Ω unbalanced or balanced with optional transformer; +19 dBm headroom before clipping |
| Headphone jack | −24 dB, nominal 8 Ω, unbalanced |
| Equalization | NAB at 15 and 7½ ips; EIA, CCIR and IEC also available |
| Overall record/playback signal-to-noise | 68 dB NAB weighted, 65 dB NAB unweighted, at both speeds |
| Signal-to-noise reference | 520 nWb/m relative to biased tape noise using Ampex 456, 3M 250 or equivalent low-noise high-output tape |
| Crosstalk | Greater than 60 dB between adjacent tracks at 1000 Hz |
| Record/playback response at 15 ips, 0 VU | 50 Hz–20 kHz ±2 dB; 35 Hz–25 kHz ±3 dB |
| Record/playback response at 7½ ips, −10 dB | 50 Hz–18 kHz ±2 dB; 40 Hz–20 kHz ±3 dB |
| Selective reproduce response at 15 ips | 100 Hz–15 kHz ±3 dB |
| Selective reproduce response at 7½ ips | 70 Hz–10 kHz ±3 dB |
| Distortion | Under 1% at 1000 Hz and 185 nWb/m |
| Test oscillator | Nominal 1000 Hz |
The 68/65 dB signal-to-noise pair is quoted against 520 nWb/m, while distortion is quoted at 185 nWb/m. Neither number should be compared with a later brochure without checking its reference level, weighting and test tape.
Cabinet and power↑ TOP
| Parameter | Mark II-2 | Mark II-4 |
|---|---|---|
| Operating position | Vertical or horizontal | Same |
| Power | 117 V/60 Hz or 220/240 V/50 Hz, single-phase AC, 105 W | Same |
| Operating environment | 5–40°C (40–104°F), 20–80% RH | Same |
| Storage environment | −20–45°C (−5–113°F), 10–80% RH | Same |
| Weight | 64 lb (29 kg) | 84 lb (38 kg) |
| Table-top console size (H × W × D) | 19 × 16½ × 25″ (483 × 419 × 635 mm) | 26 × 16½ × 25″ (660 × 419 × 635 mm) |
| Mounting | Table-top console standard; floor-console pedestal optional | Same |
The sheet lists a DC servo, empty 10½″ NAB reel, precision hold-down knob, fuse and NAB shims as standard accessories. Optional accessories are balanced low-impedance microphone transformers, balanced 600 Ω line input/output transformers, a remote-control unit and the floor-console pedestal.
Sources↑ TOP
Factory specification sheet
-
S-114, November 1976: specifications — the complete factory table, transcribed from the paper copy scanned here.
-
S-114: introduction and features — the two formats, separate electronics, standard DC servo and photo.
Period advertising
- db, January 1978 — Otari's later line-up ad naming the Mark II-2 and II-4.