MARK IV: specifications
Specifications for the four desk-top machines Otari sold as the MARK IV — the MKIV-2, MKIV-2E, MKIV-4 and MKIV-8 — with sources noted; this page prefers gaps over guesses. Not sure which machine you have? Start with Identify.
The sourcing is uneven, and the page says so. The MKIV-2 and MKIV-2E have a full factory table, in section 8 of the OS3-298 manual they share with the B-III uprights. The MKIV-4 and MKIV-8 have no manual on this site at all, so their figures come from one document: Otari's 1991 data sheet, OA-321C.
The four machines at a glance↑ TOP
This grid is Otari's own, from the 1991 data sheet, and it is kept to that single source on purpose: it is the only document that measures all four machines the same way. For the MKIV-2 and MKIV-2E it does not always agree with the manual — see the next section.
| MKIV-2 | MKIV-2E | MKIV-4 | MKIV-8 | |
|---|---|---|---|---|
| Tape width | ¼″ | ¼″ | ½″ | ½″ |
| Track configuration | 2T NAB | 2T DIN | 4T | 8T |
| Equalization | NAB/IEC selectable | NAB/IEC selectable | NAB fixed (IEC version option) | IEC fixed (NAB version option) |
| Input nominal level | +4 dBu | +4 dBu | +4 dBu/−16 dBu switchable | +4 dBu/−16 dBu switchable |
| Mic input | Transformerless active balanced, 10 kΩ | Transformerless active balanced, 10 kΩ | Unbalanced, 5 kΩ | None |
| Output load impedance | Min. 200 Ω | Min. 200 Ω | Min. 600 Ω | Min. 600 Ω |
| Frequency response, 15 ips (0 VU) | 30 Hz to 20 kHz ±2 dB | 30 Hz to 20 kHz ±2 dB | 40 Hz to 20 kHz +2/−3 dB | 40 Hz to 20 kHz +2/−3 dB |
| Signal-to-noise, 15 ips NAB, unweighted / weighted | 69 / 72 dB | 70 / 73 dB | 67 / 70 dB | 64 / 67 dB |
| Distortion (15 ips, 1 kHz, 250 nWb/m) | Max. 0.3% | Max. 0.3% | Max. 0.5% | Max. 0.5% |
| Crosstalk | Min. 55 dB | Min. 48 dB | Min. 65 dB | Min. 55 dB |
| Depth of erasure | Min. 75 dB | Min. 70 dB | Min. 70 dB | Min. 70 dB |
| Start time, 15 ips | Max. 0.5 sec | Max. 0.5 sec | Max. 0.7 sec | Max. 0.7 sec |
| Test oscillator | 1 kHz/10 kHz | 1 kHz/10 kHz | 100/1 kHz/10 kHz | 100/1 kHz/10 kHz |
| Bias and erase frequency | 133 kHz | 133 kHz | 192 kHz | 192 kHz |
| Power | 100 VA | 100 VA | 100 VA | 150 VA |
| Weight | 30 kg | 30 kg | 32 kg | 35 kg |
The sheet prints several rows once, across every machine: a D.C. brushless quartz PLL servo capstan motor and two induction reel motors; 10.5″ NAB reels maximum; the 15/7.5 and 7.5/3.75 ips speed pairs, accuracy ±0.2%; variable speed ±20% of nominal in 0.01% steps; wow and flutter (peak weighted, DIN 45507) of ±0.06% at 15 ips, ±0.08% at 7.5 and ±0.12% at 3.75; a line input of 10 kΩ with a +30 dBu maximum; outputs of 5 Ω, +4/−16 dBu switchable, with a +26 dBu maximum into each machine's rated load; and one set of dimensions, 480 × 430 × 680 mm (H × W × D). The three-speed claim carries a note — see Identify for why the MKIV-2's own manual disagrees with it.
Where the sheet and the manual disagree↑ TOP
For the MKIV-2 and MKIV-2E the two documents can be set side by side. Most rows match exactly: wow and flutter, start and stop times, fast wind, frequency response, distortion, crosstalk, depth of erasure, the test oscillator, bias frequency, the output stage, the mic input and the MKIV-2's dimensions. These do not:
| 1991 sheet (OA-321C) | Manual (OS3-298) | |
|---|---|---|
| Signal-to-noise, 15 ips IEC, MKIV-2 | 71 / 74 dB | 70 / 73 dB |
| Signal-to-noise, 7.5 ips IEC, MKIV-2 | 68 / 71 dB | 67 / 70 dB |
| Signal-to-noise, 15 ips IEC, MKIV-2E | 72 / 75 dB | 71 / 74 dB |
| Signal-to-noise, 7.5 ips IEC, MKIV-2E | 69 / 72 dB | 68 / 71 dB |
| Line input impedance | 10 kΩ | 100 kΩ |
| Weight, MKIV-2 | 30 kg | 34 kg |
| Autolocator cue-point memories | Four | Three — the SEARCH 1, 2 and 3 keys |
The signal-to-noise difference is systematic, not scattered. Every IEC figure at 15 and 7.5 ips, weighted and unweighted, is exactly 1 dB better on the sheet than in the manual; every NAB figure and every 3.75 ips figure agrees to the decibel. Both documents state the same test conditions — a 1,040 nWb/m recording level at 15 and 7.5 ips and 740 nWb/m at 3.75, the same 30 Hz to 18 kHz filter unweighted and the same NAB or ANSI "A" filter weighted — so this is not a different measurement. Neither document says which is right. The B-III's later product sheet, whose specification table is the manual's section 8 reprinted, carries the manual's figures; see B-III specifications.
The input impedance differs by a factor of ten, and the weight by 4 kg, with nothing in either document to reconcile them. The sheet's four cue-point memories are listed separately from its search-zero function, so they are not the manual's three SEARCH keys plus SEARCH ZERO counted together. Otari's own 2008 B-III sheet rewords this same 1991 sentence and says three.
The sheet's head-configuration cell for the MKIV-2 and MKIV-2E is word for word the same as the uprights' cell: it lists a mono version, a two-channel version and a four-channel version, where the sheet's own configurations table gives these two machines as 2T NAB and 2T DIN. It lists four heads for the two-channel version — reproduce, erase, record, reproduce — against the manual's three for the MKIV-2: erase, record and reproduce.
MKIV-2 and MKIV-2E: the factory table↑ TOP
Otari's specification for these two machines is transcribed in full in the OS3-298 manual, section 8.1, Tape Transport, and section 8.2, Electronics. The manual covers the B-III uprights as well; the rows below are the ones that apply to the MARK IV.
| Parameter | OS3-298 |
|---|---|
| Tape width and tracks | ¼″ tape; MKIV-2 2 Track NAB |
| Heads, MKIV-2 | Three: erase, record, reproduce |
| Motors | Capstan: DC brushless PLL servo motor. Reels: two AC induction motors |
| Tape speeds | High Speed Version 15/7.5 ips; Low Speed Version 7.5/3.75 ips |
| Speed accuracy and deviation | Max. ±0.2%; deviation max. 0.2% |
| Wow and flutter, peak weighted (DIN 45507) | 15 ips max. ±0.06%; 7.5 ips max. ±0.08%; 3.75 ips max. ±0.12% |
| Start time | 15 ips max. 0.5 sec; 7.5 ips max. 0.4 sec; 3.75 ips max. 0.3 sec |
| Stop time | 15 ips max. 0.5 sec; 7.5 ips max. 0.3 sec; 3.75 ips max. 0.3 sec |
| Fast wind | Max. 110 sec for 2500 ft (50 Hz); max. 90 sec (60 Hz) |
| Line input | Transformerless active balanced, 100 kΩ, 20 Hz–20 kHz; nominal +4 dBu, max. +30 dBu; XLR female |
| Mic input | Transformerless active balanced, 10 kΩ; min. level −70/−50 dBu/OFF switchable; mic impedance min. 150 Ω |
| Line output | Transformerless active balanced, max. 5 Ω; load min. 200 Ω; +4/−16 dBu switchable; max. +26 dBu into 200 Ω; XLR male |
| Headphone | 8 Ω load, ¼″ standard stereo phone jack |
| Equalization | NAB/IEC selectable |
| Standard reference flux | MKIV-2: 185/250/320 nWb/m. MKIV-2E: 250/320/510 nWb/m (the top figure in each open circuit) |
| Frequency response, REC/REP | 15 ips 30 Hz–20 kHz; 7.5 ips 30 Hz–18 kHz; 3.75 ips 20 Hz–10 kHz; all ±2 dB |
| Frequency response, REC/SEL-REP | 15 ips 250 Hz–7.5 kHz; 7.5 ips 250 Hz–5 kHz; 3.75 ips 250 Hz–2.5 kHz; all ±3 dB |
| Distortion | Max. 0.3% THD (15 ips, 1 kHz, 250 nWb/m, AMPEX 456) |
| Crosstalk | MKIV-2 min. 55 dB; MKIV-2E min. 48 dB |
| Depth of erasure | MKIV-2 min. 75 dB; MKIV-2E min. 70 dB |
| Test oscillator | Sine wave 1 kHz/10 kHz |
| Bias and erase frequency | 133 kHz |
| Operating environment | 5 to 40 °C (41 to 104 °F), 20 to 80% RH |
| Storage environment | −20 to 45 °C (−4 to 113 °F), 10 to 80% RH |
| Dimensions, MKIV-2 | 480 × 430 × 680 mm |
| Weight, MKIV-2 | 34 kg |
The manual's signal-to-noise table gives the two-channel machines by track width, 2 mm and 2.75 mm; the 1991 sheet labels the MKIV-2 2 mm and the MKIV-2E 2.75 mm:
| Speed | EQ | MKIV-2 (2 mm), unweighted / weighted | MKIV-2E (2.75 mm), unweighted / weighted |
|---|---|---|---|
| 15 ips | IEC | 70 / 73 dB | 71 / 74 dB |
| 15 ips | NAB | 69 / 72 dB | 70 / 73 dB |
| 7.5 ips | IEC | 67 / 70 dB | 68 / 71 dB |
| 7.5 ips | NAB | 71 / 73 dB | 72 / 74 dB |
| 3.75 ips | IEC | 64 / 67 dB | 65 / 68 dB |
| 3.75 ips | NAB | 64 / 67 dB | 65 / 68 dB |
MKIV-4 and MKIV-8↑ TOP
No factory manual for the MKIV-4 or MKIV-8 is held on this site. OS3-298 lists both in its family table but covers neither. What follows is from the 1991 sheet alone, and where the sheet has already been shown to disagree with a manual for the machines it can be checked against, that is worth bearing in mind.
| Parameter | MKIV-4 | MKIV-8 |
|---|---|---|
| Tape width and tracks | ½″, 4 tracks, 1.8 mm track width | ½″, 8 tracks, 1 mm track width |
| Heads | Erase, record, reproduce | Erase, record, reproduce |
| Equalization | NAB fixed, IEC version an option | IEC fixed, NAB version an option |
| Input and output reference level | +4 dBu/−16 dBu, switchable independently on each channel | +4 dBu/−16 dBu, switchable independently on each channel |
| Mic input | Unbalanced, 5 kΩ, min. level −70/−50 dBu switchable | No mic input |
| Output load impedance | Min. 600 Ω; max. +26 dBu into 600 Ω | Min. 600 Ω; max. +26 dBu into 600 Ω |
| Frequency response, REC/REP | 15 ips 40 Hz–20 kHz; 7.5 ips 20 Hz–18 kHz; 3.75 ips 20 Hz–10 kHz; all +2/−3 dB | the same |
| Frequency response, REC/SEL-REP | 15 ips 50 Hz–15 kHz; 7.5 ips 50 Hz–12 kHz; 3.75 ips 50 Hz–8 kHz; all ±3 dB | the same |
| Signal-to-noise, 15 ips IEC, unweighted / weighted | 69 / 72 dB | 66 / 69 dB |
| Distortion | Max. 0.5% | Max. 0.5% |
| Crosstalk | Min. 65 dB | Min. 55 dB |
| Depth of erasure | Min. 70 dB | Min. 70 dB |
| Start and stop time | 15 ips max. 0.7 sec; 7.5 ips max. 0.5 sec; 3.75 ips max. 0.4 sec | the same |
| Test oscillator | 100/1 kHz/10 kHz | 100/1 kHz/10 kHz |
| Bias and erase frequency | 192 kHz | 192 kHz |
| Power | 100 VA | 150 VA |
| Weight | 32 kg | 35 kg |
The same sheet's standard features reserve four functions for these two machines: automatic monitor switching and gapless, seamless punch-in and punch-out (both shared with the BQ-III), a rehearse function (the MKIV-4 and MKIV-8 only), and independently switchable +4 dBu or −16 dBu reference levels on each channel (shared with the BQIII). It also makes the 7.5/3.75 ips speed pair an option on them rather than a choice. Its options list names a CB-144 remote controller for the MKIV-8 and extension PCBs PB-7WXA (MKIV-4, MKIV-8 and BQ-III) and PB-7OQA (MKIV-4 and BQ-III).
The sheet gives these two machines the same 480 × 430 × 680 mm as the MKIV-2. Nothing else on this site confirms or contradicts that for either of them.
Sources↑ TOP
- MX-5050 Series data sheet OA-321C — ©1991. The configurations and specifications grid, the only figures held here for the MKIV-4 and MKIV-8, and the standard features and options.
- MX-5050 MKIV-2, BIII-2 operation and maintenance manual, OS3-298 — section 8, the MKIV-2's and MKIV-2E's factory specification.
- MX-5050 BIII product sheet — ©1999, 2008; the B-III's specification table reprinted from the manual, cited here only for the signal-to-noise comparison.