MX-5050 B-III: specifications
Specifications for the four uprights Otari sold as the B-III — the BIII-F, BIII-2, BIII-2E and the four-channel BQIII — with sources noted; this page prefers gaps over guesses. Not sure which machine you have? Start with Identify.
Three documents bear on these machines, and they do not carry equal weight. The BIII-F, BIII-2 and BIII-2E have a full factory table in section 8 of the OS3-298 manual they share with the MARK IV desk-tops. Otari's 1991 data sheet, OA-321C, measures all four side by side. And a later product sheet, ©1999 and 2008, covers the BIII two-track — with a specification table that turns out to be the manual's section 8, reprinted. The BQIII has no manual here; its figures come from the 1991 sheet alone.
The four machines at a glance↑ TOP
This grid is Otari's own, from the 1991 data sheet, kept to that single source because it is the only one that measures all four machines the same way. Where it can be checked against the manual it is not always right — see the next section.
| BQIII | BIII-F | BIII-2 | BIII-2E | |
|---|---|---|---|---|
| Tape width | ¼″ | ¼″ | ¼″ | ¼″ |
| Track configuration | 4T | Mono | 2T NAB | 2T DIN |
| Equalization | NAB fixed (IEC version option) | NAB/IEC selectable | NAB/IEC selectable | NAB/IEC selectable |
| Input nominal level | +4 dBu/−16 dBu switchable | +4 dBu | +4 dBu | +4 dBu |
| Mic input | Unbalanced, 5 kΩ | Transformerless active balanced, 10 kΩ | Transformerless active balanced, 10 kΩ | Transformerless active balanced, 10 kΩ |
| Output load impedance | Min. 600 Ω | Min. 200 Ω | Min. 200 Ω | Min. 200 Ω |
| Output impedance with the optional transformer | Max. 5 Ω | Max. 50 Ω | Max. 50 Ω | Max. 50 Ω |
| Frequency response, 15 ips (0 VU) | 40 Hz to 20 kHz +2/−3 dB | 30 Hz to 20 kHz ±2 dB | 30 Hz to 20 kHz ±2 dB | 30 Hz to 20 kHz ±2 dB |
| Signal-to-noise, 15 ips NAB, unweighted / weighted | 64 / 67 dB | 73 / 76 dB | 69 / 72 dB | 70 / 73 dB |
| Distortion (15 ips, 1 kHz, 250 nWb/m) | Max. 0.5% | Max. 0.3% | Max. 0.3% | Max. 0.3% |
| Crosstalk | Min. 55 dB | — | Min. 55 dB | Min. 48 dB |
| Depth of erasure | Min. 72 dB | Min. 75 dB | Min. 75 dB | Min. 70 dB |
| Test oscillator | 100/1 kHz/10 kHz | 1 kHz/10 kHz | 1 kHz/10 kHz | 1 kHz/10 kHz |
| Bias and erase frequency | 192 kHz | 133 kHz | 133 kHz | 133 kHz |
| Power | 100 VA | 100 VA | 100 VA | 100 VA |
| Weight | 27 kg | 24 kg | 24 kg | 24 kg |
The BIII-F's crosstalk cell is printed empty: a mono machine has no adjacent track to measure against, and the manual gives it no figure either.
Rows the sheet prints once across all four: the 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; start times of 0.5, 0.4 and 0.3 sec and stop times of 0.5, 0.3 and 0.3 sec at 15, 7.5 and 3.75 ips; 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 100 VA.
Where the sheet disagrees with the manual↑ TOP
For the BIII-F, BIII-2 and BIII-2E the 1991 sheet can be set against the manual row by row. Most rows agree: wow and flutter, start, stop and fast-wind times, frequency response, distortion, crosstalk, depth of erasure, the test oscillator, bias frequency, the output stage and the mic input. These do not:
| 1991 sheet (OA-321C) | Manual (OS3-298) | 2008 product sheet | |
|---|---|---|---|
| Signal-to-noise, IEC at 15 and 7.5 ips | 1 dB better throughout | as below | the manual's figures |
| Signal-to-noise, BIII-F, 7.5 ips NAB, unweighted / weighted | 75 / 77 dB | 75 / 75 dB | — |
| Line input impedance | 10 kΩ | 100 kΩ | 100 kΩ |
| Heads, BIII-2 | Four: reproduce, erase, record, reproduce | Three: erase, record, reproduce | Three, in its prose |
| Autolocator cue-point memories | Four | Three — the SEARCH 1, 2 and 3 keys | Three, in its prose |
| Weight | 24 kg | 28 kg | 28 kg |
| Dimensions | 480 × 430 × 680 mm (H × W × D) | 525 × 430 × 275 mm (H × W × D) | 527 × 430 × 275 mm (H × W × D) |
On every row its specification table covers, the 2008 sheet sides with the manual, and that is not a coincidence. The table is the manual's section 8 set again, down to the manual's own slips: its wow-and-flutter line reads "max. ±0.06 b%" and its slowest speed "3.75 Ips", exactly as the manual prints them. On those rows the two later documents are one source, not two.
The heads and cue-point rows are different. The 2008 table has neither; its "three" for both comes from its opening prose, which rewords the 1991 sheet's first page — keeping its "optimized three-head design", but changing "four one-touch cue-point memories" to three. That is Otari correcting its own 1991 wording, and it agrees with the manual's three SEARCH keys.
Signal-to-noise. Every IEC figure at 15 and 7.5 ips, weighted and unweighted, is exactly 1 dB better on the 1991 sheet, for all three machines; every NAB figure and every 3.75 ips figure agrees. Both documents state the same test conditions. There is one exception on the NAB side: at 7.5 ips NAB the manual gives the BIII-F 75 dB twice, unweighted and weighted, where the sheet has 75 and 77. Every other 7.5 ips NAB pair in both documents is 2 dB apart, as the sheet's is — which makes the manual's repeated figure the likely slip.
Heads. The 1991 sheet contradicts itself here. Its specification grid gives the two-channel version four heads, but its first page says every machine has an "optimized three-head design", its feature list says "Plug-in three head design", and the same list reserves a fourth head for "¼" track stereo playback" to the BIII-F alone. The manual agrees with the feature list: three heads on the BIII-2 and BIII-2E, four on the BIII-F.
Dimensions. The sheet prints a single dimension row across all eight MX-5050 models, and for the uprights it is the desk-top's: 680 mm deep. Its own drawing of the upright on page 2 contradicts it — 430 mm wide, 525 mm high, 206 mm deep across the top and 215 mm across the base (figure). The manual's table gives 525 mm high and 275 mm deep, and its own drawing 527 mm high and 206 to 220 mm deep; the 2008 sheet's table takes the drawing's 527. Setting the 1991 table aside, the documents differ by only 2 mm on height, but on depth the drawings and the tables disagree with each other by more than 50 mm. Only the 1991 table gives the uprights the desk-top's 480 mm height and 680 mm depth.
BIII-F, BIII-2 and BIII-2E: the factory table↑ TOP
Transcribed in full in the OS3-298 manual, section 8.1, Tape Transport, and section 8.2, Electronics. The rows below are the ones that apply to the B-III.
| Parameter | OS3-298 |
|---|---|
| Tape width and tracks | ¼″ tape. BIII-F Full Track; BIII-2 2 Track NAB; BIII-2E 2 Track DIN |
| Heads | BIII-F: four — repro (2T), erase, record, repro (FT). BIII-2 and BIII-2E: three — erase, record, repro |
| 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 | BIII-2 and BIII-F: 185/250/320 nWb/m. BIII-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 | BIII-2 min. 55 dB; BIII-2E min. 48 dB |
| Depth of erasure | BIII-F and BIII-2 min. 75 dB; BIII-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 | 525 × 430 × 275 mm (H × W × D) |
| Weight | 28 kg |
The manual's signal-to-noise table, by track width — 2 mm and 2.75 mm, which the 1991 sheet assigns to the BIII-2 and BIII-2E — and the full-track BIII-F:
| Speed | EQ | BIII-2 (2 mm), unweighted / weighted | BIII-2E (2.75 mm), unweighted / weighted | BIII-F, unweighted / weighted |
|---|---|---|---|---|
| 15 ips | IEC | 70 / 73 dB | 71 / 74 dB | 74 / 77 dB |
| 15 ips | NAB | 69 / 72 dB | 70 / 73 dB | 73 / 76 dB |
| 7.5 ips | IEC | 67 / 70 dB | 68 / 71 dB | 71 / 74 dB |
| 7.5 ips | NAB | 71 / 73 dB | 72 / 74 dB | 75 / 75 dB |
| 3.75 ips | IEC | 64 / 67 dB | 65 / 68 dB | 68 / 71 dB |
| 3.75 ips | NAB | 64 / 67 dB | 65 / 68 dB | 68 / 71 dB |
The BIII-2 is set to the high speed pair at the factory and can be changed to the low pair with a switch; the manual gives the procedure in section 2.7. The 2008 sheet adds one model the manual does not: the BIII-P, listed as a "2-Trk version with 1/4" Trk Playback" — see Identify for what is and is not known about it.
BQIII↑ TOP
No factory manual for the BQIII is held on this site. OS3-298 covers the other three uprights but not this one. What follows is from the 1991 sheet alone — the same sheet that, where it can be checked, gets the uprights' dimensions and head count wrong.
| Parameter | BQIII (1991 sheet) |
|---|---|
| Tape width and tracks | ¼″, 4 tracks, 1 mm track width |
| Heads | Erase, record, reproduce |
| Equalization | NAB fixed, IEC version an option |
| Input and output reference level | +4 dBu/−16 dBu, switchable independently on each channel |
| Mic input | Unbalanced, 5 kΩ, min. level −70/−50 dBu switchable |
| Output | Load min. 600 Ω; max. +26 dBu into 600 Ω; max. 5 Ω with the optional transformer |
| 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 |
| 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 |
| Signal-to-noise, 15 ips IEC, unweighted / weighted | 66 / 69 dB |
| Distortion | Max. 0.5% |
| Crosstalk | Min. 55 dB |
| Depth of erasure | Min. 72 dB |
| Test oscillator | 100/1 kHz/10 kHz |
| Bias and erase frequency | 192 kHz |
| Power | 100 VA |
| Weight | 27 kg |
In several rows the BQIII's column follows the MARK IV-4 and IV-8 desk-tops rather than the other uprights: fixed rather than selectable equalization, switchable reference levels, 600 Ω load, frequency response, 0.5% distortion, three-tone oscillator and 192 kHz bias. The sheet's standard features confirm the grouping: automatic monitor switching, gapless punch-in and punch-out, per-channel reference levels and the optional 7.5/3.75 ips pair are all given to the BQ-III and the MARK IV-4 and 8 together. Its options list the RK-2B rack mount kit and the PB-7WXA and PB-7OQA extension PCBs for it. It is not a desk-top in every row, though: it keeps the uprights' head cell and start and stop times, and its 72 dB erasure and 27 kg match none of the other seven machines.
The 2008 BIII sheet does not keep to the 1991 grouping: its highlights give the BIII two-track a rehearse function and automatic monitor switching, which the 1991 sheet reserves for the BQ-III and the MARK IV-4 and 8.
Sources↑ TOP
- MX-5050 Series data sheet OA-321C — ©1991. The configurations and specifications grid, the only figures held here for the BQIII, and the features, options and dimension drawings.
- MX-5050 MKIV-2, BIII-2 operation and maintenance manual, OS3-298 — section 8, the factory specification for the BIII-F, BIII-2 and BIII-2E; section 3 for the three SEARCH memory keys.
- MX-5050 BIII product sheet — ©1999, 2008. PDF p.2, its specification table, dimension drawing and options, including the BIII-P.