MX-5050 B-II: specifications
Specifications for the B-II — the BII-2, BII-4, BII-F and BII-2E — with sources noted; this page prefers gaps over guesses. Not sure which machine you have? Start with Identify.
Three documents are held, and they come in two kinds. The OS3-038 instruction manual has Otari's full factory table for all four models. The 1983 brochure and the 1984 data sheet (BP6847K) are sales paper, and both print one specification: the two-channel machine's. They print the same one, figure for figure — the only change in the specification is that the 1983 brochure calls the ZA-52L a "roll-around pedestal" and the 1984 sheet a "roll-around stand". So on this page they count as one source.
The factory table↑ TOP
From the OS3-038 instruction manual, Table 1-3 — which the manual itself titles "Specifications of the MX-5050B Series":
| Parameter | OS3-038 |
|---|---|
| Tape width and tracks | ¼″ (6.3 mm) tape: 2 tracks (0.079″, 2.0 mm), 4 tracks (0.040″, 1.0 mm) or full track (0.24″, 6.1 mm) |
| Tape speeds | 7½ and 15 ips, or 3¾ and 7½ ips; maximum deviation ±0.2% with 1.5 mil tape |
| Reel sizes | 7″ or 10½″ plastic or metal, EIA or NAB |
| Heads, BII-2 | Four stacks: 2T erase, 4T reproduce, 2T record, 2T reproduce |
| Heads, BII-4 | 4T erase, 2T reproduce, 4T record, 4T reproduce |
| Heads, BII-F | FT erase, 2T reproduce, FT record, FT reproduce |
| Heads, BII-2E | 2T DIN erase, 4T reproduce, 2T DIN record, 2T DIN reproduce |
| Motors | Capstan: DC servo, pitch control ±7%. Reels: two induction torque motors |
| Operating position | Vertical or horizontal |
| Line input | Minimum −15 dBm, active balanced 10 kΩ (floating); balanced 10 kΩ with optional transformer |
| Mic input | Minimum −70 dBm, active balanced, for 150 Ω to 10 kΩ mics; attenuator 0 dB, −20 dB or off |
| Line output | +4 dBm or −10 dBm, rear panel switch selectable; active balanced, 5 Ω source; load more than 600 Ω; maximum +27 into 600 Ω |
| Headphone | −24 dBm into 8 Ω; 8 Ω or greater |
| Equalization | NAB or IEC at all three speeds, switchable on the rear panel (calibration necessary) |
| Frequency response | 15 ips 30 Hz to 20 kHz; 7½ ips 20 Hz to 18 kHz; 3¾ ips 20 Hz to 10 kHz; all ±2 dB, on 3M 226 |
| Crosstalk | Greater than 55 dB at 1 kHz on adjacent tracks, 2-track and 4-track |
| Wow and flutter, NAB weighted | 15 ips less than 0.06%; 7½ ips less than 0.08%; 3¾ ips less than 0.12% |
| Distortion | Less than 0.5% at 1 kHz at 250 nWb/m |
| Erase efficiency | Greater than 75 dB |
| Test oscillator | Nominal 1 kHz and 10 kHz |
| Bias and erase frequency | 133 kHz |
| Power | 100/117/220/240 V ±10%, 50/60 Hz, single phase, 100 W |
| Operating environment | 40° to 104°F (5° to 40°C), 20 to 80% RH |
| Dimensions and weight | 527 mm (20.7″) high, 430 mm (16.9″) wide, 225 mm (8.8″) deep; 24 kg (53 lbs) |
| Mounting | Dark grey leather-finished cabinet |
Signal-to-noise, measured overall at 520 nWb/m; unweighted through a 30 Hz to 18 kHz filter, weighted through an NAB or ASA "A" filter with a 1 kHz reference:
| Tape speed | EQ | 2 track, weighted / unweighted | 4 track, weighted / unweighted | Full track, weighted / unweighted |
|---|---|---|---|---|
| 15 ips | NAB | 66 / 64 dB | 62 / 60 dB | 68 / 66 dB |
| 7½ ips | NAB | 68 / 66 dB | 63 / 61 dB | 68 / 66 dB |
| 3¾ ips | NAB | 66 / 64 dB | 62 / 60 dB | 66 / 64 dB |
| 15 ips | IEC | 66 / 62 dB | 62 / 58 dB | 62 / 60 dB |
| 7½ ips | IEC | 64 / 62 dB | 62 / 58 dB | 62 / 60 dB |
| 3¾ ips | IEC | 64 / 62 dB | 62 / 58 dB | 62 / 60 dB |
The BII-2E, the DIN version, sets its three record-level positions to 250, 320 and 520 nWb/m, where the sales sheets give the two-channel machine 185, 250 and 320.
Where the sales sheets and the manual disagree↑ TOP
The 1983 brochure and 1984 data sheet describe the two-channel machine, so the comparison is with the manual's 2-track column. Most rows agree: tape width, speeds and the ±0.2% deviation, the four-head layout, the ±7% pitch control, the input impedances, the 5 Ω output and its +27 maximum into 600 Ω, the 0.5% distortion limit at 1 kHz and 250 nWb/m (which the sheets call third harmonic, at 15 ips), and the 1 and 10 kHz test oscillator. The sheets add a 5″ reel size and a rewind time the manual does not give, and omit the manual's −15 dBm and −70 dBm input minimums. These rows do not agree:
| 1983 brochure and 1984 data sheet | OS3-038 | |
|---|---|---|
| Signal-to-noise, unweighted, NAB | 72 / 72 / 70 dB, "3% Third Harmonic to noise floor" | 64 / 66 / 64 dB, at 520 nWb/m |
| Frequency response, 15 ips | 25 Hz to 22 kHz ±2.0 dB, at 0 VU | 30 Hz to 20 kHz ±2 dB |
| Frequency response, 7½ ips | 20 Hz to 20 kHz ±2.0 dB, at −10 VU | 20 Hz to 18 kHz ±2 dB |
| Frequency response, 3¾ ips | 20 Hz to 12 kHz ±2.0 dB, at −20 VU | 20 Hz to 10 kHz ±2 dB |
| Wow and flutter | Less than 0.04 / 0.07 / 0.08% | Less than 0.06 / 0.08 / 0.12%, NAB weighted |
| Crosstalk | "Less than 55 dB" at 1 kHz | Greater than 55 dB at 1 kHz |
| Power | 140 W | 100 W |
| Weight | 60 lbs (27 kg) | 24 kg (53 lbs) |
| Mounting | Vinyl covered wood case | Dark grey leather-finished cabinet |
Speeds are given as 15 / 7½ / 3¾ ips throughout.
Frequency response is measured on the same tape — both documents name 3M 226 — and the sales sheets claim more at every speed, at the top of the band most of all. Signal-to-noise is not measured to the same reference: the manual refers its figures to a 520 nWb/m recording, the sales sheets to the level that gives 3% third harmonic distortion. The sheets do not say what flux that is, so the two cannot be put on one scale; the sheets' figures are 6 to 8 dB higher. The crosstalk row in the sales sheets reads "less than" where the manual reads "greater than" — for crosstalk only the manual's direction makes sense.
The sales sheets give the manual's maximum output as "+27 dB (ref. 0.775 V) into 600 Ohms or more". The manual prints the same figure as "+27 dBs", a unit that does not exist; the sheets' reference, 0.775 V into 600 Ω, is what makes it dBm. The 1984 sheet's feature list gives the output switch as +4 dBm or −10 dBV, where the manual says +4 dBm or −10 dBm.
Four-track, full-track and DIN machines↑ TOP
The sales sheets cover only the two-channel B-II, so for the BII-4, BII-F and BII-2E the manual's table is all there is: their head stacks, the 4-track and full-track signal-to-noise columns, the 55 dB crosstalk figure for 4-track, and the BII-2E's own record levels. The manual gives no separate power, weight or dimension figures for any of them.
For the tolerances a technician holds the B-II to, rather than the ones Otari advertised, see the 1988 alignment procedures — written for the B-II and the MKIII-2 together, and transcribed here in full.
Sources↑ TOP
- Instruction manual, OS3-038 — Edition 6, September 1984. Table 1-3, the factory specification for all four models.
- 5050B-II brochure, "Technology You Can Trust" — 1983. PDF p.8, the two-channel specification, options and dimension drawings.
- 5050 B-II data sheet — BP6847K, 1984. PDF p.2, the same specification reprinted.
- Alignment procedures, BII and MKIII-2 — Edition 2, January 1988; service tolerances.