Country of Manufacture:Norway
Speeds: 3 3/4, 7 1/2, 15
Max Reel Size("): 10.5"
Number of heads: 4
Head Composition: Permalloy
Head Configuration: Stereo
# Motors: 3
Frequency Response:15 ips: 40 - 18kHz 7½ ips: 40 - 15kHz 3¾ ips: 40 - 12kHz (±1dB)
Wow and Flutter:15 ips: <0.04% 7½ ips: 0.05% 3¾ ips: 0.1%
Sound quality rating:1 / 10
Long-term reliability rating: 1 / 10
The TD 50 is a real mystery – the dark horse at the end of the road for Tandberg. It must have been a prototype in development around the time the company finally collapsed as an audio equipment manufacturer before eventually being re-born as a manufacturer of video conferencing equipment.
I can find no information whatsoever relating to this model except for a single brochure found by chance on the internet some time ago. This was ominously entitled ‘td_50_never_released.pdf, and so I have put together the following hypothethis based on the file name of the brochure and its contents.
The TD 50 was aimed at the professional end of the market and only ever got to the prototype stage. Three models were planned. These were:
TD50 E (for editing) with full playback facility but no record circuits
TD 50 B (for broadcasting) with record/reproduce electronics
TD 50 S (for studio) – the same as the broadcast model (TD 50 B) but with the VU control console mounted separately above the transport (pictured at right).
The audio circuits were engineered in a similar style to Tandberg’s (then) current 3000A series of state-of-the-art Hi-Fi components. No integrated circuits were used, rather, all circuits employed discrete components which were located on readily-accessible modular plug-in boards.
Bias, level, EQ and mono/stereo switching were controlled by a microprocessor via a serial data buss. Editing was controlled by an 8-bit microprocessor and 64Kb of EPROM (small by today’s standards but state-of-the-art in 1984).
Track configuration: interchangeable head blocks for quarter-track or half-track stereo or mono, full-track mono
Signal to noise ratio (figures are for weighted / unweighted): 15 ips 56dB 57dB 7½ ips 53dB 57dB 3¾ ips 50dB 55dB / 15 ips: 56dB / 7½ ips: 53dB / 3¾ ips: 50dB /
Start time: less than 0.5s for wow & flutter within double specified value
Wind / rewind time: less than 120 seconds for 750m tape (10½” reel)
Stop time: less than 5 seconds from wind / rewind
Equalisation: IEC / CCIR & NAB
Erasure: less than 80dB at 1 kHz / Inputs: 0, +6 or +12 dBu level, adjustable ± 6dB maximum input level equal to or greater than 22 dBu input impedance equal to or greater than 10 Kohms
Outputs: 0, +6 or +12 dBu level, adjustable ± 6dB maximum input level equal to or greater than 22 dBu at 200 ohms /
Crosstalk: less than 40dB (60 – 12,000Hz) / Bias frequency: 200 KHz (crystal controlled) / Erase frequency: 66.6 KHz (crystal controlled)
Distortion: 185 nWb / m 320 nWb / m 510 nWb / m 15 ips 1% 1% 2% 7½ ips 1% 1% 2% 3¾ ips 1.5% 2% 3% / : 185 nWb / m / 15 ips: 1% / 7½ ips: 1% / 3¾ ips: 1.5%