Cassette Tape Recorder A721

Studer A721 is a Professional Studio Cassette Recorder/Player

Type: 3-heads, single compact cassette deck
Heads: 3- Erase, Record, Play (record/playback in a hybrid head)
Track System: 4-tracks, 2-channel stereo
Tape: 1/8” wide in a Philips Compact Cassette
Tape speed: 4.76 cm/s (0.3% tolerance)
Tape counter: digital (LCD)
Motors: 4- 2 for the Dual Capstan (dual capstan with servo control); 1 for Forward;1 for Rewind
Bias: 105 kHz, adjustable level
Equalization: Adjustable for tapes type I, type II and type IV.
Wow and Flutter: < 0.1% (weighted rms)

Signal Processing:
Noise Reduction: Dolby B and C
Balanced inputs and outputs
Calibrated (studio level) and uncalibrated modes
Tape type section: Memory for 6 configurations
Frequency response after automatic calibration (+2dB, -3 dB):
20 Hz – 18 kHz for tape type I; 20 Hz- 20 kHz for tape type II,
20 Hz to 20 kHz) for metal tape (type IV)
Erasure efficiency: 68 dB
S/N ratio: >72 dB (tape type IV + Dolby C); 55 dB (type I without Dolby)
Distortion: < 1% (type I tape) and  <1.5% (metal tape)

Input signal:
Balanced and floating line (XLR connectors)  with impedance >10 kohms
Input sensitivity (calibration: 0 dBu level = 775 mV - 225 nWb/m)
Calibrated : + 4 dBu , adjustable from -5 dBu to +15 dBu)
Uncalibrated . sensitivity can be increased by 10 dBu; Maximum input level 24 dBu

Output signal:
Balanced and floating line with transformer (XLR connectors) and impedance < 50 ohms
Input sensitivity (calibration: 0 dBu level = 775 mV - 225 nWb/m)
Calibrated: + 4 dBu, adjustable from -5 dBu to +15 dBu
Uncalibrated sensitivity can be increased by 10 dBu; Maximum output level 24 dBu

Headphone output:
Unbalanced, impedance 200 ohms; Level adjustable in 8 steps to +12 dBu.
VU meter: LCD Peak programme meter

Power Consumption: < 50 W
Remote control through a 25 pin SUB-D connector

Here you find 71 models, 66 with images and 36 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Studer-Revox; Schweiz