Cossor CR-1607

Additional Info

The Tape Recorder, August 1965 – A. Tutching
Readers of my recent reviews will have noticed that most all-in-one stereo recording and reproducing systems have been very heavy and barely transportable. Here we have one weighing a mere 20lb. This has been made possible by completely transistorising the electronics and by using a lightweight cabinet and speakers and a single motor drive two-speed deck.
For some reason, the designers have chosen to place one loudspeaker on the side of the cabinet and the other at the front. The result of this is that the stereo effect on the internal speakers is reduced almost to vanishing point unless one rests one’s chin on the front corner of the cabinet. I would have preferred a speaker on each side for the widest possible spacing, but perhaps they are being realistic in presuming that, after a few stereo experiments, the machine will be used mainly for mono and that a front facing speaker is an advantage for this application. If an external speaker is to be used for better stereo spacing, it should be plugged into the LH speaker socket, and placed to the left of the recorder. This then leaves the front speaker in the recorder as the RH stereo source.
A single switch, on the right, controls all tape movement. It is pressed down to start the tape, down again to stop it, turned to the left for rewind and turned to the right for forward wind. The matching knob to the left gives two mono positions: upper and lower track, a central stereo position, where each track plays through its own amplifier and speaker, and a PA position where the recorder is converted to a mono or stereo amplifier for playing records or for public address via the microphone.
For recording, a red button must be depressed when the tape is started, but it is automatically released, to revert to playback, when the tape is stopped. The adjacent white button is for ‘Multiplay’ or track to track transfer with extra recording, and these facilities are fully explained in the comprehensive instruction book.
The tape speeds were about 0.5 %. fast at both 1 ips and 3¾ ips. Wow and flutter were very low at 0.07-0.08% RMS at 3¾ ips and 0.08 – 0.1% RMS at 1ips. Pen recordings of the short term speed fluctuations are shown in fig. 1. A very slight trace of capstan wow at 3 Hz is visible on the 1traces.
A year or so ago such figures would have been considered excellent for tape speeds of 15 ips and 7½ ips. Nowadays they are commonplace on good quality Continental machines and, what is more important, they are maintained consistently from machine to machine, and over the lifetime of any given recorder.
Test-tapes with 140µS and 280 µS recording characteristics were played at 3¾ ips and 1ips to give the responses of fig. 2. It will be seen that the bottom head – or amplifier – equalisation is very slightly better, but that both tracks are very close to the desired playback characteristic.
System noise, with no tape running, was 40dB below test-tape level at both speeds.
Overload tests were first carried out at a test frequency of 500 Hz, and the magic-eye beams just closed at a level 11dB above test-tape level. Waveform distortion of the recorded signal was just evident at this point.
Next, test tones were recorded at test-tape level to give the record-play responses of fig. 3. The test signals were fed to the diode input, and measured on playback at the diode output socket.
Peak-recording level signal was erased and the ratio found to be 50dB. Once again, the effortless ease with which this recorder achieves test figures at the lower limit of probability must be. remarked upon!
Bands of filtered white noise were recorded at 3¾ ips on both tracks and the sound output of each speaker measured separately to give the responses shown in fig. 4. Responses are smooth from 500 Hz upwards, but the front facing speaker shows a slight cabinet resonance at 300 Hz. Sound output falls sharply below 250 Hz on both channels.
The stereo microphone supplied with this recorder consists of two dynamic cardioid microphones in a single case with facilities for setting the forward axis of the two microphones at various angles ranging from approximately 75° to 180°; red dots on the supporting ring allow the angle to be set at 90° for normal use.

The frequency response and front/back ratio of one microphone was measured in a white noise sound field and these responses are shown in fig. 5. It will be seen that the front-to-back ratio is better than 10dB over the range 500Hz to 5kHz, but that the units are nearly non-directional above and below these frequencies.

COMMENT
This recorder is as near perfect as is commercially possible at this time and at this kind of price. As a stereo recording and reproducing system, I am less optimistic. It will let the recording enthusiast experiment to a limited extent with stereo techniques, particularly if external speakers are used. but stereo sources other than the microphone will have to be used if the full recording potentialities of the machine are to be realised. Like so many other stereo recorders, it is a little before its time; we need stereo broadcasting before we can build up a library of decent stereo recordings. Otherwise. unless we have musician friends, we are reduced to copying gramophone records or marching up and down in front of the microphone to demonstrate that the voice comes first from one loudspeaker and then the other!
It is also a pity that a 7½ ips speed was not provided (even as an alternative to 1ips) as most good quality commercial stereo tape recordings are only available at this speed.
I think the real possibilities of this recorder are in the simultaneous recording of two quite different tracks, or the transfer of information from track to track with added material from microphone or disc; the excellent response. low wow and flutter and good signal noise ratio would all be exploited to the full using these ‘Multiplay’ facilities.