International photographer (Jan-Dec 1937)

PHOTOGRAPHER NOVEMBER, 1937—19 RIGHT. The Canady recorder, working parts exposed. CENTER. Dual film phonographs with provisions for keeping films in step and making lab measurements. LEFT. Details of film phonograph, reel housing for film loop at top, adjusting and measuring apparatus in middle and bottom sound head exposed showing photo-eell housing. ST<W Aiding Research Modern Canady sound equipment used in phonetic lab of Oberlin College Department of Psychology. Sound recording and reproducing equipment is finding an important place in modern education, not only in the commonly known "visual education," but also in the higher branches of science and learning. An excellent example is the installation of equipment at Oberlin College by the Canady Sound Appliance Company of Cleveland. The Ohio institution, far-famed for its high standards and many honored graduates, uses Canady sound devices in the Phonetic Laboratory of its Department of Psychology for many detailed investigations in that field. The recording and playing back of speech and oscillatory sounds required Hi-Fidelity and stable apparatus. Sound recording motion picture film is now used for this work. Other forms of record, such as acetate discs, were found to have an objectionable needle scratch and to wear out when subjected to repeated reproduction. In this film apparatus the essential parts furnished by the Canady organization consist of a recorder using the Canady recording lamp, and of two film-phonographs. The duplicate film-phonographs are driven by the same motor for the sake of synchrony. The 1 6 H.P. synchronous motor is equipped with a large flv-wheel to smooth the more or less 2.5 per cent voltage and the more or less .05 cycle fluctuations in the 110 volt. 60 cycle power line. Also, each filmphonograph has a friction flv-wheel. The film-phonographs are equipped to maintain a given relative position within 1 32 inch I about 2 milliseconds I . Idlers for continuous film loops are provided, and the phonographs may be threaded without cutting the endless loops. Standard 1000 foot reels are interchangeable with the idler system. Between the reel housing and the sound head there is placed an additional housing to accommodate short lengths of film. This housing contains two flashlight bulb set-ups to serve for reference and for measuring. The sound head consists of an exciter lamp, a Canady optical system, and a right-angle prism, and a passagewav through the door for the lightbeam. The R.C.A. number 919 photocell and another R.C.A. number 917 are mounted outside the sound-head in the short-length of 3-inch pipe as shown in the accompanying photographs. These constitute the major part of a pre-amplifier that is also mounted in the swinging 3-inch concentric line system to the right and above the apparatus. The concentric line then leads to the speech amplifiers. The Canady Recorder contains, in addition to the three fly-wheels, synchronous motor, etc., a special feature in the Canady recording lamp. Once the slit is adjusted in the lamp's sleeve, no other adjustments need be made. The lamp then may be taken out of the machine at will, and another substituted for it without additional adjustment. The lamp is quite stable from dav to day and has a high impedance, which simplifies its coupling to power amplifiers. Frequencies up to 10.000 cycles have been recorded and satisfactorily reproduced. T and H Pads Series of practical sound tables siarts with figures on design of symmetrical pads. In following the lead of Fred Westerberg's Cinematographers Book of Tables the most obvious need in the sound field is for a pocket sized compilation of tables relating to sound recording.