International projectionist (Jan 1959-Dec 1960)

mechanical vibration of the moving parts of the turntable transformed into sound by the pickup itself and heard through the loudspeaker. An important difference between good and poor turntables is the amount of rumble. With steieo, both lateral (conventional) motion of the stylus and vertical motion will produce output, hence if there is vibration in both directions in a turntable it will be more noticeable with a stereo pickup than with most LP pickups. Manufacturers of cheap stereo pickups which have no separation between channels at low frequencies sometimes claim this is an advantage with regard to rumble. Statements that a certain pickup "has no rumble" are something like claiming a horse to be better than an automobile since a horse uses no gasoline. Of course the pickup "has no rumble." The turntable has. But if the cartridge is capable of picking up a signal it will also pick up the turntable vibration. Here, as always, you get what you pay for. A cheap table will have more rumble than a good table; a cheap pickup will likewise produce more distortion and poorer separation of channels than a good one. How many wires are needed? There are four wires from a stereo pickup cartridge, but in some cartridges the four are reduced to three, since two of the wires are ground leads. This means two, not four, conventional cables from the pickup arm instead of one, since each phonograph lead contains two conductors — the signal wire and a braided shield around it. Two plugs are needed, one for each preamplifier input. Balancing levels between channels. This must be done by ear to obtain the best effect. It is useless to try to set level by use of separate meters or other indicators for each channel, for the obvious reason that the channels will mostly have different levels on them, and also the speaker and amplifier may be different. The best way to set level is to play a lateral recording with the stereo pickup and to adjust for equal volume from each loudspeaker. After that, every thing played back would have approximately the same balance as originally recorded. Personal preference may dictate slight changes in balance, just as is now done with adjustment of tone controls, but the starting point should be equal speaker output for equal recorded signal. In practice this is not very hard to achieve by ear, but it is a great advantage to have the two channels fitted GET IRE FOR YOUR LLAR VICTOR 1600 ARC If the high cost of 16mm arc projectors is forcing you to "make do" with an auditorium-type incandescent — you owe it to yourself to consider the Victor 1600 Arc. It delivers a full 1600 lumens of light on the screen at 30 amps with Mark II Shutter— more than three times that of any incandescent — yet it's still easier on your budget than other 16mm arcs. It incorporates aU advanced Victor projector features and a powerful 25watt amplifier. The 1600 Arc runs for a full hour on one set of carbons, does not require a special projection booth, and is the only arc projector made with 3-case portability. VICTOR MODELS FOR SMALLER AUDIENCES OFFER QUALITY FEATURES FOUND ON THE 1600 ARC SEND FOR FREE LITERATURE ON VICTOR 1600 ARC AND OTHER VICTOR A-V PRODUCTS vicTor?---- RPORATION . EST. 1910 1 A DIVISION OF KALART Producers of precision photographic and A-V equipment PLAINVILLE, CONNECTICUT Name. State. Oept. IP-3 1A INTERNATIONAL PROJECTIONIST • MARCH 1959 19