Phonograph Monthly Review, Vol. 4, No. 12 (1930-09)

404 The Phonograph Monthly Review * The 1930-1931 Phono-Radio Models T HE new lines of radios and phonograph-radio combina- tions announced by the leading manufacturers for 1930- 1931 show an increasing interest in the attainment of pure and pleasing tone. A device for tonal color control is a feature of a number of the new models. Even more sig- nificant is that growing emphasis on the combination instru- ment. Not only the phonograph companies but practically all of the leading radio companies now issue the duplex in- struments—some with automatic record changing devices. Radio men have come to realize essential kinship of their instruments with the phonograph. The dealer finds it a pro- fitable source of income to augment his instrument sale by a constant sale of discs to the owners of combinations. In larger cities the demonstration of radios is handicapped by the excessively difficult receiving conditions and it is seldom that the tonal qualities of the instrument can be accurately appraised in a dealer’s showrooms. Demonstration of the phonograph portion, however, exhibits the true tone in un- distorted beauty. Descriptive material on some of the new models, beginning with those issued by the leading phonograph companies, is given below. In some cases full information is not yet avail- able or has not yet been released for publication. Where pos- sible, list prices are given, but as these are subject to change, they cannot be guaranteed as accurate. In every case the price given does not include tubes. Prices are usually higher west of the Rockies. Readers who are interested in any of the various models can obtain further information and hear a demonstration of the instrument itself at the maker’s local dealer. It is usually possible for responsible persons to have one installed for trial in the home so that it may be judged under the conditions under which it will be played. Brunswick A special feature of the new Brunswick instruments is the “Uni-Selector” Dial. All operating controls are located in the center of the control panel and consist of a switch and volume control knob mounted concentrically inside of a larger tuning knob. This one knob switches the set on and off, adjusts the volume, tunes in stations, adjusts antenna for local or distant reception, and—in the combination instru- men t—changes the circuit from radio to record reproduction. This single-hand control eliminates the necessity of em- ploying two hands, eliminates sliding and noisy contacts and resistance wires, and keeps the tubes operating always at maximum efficiency for the best sensitivity and tone quality. Control is effected by varying the first coupling condenser, thus regulating the amount of energy transferred from the first to the succeeding radio frequency amplifying tubes. The total distance switch has a smooth positive action and does not detune the antenna stage, thereby assuring maximum selectivity and tone quality on either local or distant recep- tion. A new illuminated horizontal tuning scale, calibrated in kilocycles with a larger range of vision and with provision for logging stations directly on the calibrated scale, makes tuning effortless and accurate. The wood of the cabinets is matched American walnut ven- eer with two tone finish and artistic carvings on the front pan- el. Fluted corner panels add to its general beauty. There are two sizes of cabinets, a Low-boy (Model 15) somewhat similar to the older Model S-14, but with sloping front-corner pan- els and slightly greater depth; and a High-bov (Model 22), somewhat similar to tb^ older Model S-21, but with French doors and a new design of fluted corner panels. The chassis base (Style “B”) is of unique design, a deep- drawn steel shell, 4 and 5/8 inches in depth, rectangular in form and measuring 11 by 15 inches. The power-transformer cover and screen-grid tube cover are also drawn shells, which greatly enhance the appearance and staunchness of the com- Brunswick Model 15 plete receiver. So successfully has the shielding been com- bined with the chassis construction that it is impossible to impair the operation of the receiver without maliciously in- tending to do so, and then only by resorting to drastic meas- ure. All critical parts of the chassis are shielded and cannot be tampered with by the uninitiated, yet the service man has only to remove two bolts to have ready and complete access to all parts of the chassis. The circuit consists of three-tuned screen-grid stages of radio frequency amplification and a linear power detector, using the screen-grid tube, resistance coupled to two ’45 power tubes operated in parallel—a total of seven tubes, in- cluding the rectifier tube. The circuit makes a very efficient and economical receiver that consumes only 85 watts of energy from the house lighting circuit, or a cost of less than the operation of one and one-half 60-watt lights. Power unit and tuning unit are housed in a single artistically formed chassis, which permits a simpler and more direct wiring ar- rangement. Only two iron core transformers are used—the power transformer and the output transformer mounted on the speaker—and these are made extra heavy with a big safety factor to prevent any possibility of transformer trouble. The fixed condensers are made in Brunswick’s own condenser plant and are said to be fully 25% stronger than the average. The voltage dividor resistors are of the car- bon rod and wire-bound type, and will stand large overloads without changing their resistance value. ‘A Brunswick-made speaker with 1 3/4 inch non-warping voice coil and ten-inch rattleproof cone reproduces the mu- sic with a brilliance and timbre so realistic and effortless that the volume seems much less than it actually is. There is a special tone control adjustment which is stan- dard equipment on all of the new models. Through this ad- justment, which is placed on the front panel directly below the operating control knob, the tone can be regulated to suit the fancy of the listener. The bass, the string section, or any part of the ensemble can be accentuated at will through a simple manipulation of this adjustment. Model 42 combines an automatic Panatrope with the radio receiver, and is the result of three years’ effort on the part of Brunswick engineering staff to perfect a fool-proof auto- matic device. It is capable of playing twenty standard-size records without attention. Further details will be available later.