The Colossus of Radio
Apr 1, 2007 12:00 PM, by Michael A. Banks
In 1935, Zenith Radio produced a radio receiver called the Stratosphere model 1000Z. The set used 25 tubes and three loudspeakers, more than any other radio to date. A then-amazing 50W drove its three speakers � one 6" dynamic high-frequency and two 12" dynamic low-frequency speakers.
The WLW model included a crystal mic so that the receiver could be used as a public address system.
Standing 50�" tall, the Stratosphere sold for $750 � more than many automobiles. (In comparison, a new Ford cost $652.) At that price it's no wonder that only about 350 sets were produced during the four years the Stratosphere was offered.
This achievement impressed Powel Crosley Jr., the president of the Crosley Radio, who praised it as a fine example of quality in radio construction. But, it used only 25 tubes and three speakers. Crosley, who also owned the 500kW powerhouse WLW, was inspired to surpass Zenith by bringing the world the largest and most powerful radio receiver yet known.
A close friend of Commander Eugene MacDonald, president of Zenith, Crosley may have taken the Stratosphere as a light-hearted challenge. That aside, as Crosley said later, �It is fitting that the owner of the world's most powerful radio station make the world's greatest radio receiver.�
Crosley's engineering and marketing staffs urged him to forget the idea. They felt it was an impractical exercise from an engineering standpoint, and that the market for such a radio � if one existed � would be miniscule. But Crosley was not easily discouraged, and, as one employee put it at the time, �It is characteristic of Mr. Crosley that he is a good salesman, enough so to win his point in an amiable manner.� Of course, the fact that Crosley owned the company had some bearing on the matter.
A major undertaking
Surpassing the Zenith Stratosphere turned into a bigger project than anyone had expected. Many engineering conferences were held throughout the winter months, some of which included the Crosley advertising, sales, cost and purchasing departments. To aid with speaker selection and the acoustics involved in cabinet design, the chief engineer of the Jensen Radio Manufacturing Company (the same company that today manufactures speakers) was retained as a consultant.
Out of the numerous meetings and Crosley's imagination came the basic specifications: the radio would be a superhetrodyne receiver with no fewer than 30 tubes, six loudspeakers, four chassis and be housed in a suitable cabinet. More intricate than any set ever built, it would naturally have the highest possible quality and richness of tone.
Detail of the tuning dial with its various unique displays.
The set would be called the WLW Model Super-Power Radio Receiver. This name was chosen by Powel Crosley Jr., a spokesman said, as �symbolical of the great 500,000W broadcasting station, the most powerful in the world.� (Crosley never missed an opportunity to use one product to promote another.)
Early in the spring of 1936 Crosley assigned one of his engineers, Amyle P. Richards, the task of designing the radio. The 31-year-old Richards had his doubts about the project at first. �The logic of the situation was not at once apparent when Mr. Crosley gave the orders for construction,� he was quoted as saying. �From the cost angle � engineers cannot ignore costs � it was perhaps the best plan, but from the angle of sheer engineering skill, it was not a desirable plan. But it also must be understood that the plan here adopted was necessarily in accordance with the wishes of Mr. Crosley.�
Although his engineer's mind questioned the project, Richards enjoyed the challenges the project presented. In fact, he later wrote that he �enjoyed every minute spent on the creation of this receiver and welcomed the responsibility of making it a commercial possibility.�
The project involved four basic segments: a variable radio frequency or pre-selecting amplifier, an intermediate frequency amplifier, a pre-audio amplifier and the power supply. Richards designed a separate chassis for each segment. Three audio channels handled low, medium and high frequency ranges, and a triple-tuned transformer.
Every feature that could be built into a radio was included. Automatic volume control (actually gain control, then a relatively new idea) minimized undesired volume increases when a station's signal power suddenly increased, or a listener tuned from a distant station to a more powerful local station. Automatic frequency control prevented drifts from the tuned frequency. By increasing or decreasing volume to match variations in signal modulation strength, an automatic volume expansion feature compensated for the natural or intentional variations in the volume of the music or other program being broadcast.
In its completed form, the WLW Model Super-Power Radio Receiver indeed surpassed the Zenith Stratosphere model. It had 37 tubes, six speakers and 75W of power. The cabinet stood 58" tall, 42" wide and 22" deep. Everything inside the cabinet that could be was chromium-plated. The transformer coils, tubes and speaker frames were finished in black, and each chassis had its own serial-number plate.
The inner workings
The speaker bank consisted of three high-range tweeters and two 12" mezzo or mid-range speakers, plus an 18" auditorium speaker for the low range, with the voice coil circuits phased for maximum quality sound reproduction. The speakers were focused in three directions, and the low-range speaker sat in a special cushioned mounting to prevent cabinet resonance. Because of weight considerations, the WLW model was shipped with the speakers uninstalled. (The 18" speaker alone weighed 85 pounds.) With the speakers installed, the WLW Model Super-Power Receiver tipped the scales at 475 pounds.
In keeping with the Crosley tradition of adding something extra to everything the company built, the radio receiver featured a public address system and microphone. The microphone was a 4" crystal type, attached to the set by a 25' cord. The microphone's input could be switched to any or all of the set's three audio channels. A two-way switch cut out the radio entirely, or allowed the microphone's input to be blended with a radio program. This was probably the first instance of a radio equipped with a PA system. The designer rated it as having enough volume to address a crowd of 10,000.
The receiver could reproduce the entire range of audible sound, from 20 to 20,000 cycles per second. Its tuner brought in every frequency from 540 to 18,300 kilocycles, which at the time encompassed the commercial broadcast, police, amateur, and ship bands as well as foreign stations.
A look inside the rear cabinet of the WLW model showing the multiple assemblies
Such an impressive radio demanded a impressive cabinet. A modernistic style was chosen, and seven types of wood went into the cabinet's construction. A grille cloth designed especially for the Crosley WLW model completed the exterior. The fabric's design was a classic flame motif, popular in tapestry and furniture upholstery, as well.
Every imaginable user control was included. An eye-catching 12" airplane-style tuning dial was mounted at chest-level, and beneath it were two volume controls (one for low and middle frequencies and the other for high frequencies), two tuning knobs, and a special fidelity control that incorporated the on/off switch.
The fidelity control allowed the user to select from five preset frequency ranges. The normal selection passed only the middle range of audio frequencies. A high fidelity selection, intended for listening to music, increased the response for 40- and 4,000-cycle frequencies by several decibels. A mellow tone setting made whatever radio program was on sound as though it were issuing from the inside of a large barrel. This was accomplished by suppressing high-frequency response. A bass selection accentuated bass response and cut off high frequencies. The final setting offered by the fidelity control, noise reducing, emphasized the high- and low-frequency response. A mechanical display to the right of the tuning dial's center indicated which fidelity setting was in use (including off).
The fidelity control feature was apparently popular for only a few years in the mid-1930s. It probably added too much to a radio receiver's cost to appear on any but the high-end models. Also, many radio owners may have found it too complicated to use.
Tuning was accomplished with two knobs, one for fine and one for broad adjustments. The knobs turned two clock-like sweep hands (one short, one long) on the dial's face. Appropriately, the outer rim of the dial was marked with the numbers one through 12, just like a clock face. The clock numbers and sweep hands composed a mnemonic device for remembering station settings. A station tuned in with the short hand pointing at 10 and the long hand pointing at three on the dial might thus be remembered as 10:15. The feature was called Timelog Tuning.
A mechanical display to the left of the dial's center displayed the name of the band tuned in.
Three tone controls were set in their own panel on the left side of the cabinet � one for bass, mezzo and treble control. On the right side of the cabinet were the microphone input and controls. Hinged, curving wood panels covered both sets of controls.
An external feature of special interest was a visual tuning indicator, which was Crosley's answer to RCA's Magic Eye indicator. This was incorporated into the Crosley trademark at the top of the tuning dial.
The trademark consisted of the name Crosley with a bolt of lightning passing through it. The lightning part of the logo was cut out and a neon tube was installed behind it. The intensity of this tube's glow increased or decreased as the voltage in a dc amplifier varied. The net effect was to light an orange-red flash of lightning through the Crosley trademark when a station was tuned in. The stronger the station, the brighter the flash. So, tuning into WLW would make the most of this feature.
The WLW Model Super-Power Radio Receiver was announced on Nov. 25, 1936. The press release for the set was headlined �Here is the Colossus of Radio,� and offered a breathless listing of the components and capabilities of this new wonder of the radio world. The receiver was presented as powerful and practical. �In spite of the fact that it has tremendous volume range with a maximum output of 75W,� the release explained, �this gigantic receiver can be toned down to arm-chair or living-room levels and still retain all the original expression of the music as rendered in the studios.�
The set made for excellent PR, and Powel Crosley Jr. surely had a laugh over it with his friend Eugene MacDonald at Zenith.
The set was priced at $1,500. There is no record of how many of the WLW Model Super-Power Radio Receivers were built, but the first sale was made to Wheless Gambill, a Crosley distributor in Nashville, TN. Powel Crosley Jr. certainly put one in his home, and probably sent one to Eugene MacDonald at Zenith.
Designer Amyle Richards received a bonus of sorts for his work. He had earned a Bachelor of Science degree in Electrical Engineering from the Oklahoma Agricultural and Mechanical College in 1927. In 1939 he submitted a thesis to the college's engineering department based on the WLW receiver, and on the basis of the project was granted a professional degree in electrical engineering.
Banks is the author of more than 40 books, the most recent of which is Crosley: Two Brothers and a Business Empire that Transformed the Nation (Clerisy Press, 2006).