High Fidelity Loud-Speaker: The 200X and 201X utilized a new Philco electro-dynamic speaker design whose
cone was constructed out of two different grades of paper to form a stiff central part and a lighter outer region.
By this means, the entire cone was effective in reproducing lower frequencies while the stiff inner region
followed the highs. In addition, the voice coil was wound using aluminum wire for weight savings, again helping
the unit's high frequency response. An enlarged view of the cone on my 201X may be seen by clicking the
thumbnail to the right.
Sound Diffusing Cabinet with Inclined Sounding Board: The 200X and 201X use a concealed version of
Philco's famous Inclined Sounding Board, the purpose of which is to direct the sound field up towards the
listener and away from the floor (see models 112X, 16L and 116X). Additionally, metallic sound diffusing fins
are mounted in front of the speaker, hidden from view behind the grille cloth, to mitigate high-frequency
beaming effects. Four vertical fins provide lateral diffusion whilst a solitary horizontal fin serves to direct some of
the high frequency energy upwards. The whole was intended to act not only to provide equal tonal rendition to
persons seated a distance around the front of the radio, but also to an individual while adjusting the receiver. A
final aspect of the sound diffusion system is that the speaker grill extends around the cabinet somewhat to
enhance the overall effectiveness of the diffusion.
Echo Absorbing Screen: The rear of the speaker chambers have a cover that Philco called their "Echo
Absorbing Screen". This was designed to reduce the muffling effect of sound radiated from the rear of the
cabinet and reflected back into the sound field off of walls behind the enclosure.
Sturdy Cabinet: The cabinets are of heavy and sturdy construction, rendering them acoustically "neutral".
Overall, Philco referred to these models as using their "High Fidelity Sound Diffusing Cabinet", claimed to
eliminate directional effects and allow the listener to enjoy outstanding tonal quality regardless of where they
were seated in a room. My 200X and 201X sets can be viewed side-by-side here.
Philco Models 200X & 201X High-Fidelity Console Radios (1934/35)
Philco introduced the model 200X, the industry's first High-Fidelity radio, in
June of 1934 and followed it in the fall with the model 201X. Whereas the
200X covers only the standard broadcast band and was listed at $200, the
201X added shortwave coverage and was offered at $250. Both the 200 and
201 continued to be available from Philco through June of 1935, after which
time they were replaced by the model 680X.
Much to the chagrin of other manufacturers, who had spent a lot of time just
talking about High-Fidelity, Philco had quietly forged ahead and solved the
key technical problems, enabling them to offer a set ahead of the rest of the
industry and thereby steal an early sales lead. Others were nevertheless hot
on Philco's heels and would, in just a few months, be offering sets of their own.
The era of AM High-Fidelity radio had begun! However, for various reasons,
including the imminence of FM and Television, it would prove to be short-lived.
To capitalize on their early lead, and to attract the kind of buyer who could
afford high-fidelity, Philco hired public relations consultant Edward L.
Bernays. They promoted the 200X by mounting a highly orchestrated pub-
licity campaign. In addition to newspaper advertising, demonstrations of
Philco High Fidelity were staged at high profile establishments, such as this
one at the Waldorf-Astoria Hotel, announced in the August 26th 1934
edition of the New York Times:-
...radio's greatest achievement - High Fidelity radio
Overview: The model 200X is a ten-tube AC superheterodyne receiver providing coverage of the standard broadcast band from 540-
1720kc. The model 201X, which is electrically very similar, added coverage of the shortwave band from 4.2-12.0mc. Both sets feature a
tuned RF stage, two stages of IF amplification with variable bandwidth control, AVC, shadow tuning meter, push-pull "super class A"
output, High Fidelity speaker system with Inclined Sounding Board and a sound diffusing cabinet. The tube line up is:- 78 (tuned RF
amp), 6A7 (mixer/LO), 78 (first IF), 78 (2nd IF), 75 (2nd detector/AVC/shadow-tuning/1st AF), 37 (shadow meter control), 42 (AF triode-
connected driver), 42 *2 (push-pull triode-connected output stage) and 5Z3 (rectifier). For the 200X the input to the RF stage features
"double tuning" using a four gang tuning condensor, whereas the 201X's input is single tuned with a 3-gang condensor. The schematic
for the 200X is available here, and for the 201X here, courtesy of NostalgiaAir.
Selectivity Control: The 200 and 201X both feature variable IF bandwidth, adjusted using the front panel "fidelity control" knob. When
tuned to a local "high-fidelity" broadcast station, widening the bandwidth improves the high-frequency response of the audio output.
According to Philco advertising, at its widest setting "the total range of this new Philco is 50 to 7500 cycles as compared to 50 to
4000 cycles of the best previous radio".
The broadening of the IF is accomplished through the addition of a third winding to each of the first two IF transformers. This winding is
tuned for resonance at the IF using a shunt capacitance in the usual way but this capacitance is in series with a variable resistance.
When this resistance is set to maximum, its effect on the IF response is minimal and a selectivity of around +/-2000Hz is provided.
However, as the resistance is reduced, increased IF signal energy is absorbed from the neighboring windings and the amplitude of the
secondary output is reduced at the same time as the bandwidth is broadened, up to a maximum of around +/-7500Hz. The reduction in
output is compensated by increasing the gain of the 1st and 2nd IF stages, achieved by reducing the amount of cathode self-bias
applied to these stages. The set's normal AVC helps out here too. Note that the 200X operates slightly differently in that the gain of the
mixer/LO and 1st IF stage is adjusted, rather than the gain of the first and second IFs as in the 201X.
A low-pass filter with a 7500Hz cut-off is inserted in the plate circuit of the 1st AF amplifier in order to reduce the deleterious effects of
adjacent channel interference when the IF is bandwidth is opened up. Without this, whistles and hash ("birdies") would be heard in the
loudspeaker under certain conditions.
Philco's Design Patent. The design of Philco's selectivity control is attributed to Philco employee Andrew P. Montgomery in US patent
number 2,153,583 (assignee Philco Storage Battery Co.). It is curious that this patent was filed in May of 1935, 11 months after the debut
of the model 200X, almost at the end of the twelve month window from time of first public disclosure allowed in the US for the filing of
related patents. In Great Britain I believe no such window exists and patents must be filed prior to public disclosure. Philco had therefore
filed the patent in Britain a full one year earlier than in the US, in May of 1934.
The Hazeltine Connection. I have often seen it written that the design of Philco's selectivity control for the 200X/201X, along with several
other of its developments, are attributable, at least in part, to the Hazeltine Corporation. However, on the basis of this patent one is
inclined to dispute this claim, as there is no citation made within the patent to pre-existing Hazeltine state of the art. Furthermore, Radio
Retailing's "Progress in High-Fidelity" article (page 19 - see Bibliography below) states that Philco worked "independently [of Hazeltine]
but along closely parallel lines" on their High-Fidelity developments for the 200X/201X.
Bass Compensation: A switch on the side of the 201X's cabinet is used to activate/deactivate automatic bass compensation. When
active, this serves to progressively boost the bass response from the radio as the volume is reduced in order to compensate for
audiometric effects. The 200X provides a three point bass control but this was omitted on the 201X to make way for the bandswitch.
Automatic Volume Control: AVC in the models 200X and 201X is applied to the tuned RF stage, 6A7 mixer/LO and the 1st IF.
Shadow Tuning: The 200X and 201X employ shadow tuning meters to assist with the accurate tuning of stations. For a description of
this device, see my model 19B page. To ensure that this meter provides a precise indication of the correct tuning point even when the
selectivity control is at its widest, the shadow meter control is derived from a separate tuned winding on the final IF transformer. This
winding provides an effective bandwidth commensurate with the narrowest setting of the selectivity control and in turn feeds a dedicated
shadow meter detector diode (part of the type 75 tube) and control amplifier (tube type 37). In this way, the bandwidth of the tuning meter
path stays substantially constant even as the selectivity control is adjusted (see Philco patent #2153583).
Super Class A Push-Pull Output: The 200X and 201X utilize Philco's tried and trusted super-class A output stage, comprising a pair of
triode-connected push-pull type 42 tubes fed by a triode-connected type 42 driver and developing 15W of undistorted output. This stage
was used on many Philco sets, including the 16 and 18 series.
|Radio 'Sound Diffuser' To Be Demonstrated
A "sound beam diffuser", designed for high-fidelity reception, will be
demonstrated by Philco Radio and Television engineers on Sept 12th at the
Waldorf-Astoria Hotel. Mme Lucrezia Bori, Metropolitan Opera soprano, will
sing to illustrate the instrument's effectiveness.
The mechanism comprises special circuits and a loud-speaker designed to
reproduce with relative intensity all musical tones between 50 and 7,500 cycles.
The diffuser proper is a scientifically treated cabinet utilized to direct the
music to all parts of the room without difference in volume"
The demonstration took place in the evening before an invited audience of
400 distinguished musicians, critics, educators and artists. Parts of it were
broadcast simultaneously over CBS radio between 6.45pm and 7.00pm in a
segment hosted by Boake Carter. Miss Bori first gave a concert recital of
one of her well-known songs, after which she entered a glass booth and
repeated it, with her voice transmitted to the live audience and radio listen-
ers through one of the new high-fidelity 200X receivers. Of course, the
majority of radio listeners would not have enjoyed the benefits of the new
receiver in the same manner as did the live audience, as their receivers
would mostly not have been of the new type.
The day following the demonstration, on Sept 13th, Philco and their dealers
commenced the running of newspaper ads describing the event and inviting
listeners to visit their local Philco dealership in order to experience "radio's
newest sensation" for themselves.
|Last night, America's music leaders HAILED the new High-Fidelity radio
at the Waldorf Astoria
"...Answering the demand of music lovers for a finer musical instrument, this
sensational Philco made its triumphant debut last evening at the Waldorf
Astoria, New York's most luxurious hotel in the presence of 400 leaders in the
field of music, composers, critics and artists, including Miss Lucrezia Bori,
renowned soprano of the Metroplitan Opera Company.
You will thrill to the magnificent, natural tone of this sensational radio, just
as those did who heard Miss Lucrezia Bori's lovely voice in last evening's
Ask for a Demonstration
Words cannot describe this magnificent High-Fidelity radio. You must have a
demonstration to appreciate the startling "newness" - the amazing difference in
Philco high fidelity reproduction. Your Philco dealer is ready and eager to
demonstrate the new Philco 200X and explain how you can take advantage of the
exceedingly easy payment plan. See your dealer now!
The Charleston Gazette, Thur Sept 13th 1934
In preparing for the release of the 200X, one of Bernays' first acts was to comm-
ission Pitts Sanborn, music critic of the New York World-Telegram, to write to
hundreds of "leaders" of the music world, posing the question "is it not time that
a better radio was produced?". Many musicians replied in the affirmative, and
Bernays compiled a series of quotes from their letters into a booklet, authentic-
ated with Sanborn's signature, and mailed it to newspaper editors, along with a
letter pointing out that musical leaders were "demanding better quality in radio
reproduction". The matter received widespread publicity, in the midst of which
Philco announced their model 200X flagship high-fidelity receiver, proclaiming it
as "Philco's Gift to the Musical World". Advertisements for the 200X and 201X,
published in 1934 and reflecting the above theme, can be seen by clicking on
the thumbnails to the right.
|"Enjoy those overtones the ordinary radio cannot give you.
The total range of this new Philco is 50 to 7500 cycles as
compared to 50 to 4000 cycles of the best previous radio.
You can adjust the receiver to get the full benefit of the
maximum tonal range of any American station"
Philco presents High Fidelity radio.. Philco's gift to the Musical World.
|Technical Details of the 200X and 201X
Bibliography & Further Reading:
"Progress in High Fidelity", Radio Retailing, June 1934, pages 19 & 31.
Various newspaper & magazine advertisements and reports from 1934 & 1935.
The Philco High-Fidelity Receiver, Edward Sheldon.
Time magazine, April 3rd 1939, "The Corporate Sole"
|Philco's Gift to the Musical World
The radio the world has been waiting for! High Fidelity Philco.
One objective of this and similar advertising was of course to get the public into the stores to see, hear and buy a Philco high-fidelity radio.
Most would not however be able to afford a 200X or 201X, so the hope was that, inspired by the experience, they would end up buying the
highest priced Philco set that they could afford.
Over the next several years Philco continued to evolve High-Fidelity radio and introduced a series of innovative models, comprising the
116X, 680X, 37-116X, 37-690X, 38-116XX and 38-690XX. However, at the start of the 1939 season whilst at the peak of their techno-
logical prowess, in an astonishing about-turn they changed course and forever discontinued their Hi-Fi AM offerings. Much of the rest of
the industry also did the same thing.