|"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 200X & 201X High-Fidelity Console Radios (1934/35)
Philco introduced the model 200X, the industry's first High-Fidel-
ity 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 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 quietly forged
ahead and took a lead in solving 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 short time, 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 cons-
ultant Edward L. Bernays. They promoted the 200X by mounting
a highly orchestrated publicity campaign. In addition to news-
paper advertising, demonstrations of Philco High Fidelity were
staged at high profile establishments, such as this one in the
Ballroom at the luxurious Waldorf-Astoria Hotel, announced in the
August 26th 1934 edition of the New York Times:-
|...radio's greatest achievement - High Fidelity radio
|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
Philco's Gift to the Musical World
In preparing for the release of the 200X, one of Bernays' first acts
was to commission 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 Ber-
nays compiled a series of quotes from their letters into a booklet,
authenticated with Sanborn's signature, and mailed it to news-
paper 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 annou-
nced 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.
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 technological 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.
Technical Details of the 200X and 201X
Overview: The model 200X is a ten-tube AC superheterodyne
providing coverage of standard broadcast 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) & 5Z3 (rectifier). The 200X uses a four gang
tuning condensor with a double-tuned RF stage, whereas the
201X's input is single tuned and it uses 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". 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 wind-
ing 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.
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 200X debuted, just making the twelve month filing limit in
the USA following public disclosure. In Great Britain I believe no
such grace period 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 read 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 question 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-Fidel-
ity 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
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 42 pentodes fed by a
triode-connected 42 driver, developing 15W of undistorted
output. This arrangement was used on many Philco sets,
including the 16 and 18 series.
High Fidelity Loud-Speaker: The 200X and 201X utilized a new
Philco electro-dynamic speaker design whose cone was cons-
tructed 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
grille extends around the cabinet somewhat to enhance the
overall effectiveness of the diffusion.
Echo Absorbing Screen: The rear of the speaker chamber has
a cover that Philco called their "Echo Absorbing Screen" (see
right). 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.
|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
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 Car-
ter. 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 listeners
through one of the new high-fidelity 200X receivers. Of course,
the majority of radio listeners would not have enjoyed the ben-
efits of the new receiver in the same manner as did the live
audience, as their receivers would mostly not have been of the
The day following the demonstration, on Sept 13th, Philco and
their dealers commenced the running of newspaper ads describ-
ing the event and inviting listeners to visit their local Philco deal-
ership in order to experience "radio's newest sensation" for
|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
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
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
Philco presents High Fidelity radio.. Philco's gift to the
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"
|The radio the world has been waiting for! High Fidelity Philco.