Philco Model 201X High-Fidelity Console Radio (1934)
In June of 1934, as part of their line-up for 1935, Philco introduced the
industry's first High-Fidelity set, the 200X. It was quickly joined in the fall by
the model 201X, an example of which is photographed here. Whereas the
200X provides coverage of the standard broadcast band only and initially
listed for $200, the 201X added shortwave coverage and was offered at the
increased retail price of $250. Both sets would continue to be available for
sale in Philco dealerships through June of 1935.
While many other manufacturer's had been just talking about High-Fidelity,
Philco had quietly gone out and solved the key technical problems, enabling
them to offer sets ahead of the rest of the industry and to steal an early
sales lead. Several other manufacturers were nevertheless hot on their
heels and would, in just a matter of weeks, be offering sets of their own. The
era of AM High-Fidelity radio had begun!
To capitalize on their early lead, Philco promoted the 200X by mounting a
highly orchestrated publicity campaign. In addition to newspaper advertising,
demonstrations of Philco High Fidelity were staged at high profile establish-
ments, such as this one at the Waldorf-Astoria Hotel, announced in the
August 26th 1934 edition of the New York Times:-
industry's first High-Fidelity set, the 200X. It was quickly joined in the fall by
the model 201X, an example of which is photographed here. Whereas the
200X provides coverage of the standard broadcast band only and initially
listed for $200, the 201X added shortwave coverage and was offered at the
increased retail price of $250. Both sets would continue to be available for
sale in Philco dealerships through June of 1935.
While many other manufacturer's had been just talking about High-Fidelity,
Philco had quietly gone out and solved the key technical problems, enabling
them to offer sets ahead of the rest of the industry and to steal an early
sales lead. Several other manufacturers were nevertheless hot on their
heels and would, in just a matter of weeks, be offering sets of their own. The
era of AM High-Fidelity radio had begun!
To capitalize on their early lead, Philco promoted the 200X by mounting a
highly orchestrated publicity campaign. In addition to newspaper advertising,
demonstrations of Philco High Fidelity were staged at high profile establish-
ments, such as this one at the Waldorf-Astoria Hotel, announced in the
August 26th 1934 edition of the New York Times:-
Copyright TubeRadioLand.com
 | |  | |  | |  | |  | |  | |  | |  | |  | |  | |  | |  |
...radio's greatest achievement - High Fidelity radio
Overview: The model 201X is a ten-tube AC superheterodyne receiver providing coverage of the standard broadcast band from
540-1720kc and the shortwave band from 4.2-12.0mc. It features a tuned RF stage, two stages of IF 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 driver), 42 *2 (push-pull triode connected output stage) and 5Z3 (rectifier). The
schematic is available here, courtesy of NostalgiaAir. For comparison purposes, the schematic of the 200X may be found here.
Selectivity Control: The 201X features variable IF bandwidth, adjusted using the front panel "fidelity control" knob. When tuned to a
local "high-fidelity" broadcast station, widening the bandwidth improved 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 set's 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. Apparently, without this whistles and hash would be heard in the
loudspeaker under certain conditions.
Bass Compensation: A switch on the side of the cabinet is used to activate/de-activate 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 provided a three point bass control but this was surrendered on the 201X to make way for the bandswitch.
Automatic Volume Control: AVC in the model 201X is applied to the tuned RF stage, 6A7 mixer/LO and the 1st IF.
Shadow Tuning: The 201X employs a shadow tuning meter to assist in 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.
Super Class A Push-Pull Output: The 201X utilizes Philco's tried and trusted super-class A output stage, comprising a pair of triode
connected push-pull type 42 tubes developing 15W of undistorted output. This stage was used on many Philco sets, including the 16
and 18 series.
540-1720kc and the shortwave band from 4.2-12.0mc. It features a tuned RF stage, two stages of IF 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 driver), 42 *2 (push-pull triode connected output stage) and 5Z3 (rectifier). The
schematic is available here, courtesy of NostalgiaAir. For comparison purposes, the schematic of the 200X may be found here.
Selectivity Control: The 201X features variable IF bandwidth, adjusted using the front panel "fidelity control" knob. When tuned to a
local "high-fidelity" broadcast station, widening the bandwidth improved 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 set's 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. Apparently, without this whistles and hash would be heard in the
loudspeaker under certain conditions.
Bass Compensation: A switch on the side of the cabinet is used to activate/de-activate 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 provided a three point bass control but this was surrendered on the 201X to make way for the bandswitch.
Automatic Volume Control: AVC in the model 201X is applied to the tuned RF stage, 6A7 mixer/LO and the 1st IF.
Shadow Tuning: The 201X employs a shadow tuning meter to assist in 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.
Super Class A Push-Pull Output: The 201X utilizes Philco's tried and trusted super-class A output stage, comprising a pair of triode
connected push-pull type 42 tubes 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 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.
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 demonstration..." 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 |
The objective in this advertising was of course to get the public into the
stores to see and hear the radio. Most would not be able to afford a 200X,
but the hope was that, inspired by the experience, they would end up buying
the highest priced Philco set that they could afford.
An advertisement for the 201X, published in the December 29th 1934 edition
of the Saturday Evening Post, can be seen here. Philco also offered a radio-
phonograph based on the 201X chassis, the 509X, priced at $600.
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, after this run, at the
start of the 1939 season, in an astonishing about-turn they changed course
and forever discontinued their Hi-Fi AM offerings.
stores to see and hear the radio. Most would not be able to afford a 200X,
but the hope was that, inspired by the experience, they would end up buying
the highest priced Philco set that they could afford.
An advertisement for the 201X, published in the December 29th 1934 edition
of the Saturday Evening Post, can be seen here. Philco also offered a radio-
phonograph based on the 201X chassis, the 509X, priced at $600.
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, after this run, at the
start of the 1939 season, in an astonishing about-turn they changed course
and forever discontinued their Hi-Fi AM offerings.
| "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 |
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 may be seen by clicking the
thumbnail to the right.
Sound Diffusing Cabinet with Inclined Sounding Board: The 201X uses 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 freq-
uency 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 201X's sound diffusion 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 chamber has 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 201X's cabinet is of heavy and sturdy construction, rendering it acoustically "neutral".
Overall, Philco referred to the 201X 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.
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 may be seen by clicking the
thumbnail to the right.
Sound Diffusing Cabinet with Inclined Sounding Board: The 201X uses 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 freq-
uency 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 201X's sound diffusion 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 chamber has 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 201X's cabinet is of heavy and sturdy construction, rendering it acoustically "neutral".
Overall, Philco referred to the 201X 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.
Copyright www.TubeRadioLand.com
Bibliography & Further Reading:
"Progress in High Fidelity", Radio Retailing, June 1934, pages 19 & 31.
Various newspaper & magazine advertisements from 1934 & 1935.
philcoradio.com website
The Philco High-Fidelity Receiver, Edward Sheldon.
"Progress in High Fidelity", Radio Retailing, June 1934, pages 19 & 31.
Various newspaper & magazine advertisements from 1934 & 1935.
philcoradio.com website
The Philco High-Fidelity Receiver, Edward Sheldon.