Gilding the Lily:
Circuit Evolution of the
E.H. Scott Quaranta
and Custom Series Receivers from the
Range High Fidelity Receiver
by Norman S. Braithwaite
In the 1930s, E.H. Scott Laboratories introduced enhanced
models of its famous high-fidelity receivers. Norm Braithwaite
describes the evolutionary process that produced the receivers of
ever increasing complexity. Since 1987, Norman Braithwaite has
contributed numerous articles to A.R.C. on the subject of E.H.
During the early 1930s, the E.H. Scott Radio Laboratories became
known for building the finest line of full featured, high performance
receivers that could be built. The line started with their 12-tube
"Allwave Superhetrodyne" receiver of 1931 and progressed
through the 23-tube "Full Range High Fidelity" receiver of
1936. This set, is shown in Figure 1.
During this period, the E.H. Scott Radio Laboratories offered a
single basic chassis layout and incorporated new developments and
improvements as they became available. However Scott had held back
from using single dial operation and continued to use 2-dial tuning
to allow optimum oscillator and
Figure 1. A front view of the 23-tube
Scott Full Range High Fidelity receiver.
detector tuning resulting in superior sensitivity and selectivity.
This was especially important for shortwave reception. Advancement to
a single dial receiver, accommodated by improved tracking capability
of the newer tuning gangs, justified the new model name "Allwave
Deluxe". Other significant improvements were also incorporated.
New models names were assigned when the tube count changed or
other improvements were made. Circuit variations associated with
improvements are common among the individual models, especially the
By the mid-1930s, Scott's Full Range High Fidelity receiver
boasted 13- to 550-meter reception using two stages of RF
amplification, four stages of gain-compensated, continuously
variable-selectivity IF amplification, separate bass and treble
controls, and a 35-watt power amplifier driving a 12-inch bass
speaker and two 5-inch tweeters.
Arguably, the Full Range High Fidelity receiver could be
considered the finest and most practical all-wave high fidelity
receiver of the 1930s. Further improvements to the Full Range High
Fidelity receiver were limited to improving record reproduction,
adding accessories, and keeping up with electronic component
technology. The RF and IF circuits of the Full Range High Fidelity
receiver were incorporated into the subsequent Philharmonic receivers
with virtually no changes through 1941.
Figure 4. The Scott accessory volume range expander
with the top removed.
E.H. Scott recognized that not all potential customers would want
or be able to afford a receiver incorporating all possible
improvements; however, offering all possible improvements was
necessary for marketing to the upper classes, Scott's largest market.
Consequently, turntables, automatic record changers, deluxe
amplifiers, tweeters and some other nonessential features were
offered as options. By special order, custom receivers were built to
meet the specific desiresof wealthy clients. These receivers often
included phonographs, record lathes, special amplifiers, special
cabinets and accessories.
Anyone who has spent much time researching the E.H. Scott Radio
Laboratories or reviewing E.H. Scott literature is likely to be aware
of the 40-tube "Quaranta" receivers custom built for a New
York customer and for E.H. Scott himself, and of the 48-tube custom
receivers built for John J. Mitchell and John Arnold.
Figure 5. This
adapter cable connects the volume range expander to the power supply
and the tuner chassis.
The John J. Mitchell receiver is described in the May 1936 Scott
News article and calls the Custom Receiver a Quaranta. (Note that
Scott literature states that the name "Quaranta" was
derived from the Spanish word for "forty."
"Quaranta" is, in fact, the Italian word for
"forty.") In that article, a photo of the receiver chassis
clearly shows the presence of a record amplifier hence the receiver
was definitely a 48-Tube Custom Receiver as identified in the April
1936 Scott News article. The Mitchell receiver was also rumored to
have had 57-tubes. This may be true if the receiver was modified to
a 50-tube version (second 50-tube version described following) and an
accessory amplifier (similar to the record amplifier) was added to
drive additional speakers. There is another rumor that Mr. Mitchell
owned both a Quaranta and a 48-Tube Custom Receiver. This is
unlikely due to the obvious use of the name "Quaranta" used
in reference to a 48-Tube Custom Receiver in the May 1936 Scott News
and because no second receiver was disclosed when Russ Mappin
interviewed John Mitchell many years ago.
Less well known are the 27-tube version of the Full Range High
Fidelity receiver, now sometimes referred to as "Mini
Quaranta," and the two 50-tube versions of the Custom Receiver
At the present time, no schematics have been located for the
27-tube version of the Full Range High Fidelity receiver or the
Quaranta. Schematics for the tuner and mid-amplifier of a 50-tube
variant of the Quaranta came to the attention of collectors in 1988
after collectors had become acquainted with Murray Clay, Chief
Engineer of the E.H. Scott Radio Laboratories prior to Marvin Hobbs.
Figure 8. The 19-tube tuner chassis used in the Quaranta series of
From these schematics, from one existing tuner and mid-amplifier
chassis (found by Earl England in the late 1970s, serial no. X494)
and from the few other original chassis associated with the Quaranta
and Custom series receivers, the general circuits of most of the
Custom series and the 27-tube version of the Full Range High Fidelity
receiver have been identified. Although the progression of these
circuits is described in order of complexity, their probable order of
appearance on the market is shown in Table I.
Scott Radio Laboratories introduced the 30-tube Philharmonic model
in April 1937 ending the long run of chassis based on the layout
developed for the Allwave Superhetrodyne receiver.
Full Range High Fidelity Receiver:
The Full Range High Fidelity receiver had been introduced as the
"Allwave Imperial" in March 1935. It was renamed within a
couple of months to better attract the attention of customers.
Customers who had purchased the receiver before it was renamed were
sent "corrected" instruction manuals with the new receiver
name on the cover (the only correction!). This Full Range High
Fidelity receiver, which was probably the best designed receiver of
the 1930s, evolved from E.H. Scott receivers dating back to 1931.
The chassis layout for the tuner chassis of this receiver is shown
in Figure 2 (see print version).
Full Range High Fidelity Receiver with Accessory
Volume Range Expander
An accessory volume range expander (VRX), shown in Figures 3 (see
print version) and 4, was introduced for the Full Range High Fidelity
receiver in March 1936. The VRX unit employs the following tube
types: 76 rectifier, 6C6 amplifier and two 6A7 expanders. Power for
the 4-tube expander unit was tapped from the Full Range High Fidelity
power supply using the special adapter cable shown in Figure 5. The
audio signal was taken from and returned to the tuner chassis at the
grids of the second audio frequency amplifiers. Installation of an
accessory volume range expander produced a total tube count of 27
tubes, but their functions differed from those of the soon to be
introduced Full Range High Fidelity receiver with integral volume
Full Range High Fidelity Receiver with Integral
Volume Range Expander
The time when the Full Range High Fidelity Receiver with an
integral volume range expander was introduced is not well known, but
it is certain to be after the introduction of the Quaranta and likely
a few months after introduction of the accessory volume range
expander. Its chassis layout is shown in Figure 6 (see print
version). This receiver was offered concurrent with the more familiar
23-tube version of the Full Range High Fidelity receiver without a
volume range expander.
The expander circuit was accommodated by replacing tubes that
provided the BFO and meter amplifier functions and moving the
push-pull second audio amplifier stage to the power amplifier
chassis. Two "eye" tubes were added to the tuner to
indicate signal strength and degree of volume expansion.
This receiver provided the same essential functions as the
previously introduced Quaranta and was offered as a much lower cost
alternative to the Quaranta. Unfortunately, the E.H. Scott Radio
Laboratories did not publicize this receiver in their brochures,
price lists or news organs; therefore, less is known about this
receiver than most others.
The Quaranta, shown in Figures 7 (see print version) and 8, was
introduced in December of 1935 as the "most perfect sound
reproducing instrument that could be designed regardless of
cost". The receiver could be purchased for $2,500 in 1936. A
search of Scott literature yields references to only two of these
receivers. One of these is the receiver constructed to fulfil the
order from an unnamed New York customer and the other for E.H. Scott
himself. No examples of a 40-tube Quaranta are known to exist today.
In addition to being housed in two separate consoles, the Quaranta
differed from the Full Range High Fidelity Receiver (its direct
predecessor) by the addition of an on-board volume range expander, a
"mid-amplifier," a two channel power amplifier, and a high
quality theater speaker system. In addition to providing voltage
amplification, the mid-amplifier divided the audio signal into a bass
frequency band below 125 Hz and a mid- and high-frequency band above
The power amplifier was essentially two Full Range High Fidelity
Receiver power amplifiers constructed side by side on a single
chassis. The power amplifier was described by the E.H. Scott Radio
Laboratories as providing 50-watts of "undistorted" power
per audio channel. The bass amplifier was used to drive an 18-inch
Jensen theater speaker. The mid- and high-frequency amplifier was
used to drive a single 12-inch Magnavoxmidrange speaker and a pair of
Jensen "Q-Series" horn type theater tweeters. The function
of the 40th tube remains unknown today.
Scott 48-Tube Custom Receiver
Shortly after introducing the Quaranta, the E.H. Scott Radio
Laboratories produced a similar receiver, the 48-tube Custom Receiver
shown in Figures 9 (see print version), 10 and 11. This model added
the capability to cut records. A 7-tube recording amplifier, shown in
Figure 12, was created from the power amplifier of a Full Range High
Fidelity receiver by modification to include an extra stage of
The Full Range High Fidelity receiver power amplifier relied on a
speaker field coil for filtering. Rather than create a new chassis
for a choke and output transformer, the E.H. Scott Radio Laboratories
mounted a standard 12-inch Full Range High Fidelity receiver speaker
against the inside wall of the receiver cabinet and plugged it into
the record amplifier to provide the needed functions. The voice coil
leads of the speaker were disconnected and the signal from the output
transformer routed to the cutting head on the record lathe. Along
with an additional midrange speaker in the speaker console, this
produced a total speaker count of six, but only five were used for
sound reproduction. An additional 2-tube microphone preamplifier
chassis (bringing the total tube count to 48,) shown in Figure 13,
and dual ribbon Amperite microphone were also included with the
The record lathe was a 12-inch Presto model mounted adjacent to a
Garrard automatic record changer on a shelf below the tuner. The
recording amplifier, the microphone preamplifier and the relay power
supply (shown in Figure 13) were installed below the turntable shelf.
The relay power supply provided 24-volts DC to operate an AC power
relay in the main power amplifier that had been moved to the base of
the speaker console. Use of AC for this function would have produced
A selenium rectifier was used for rectification of the relay
supply current rather than another tube. (The relay supply and power
relay was not needed in the 40-tube Quaranta because the power
amplifier was housed in the receiver console and AC lines were easily
separated from the speaker signal.)
Scott literature identifies two of these receivers that were
built, one for John J. Mitchell of Santa Barbara, California, and one
for John Arnold in Hollywood. These receivers were probably sold for
around $3,000. Three power amplifiers from 48-Tube Custom Receivers
or larger variants have been found to date. The only completely
original "Quaranta" type Custom Receiver presently known to
exist is being restored as a 48-tube version.
Figure 10. Below, a side view of the
Scott 48-tube Custom Receiver. Note that the placement of the record
cutting amplifier and the power supply/power amplifier are
interchanged from the chassis layout.
50-Tube Custom Receiver,
Unbeknownst to the public, the radio industry, and radio
collectors alike until after the mid-1980s, the E.H. Scott Radio
Laboratories manufactured more elaborate receivers. During the early
1980s a complete set of three console cabinets was found with a
16-inch Presto recording lathe, Capehart automatic record changer,
and all of the unique supporting chassis associated with the models
containing 48 or more tubes. The tuner and mid-amplifier chassis for
this receiver had been removed many years earlier and have never been
found. Photos of this exceptional receiver are included in the second
edition of E.H. Scott, Dean of DX by Marvin Hobbs.
Although we may never know for certain if this particular receiver
was a 50-tube variant, one piece of evidence lends a strong argument
that it was. The receiver had been owned by Mr. Beardsley, co-owner
of the Beardsley and Piper Company in Chicago, which manufactured
equipment used by foundries throughout the world. In 1939, the
Beardsley and Piper Company hired Murray Clay from the E.H. Scott
Radio Laboratories. Mr. Clay was an accomplished inventor and was
responsible for technical development of the Full Range High Fidelity
Receiver, for the Quaranta, and for several patents during his tenure
at the E.H. Scott Radio Laboratories. Mr. Clay was personally
acquainted with the Beardsley family and, while still working with
the E.H. Scott Radio Laboratories, designed an automatic control
system for sand packing molds of large castings.
Figure 11. A 3/4 view of the Scott 48-tube Custom
It is believed that this work "on the side" was
ultimately the reason for Murray's discharge from the E.H. Scott
Radio Laboratories. Murray and Mr. Beardsley remained well acquainted
until Mr. Beardsley's death in 1951. After Murray had come to the
attention of radio collectors, it was found that he had kept
blueprints of the tuner and mid-amplifier schematics for a 50-tube
variant of the Quaranta. The blueprints are indisputable proof of the
existence of 50-tube variants and were most likely retained to assist
in maintaining the receiver purchased by Mr. Beardsley.
The first 50-tube variant differed from the 48-Tube Custom
Receiver in the addition of a record scratch suppressor, an early
version of a dynamic noise suppressor, plus replacement of some tubes
with newer octal types. The scratch suppressor addition was placed on
the tuner and was accommodated by moving the expander tubes to the
mid-amplifier chassis. Two filter capacitors on one end of the
mid-amplifier chassis were removed to accommodate the expander tubes.
Figure 14 (see print version) shows the modified chassis layouts of
the mid-amplifier and tuner.
Figure 12. The recording amplifier used in the 48-tube custom
Unfortunately this new addition required physically connecting the
tuner chassis and mid-amplifier chassis and routing eight wires
through new holes between the chassis (resulting in a single chassis
of size and weight rivaling RCA's first consumer color television
According to Mr. Beardsley's widow, the receiver cost $3,500. Of
this she was sure! (Personal communication, 1985.) The elaborate
3-console, 50-tube variant was not advertised or disclosed anywhere
in literature of the E.H. Scott Radio Laboratories. This may have
been due to E.H. Scott Radio Laboratories having already sold several
lesser receivers under the pretence of being the most elaborate they
would ever build.
50-Tube Custom Receiver, Second Variant
Although not originally recognized as such, the chassis set found
by Earl England during the 1970s was part of a 48-Tube Custom
Receiver later modified to a 50-tube variant. See Figure 15 (see
print version). The modifications in the tuner and mid-amplifier
chassis were not well understood until the blueprints saved by Murray
Clay came to the attention of collectors and were compared to the
The modifications were recognized as having been made during the
late 1930s and substantially recognized as an added record scratch
suppressor, but it was not known if the modifications had been
conducted by the E.H. Scott Radio Laboratories or by others.
Comparison of the chassis to the schematic confirmed that the
modifications included adding a record scratch suppressor in the same
manner as identified on the schematic.
Figure 13. The microphone
preamplifier (left) and the relay power supply (right) used in the
48-tube custom receiver.
Other modifications consisted of replacing some tubes with more
modern octal equivalents. Given the correlation between the Scott
schematic and the receiver circuit combined with the materials and
construction practices employed, the modifications could only have
been conducted by the E.H. Scott Radio Laboratories.
The author wishes to recognize John Meredith, Kent King and Craig
Korpac for assistance with some of the historic details presented in
Scott News, E.H. Scott Radio Laboratories: V8, N1, March
1935; V8, N12, December 1935; V10, N2, March 1936; V9, N3, April
1936; V9, N4, May 1936; V2, N10, April 1937.
Antique Radio Topics and Classic Radio Collectors
Newsletter, Puett Electronics, V10, N7, undated, 1980.
(Norman S. Braithwaite, P.O. Box 992443, Redding, CA 96099;
In 1975, Norman Braithwaite, a civil engineer, began collecting
antique radios, especially those manufactured by E.H. Scott and its
competitors. His collection includes representative sets from 1917 to
1960, the prize being a rare Scott 48-tube custom receiver.