January 1968 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
Popular Electronics,
published October 1954 - April 1985. All copyrights are hereby acknowledged.
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It is doubtful that
as many people today build their own stereo speaker enclosures as was the case
back in the 1950s through about the 1970s. During those decades stereo equipment
was a really big deal, as evidenced by the large number of articles in technical
and hobby magazines. I have posted a couple dozen articles on the subject here
on RF Cafe. Topics included equipment reviews and feature comparisons,
troubleshooting and alignment, modifications to commercial units,
build-it-yourself projects, optimized room layout and construction, and even
advice on how to best enjoy your stereo system. Lots of comics appeared in the
magazines as well poking fun at how a stereo enthusiast's family members and
neighbor might not appreciate the ear drum-busting power capability of your
system. There were also quizzes like this one on speaker enclosure baffle design
to challenge the stereo buff's technical knowledge (search the list below).
A Baffling Quiz
By Robert P. Balin
Speaker enclosure designs differ mainly in the
way they employ baffles, ports, tubes, columns, ducts, and horns to control the
sound radiated from the front and back of the speaker. To see how much you are baffled
by enclosures, try matching the cross-section drawings (A-J) of commonly used enclosures
with the names by which they are known (1-10).
1 Acoustic labyrinth ___
2 Air coupler ___
3 Baffle ___
4 Ducted-port phase inverter ___
5 Folded horn ___
6 Helmholtz resonator ___
7 Horn-loaded reflex ___
8 Infinite baffle ___
9 Klipschorn ___
10 Resonant column ___

<see answers below>
Quizzes from vintage electronics magazines such as Popular
Electronics, Electronics-World, QST, and Radio News were published
over the years - some really simple and others not so simple. Robert P. Balin
created most of the quizzes for Popular Electronics. This is a listing
of all I have posted thus far.
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-
Elementary
Radio Quiz - December 1947 Radio-Craft
- Hi-Fi
Quiz - October 1955 Radio & Television News
- Electronics Physics
Quiz - March 1974 Popular Electronics
- A Baffling Quiz
- January 1968 Popular Electronics
- Electronics IQ
Quiz - May 1967 Popular Electronics
- Plug and Jack
Quiz - December 1967 Popular Electronics
- Electronic
Switching Quiz - October 1967 Popular Electronics
- Electronic
Angle Quiz - September 1967 Popular Electronics
- International
Electronics Quiz - July 1967 Popular Electronics
- FM Radio
Quiz - April 1950 Radio & Television News
- Bridge Circuit
Quiz -December 1966 Popular Electronics
- Diode Function
Quiz - August 1965 Popular Electronics
- Diagram Quiz,
August 1966 Popular Electronics
- Quist Quiz - November
1953 QST
- TV Trouble Quiz,
July 1966 Popular Electronics
- Electronics History Quiz,
December 1965 Popular Electronics
- Scope-Trace Quiz,
March 1965 Popular Electronics
-
Electronic
Circuit Analogy Quiz, April 1973
-
Test Your Knowledge of Semiconductors, August 1972 Popular Electronics
- Ganged Switching
Quiz, April 1972 Popular Electronics
- Lamp Brightness
Quiz, January 1969 Popular Electronics
- Lissajous Pattern Quiz, September 1963 Popular Electronics
- Electronic
Quizoo, October 1962 Popular Electronics
- Electronic Photo Album Quiz, March 1963 Popular Electronics
- Electronic Alphabet Quiz, May 1963 Popular Electronics
- Quiz: Resistive?
Inductive? or Capacitive?, October 1960 Popular Electronics
- Vector-Circuit Matching Quiz, June 1970 Popular Electronics
- Inductance
Quiz, September 1961 Popular Electronics
- RC Circuit Quiz,
June 1963 Popular Electronics
- Diode Quiz, July
1961 Popular Electronics
- Electronic Curves Quiz, February 1963 Popular Electronics
- Electronic Numbers Quiz, December 1962 Popular Electronics
- Energy Conversion Quiz, April 1963 Popular Electronics
- Coil Function
Quiz, June 1962 Popular Electronics
-
Co-Inventors Quiz - January 1965 Electronics World
-
"-Tron" Teasers Quiz - October 1963 Electronics World
- Polarity Quiz
- March 1968 Popular Electronics
-
Television
I.Q. Quiz - October 1948 Radio & Television News
- Amplifier Quiz
Part I - February 1964 Popular Electronics
- Semiconductor
Quiz - February 1967 Popular Electronics
- Unknown
Frequency Quiz - September 1965 Popular Electronics
- Electronics
Metals Quiz - October 1964 Popular Electronics
- Electronics
Measurement Quiz - August 1967 Popular Electronics
- Meter-Reading
Quiz, June 1966 Popular Electronics
- Electronic
Geometry Quiz, January 1965 Popular Electronics
- Electronic
Factor Quiz, November 1966 Popular Electronics
- Electronics
Math Quiz, November 1965 Popular Electronics
- Series Circuit
Quiz, May 1966 Popular Electronics
- Electrochemistry
Quiz, March 1966 Popular Electronics
- Biz
Quiz: Test Your Sales Ability - April 1947 Radio News
- Electronic
Analogy Quiz, November 1961 Popular Electronics
- Electronic
Coupling Quiz, August 1973 Popular Electronics
- Electronics Analogy Quiz, August 1960 Popular Electronics
- Audio Quiz, April
1955 Popular Electronics
- Electronic Unit
Quiz, May 1962 Popular Electronics
- Capacitor
Circuit Quiz, June 1968 Popular Electronics
- Quiz on AC Circuit Theory, December 1970 Popular Electronics
- Magnetic Phenomena Quiz, February 1962 Popular Electronics
- Electronics Geography Quiz, April 1970 Popular Electronics
- Electronic
Menu Quiz, August 1963 Popular Electronics
- Electronic Noise Quiz, August 1962 Popular Electronics
- Electronic Current Quiz, October 1963 Popular Electronics
- Electronic Inventors Quiz, November 1963 Popular Electronics
- Resistor Function
Quiz, January 1962 Popular Electronics
- Electronic Measurement Quiz, January 1963 Popular Electronics
- Vacuum Tube Quiz,
February 1961 Popular Electronics
- Kool-Keeping Kwiz, June
1970 Popular Electronics
- Find the Brightest
Bulb Quiz, April 1960 Popular Electronics
-
Where Do the Scientists Belong? - Feb 19, 1949 Saturday Evening
Post
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Baffling Quiz Answers
1 - D) An Acoustic Labyrinth is a form of bass-reflex enclosure which uses
a folded rear air column designed to be one-quarter wavelength at the low-frequency
resonant point of the speaker. The resonant column dampens the resonant peak of
the speaker and extends the low-frequency response.
2 - I) An Air Coupler is an air column designed to be one-quarter wavelength
at the speaker's low-frequency resonance point to minimize the resonant peak and
provide improved speaker-to-room (free air) acoustic impedance-matching.
3 - G) The Baffle, box baffle, or Hartley-Turner enclosure, uses a series
of vented, sound-absorbent baffles to absorb back radiation and minimize back loading.
4 - A) A Ducted-Port Phase Inverter is a form of bass-reflex enclosure
in which a duct provides additional acoustic inductance to resonate with the acoustic
capacitance provided by the volume of the enclosure. The reduced acoustic capacitance
requirement permits a more compact cabinet for the same speaker resonant frequency.
5 - F) A Folded Horn offers the advantages of speaker-to-room acoustical
impedance matching in a more compact cabinet than an otherwise impractically large
straight horn design.
6 - B) The Helmholtz Resonator, or R-J enclosure, is a form of bass-reflex
enclosure in which the port, in the form of a narrow, circular slit surrounding
the speaker, supplies additional acoustical resistance for improved low-frequency
damping of the speaker.
7 - E) The Horn-Loaded Reflex enclosure is a form of ducted-port phase
inverter having the increased radiation resistance and higher efficiency provided
by the horn-shaped duct.
8 - C) An Infinite Baffle enclosure is not really infinite in the sense
that all of the front radiation will go forward without refraction, but back-enclosed
cabinets do prevent the back radiation from interfering with the sound radiated
from the front of the speaker and, in that sense, are considered a practical form
of infinite baffle.
9 - H) A Klipschorn enclosure is a folded, exponential horn which uses
the corner of the room as the final flare of the horn mouth, and thereby, in effect,
places the listener within the horn.
10 - J) A Resonant Column is a cross between an infinite baffle and a tuned
pipe coupler that provides the large air volume of an infinite baffle in an enclosure
design which requires less floor space.
Posted September 5, 2019
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