May 1957 Radio & TV News
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Radio & Television News, published 1919-1959. All copyrights hereby
is a brand well known to stereo hobbyists and professionals for
more than half a century.
Wireless Works was founded by British entrepreneur Gilbert Briggs
in 1933, and still sells speakers under the name 'Wharfdale.'
As a pioneer in high fidelity sound reproduction, Mr. Briggs was
highly sought as an author by electronics and audio media. In May
1957, he wrote this article for Radio & TV News magazine.
Studies of the audio response of the human ear and the physics of
the space where speakers and listeners would be were undertaken
as the electronics age progressed in the post-war years and consumers
began seeking more than simply noise emanating from a loudspeaker.
All About Audio and Hi-Fi
Editor's Note: We take great pleasure in welcoming to
these pages one whose wide experience and knowledge truly
entitle him to be called a "noted authority" in the hi-fi
field, Mr. G. A. Briggs' pre-eminence stems not from a theoretical,
ivory-tower approach to the subject, but rather it is the
result of endless experimentation, a well-developed sense
of inquiry, and a serious (although good-humored) interest
in good audio reproduction. Besides all this, Mr. Briggs
has the peculiar ability to tell of his experiences in a
crystal-clear, personal, down-to-earth manner that is a
pleasure to read.
G. A. Briggs is managing director of the Wharfedale Wireless
Works Ltd., England, which is engaged in making loudspeakers.
Mr. Briggs started constructing acoustic phonographs, radios,
and loudspeakers as a hobby around 1930. He started making
speakers commercially in 1933. He has also dabbled in pianos
and during the course of the last 25 years he has had forty
different instruments in his home. Mr. Briggs is the author
of the best-seller, "Loudspeakers," which is now in its
fourth edition, as well as the popular "Sound Reproduction,"
"Pianos, Pianists, and Sonics," and "High Fidelity - the
Why and How for Amateurs." Also, during the last three years,
he has conducted nine lecture-demonstrations on sound reproduction
in Canada, England, and in Carnegie Hall, New York.
We feel quite sure all our readers will derive both pleasure
and profit from Mr. Briggs' series, "All About Audio and
Hi-Fi," which begins in this issue.
G. A. Briggs
Managing Director Wharfedale Wireless Works Ltd.
Part 1. An informative and interesting series that will discuss
high fidelity reproduction from the listener's point of view. Opening
article describes the main qualities of the human ear as they are
related to sound reproduction.
As the year 1956 was drawing to its quasi-peaceful close, I was
very pleased to receive from the editors of this magazine an invitation
to contribute a series of articles on audio topics, now generally
designated as hi-fi. Because I am constantly making tests and experiments,
it is very useful to have an incentive to place the results on record
whilst they are fresh in the mind. In these experiments I have the
valuable cooperation of our technical director, Mr. R. E. Cooke,
B.Sc. (Eng.), who joined my firm some two years ago after spending
a few years in the Designs Department of the BBC where he was engaged
on problems connected with sound recording and reproduction.
Another reason for satisfaction is that I believe that any interchange
of experience and opinion between our two countries is a good thing
in the present state of the world, apart from the obvious fact that
we can learn a lot from each other. (For instance, although we are
fond of saying that you cannot make tea, I have developed the habit
of using tea bags at home as a result of visits to America, and
I should hate to go back to the messy business of loose tea leaves.)
Fig. 1. Photograph of the main items of test equipment
used in tests forming the basis of this series of articles,
Mr. R. E. Cooke is recording some information.
American radio and audio magazines are read with avidity over
here, and it would be a good thing if British journals could include
more contributions from American writers, although the usual rates
of pay are rather thin; translated into dollars they would just
about keep a moderate smoker in cigarettes.
On the more technical side we have nothing in this country to
compare with some of your fine technical magazines, and, when it
comes to test reports on instruments and equipment, your consumer
testing organization reports are unique for candor and thoroughness,
(Your greyhounds are halfway round the track before ours have realized
that the traps are open and the hares are off!)
To conclude this preamble, I would like to stress the point that
music and its reproduction are intended for man's delight, and my
main reason for writing on the subject is that I enjoy doing so,
Let us therefore approach all problems in a gay rather than a somber
Scope of Articles
The title, "All About Audio and Hi-Fi," may be rather ambiguous.
It does not mean that I am going to tell you all there is to know
about it. (I do not know it all, nor do I think I know!) It simply
means that I have a roving commission to deal with all or any aspects
of the subject, I sometimes think that the term "high fidelity"
has just about reached the limit set by the large notice which appears
on the front door of a dance hall on Broadway, which reads: "Most
Exclusive Place in Town - Everybody Welcome." It is now quite usual
to see portable radio sets and record players advertised in England
as "hi-fi"; but despite this the term means something when properly
applied, and it is very difficult to replace by a better one.
As the main basis of this and subsequent articles will be actual
tests and experiments, a brief outline of the instruments available
will not be out of place, although I always believe that the skill
and judgment of the investigators mean more than the cost of the
Photographs of the Wharfedale laboratory are reproduced in Figs.
1 and 2.
In Fig. 1 the main item is, of course, our Mr. Cooke, but other
items worthy of note are, from left to right, automatic response
curve recorder, a.f. oscillator, microscope, stroboscope, vacuum-tube
voltmeters, sound level meter, phase-angle and impedance meter,
oscilloscope with camera, etc.
Fig. 2. Another part of the lab showing some speakers
used for comparative tests.
In Fig. 2 the corner enclosure on the left is built of bricks,
and to the left of that is an artificial reverberation device of
Danish design. Moving to the right (no doubt wisely) we see a small
RJ cabinet followed by a larger enclosure with special acoustic
filter, to which we shall probably refer again in a later article.
Sitting atop this cabinet is a 3" tweeter with volume control, and
on the windowsill is a Janszen electrostatic speaker. Then we have
a sand-filled baffle accommodating three speakers, with an exploded
view of a Klipschorn. on the extreme right. (The fact that three
out of the six speakers shown are of American design does at least
indicate that we are broadminded!)
When listening to loudspeakers in unusual rooms, allowance must
be made for differences compared to furnished rooms in which domestic
speakers are normally used. For instance, the laboratory in question
has a longer reverberation time and sounds much brighter than an
ordinary room. Some beneficial acoustic treatment has been applied;
perforated Celotex tiles absorb excessive high frequencies over
part of the walls, and half a dozen acoustic absorbers, designed
by R. E. Cooke, each 5 ft. x 2 ft., operate in the range 100 to
8000 cps. (One of these can be seen in each photograph.) These units
combine the functions of a Helmholtz resonator, stagger-tuned over
the frequency range 700-1300 cps, and a membrane absorber. Nevertheless,
I still prefer to make a final loudspeaker test at home, when domestic
types are involved.
Room effects obviously play havoc with any loudspeaker response,
although they do not invalidate the merits of level response as
a starting point.
In view of the importance of listening tests, we cannot do better
than devote the remainder of this article to an elementary study
of the function of the human ear as related to the problems of sound
Its main qualities could, I think, be classified very simply
as follows: (1) Sensitivity, or general acuity of hearing; (2) Response,
or variation of acuity with frequency; (3) Tonal discrimination
and power to assess volume levels accurately; (4) Sense of pitch;
(5) Musical reaction and talent; and (6) Uniformity of qualities
1 and 2 between left and right ear.
For our purpose, the most important is No.3, tonal discrimination,
but we will deal with the others first.
Qualities 4 and 5: It is obvious that any of the six qualities
could be possessed to an exceptional degree by one person, with
only fair or even poor ability in the others, although it is reasonable
to assume that Nos. 4 and 5 usually go together. (It is difficult
to imagine that even an ultra-modern composer cannot hit the right
note - or at least the one he wants.)
But experience shows that professional musicians are often poor
judges of quality No.3, and may be defective in qualities 1 and
2. (Beethoven was deaf for many years.) The reason for No. 3 failure
is that the musician usually spends so much time near to the source
of sound. I remember at rehearsals in the Royal Festival Hall, the
organist Ralph Downes always maintained that we were reproducing
the organ too loudly when he came into the body of the hall to listen.
Similarly, a member of an orchestra hears something quite different
from the conglomeration of direct and reflected sound heard by members
of the audience. Volume level has a lot to do with it; I always
maintain that the art of attaining realistic reproduction starts
with setting the volume control correctly. The slightest touch up
or down can make all the difference. The organist, when playing
on a console placed near the pipes, hears less than his audience,
but a member of an orchestra hears more, so the training for No.3
is poor in both cases.
Fig. 3. Results of hearing tests made by M. G. Scroggie
on persons of normal hearing between the ages of 5 and 55.
Curves have been compensated for Fletcher-Munsen threshold
levels. (Curves redrawn from "Wireless World")
Fig. 4. Response curves of the 3·inch speaker used in
the listening tests.
It is also difficult for very musical people to ignore the music
and performance, and concentrate on quality of reproduction. Many
hi-fi fans err in the opposite direction!
Qualities 1 and 2: At the outset, we must be careful not to attach
too much importance to acuity of hearing. We have already agreed
that it has little to do with musical ability, and it is fairly
easy to prove that sensitive ears are not necessarily discriminating
ears, any more than a man with good eyesight is ipso facto an artist
or a good judge of line and color.
But a reasonably good range of hearing is obviously required
before any reliable assessment of tonal quality can be made. This
was brought home to me recently during a rehearsal for a record
concert, the items for which had been chosen by a talented musician
and composer, who was apparently stone deaf above 5000 cycles and
so remained quite oblivious to surface hiss, plops, and screaming
highs which came from some records.
It is well known that hearing at high frequencies falls off with
advancing years, but constant use of the ears in listening tests
delays the decay.
The September, 1956 issue of Wireless World contained an interesting
article on age, hearing, and hi-fi, entitled "Too Old at -?" by
M. G. Scroggie, who said that those of us who are not so young as
we were may be wondering why we should spend a lot of money on equipment
for reproducing frequencies we cannot hear. Some measurements made
on a few individuals by Mr. Scroggie are reproduced in Fig. 3, the
numbers against the curves indicating the ages of the people tested.
Frequencies below 1000 cps are omitted because no significant differences
After studying these curves, we decided to make a few tests ourselves
on members of our staff, but whereas Mr. Scroggie used moving-coil
headphones, we used moving-coil speakers, and this may account for
the fact that our results showed much better standards of hearing
at the high frequencies than did those of Mr. Scroggie and previous
investigators. (After all, it is more natural to listen with two
ears open to the air than with clamped-on headphones.)
A 3-inch unit with aluminum voice coil and light Bakelized cone
was used as the sound generator. Although not flat, the response
goes up to 20,000 cps (see Fig. 4) and the unit should be at least
as good as a headphone. I was astonished that all those tested -
ages between 20 and 46 - could actually hear 18,000 cycles (usually
with a boost of 50 db or more) as I am stone deaf in that region.
Now there are three people whose hearing and tonal judgment I
have always rated very highly when assessing speaker performance.
They are (1) my daughter, age 22; (2) our works manager, Mr. E.
R. Broadley, age 46; and (3) myself. Please do not take the inclusion
of myself as a sign of arrogance or conceit. We all think that what
we hear is right because we never hear anything else.
As a matter of interest, response curves of these three subjects,
prepared by Mr. Cooke, are shown in Fig. 5.
As already mentioned, Mr. Scrog-coil and light bakelized
cone was used phones, no doubt in a very quiet room, and in such
circumstances the threshold-level Fletcher-Munson curve gives appropriate
Our experiments were made without headphones in a laboratory
where slight background noise may be expected to produce some degree
of masking at low intensities. The results have therefore been compensated
by the Jensen threshold curve for a critical listener in low noise
level. (Jensen Technical Monograph No.3, page 5, Fig. 5.)
These tests show that it is possible for a young person of 22
to hear perfectly up to 14,000 cycles and quite well up to 18,000
cycles, Our sales director, Mr. Escott, age 31, and Mr. Cooke, age
32, kept within 15 db of this standard up to the 18,000 cycles limit
imposed. Although I can actually hear 14,000 cycles, I was shocked
to learn that I am some 90 db down at this frequency. The most interesting
ears belong to Mr. Broadley, whose acuity is below mine up to about
10,000 cycles, but then remains very even up to 18,000 cycles, in
spite of his 46 years. He has been making and testing loudspeakers
along with me some 25 years, and I rate his judgment of performance
The general conclusion, as a result of these tests, is that loss
of hearing with advancing years is frequently not as bad as has
so often been assumed, and the faculty of hearing - in common with
many other human accomplishments - is preserved by regular exercise
or practice (like playing the piano or knitting).
Fig. 5. Hearing curves taken with speaker held a few
inches away from the right ear. Curves are corrected for
loudness contour and are smoothed below 3000 cycles. Curve
(A) is for Miss Briggs. age 22; curve (B) is for G. A. Briggs.
age 66; and curve (C) is for E. R. Broadley, age 46. See
It is a pity that deficiencies in hearing cannot be adjusted
by "spectacles" which are so easy to prescribe for the eyes. Deaf
aids are little better than resorting to any port in a storm.
Quality No.6: Few people hear equally with both ears, but I believe
the natural tendency is to adjust the balance by turning the weaker
ear towards the source of sound, so that quite wide variations could
exist in one pair of ears without disqualifying the owner from a
shrewd exercise of tonal judgment.
Quality No.3: As with the gift of perfect pitch, the main basis
of tonal discrimination is memory, coupled with the ability to hear
and recognize resonances, harmonics, transients, and all the other
qualities which go to make up a musical picture, plus a sensitive
reaction to any form of distortion. An appreciation of music and
regular concert-going to keep the ears fresh are obvious advantages.
Anybody who unwittingly plays records too loudly or too softly is
disqualified from the start, and it does not matter whether his
amplifier is 10 watts or 100 watts. The "larger than life" platoon
cannot be admitted into this select company.
Again in common with the gift of pitch, you either have tonal
judgment or you have it not, and it is easily recognized in listeners
when demonstrating sound equipment to various people, in spite of
enormous variations in preference and taste. A spark of the talent
- and talent it undoubtedly is - can develop into a flame by regular
I suppose the most skilled in the art are recording engineers
who almost daily compare live with recorded speech and music and
can recognize on a monitor speaker which piano out of a half a dozen
studio models is being played. My complaint is that recording engineers
hardly ever write about their activities (probably due to hush-hush
policy) so views on the subject are left to be aired by semi-skilled
but interested parties like your humble servant.
The most difficult application of tonal judgment - after recognizing
that something is wrong - is the ability to recognize where the
trouble originates. Poor recording, bad studio acoustics, line distortion,
antenna or reception faults on FM, pickup distortion, amplifier
faults, speaker trouble, listening room coloration, wrong setting
of playback characteristics, wrong volume levels; these and many
other sources of error need watching before final performance can
be fairly judged.
For instance, the quality from FM at its best is so good that
any shortcomings in the quality of program material are ruthlessly
exposed on wide-range reproducers. A poor record via FM may sound
as though the loudspeaker is out of center, and may actually sound
better on a small speaker in a resonant cabinet than on a hi-fi
So we will conclude this article by stating that tonal discrimination
is the most vital quality of the ear in audio activities, and that
it involves placing a source of distortion quite as much as noticing
it. In short, do not always blame the loudspeaker.
In our next article, we will have a look at room effects.
(To be continued)
Posted December 1, 2014