Hiroyasu Kondo
Kondo-San was founder of Audio Note and Kondo Audio Note. I will not get into the history of the split with Audio Note UK. This is obviously not a definitive history as you can get that on the internet pretty easily. In brief Kondo-San worked for Teac and CBS Recording after college but he left CBS to form his own company in 1979 called Note and later Audio Note. Kondo did things differently and has influenced many builders to come. He was called the Silversmith because he wound transformers and capacitors with silver. He did a tremendous amount of research into building with silver. He was also an early fan of single ended, no feedback, directly heated triodes, alnico and obviously silver. Of all the Kondo gear I have researched I'd really like to here a Kondo cartridge which uses alnico and silver wire so you might as well also use his famous MC SU. Although part of me does not want to know how good that can sound....
I first learned about Kondo years back when I first researched single ended amps. I bought my first SET in 2001 so I was behind the times. Anyhow what I liked about Kondo was how he talked about audio. He sounds like what he is the son of a priest born in a Buddhist temple turned electrical engineer. Here is a collection of his essays.
MY THOUGHTS ON HI-FI
by Hiroyasu Kondo, Audio Note Co., Ltd., Tokyo
Translations by Hiro Yoshizumi, Sibatech Correspondent in Calgary, Canada
by Hiroyasu Kondo, Audio Note Co., Ltd., Tokyo
Translations by Hiro Yoshizumi, Sibatech Correspondent in Calgary, Canada
Part 1 (written early summer, 1999)
Particles and Wave Motion
Albert Einstein said that motion is energy. I believe that motion
is sound. I am all the more convinced of my belief when I listen to the
swelling mass of sound in the mildle of Wagner's Tannhauser overture.
Especially so when listening to the same music performed by the great
maestro, Arturo Toscanini at his last concert of April 4,1954. which
sounds as if the particles of the sound were colliding with one another
and whirling in a thunderous march. It seems to me that those particles
made unimaginable movements. I can easily put myself in that scene where
the 87-year-old maestro was giving everything he could to his farewell
performance and the orchestra was responding to its fullest capacity.
Sound
is said to be propagated as wave motion. This is only true in a large
room with no obstruction. In reality, however, sound waves move in much
more complicated way, colliding and jostling here and there, sometimes
in a whirl. We audio engineers should try to visualize in our head how
the sound waves are behaving, which cannot be explained by electrical
theory. There seem to be still countless unknown factors challenging
audio engineers. The more you think about audio, the deeper it appears
to become.
Solemn Sound
Two hundred Zen monks
begin prayer at five o'clock every morning at the Soji-ji, the head
temple of Zen Buddhism. The monks sitting in the left and right files
serenely recite sutra-chanting. What a solemn tone! This daily ritual
invites people to the world of nirvana. What should I do if I am
requested to express this solemnity with the sound reproduction
equipment?
First off, I must think of how to collect the sound.
According to the current recording method, a number of microphones would
be placed in various locations like chessmen. But I am skeptical about
this method, primarily because the more microphones are used, the more
emphatically the original sound near the microphones is recorded, thus
disturbing the sound wave harmony that most counts. Just imagine the
noise emitted from a twin-engine plane. It may sound like "Brrr...",
which is produced by subtle differences in frequency. Most musical
instrumients or vocal congregations always produce "difference tone". It
seems to me that this gentle trembling vibrates harmonics, further
producing chords and as the result, a beautiful tone. If you want to
produce a beautiful tone, you must first think of the mechanism in which
it is produced.
Analog Sound Is Digital Sound
The
analog disk does not always mean to have analog sound, nor the digital
disk digital sound. To me the audio systems now available on market
sound like digital even in their analog-processing stage. Each note
sounds as sharp and acute as the square wave. It is Iike digital photo
prints showing every detail of the object so clearty. Its first
impression is superb and its resolution is of first rate, yet I wonder
if this is the royal road to audio.
The kind of sound that I
want to produce is such that its individual particles might have
correlation. It is easy to produce so-caled "mellow" sound by choosing
proper parts and circuits, but this "melow" property is tricky. It is a
technique to gradate boundary lines. Vacuum tubes of 30 years ago
happened to produce such a sound and this trend still continues. If any
change ever occurred, it can be said that digital-like sound has been
added. I cannot agree to this trend. I want to produce a sound in which
its individual particles may radiate energy into the ambient space just
like the sun and fuse into one. After all, I think I must go back to the
stage of picking up sound.
Sound of Electron
Have
you ever seen the movements of electrons? The textbook says that the
electrons move around the protons with a furious velocity. Sometimes I
can vlsualize those movements very clearly. They are the behaviour of
the thermoelectrons. The sound produced by the efficiency-oriented
vacuum tubes is heavy whle the one by the vacuum tubes of simple
structure is transparent. I imagine that this difference might lie in
the relationship of the magnitude of the emission to the plate voltage.
The thermoelectrons float around the heater or cathode like a sea of
clouds. The bigger the emission, the more the thermoelectrons. Each
thermoelectron must be separated from the clouds and be made to reach
the plate. This process is related to the voltage applied to the plate.
Let's
think of the structure of the pentode tube. Electrons overflow from the
cathode, forming huge clouds. As the primary grid with a fine mesh
controlling the electrons stands up nearby, the floating thermoelectrons
are at a loss with the electron and grid, both negative. It seems to me
that this state might have something to do with the "melow" sound
produced by the pentode tube. Then, how can you reduce the floating
electrons? In conclusion, there will be no alternative but to adopt a
coarse mesh for the grid like VT-C and raise the plate voltage, using
the directly heated triode. But now the heater becomes shaky, rattling
the electrons, which is to affect the sound. How difficult audio is!
Part 2 (written in summer, 1999)
Sound of Transformer Part 1
Those
who have studied electricity have little knowledge of transformers,
because school usually teaches only industrial-use power transformers.
Therefore, audiophiles or audio engineers are forced to study
transformers through Hi-Fi specialty magazines. Even those publications
do not give much space to articles on transformers. Is this an
indication that audio transformers are a history? Certainly, the
transformer has some inherent problems such as mu-linearity of magnetic
core, distortion of exciting current, and Barkhausen noise. Fastidious
theoreticians cannot stand these kinds of problems. Cost-conscious
engineers try to avoid transformers and design circuits consisting of
only capacitors and resistors. Transformers were excluded from
electrical circuits. I think this is wrong. I still believe that
high-quality transformers produce nice tone.
I can quote a number
of good examples. At broadcasting stations, for one, sound signals are
transmitted through tens of transformers from their entrance to exit. If
the transformer is the root of all problems, TV and FM stations are to
be delivering terrible sound. But actually their sound is not bad. Why
is that? I want to answer this question.
Sound of Transformer Part 2
It
really interests me how tone quality changes when the sound passes
through a transformer. The transformer can be regarded as a filter with
time constant in the low and high frequency ranges. This explains why
audio engineers were greatly concerned over expanding the frequency
response in that prime era of transformers. Even today I fear to leave a
transformer on for a long time, because I remember that over-heated
power transformers caused fire from time to time. It was quite a task to
manufacture high-quality transformers when both iron cores and wire
materials were of inferior quality. As the result of having experimented
with many different transformers I can classify tone quality into two
categories: soft tone and hard tone. A major factor deciding tone
quality lies in materials of wires and cores. Let's start with core
materials. There are permalloy for small signals and silicon steel for
medium and large signals. If a certain kind of core is good for all,
this would be the most ideal. In reality, however, a proper core must be
chosen depending on the initial responding speed of magnetic flux in
the small range and the maximum magnetic flux density. Permalloy and
silicon steel produce respective different tones.
Sound of Iron Core
Iron
cores are used for transformers. As the signal transformer has a
voluminous winding, signals directly pass, even without the iron core,
in the high frequency range. Problem is the low and medium frequency
ranges. Here lies a problem inherent in the transformer. The property of
the iron core is first judged by its hysteresis curve. But this is
merely a criterion, because measuring is done on the winding iron core.
Next, it is judged by how much magnetic flux can pass through it and
where the saturation point is. While these procedures are enough for
power transformers, further studies are required of for audio
transformers. In case of the power transformer transmission of minute
signals does not have to be considered. In order to transmit minute
signals an iron core is needed that sensitively reacts in a very low
magnetic field. To this end, a core named "nickel core" containing 45 to
78% nickel is usually necessary. A problem with the nickel core is its
low density of the maximum magnetic flux. Furthermore, there are so many
different kinds of nickel cores, each producing different tones.
Generally speaking, the less the nickel content, the harder the tone. On
the other hand, the tone produced by silicon steel (OPT) tends to be
soft. The tone has little clear boundaries, because magnetic flux does
not occur in the small signal range.
Rendezvous of Transformer and Silver Wire
There
are many factors that might decide tone quality of the transformer. In
particular, winding materials play an important role. In comparison of
tone quality between OPT for the single-ended amplifier and that for the
push-pull amplifier, the former seems to produce clearer outline of
tone. I can think of various factors to explain this difference, but
there is one thing that nobody has so far taken notice of. It is whether
there exists any magnetic field generated by the direct current applied
to the winding material, depending on OPT for the single-ended
amplifier or that for the push-pull amplifier. It seems to me that this
magnetic field generated by the direct current might make the difference
of tone quality between the two winding materials. In other words, this
is the relationship between the magnetic field and the behaviour of the
electron. Experience tells that when you wind wire around a
horseshoe-shaped magnet and send signals through it you would notice a
more conspicuous change in tone quality due to the difference of wire
materials than when there is no magnet. Repeated experiments show that
the "silver wire" produces less changes. The "copper wire" usually make
the tone coarse. If you wind silver wire around the transformer the
conventional tone changes dramatically. Now, the statement that the
transformer deteriorates tone quality seems to be rootless. This fact
cannot be denied just because electric theory has not clarified the
relationship between magnetic field and silver yet. Sooner or later,
people will start looking squarely at the reality. I might add that
direct current magnetic field still remains in OPT for the push-pull
amplifier of Audio Note Japan.
Part 3 (written in late summer, 1999)
High Voltage Resistant FET Amplifier
The
first product made by Audio Note Japan was a pre-amplifier, for which I
used a high voltage resistant FET developed by Mr. Shigeru Terada in
cooperation with Shindengen. The field-effect transistor was usually
used as a voltage element like a vacuum tube. But because of its big
distortion this transistor was not used for an amplifier pursuing a high
performance. When used as a voltage element in place of a vacuum tube,
FET showed a Vp-Ip curve peculiar to the semiconductors and profusely
generated second higher harmonics. Moreover, its low voltage resistance
(about 50V) made FET difficult to be used. Then, Mr. Terada developed a
FET that could resist 200V. This phenomenal improvement made the job of
amplifier designing much easier and expanded ranges of low distortion. I
designed a pre-amplifier using this FET, which brought about
"Meister-7", alias "M-7". The photo below shows the first unit of this
model. The large box on the top contains oil-condensers and chemical
condensers for the power source. After that, I designed a more compact
"M7-II" with low distortion, for which I chose a Cascode circuit in the
amplification stage. This circuit contributed to success in reducing
leakage current dramatically and at the same time canceling distortion. I
used an oil-condenser for the coupling condenser. The discontinuation
of production of FET called a halt to the production of M-7, which had
reached 100 units. I hear that some units are still being cherished.
Emergence of "Ongaku" Amplifier
Why
is the tone of the vacuum tube amplifier favored? One of the factors in
terms of the circuit will be its ability to handle high B-voltage.
Among the tubes available to us today, "211" can take as much as 1,000V.
"211" is equipped with a coarse grid and has very few stray electrons
thanks to its low bias, which means that this tube has excellent
linearity of Vp-Ip characteristic. In fact, the mu (amplification factor
= 4) linearity is flat. Everybody might think that he can design a high
performance amplifier only if he uses such a fabulous element. I made a
number of 211-S amplifiers, but was not thoroughly satisfied with their
tone quality although they showed excellent characteristic. They lacked
'tenderness' of 2A3 and 'depth' of 300B. After a succession of trial
and error I reached a conclusion that the problem had something to do
with the tone quality of the circuit elements used for "211" that leaves
little ambiguity. Therefore, Mr. Yasuhiro Oishi helped me wind silver
wires around the silicon steel. The result was just incredible. What a
marvelous sound! Encouraged by this discovery, I next made silver-plated
condensers. These inventions produced the kind of tone that nobody had
ever experienced before, and Mr. Masahiro Shibazaki of Sibatech Inc.
aptly named the amplifier "Ongaku" (music).
Tchaikovsky's "Pathetique" Symphony
What
an introvert music! Its mood is transformed all of the sudden after the
second theme of the first movement. I tried to make my own
interpretation of this music. A young man starts on his journey of life
with anxiety. He fights to the limit with himself and the world. A
glimpse of light rescues him and he wins. But there is little time left
for even a transient relief. Now he must confront underground spirits.
The roaring timpani spellbinds listeners with fear. In time he
reconciles with the spirits and calmly falls into sleep with a deep
sigh. This symphony is full of strange orchestrations. Brass instruments
always follow bass clef of woodwinds. Low string instruments sound
groaning throughout. A thunderous fortissimo is followed by an
impossible pianissimo. Ritardando and accelerando are alternately and
obstinately repeated. High performance techniques are required of the
orchestra, and preposterous technology is demanded of the sound
reproduction equipment. I seriously wonder if mediocre amplifiers and
speaker systems can fully reproduce the consideration that Tchaikovsky
intended to pay to that delicate music. At this point of time I am
confident that my amplifiers, speaker systems and cartridges can convey
the exquisite shades of the music more deeply and faithfully than any
other equipment. My equipment stands on its own.
"211" and "300B"
The
performance of "300B" is almost comparable with that of "211'. Both
were American inventions at the time when that country was still
enthusiastic in making of consumer products. In a way '300B" is easier
to use, because it only requires 400V for B power. It was Japanese
audiophiles that made the world recognize the superb tone of "300B". If
you make a 300B amplifier you would understand that it has a unique
tone. Someone said that the secret lies in in its structure in which the
filament is hung down. You will see a spring hang the filament.
Remember that the echo machine was of spring-type. That echo machine was
relived inside a vacuum tube. When you hit the glass, it sounds somehow
convincing. The material of the heater makes the difference between
"211" and "300B". "211" is filled with thorium to increase the strength.
Mind you, this tube had been intended for military tanks! The
difference of materials for the heater affects the tone of the
amplifier. The tone of the 211 amplifier is crisp and firm. I should add
that Golden Dragon's 300B shows satisfactory electrical characteristic.
I am proud to say, because that tube is equipped with the tungsten
invented by Japan's most advanced technology.
Part 4 (written early autumn, 1999)
How to Listen to Toscanini
LP
records were invented around 1949, when tape recorders were put into
use for broadcasting. Experiments in stereo recording started around
1955. The first half of the 1950's saw a dizzying pace of innovations in
the music world as well as tremendous advance in quality of sound
reproduction. In particular, the invention of LP records can be compared
to that of Edison's wax-coated cylindrical gramophone in its impact. LP
records were invented by CBS Laboratories' Peter Goldmark and other
engineers. When I visited CBS Laboratories in 1970's I saw the first
cutter of LP records that was proudly on display. The cutter was a
lathe-improved machine, thus being called "Lather". CBS approached their
rival RCA for the new invention. CBS and RCA were the world's leaders
of music recording at that time. David Sarnoff, the then president of
RCA immediately instructed his engineers to develop compact, light
discs, and as a result EP records were born. In time the application of
LP and EP records was divided up in such a way that LP records were used
for long-playing music and EP records for short-playing like popular
music. I hope readers understand the background of such a phenomenal
era. History repeats itself. You never know if large-size records might
be revived in the future.
Episode 1
"I am eager to
attend your performance at Bayreuth as Fuhrer of The Third Reich." "My
music is not for a devil." These are the words in the letters exchanged
between a modest Hitler and Great Maestro Toscanini. 1930's saw a number
of serious problems smolder the world. The Empire State Building was
about to shake off its shameful nickname, "The Empty State Building."
You will notice interesting street scenes if you walk in Duomo of Milano
in the evening. People are engaged in feverish debating here and there.
Certainly, Italian people like to debate on anything. Toscanini
courageously stood up for democracy at those difficult times. In a later
year, said Albert Einstein, "You are not only the world's greatest
conductor but also proved your noble character in fighting fascism."
Toscanini left his footmarks of historical importance in the European
music community in 1930's. In January, 1937, he made a crucial decision,
which led him to working exclusively for an American broadcasting
station.
Socony Oil Company
It came to my notice
that a Toscanini's CD which I recently purchased gave a credit to Socony
Oil Company as its sponsor. Toscanini who had wanted to retire moved to
America very grudgingly. Therefore, they treated him with their senses
honed. To RCA money was no object in founding a world-class orchestra
for The Great Maestro. Socony Oil Company became the sponsor for the
newly-founded orchestra's broadcasting. Remember, the American
prosperity was brought about by her infinite underground resources. We
should consider it quite lucky that irreplaceable music assets were left
behind. About the same time an epoch-making radio receiver that was to
be called "Superheterodyne receiver" was invented by Edwin H. Armstrong,
an American engineer. The new receiver made great strides in improving
the receiving quality, but the reproduced sound was not entirely
satisfactory yet. So-called magnetic speakers were prevalent at that
time. RCA worked very hard to make magnetic speakers reproduce
Toscanini's sound at its best form with the result that the notorious 8H
Studio came into being. Reverberation was minimized in the studio. If
you listen to Toscanini's historical performance of Beethoven's Fifth
Symphony you will hear individual instruments distinctively. But you
will also realize that it was recorded in a studio of dead sound. A
Great Maestro's plaque is still displayed at the entrance of the 8H
Studio.
Ribbon Microphone
The microphone setting
that looks unique from today's standards consists of 3 microphones in
the upper location: the main microphone in the center, the spare one at
the right end and the one for shortwave at the left end. They are all
ribbon microphones made by RCA. Ribbon microphones are still in use. For
example, they are used for AM broadcasting, because they are most
appropriate for recording vocal sound clearly. A ribbon microphone is
constructed in such a way that an ultra-light diaphragm is hung down in a
strong magnetic field. It pliably follows soundwave just like willow
leaves rustling in the wind. Trouble with it is that thanks to its
extreme softness rather than its lightness the oscillatory frequency
resonance is very low and the low frequency characteristic rises up.
Besides, there is no electric generation seen in the horizontal
direction of the microphone. Here you will notice the tone
characteristic of the reproduction of Toscanini's music. He arranged the
first violins at the left of the stage and the second violins at the
right, by which the expanse of strings and balanced harmony would be
materialized in a concert hall, but the 8-letter directional microphones
were not as effective. Presumably, that is why the microphones were set
up very close to the ceiling. A ribbon microphone has its frequency
characteristic only up to about 7KHz, thus cutting off thrilling high
tone. However, it beautifully records the sound of low strings and
percussion instruments.
Part 5 (written in July, 2000)
Intelligence of Mankind - Cutter Head
The
cutter head is a device indispensable to production of analog discs.
The world's first cutter head with which Edison recorded "Saint's Name
had the same structure as the SP soundbox. With the advent of the
stereophonic recording the cutter head made astonishing progress. As is
usual, a race for technical dominance occurred between the V-L method
and the 45-45 method. In the early stage there was a so-called
mono-compatible stereo in which mono cartridges were used for
reproduction. This was invented by an economy-minded European. In no
time Westrex, a subsidiary of the then world's top electric manufacturer
came out with the 45-45 method. The difference of mere 45 degrees gave
the decision in favor of the 45-45 method. Just remember that sound
grooves are cut horizontally in the monaural recording. In the 45-45
method "L" and "R" are cut downward with an angle of 45 degrees
respectively. Harmony signals are recorded in the horizontal grooves
while difference signals in the vertical grooves. The respective signals
of "L" and "R" that are not independent form a vector resultant. The
signals are never divided up. When you look at the grooves of an analog
record through a microscope you see nothing but uneven protuberances. It
is indeed amazing that these grooves contain information of all the
instruments of an orchestra. However, you might say that you do not need
to take such a trouble as analyzing sound waves just to enjoy listening
to music.
The cutter head is able to present complex music
information in a visible form. See the the photo below. This photo shows
the grooves of a stereo record. Notice the circles area. The zigzag
line representing horizontal signals shows a harmony signal that is
monaural, and the amplitude shows the volume. Furthermore, the area
where the lines are thin or thick represents vertical signals, or
"difference signals" , showing the expanse of sound. Then, where are "L"
and "R" signals? They are contained in the walls of the grooves. Their
look is just like the Hakone mountain range. The frequency of horizontal
and vertical signals is recognized by the number of plus and minus
cycles per second. The standard of describing a signal strength in terms
of speed is 5 centimeter per second, which means that sound grooves are
cut at the rate of 5 centimeter per second.
Westrex 3C
Let's
look at the structure of the venerable Westrex 3C cutter head. As it
requires a fairly big power to cut wave forms on a soft "lacquer disc",
its cantilever has about 5mm thickness. Its characteristics feature
minimum resistance and extremely big mechanical resonance. The engineers
had to decide where they should set the center of the resonance. Music
information is centered in the midrange and human sense of sound is
centered at 1KHz. So, let's set the resonance point at 1KHz. Thus, a
decision of historical importance was made. Naturally, the tone quality
at this kind of characteristic was poorer than that of the telephone.
First of all, the frequency had to be made flat. The motional feedback
(MFB) helped to solve this problem, but at the same time posed other
problems. The first problem was uncontrollable frequency characteristic
in the range beyond the ability of MFB. The second was power required of
the lower and higher ranges. At the recording of pop music the sound of
drums and cymbals directly recorded "on mike" presented very difficult
conditions. But these problems were solved in a unique way.
Cutter Amplifier
There
is a vacuum tube called EL-156, which was developed for the cutter
amplifier. Thanks to EL-156, power was raised from 60W to 100W. RIAA
characteristic demanded power. This characteristic that should be
correctly called the reverse RIAA characteristic rises as much as 20dB
at 20KHz. If, therefore, 1KHz requires 10W, 20KHz needs 100W. Ampliers
as powerful as 600W are available today. It is incredible that a power
of 600W goes through that small drive coil even if momentarily. Some
music records such a huge current as 50A on the ammeter. So, the
engineers used a circuit breaker, then the sound got murky. They found
that it was caused by "chattering" at the contact of the circuit
breaker. You never know what will happen if as much as 50A of current
runs.
I should add that only two companies were capable of
manufacturing the cutter machine in the world. The cutter head was
produced by Westrex, Neuman and Ortofon, but the cutter machine only by
the said two. Westrex is an American manufacturer while Neuman a German
manufacturer. Their products are distinctly different in tone
characteristic. One of the solutions for compensating the problem of the
cutter head was "half-cutting", whereby the disc revolution is reduced
by half and so is the tape speed of the taperecorder.
Part 6 (written in autumn, 2000)
Sony C-37A
Not
many people will deny that Arturo Toscanini, Wilhelm Furtwangler and
Bruno Walter are the most prominent conductors that the 20th century has
produced. It may be interesting to know how these conductors behaved
towards "Machine". Bruno Walter drove a car himself in an era when the
automobiles were regarded as a status symbol of high society. Arturo
Toscanini had a chauffeur named Emilio. It was to Wilhelm Furwangler
that Richard Straus declared "Never will I ride on a car you drive." In
his later years Bruno Walter lived in the balmy Los Angeles and actively
made recordings with John McClure. They used multi-microphones, among
which Sony C-37A was most frequently adopted to effectively produce from
a less than 50 orchestra the same volume as a full member orchestra.
Walter said, "this microphone conveyed my music."
Neuman M-50
It
may be safely said that the principles of microphones and speakers will
not change forever even in the digital age. Current microphones were
first produced around 1950. Particularly noted was Neuman's condenser
microphone. Germany, though defeated in World War II, retained her
engineering ingeniousness. One year after Sony introduced CU-1 (C-37A),
Neuman M-49 was born to conquer the recording studios all over the
world. With the advent of the stereophonic age Neuman microphones gave
birth to the "brilliant" recording tone. I never forget that
characteristic "mellow" tone. Neuman next brought out M-50. Its
structure was about the same as that of M-49, but surprisingly, they
crammed the microphone unit in a globe-shaped ball. As a result, smooth
frequency characteristic and controllable medium/high tone were
achieved. My physics teacher used to say, "Round off the angles." The
same may apply to audio.
Ribbon Microphone
Microphones
are basically either non-directional or 8-figure directional.
Therefore, there is no rationale in pursuing "uni-directional" for
microphones. Usually the back of vibration element is covered, which
explains why the tone produced sounds kind of murky. The ribbon
microphone, in particular, due to its audio tube called "labyrinth",
cannot avoid bouncing or reflecting effect, thus producing
characteristic murky tone. Just ask people which they think clearer in
tone, ribbon or condenser type. 99 of 100 people will go for condenser
type. You may then think ribbon type is now histroy, but it still
survives in some areas. AM radio is one. The gist of AM radio is voice.
That is why ribbon type that has good separation is appreciated by AM
radio people. A certain ribbon microphone captured my attention. It was
Aiwa VM-18. As its ribbon area is small, so is the substance. As a
result, it is very compliant to incoming sound even in the high tone
range. It is doubtful the frequency characteristic is rightfully flat.
It sounds more natural to me if it is a little raised around 10KHz when
"off-mike."
Improving of Ribbon Microphone
The
ribbon microphone has such a structure that a duralmin foil of about
30mm in length, about 5mm in width and about 10 micron in thickness is
hung in a strong, criss-cross magnetic field. The ribbon is notched so
it may move freely. While I studied the tone of the ribbon microphone I
discovered that there were two problems intrinsic to the ribbon
microphone. One problem is the noise of the ribbon itself. The ribbon
microphone uses a ribbon made of duralmin that is anti-corrosive. The
ringing noise of duralmin cannot be shaken off. This noise is what you
hear when you crush aluminum foil. That is a minute split resonance.
That understood, I tried silver foil of 3 micron. Silver foil did not
emit that stimulating split resonance. Another problem lies in the
matching transformer. Vibration is produced by ultra-low resistance. A
transformer is indispensable to raise the generating voltage to make the
small resistance practically usable. However, it is this transformer
that prevents the tone of the ribbon microphone from fully performing
its merit. For the core of the transformer I chose a material in which
magnetic flux goes through in ultra-low magnetic field. For winding coil
there was no alternative but silver coil. Transmission characteristic
in the minute level of the silver coil totally changed the tone of the
ribbon.
A youtube video of current president of Kondo that is in Japanese but has wonderful eye candy or ear candy.
A very good interview with Kondo http://www.stereophile.com/interviews/597kondo/
Of course Joe Roberts http://junkyardjukebox.blogspot.com/ published an article by Hiroyasu Kondo Fall 1992 http://www.enjoythemusic.com/magazine/sound_practices/2/ongaku.htm
Of course Joe Roberts http://junkyardjukebox.blogspot.com/ published an article by Hiroyasu Kondo Fall 1992 http://www.enjoythemusic.com/magazine/sound_practices/2/ongaku.htm