The Giant Loudspeaker Housing...

Hi to everybody,

today I would like to tell you about a never ending running rivalry in the hifi-world. Probably everyone who reads here knows he competition about the most efficient loudspeaker designs in history. All these well known speaker designs are huge space occupying concepts, enclosures as big as furniture. Everybody who knows about the facts knowns, only big cabinets, mostly horns speaker designs, will do the best efficiency. This article is not meant to serious and more dedicated to entertain owners of large volume Altec, Western Electric or Tannoy enclosures.

Owners of these classic speakers will learn now, there are some much bigger professional concepts existing, than they did know. And even when not well known at all, they are made for highly professional demands.

Two HF-horn units per opening in the first four rows and one MF-horn driver in the middle three rows, combined with LF-drivers of 15'' size in the lower four rows, all with funnels made from concrete.

The HF-units share one caving

For many of us such speakers have to score as a one to the models from the "Voice of the Cinema " range, or the huge WE Cinema Systems like the WE 15 and similar types. Even the described "Tannoy Autograph" speakers use cabinets of such dimensions for a competition. But all named examples are "small-scale" transducer for home use, when compared against the speakers I want to present here now.

Each HF-unit is connected to three drivers

In a tv documentary I recently saw a reportage about Taiwan. In this film it was shown how the politicians tried to liberate from the historic guardian of the People's Republic of China. To get rid off the electronic eavesdropping from the mainland they installed giant loudspeaker enclosures along the coast to China in order to drown Chinas directional installed surveillance microphones.

The enclosures are house sized concrete buildings with almost 100 different drivers installed in a multiplied molded horn funnel design. I do not know anything about real efficiency and the used amplifying systems, but taking the time into account, it must have been fed by tube amplifiers in the 1950ties.

So this is an invitation to collectors in the asian pacific area to get hold of  these installations, they are still intact. And there a lots of these housings around the western coast line. Maybe it will be a very exotic extension for your hifi collection to get the biggest speakers of all time, may be for the outdoor summer season in your park...?!

Read on soon, Volker

Billie Holiday – Long Playing Records on Verve Label

Billie Holiday (born as Eleanora Fagan at 7th of April 1915 died at the 17th of July 1959) was an african american jazz singer and songwriter. Billie Holiday was one of the most extraordinary singers of the 20th century.
She was one of the first black stars in the media business and the first foremost female jazz singer known to a wider even white skinned audience. Her distinctive delivery made Billie Holiday's performances instantly recognizable throughout her career. A master of improvisation, Billie's well-trained ear more than compensated for her lack of music education. Her voice lacked range and was somewhat thin, plus years of excessive drug use eventually altered its texture and gave it a prepossessing fragility. The emotion with which she imbued each song remained not only intact but also profound.

First release long play records from Verve label, in the background on the left side the extremely rare record  "The Mellow Side of...".

From that point of view her late recordings are some of the most extraordinary songs in all jazz music history. These late recordings are made by Norman Granz, the founder of Nogran Records (1946), later Clef Records (1953), which got 1956 absorbed into Verve Records. Verve was created just as the twelve-inch long playing album became the industry standard, its ten-inch counterpart for the most part discontinued. Holiday's late recordings on Verve constitute about a third of her commercial recorded legacy and are as popular as her earlier work for the Columbia, Commodore and Decca labels. In later years, her voice became more fragile, but it never lost the edge that had always made it so distinctive.
Holiday's autobiography, "Lady Sings the Blues", was ghostwritten by William Dufty and published in 1956. Dufty, a New York Post writer and editor then married to Holiday's close friend Maely Dufty, wrote the book quickly from a series of conversations with the singer in the Duftys' 93rd Street apartment. He drew on the work of earlier interviewers as well and intended to let Holiday tell her story in her own way. To accompany her autobiography, Holiday released an LP in June 1956 entitled Lady Sings the Blues. 

The album featured four new tracks, "Lady Sings the Blues" (title track), "Too Marvelous for Words", "Willow Weep for Me", and "I Thought About You", as well as eight new recordings of Holiday's biggest hits to date. The re-recordings included "Trav'lin' Light", "Strange Fruit" and "God Bless the Child". On December 22, 1956, Billboard magazine reviewed Lady Sings the Blues, calling it a worthy musical complement to her autobiography. "Holiday is in good voice now," said the reviewer, "and these new readings will be much appreciated by her following." "Strange Fruit" and "God Bless the Child" were called classics, and "Good Morning Heartache", another reissued track in the LP, was also noted positively.
On November 10, 1956, Holiday performed two concerts before packed audiences at Carnegie Hall, a major accomplishment for any artist, especially a black artist of the segregated period of american history. Live recordings of the second Carnegie Hall concert were released on a Verve-album in late 1961 called The Essential Billie Holiday. The thirteen tracks included on this album featured her own songs, "I Love My Man", "Don't Explain" and "Fine And Mellow", together with other songs closely associated with her, including "Body and Soul", "My Man", and "Lady Sings the Blues" (her lyrics accompanied a tune by pianist Herbie Nichols).

Late Release in 1961, but recorded live at Carnegie Hall in 1956, "The Essential Billie Holiday" the narrated autobiography "Lady sings the Blues".

The liner notes on this album were written partly by Gilbert Millstein of The New York Times, who, according to these notes, served as narrator in the Carnegie Hall concerts. Interspersed among Holiday's songs, Millstein read aloud four lengthy passages from her autobiography "Lady Sings The Blues".
The critic Nat Hentoff of Down Beat magazine, who attended the Carnegie Hall concert, wrote the remainder of the sleeve notes on the 1961 album. He wrote of Holiday's performance:
Throughout the night, Billie was in superior form to what had sometimes been the case in the last years of her life. Not only was there assurance of phrasing and intonation; but there was also an outgoing warmth, a palpable eagerness to reach and touch the audience. And there was mocking wit. A smile was often lightly evident on her lips and her eyes as if, for once, she could accept the fact that there were people who did dig her.

Several Verve covers are illustrated by the well known designer David Stone-Martin

Billie Holiday recorded extensively for four labels: Columbia Records, issued on its subsidiary labels Brunswick Records,Vocalion Records, and OKeh Records, from 1933 through 1942; Commodore Records in 1939 and 1944; Decca Records from 1944 through 1950; briefly for Aladdin Records in 1951; Verve Records and on its earlier imprint Clef Records; from 1952 through 1957, then again for Columbia Records from 1957 to 1958 and finally for MGM Records in 1959. Many of Holiday's recordings appeared on 78 rpm records prior to the long-playing vinyl record era, and only Clef, Verve, and Columbia issued Holiday albums during her lifetime that were not compilations of previously released material.

Early Verve "trumpeter label"  (icon by David Stone-Martin) with deep groove indention.

Lots of records are late published transcriptions of earlier 78 rpm recordings, these are mostly very poor transcripted to vinyl, but the worst quality comes from the early digitalized versions for CD release from the 1990ties. The most of them do sound very poor and thin. The only recordings of quite good sound quality are the Verve records taken in the LP era to be issued on vinyl. Here a quite realistic insight into Billie Holidays performance practice is reproduced. Some of them are previously released as 10'' versions with Clef Records, these first Verve releases are clearly identified by their "trumpeter label". The Nograns, the Clefs and this early "Trumpeter-Verves" are highly collectible, no question that they reach today already serious money lines. Some of them are live recordings and give a good idea of the presence and intimacy of Holidays performances at this period. Unforgotten is the recording taken in Los Angeles during a gig in a private club were you can here the airplanes of the nearby airport crossing the club. 
The long play Verve albums are the records with the best fidelity available from the Billie Holidays legacy. Amoung them is the studio record Songs for Distingue Lovers, the only true stereo recording of all of them. 

One of the best recorded albums from the Verve series, as far as I know, the only true stereo recording of all Verve albums with Billie Holiday.

Read on soon about other lady singers like Nina Simone, Abbey Lincoln or Cassandra Wilson, Volker


For further informations and discography look:



Notes:
"Full of lies, But It Gets at Jazz Great's Corre" San Francisco Chronicle. Retrieved July 31, 2010.
and some basic informations from wikipedia

A Record Washing Machine for the Vinyl Collector II

When I was staying in the US I did buy almost 1000 vintage first release jazz records. When I did come back to Germany I desperately needed to use a record cleaning machine. I was rethinking the design of the Keith Monks machines and decided that three motors for different tasks and a lot of details can be improved, beside these facts I wanted a more compact design to store it away when not in use. This brought me to the principle of cnc operated machines do work. A linear track for the sucking nozzle and one motor for all moving elements.

Here it can be seen how the angled gear does transmit the platter turns into the linear slide. The ball point lever positions the nozzle to the surface, while it gears the unit into transmission. Underneath there is the brush turned to the camera lens into dripping position, A row of holes opens to the record surface for the cleaning solvent. As well it can be seen the original filament for protection as first version.

Here in upright position the underside of the sliding unit can be seen. The brush with wholes and the felt padded nozzle.

I did use a ac-motor from a garage door with integrated gear box for the turning of the record. With this motor I had a speed of 60 turns per minute and loads of torque. I did use a former winding plate from a Revox tape recorder as platter for the records. The center spindle got a thread inside. I used a linear slide for industrial applications for guiding the nozzle over surface. I did further use a angled gear to transmit the turning of the platter to the advance of the linear slide. So it takes 30 seconds to move the nozzle from the inside groove to the outer rim. At the end of the slide the nozzle will be mechanically lifted off the record.

The Revox platters with laminated rubber discs to introduce the friction to the record and to prevent the label from the solvent

After pumping some solvent to the surface, the brush can be moved sideways and as well forward and backward to introduce the solvent perfectly into the grooves

For the introduction of the cleaning solvent into the grooves I do use the typical goat hair brushes from other cleaning machines underneath the linear slide. It is  mounted around a tubed axis, so it can be turned left and right with a lever. The tube guides the cleaning solvent coming from the pump through a silicone tube. The holder of the brush is perforated to one side, so that the brush in parking position will give way for the solvent over the surface of the record. Pushing the button for 2 seconds will bring the right amount of solvent on to the surface of the record. Turning the brush down and moving the record two turns forwards and two turns backwards will supply the solvent perfectly spread on the first side. After waiting for one minute to soak in I turn the motor on for at least 10 turns of every direction, before I start the sucking process.

The with felt rings improved nozzle is set into advance to suck of all solvent from the lever. This takes 30 seconds till it reaches the outer rim. There the nozzle will be automatically lifted off the record.

After this I push the sliding saddle into the middle of the record at the very left end. In this position I switch the turning motor on again. The lever will be pushed down, as a result the nozzle will be lowered into a perfect close position to the surface ( the nozzle is spring supported to keep contact). In the same act the lever will engage the carriage into the move of the turning motor. The geared transport of the linear slide brings the nozzle within 30 seconds to the outer rim, where it is automatically gets lifted off and disengaged. I open the knurled main screw to lift the whole unit into upright position. Now I can change to the second side of the record and start the whole procedure again.
With my machine I can clean and dry a records at both sides within 4 minutes. They are really clean and dry afterwards. It is working quietly, so quiet that I can proceed it during I listen to my records. I have built it very compact, so that I am able to lock it away, when I don't use it. Other advanced record cleaners are as big as record players, they need to be standing around. Mine is quite heavy (10 kg), but its compact box of 36cm hight, 36cm depth and 24cm width with a solid carrying handle on top. It has all necessary equipment in its lid, like a power cord, micro fiber textile and brushes. It is looking and acting like a professional functional service unit, which I like a lot better than the most "high end chichi".

After cleaning the first side of the record the complete sliding mechanic can be folded up.

Now I do use felt rings at the tip of the nozzle for the record protection. These give a much improved vacuum for the drying process. With the former filament I had a vacuum of -0.2 bar, with the felt rings I get up to -1 bar. So the record will come perfectly dried from the machine.

I use a standard recipe for the cleaning solvent, made from 70% destilled water, 29% isopropanol alcohol and 1% wetting agent. The felt rings are made from 100% woolen felt to prevent statics, but I am actually testing micro fibre pads to replace them. I have to punch them from felt mats, the micro fabrics have a more solid structure and disintegrate not that fast. I am testing a different formed tip, were a micro fiber cloth cover will be fixed with a metal ring.

I actually did built the machine just with a battery drill on top of my kitchen table. So, if I would have had better and more precise opportunities, like a mini lathe or a stand alone drill, the whole machine would have been made with much better precision, but with such archaic methods it is almost not possible. But I tried my best ;-), and it is reasonable made. So it is up to you to improve ...

Read on soon, Volker

A Record Washing Machine for the Vinyl Collector

Those who collect vinyl, foremost quite old vinyl, do not come around in the longer term to own a reasonable working record washing machine. There are now a number of very different functional units in the market. With different technologies the cleaning and the drying process is performed. Some of these devices are made very complicated, expensive, accordingly, these are then also sold for good money. Everyone buying old records needs to think about how valuable his record collection is going to be. How much effort is he willing to contribute to clean his records. Basically a cleaned vinyl record usually runs much quieter in terms of surface noise, also a freshly washed record with still slightly wet grooves sounds significantly better than the same without lubrication (still there are a lot of arguments for the old days "Lenco clean", beside its crystallization when dried in).

My cleaning machine is a compact unit with carrying handle on top, like a service box. All necessary equipment is hidden in the lid, like the ac cord and brushes. So it can be stored away when not in use.

Basically, several record washing machines differ mostly according to two different designs for the drying process: the point vacuum tip and the slot of 10 cm length, which sucks at the complete width of one record side. The cleaning process mostly is based on a cleaning solvent brought to the records surface with brushes or micro fiber clothes. In addition, there are as well machines which use a ultrasonic cleaning bath. A basic distinction between the cleaning technology and drying technology has to be made. The cheaper devices usually clean in a manual mode with cleaning solvents. which are applied by hand or supported with tools and turn the record (the well known Nitty Gritty models are since decades in the market). These machines use vacuum cleaner motors for sucking off the solvent through a slot of the length of one grooved side. The more expensive machines use pumps, turning motors for the record and dedicated mechanic precisely positioned brushes for a more comfortable cleaning process. All these machines do their job quite good, Their increase in the price range is a increase to comfort and speed, but they are very noisy (vacuum cleaner motor). It is impossible to use them during the listening to music.

Some more meticulously designed devices use real vacuum pumps with precisely point-operated sucking nozzles to ensure highly improved cleaning results. Here, the suction pipe must be accurately guided to obtain a improvement, but greatly complicate the effort. The "Keith Monks" or similar devices, like the Loricraft set the value for years. Meanwhile, there are now devices, which drop the records in a solvent bath to thereby use ultrasonic waves for the cleaning process. Some use warm blown air for the drying of the surface. I cannot believe that this will not blow dust particles again into the grooves.

All advanced machines are quite expensive, far in the k-dollare range, so it is a big investment to go for. Some people will argument, the amount is nothing comparing the value of the records, but still a Keith Monks will be more expensive than the most record players in the market. So, if you count your money, only one option will bring you the clean records, you need to build one for your self.

I did so some years ago. When I started to think about (around 1995), I started with a simple wooden box, a build in ball geared cranked platter of label size beneath a sealed under sided slot in the box connected to a tight adapter for the vacuum cleaner to suck of the cleaning solvent (the Nitty Gritty design). It did work quite well, the alcohol/water ruined my vacuum cleaners motor pretty fast and it was very very uncomfortable and noisy. So I decided to built something more complex, like the Keith Monks. For this principle a strong old idler wheel turntable is a good base (like the original Monks). Here are the cheaper ones with 78 r.p.m. with strong torque on demand. The turntable will turn the record for cleaning and drying. Than a pump is needed, which will precisely pump the amount of solvent on to the surface needed to clean one side. In the 90ties the windshield wiper pumps of the well known Citroen 2CV have been a perfect solution. They were available as regular spares and they were cheap. These pumps were pure mechanical ball operated systems, one push and the liquid was exact dosed at the surface. Today I would go for a Ulka pump from almost any espresso machine, they will pump in three seconds exactly the right amount of solvent to the surface, but need AC power, either 110V or 220V. But you can as well bring the cleaning solvent on with a independent spray pump for gardening, this will dramatically reduce the outlay of the machine.

Here you can see the basic first design. Upper left the platter for the record and the fixing screw. Upper right the the slider with sucking nozzle (ball lever op.). The early stage design with teethed wheel lever to dose the filament advance. At the right end of the sliding unit you can see the lever to position the brush and the silicon tube introducing the cleaning solvent through it.
Down from left: the vacuum meter, the push button for the solvent pump, the switch for reversing the direction and the mains switch for the motor.

Once you have pumped the solvent to the surface, you need a fine haired brush or a micro fiber tissue for the cleaning process. With the brush you can introduce the solvent perfectly into the grooves, by turning it forward and backwards parallel to the grooves. After that soaking the dirty solvent a sucking process is necessary. Here the final quality of the cleaning will happen. The best sucking technology will bring the cleanest results. For this reason it needs a good vacuum pump. There are diaphragm pumps available, which can produce a vacuum of -1 bar. These are widely used in several technical applications, so these are quite easy to obtain on ebay.
Next you need to build a guiding arm to move the nozzle precisely over the complete surface of the record, so that it can suck off all the solvent. With a 2 mm diameter whole in the nozzle it will be operated for approximately 30 seconds from the inner groove to the outer rim in order to suck off all liquid. You need to connect the nozzle to a silicon tube (5/8 mm inside/outside) to a collecting container (marmelade jar). With another silicone tube you connect the collecting container to the pump, so this principle makes possible that the pump will not see any liquid, if necessary. On the other hand the contaminated solvent cannot stop the pump housing.

From upper left: the turning motor with gear box, the vacuum compressor. Lower row from left: underneath just a little bit red the (Ulka) solvent pump, the solvent tank on top and far right the intermediate jar glass to capture the used dirty solvent.

Keith Monks has installed at the shaft of the arm a slow turning gearbox and a dc motor, so that the arm will turn exactly that amount in a minute to cross the grooves. Several people I know have used transmissions with rubber rings between shaft and geared motor wheel to find the right speed. Additionally the rubber ring can spin at the end of the record without damaging the record.
The most problematic part of the construction is the nozzle itself and an element keeping the nozzle off the surface of the record, but still very close in order to prevent the right vacuum. Keith Monks uses for this reason a sewing filament. This filament is sucked in together with the cleaning solvent. The supplying bobbin is retarded by a spring. The nozzle itself is made from teflon to prevent surface scratches to the vinyl. It is a quite complicated procedure to follow up. Three motors at different speeds and a pump – I thought there might be other ways to come by?

So I never did built one of this machines for myself, some friends of mine did it in the 1990ties. So I could participate at their experiences. To me it was to much complication to get get working pleasantly.

Read on soon about the use of the machine, Volker

Bill Evans – The Village Vanguard Sessions

The two records of the Bill Evans Trio "Sunday at the Village Vanguard", "Waltz for Debbie" taken at the 25th of June 1961 at the Village Vanguard club in NYC are such a rare moments of recording history (Riverside RS-9376 and RS-9399, both the first stereo releases). They mark a very special moment in Bill Evans biography.

The critic Joachim-Ernst Berendt wrote: "Bill Evans has revolutionized back to the twenties reaching genre of piano trios in jazz. Simply put: Up to 1959 founded Evans Trio played jazz piano trio 'two-dimensional'. On one hand, dominated and led the piano, on the other hand, the rhythm section of bass and drums fell the task of creating the appropriate foundation. In contrast, the Bill Evans Trio played the first piano group in jazz 'three-dimensional': each instrument of the trio could now fall to a leadership role, which had the consequence that Scott LaFaro on bass, not just walking-lines - four quarter notes per measure - played, but also lines he phrased melodically and rhythmically independent of its support function. To the same extent Paul Motian was a play that the timekeeping - marking the Beat-Opened and expanded the melodic percussion additional options "
According to Herbie Hancock opened his concept of the piano trio musicians a whole new way completely to work coherently together. The very first joint album "Portrait in Jazz" from 1959 already shows a then new band concept. Evans, LaFaro and Motian been playing during the presentation of the issues, and not only in the solos, completely equal footing and with each other. The bass takes over melody lines in the upper register, and the drums keep it together with "commenting" interjections. Miroslav Vitouš ruled: "[...]. Communication between the musicians makes it one of the most important ensembles" [Kunzler] "In fact, the trio led, among other conversations in which tender partner, almost seismographic responded to each other," said Michael Naura [Kunzler] Evans achieved its almost "telepathic" communication and intimacy between the musicians. This "chamber music" density was henceforth one of his trademark for decades to come. He left - quite different than he had experienced before - his fellow musicians come to fruition. To his game in the trio and other groups Evans expressed himself thus:

"When I play with a group, I must of course take considerations, because none of these musicians can guess what comes to mind - perhaps to change the key or to change the rhythm. Because it really requires a common intend to a musical unit created. The inner freedom must not remain on the track. It actually strengthens it. "

Tragically 10 days after that sessions at the Village Vanguard in NYC Scott LaFaro died at a car accident.

If you want to play these recordings at their finest level of reproduction possible from a storage medium the vinyl record will do best. Like with almost any recording of that age the first pressing is not only a collectors item, it will bring the best fidelity of this live sessions. Unfortunatly in this case these first releases are very expensive. As tremendous improvement in almost all criteria of fidelity, like dynamics, details, space and finesse, the the Analogue Productions reissues are the records to play today. The early 1990ties release of "Waltz for Debbie" (APJ-009) is nowdays a rare item and therefore quite expensive as well, but its finest fidelity improves a lot about the original Riverside releases. Analogue Production releases of the formative years between 1990 and 2000 are always the best possible sounding records pressed into vinyl. The later (2007) release of "Sunday at the Village Vanguard" (OJC-140) is as well very good indeed.

Read on soon, Volker


Joachim-Ernst Behrendt: Das Jazzbuch – von New Orleans bis in die achtziger Jahre. Überarb. und fortgeführt von Günther Huesmann. 4. Auflage, Wolfgang Krüger Verlag, Frankfurt am Main 1992
Martin Kunzler; Jazzlexikon. Rowohlt, Reinbek

The Tannoy Speaker Design

In the history of loudspeaker development during the first phase cone equipped speakers were primarily developed with an electro magnetic unit (so called field coil speakers). It was not until the end of the second world war that permanent magnets were introduced, due to the fact that materials such as cobalt, nickel, aluminum in greater quantity were available again. So that commonly named alloy "alnico" produced magnets of before unknown strength. So they did resemble the complex (wound coil with iron core and dedicated power supply) and expensive systems from before (cost cutting). At this time the coaxial called loudspeaker systems have been designed by almost every well known speaker company. In this constructions up to three different speakers are usually arranged concentrically in one physical chassis. This had the advantage that it needed only one cut out in the cabinet to make and the speaker did act almost like a point source over the entire frequency range. In the most cases, a strong horn tweeter and a generously sized cone loudspeaker (twelve to fifteen inches) were combined for efficiency-optimized applications. Many manufacturers such Westerrn Electric, later Altec, RCA, James B. Lansing (JBL), Jensen, Stephens and others had been in competition about that sort of speakers for professional demands. They all were quite similiar from that point of view, 15'' low frequency cone and a high frequency horn cut at around 800 hz to the lower frequency with a simple crossover design to prevent efficiency in the days of low power tube amplifiers. But from another point of view the Tannoy design was completely different and superior to all its competitors. The HF-horn uses the shape of the LF-cone as seamless extension for its horn development as the first unique position. The second is the use of the same magnet system for both drivers, which compensates maturity differences perfectly. Have a look at the cut away drawing to understand. Both advantages lead into a much smoother integration of both frequency parts and to a more homogenious sound stage.

The LF-cone completes perfectly the HF-horn development. Both systems use the same magnet at both ends for compensation

All other designs set the HF-horn as a separate unit with own magnet system in the center of the LF-cone without any physical correspondence. I do not actually know if this important difference was regulated by patent regulations made by Tannoy in the very early 1930ties, at the beginning of the companies success. And even later in 1950 when a lot of following companies continued to produce coaxial or duplex designs (University, Goodmans, Altobass, Stentorian, Parmeko, but also later asian replicas from Pioneer or Coral), this ground braking difference never got touched by others.

Casted chassis from 12' Monitor HPD close to the disassembled "Alnico"-magnet showing its construction just before reconing process.
The so called "pepper-pot"-tweeter, the HF-compression chamber with phase compensating elements

The Beginning

The major design of Tannoy speakers started in 1947 with the first "Dual Concentric Speaker" designed by Ronnie H. Rackham from Tannoy. He married the two drivers together so that the flare shape of the 15" bass unit continued the flare rate of the high frequency unit. 

It was designated as the '15" Monitor Black'. It had a power handling of 20 Watts RMS, a voice coil impedance of 15 Ohms and a crossover point of 1 kHz. Magnetic gap fluxes were provided by a cast iron alloy magnet at 12,000 gauss for the low frequency voice coil and 18,000 gauss for the HF coil. (10,000 gauss = 1 Tesla). At 20 Watts power handling in 1947 the unit was very well received and this coupled with a sensitivity close to 92 dB for 1 Watt at 1 meter right up to the highest frequencies, was a milestone for the company in providing high quality speech and music capabilities in an efficient way. With this design Tannoy layed the ground for 30 years of succesfull manufacture of this design before significant changes took place. During that time four generations of "Dual Concentric" speakers were launched which all were based on this incomparable principle design of the first "Monitor Black".

The structure of the casted aluminium chassis can be seen with its typical connectors. The magnet assembly from the side.
Both designs existed without significant change between 1954 and 1978 troughout the Monitor Range of speakers.

The Model Line

In 1954 the "Monitor Silver" replaced the former "Monitor Black" without significant changes in the technical data, accompanied by a scaled down smaller version with a 12'-cone. Both had got a new lighter casted chassis, painted in hammertone silver with a barrel shaped magnet cover of the same color. This new casted chassis marked the way for the next 30 years without change for both sizes. These two sizes spread into the recording industry first in Great Britain, later throughout the Commonwealth till today were you will find them in recording studios world wide.

In 1958 the silver range got to be replaced by the next generation, the "Monitor Red". Now the chassis was painted in darker blueish gray hammertone with new formed pinkred metal magnet covers. Basically the same two speakers with little increased power handling capacity. But they got a small 10'' brother beside, which was mainly designed for the "near field monitoring" needs in the recording industry (III-LZ). This speaker is the only Tannoy design with a 2.5'' voice coil for the LF-cone, were all others are equipped with 2'' coils. This design delivers a perfectly controlled operated LF-cone and its refined resolution of detail up to 1500 hz, a big advantage for near field monitor use.

In 1967 the reds were upgraded to the new "Monitor Gold" line. The chassis got a grey paint with golden plastic mold magnet covers. Now the first important changes were introduced. The crossovers got transformer operated controls for hf-energy and for cut off frequency. The speakers had to follow the market changes. Now transistor amplifiers were used with higher power priority. As a result, the impedance was reduced to 8 ohms to match the transformerless output stages of the new power amplifiers. As well the increased power handling capacity with corresponding heavier voice coil was a requirement for the new line.

Two 12'' chassis from two generations showing their design progress, the 1958 Monitor Red on the left beside the 1974 Monitor HPD frame needing cone and diaphragm to complete (without plasic cover).

1974 the new "Monitor HPD"- Line got introduced with 15'' (HPD 385), 12'' (HPD 315) and 10'' (HPD 295) versions. These speakers are sold in Canada as Monitor Royal line with blue magnet covers. The new chassis had golden paint with gray plastic covers. They (HPD = High Power Drive) followed its predessors with hardly improved power handling capacity. For this reason the paper cones got redesigned. The cones have been equipped with agile foam surrounds instead of the former hard paper edges (the foam surrounds show typical aging after 20 years been exposed to uv-light and need replacing). As second treatment for increased power handling capacity the cones got stiffened out through 8 paper bars ("Girdacustic" called) glued to the back of the cones and a reinforced voice coil with better temperature abilities. This changes make a wider cone deflection possible to high power input, resulting in less deformations of the cone structure and a smoother response as resulting benefit.


Exceptions of the production line between 1947 and 1978

Tannoy is the only speaker company of this age I know which completely concentrated on the dual concentric design principle. Some rare exceptions from this continuation of model history are known. During the Monitor Silver range Tannoy released a 12'' direct radiator speaker (without the HF-unit) based on the standard chassis with green colored magnet. It was completed by a HF-unit based on the standard magnet assembly extended with a metal horn of the size and shape of the 12'' paper cone.
The Monitor Blue called speaker which is based on the HPD series as direct radiator chassis without HF-unit available in 12'' and 15'' to extend the standard series.
Through out a long period (I do not have any precise knowledge about that product and any advice and help would be appreciated), Tannoy is most famous for its eight inch (?) direct radiator units made for the british railroad stations. These speakers have been spread widely common for announcements made for departures/arrivals in lots of stations in the UK. This use has made the company name Tannoy so popular that these sorts of announcements are populary named: a tannoy. (to be continued).


The crossovers

The crossovers of the different generations did start very simple with a 6 db filter for the 1000 hz cut frequency at the beginning. Tannoy used huge paper capacitors and waxed impregnated copper coils for the Monitor Black. With higher production numbers of the Monitor Silvers they got a specially made paper capacitor with three units in one can supplied. With Monitor Reds Tannoy started to use electrolytics for the crossovers (cost cutting). The Silver and Red 12'' versions did drive the cone in full range mode, just the tweeter got cut to be protected for the low frequencies. All the crossover designs kept efficiency in the foremost stage. With Monitor Gold and the new lower impedances of 8 ohms the crossovers needed to be redesigned completely. Tannoy used the chance to change to more complex filters with the possiibility to cut or damp the HF-horn in four steps each for all three sizes. This new luxury brought the opportunity for room compensation of the cabinets. Thanks to the believe in quality Tannoy made these attenuators with switched auto transformers, the by far superior way to do so (expensive). And they supplied compensating filters to improve measured linearity over the entire spectrum. All supplied "improvements" were accepted as further degradation of efficiency as tolerable side effect.

Over the years the speakers have been treated with numerous improvements, mostly in order to improve power handling capabilities for high output transistor devices. The company tried to follow the tremendous increase of power output in amplifier design, right to a point were it found a simple physical limitation. Seen from today the treatments did not always improve the general performance soundwise, in particular if you do use them with low powered tube amps. It is more like permanent stepping backward. At the end the lightweight cone with the 30 watts voice coil of the early designs, added up to the double weight with the HPD range. These differences together with more complex crossovers lead to clearly listenable degradations, foremost in terms of lost dynamics and a decrease of fine details. If you ever have compared a Monitor Silver to a Monitor HPD you might know what I am talking about.
In this logic a lot of products did not benefit from the advantage of its "market advance"; i.e. means have fallen down their staircase of development. This is fairly common observation and a poor truth at the end of modernism and industrialized mass production with almost any of its products.

When Guy R. Fountain, the founder of the Tannoy company died in 1977, the company was sold. This chapter ended the "West Norwood"-history and the company was moved to Scotland by its new owners in order to cut production costs. From 1978 the "Dual Concentric"-speaker got completely redesigned with ferrite magnets for both frequency parts. New materials got applied, as well a new hf-driver design was developed to cut production costs. Only within the Prestige-Series some of the old magnets ("alcomax 3" named) get installed in countable amounts to enclosures at tremendous price ranges. The other dual concentric designs got a horn amplified dome tweeter design ("tulip wave guide" marketing speech) with hefty coils wound, able to play 300 watts of power, as a tribute to modern demands of audio fidelity.

Read on soon, Volker


For further informations on vintage Tannoy chassis and specific data base about visit: http://www.44bx.com/tannoy/

The Tannoy Autograph II – Improvements on a legend

Hello again,
for some continuation of the story about Tannoys legendary vintage full range horn speaker cabinet.

Klaus and me met again three weeks later for a Sunday to work at the cabinets. Klaus had tested in the meanwhile different positions in his room for the cabinets instead the dedicated corner position. They were placed like ordinary speakers with distance to the rear and side walls and some 15° degree inverted angle to the listening position – with good success how he said?! A much better low frequency response with much reduced boost effect in the region around 100-200 hz was listenable. Of course this type of positioning must have this sort of influence to the sound performance. The cut horn openings (off the walls extension) will lift the cutoff frequency of the lf-horn up into the registers of 150-200 hz region. Together with a shortened opening it will decrease the efficiency for some decibels, so the horn will be a lot less present in the all around performance of the speakers.
The inverted angled position of the them make the front loaded horns to work better focused in the listening position. So the illusion of imaging in the projection seem to improve a lot. A by far more defined soundstage with much better width and depth was the result of the new position.
Klaus did finish the covers and ordered some 12mm woolen felt as new damping for the compression chambers. The felt was used to exchange the former acoustic foam in the compression chamber. This implies the same sort of damping, but with thinner and stiffer materials, taken less air space and therefore a better adjusted chamber volume?

The new damping of the compression chamber and a new seal for the speakers. These will be mounted now at the baffle board instead the wrong mounting behind the front horn.

When I arrived at Klaus house he needed my helping hand to get the speakers layed back on the floor. With a good 100 kg of total weight these speakers are not easy to handle, for every step you need a helping hand, better two. On the floor he could apply the felt in the compression chamber and mount the speakers in their original dedicated position.
We installed the new boards covered with grill cloth for both side openings of the cabinets. Klaus still did insist that the covers will reduce the effective openings to 50% of their former uncovered surface. This will have a noticeable influence in damping the back loaded horns.
The drivers got now screwed to the originally dedicated baffle boards of the compression chambers and were sealed it with new foam tape. Between front horn and driver now there is a 5mm air gap without physical connection, this helps to prevent the introduction of resonant energy, which will be boosted from the horn itself. This has a tremendous effect in reducing the resonances around 500 hz, which were more than present before. We placed the cabinets back in the corners and started the second audition after several hours of work.

Working at the second speaker in front of the finished speaker. The decoupling of the funnel can be seen by the disappearing of the four screws in the corners of the funnels base board.

 After six hours workwe started to drink some remarkable wine from Klaus vine cellar as a good alternative for
listening to good jazz music.

They did already look like originals from the 1950ties with the newly made covers and the perfect matching grille cloth. The sound improvements introduced by the changes were nothing else than tremendous, from the first moment the big bass boost and the whooly mids did disappear completely, the tonal range opened up to a much better audible richness of tonal color spectrum. As well the illusion of the projected space has got a much better dimension, even when it is not the perfect discipline of this angled construction. The corner design fixes the inverted angle of the hf-horns to a 45° degree position, which is mostly not a optimized angle seen from the listening position. The complete wrongness of the first audition did disappear and as a new dimension it was noticeable that we did listen to 15-inch Tannoy speakers with their typical sound stage and advantages, other duplex speaker constructions of that time don't have.

We did listen to several records and switched to digital programme material later on. After another three hours we closed the test and cooked a late night meal. Eating and drinking was a must to complete our discussion about further improvements in the coming future. Some french "soupe de poissons" closed the day at 1:00h o'clock late at night. We decided that it will need further improvement into the same direction and I needed desperatly to drive home to get some sleep.

Delicious "Soupe de Poissons a la Provencale" as a late night meal

On my way back home I made a summary of the today realized improvements. But I am still very sceptical about the process of damping to a given horn development and its "resulting improvements". – Yes the improvements were listenable, but from a technical point of view this change does not make sense to me.  My expectations of the "legendary horn design" and all the internet gossip did not match reality, the all around performance of this speakers still does not impress me. After 25 years of living with Tannoy sound I still did expect some more affection from incomparable qualities other speakers don't can deliver.

If there will be somebody out who has some personal experience with this or similiar type of speakers like the Westminster I would be interested to know about. Read on soon on further improvements on this legends, Volker