Tuesday, 25 June 2013

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

Sunday, 23 June 2013

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/

Tuesday, 11 June 2013

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