Thursday, 26 December 2013

Tannoy Autograph III – The Implementation into the System

Yesterday I visited my friend Klaus in order to have a very nice christmas evening with good food and nice conversation, acompanied by wonderful Brunello wine and of course listening to jazz music. For some month I did not have any chance to listen to the finished Autograph enclosures, which have settled down in their final room position. For the perfect accommodation Klaus has reorganized some furniture and the shelves around the speakers in his listening room. Now the corner enclosures are positioned in the corners of his listening room. In former listenings when the speakers have been in evaluation, they were positioned in front of his shelves. Not ideal, this design needs the extension of the flanking walls for the best support of the low frequency response. Now in the customized position, the backloaded horn developments are functioning as been designed. Now, to make a short cut, the LF-response performs a new level of response quality, fast, deep and with natural dynamics.
To remember some month ago back, Klaus experimented with different stages of internal damping of the backloaded horn. The compression chamber was main part of this tests, but as well the beginning of the horn development. He did experiment with damping of its openings, which did find its final damping with the dedicated covers (i.e. grill cloth, decoration bars and the holding panels). To me unbelievable, he worked out that the enclosures need the side covers installed, otherwise the Lf-part of the spectrum was more than prominent.

In final position, the Tannoy Autograph enclosures driven from Maihak V53 EL11 PP amplifier
View into the uncovered side openings of the horn development,
all damping materials have been removed. 

Our Christmas audition started at the first glance with a optimized overall neutral tonality, which I had not heard before in Klaus system with these speakers. For this neutrality several improvements have been made, some did take place in the amplifying chain in order to optimize the signal quality. Others came from further improvements with the damping of the compression chamber of the enclosures.

In the late afternoon of Christmas evening we had started to listen with Chico Freemans Spirit Sensitive, reissued from Analogue Production in perfect quality some years ago, like always the reissues of that early time are better than perfect and top always the original releases. We switched after a while to Chet Bakers Let's get lost, a mid 1980ties recording with extremely well preserved fine modulation of the tonal dynamics. Both records I do use regulary within my own setup, so I know them extremely well. The latter one is known to me as almost invisible holographic presentation, showing not even the smallest remnant of electronic errors like phase shifts or typical hardening of some frequency edges. Today it presents a extended low frequency response, with fast, deep transient response. But as well a mild softening of the upper mids was audible, the overall tonality showed some little woolliness in this region. All records we did listened to, did show this same tonal effect. So it was obvious, that this was a characteristic which had taken place. A quick switch to digital sources showed a much more linear response here, without any woolliness, two more Cds did confirm the impression. So it was quite obvious that the found deviation was not a inlinearity of the Autograph speakers, it must be something coming from his analogue deemphasis and amplification chain.

Some records used within our audition at Christmas Evening 2013

In the last month Klaus has made some service at his RIAA equalizer. He uses a double mono set of customized Telefunken V87 studio modules original used for tape recorders, modified after Neumann WV2a design for his RIAA equalization. The Neumann units are designed with similar tubes, output transformers and PSU, but have selectable deemphasis curves. Klaus implemented only the Neumann RIAA filter for his use. Here some electrolytics and resistors had run out tolerance and were in the need of exchange. He selected some pio caps and carbon resistors to close as possible tolerances and for stereo matching.  He had to replace  almost all components within the filter unit. He did measure the final result with his oscilloscope and further measurement equipment and stated that the equalizer now is back to closest tolerances of the ideal RIAA curve. From my personal experience pio caps sound inferior to any other capacitor made, even within passive RIAA equalization filters, but they add a very typical fingerprint to the sound. Together with the preferred natural smoothness, they lower the audible effect the hf-deempasis. Even with perfect measurements, the sound of the correction seems to low. A lot of users would replace the capacitors for compound foil types, I never did like these and would suggest to keep the positive advantages of the pio caps, instead I would adwise a readjustment of the filter to get rid of the unwanted effect.

Telefunken V87 amplifiers, here customized to Neumann WV2a design with RIAA deemphasis curve,
since the original offers switchable alternative equalizing curves.

Platine Verdier derivate magnet bearing record player with SME 3012/II and Ortofon SPU Gold

A second task of the day was the collective cooking of the Christmas dinner with three courses and a lot of communication. Klaus had prepared some dear goulash some days ago, he had marinated the meat with several herbs and spices, oranges and lots of red wine for the main coarse in advance. Since I had marinated and cooked for hours the red cabbage with typical herbal ingredients like cinnamon and laurel as perfect christmas flavor. As well I did prepare some dumplings from fresh potatoes and dried bread for the main course and a creme brûlée as final end.
Together we started our cooking with some fine cut air dried spanish ham and some salad with a first glass of Brunello di Montalcino wine.
One of the first records of Brunello was a red wine that was made in the Montalcino area in the early 14th century. In 1831, marchese Cosimo Ridolfi (who was later appointed Prime Minister of Tuscany by the Grand Duke Leopold II) praised the merits of the red wines of Montalcino above all others in Tuscany. In 1865, an agricultural fair in Montalcino noted that the prize winning wine of the event was a "select red wine" known as a Brunello. In the mid-19th century, a local farmer named Clemente Santi isolated certain plantings of Sangiovese vines in order to produce a 100% varietal wine that could be aged for a considerable period of time. In 1888, his grandson Ferruccio Biondi-Santi-a veteran soldier who fought underGiuseppe Garibaldi during the Risorgimento-released the first "modern version" of Brunello di Montalcino that was aged for over a decade in large wood barrels.
By the end of World War II, Brunello di Montalcino had developed a reputation as one of Italy's rarest wines. The only commercial producer recorded in government documents was the Biondi-Santi firm who had declared only four vintages up to that point-1888, 1891, 1925 and 1945. The high price and prestige of these wines soon encouraged other producers to emulate Biondi-Santi's success. By the 1960s there were 11 producers making Brunello, and in 1968 the region was granted Denominazione di Origine Controllata (DOC) status. By 1970 the number of producers had more than doubled to 25, and by 1980 there were 53 producers. In 1980, the Montalcino region was the first Italian wine region to be awarded Denominazione di Origine Controllata e Garantita (DOCG) designation. By the turn of the 21st century, there were nearly 200 producers of Brunello di Montalcino, mostly small farmers and family estates, producing nearly 330,000 cases a year.
By the end of World War II, Brunello di Montalcino had developed a reputation as one of Italy's rarest wines. The only commercial producer recorded in government documents was the Biondi-Santi firm who had declared only four vintages up to that point-1888, 1891, 1925 and 1945. The high price and prestige of these wines soon encouraged other producers to emulate Biondi-Santi's success. By the 1960s there were 11 producers making Brunello, and in 1968 the region was granted Denominazione di Origine Controllata (DOC) status. By 1970 the number of producers had more than doubled to 25, and by 1980 there were 53 producers. In 1980, the Montalcino region was the first Italian wine region to be awarded Denominazione di Origine Controllata e Garantita (DOCG) designation. By the turn of the 21st century, there were nearly 200 producers of Brunello di Montalcino, mostly small farmers and family estates, producing nearly 330,000 cases a year.
When the dear goulash was set into the oven, we had time again to combine our enjoyments upstairs for further listening to other records. When the meat had roasted to finished stage in the oven (2 hours), we completed it with my side dishes for main course. We were eating and talking for more than two hours before we continued listening to music with another bottle of the Brunello. We completed the evening (and the most of the night) with further music and talks. I demonstrated Klaus my headshell tests and we used two SPU pick ups beside his own SPU Gold for evaluation of the differences in materials. We finished very late (or lets say early) with the agreement, that the Autograph speakers now have lost their former problems and are working nicely beyond any other Tannoy enclosure Klaus has owned before. At 4h o'clock in the night I did fall almost asleep in the listening room, so I realized that I will need some sleep soon.

Frontloaded Horn opening with 15'' Tannoy Monitor Gold Speakers, a unique and
tremendously important design feature for the Tannoy Dual Concentric principle.

I am sure Klaus will refine the last problems in his analogue rail and afterwards he has found after 30 years his final loudspeaker. Thanks to the powerful attributes of the horn loading principle, here with respect to a front loading funnel and a long folded back loading horn enclosure, extended by flanking room walls, the speakers convince with a rare quality of response. They are a tremendous efficient system, able to transmit almost natural dynamics of real instruments with low power tube amplification.
Of course these "instruments" are not every bodies "cup of tea", they are expensive and their room preferences will limit the club of owners with a natural choice. Which means, the listening room must have a ideal geometry and size to make this particular design work. If you are willing to match such conditions, the Autograph enclosures may be the best vintage speaker enclosure for the imcomparable dual concentric loudspeaker from the Tannoy line. And they will work even very well without the wine from Montalcino....

Read on next week for my new enclosures for the Tannoy line, Volker

Thursday, 19 December 2013

A Tannoy 15'' Enclosure for the Enthusiast – Part IV

In the last couple of month I have tried to find a solution for the incomparable 15'' Tannoy driver to be used in a sort of universal enclosure. I concentrated on two nested main questions, the best possible response coming from a living room friendly sized cabinet. My main aim in this process was, independant from any technical design principle (i.e. reflex, open baffle, sealed, horn development), to archive a foremost natural tonal response. It is best described as a transformation of the electrical signal into a acoustic representation of music, lacking any typical electrical significance or sort of common compressions arising. My ideal response is orientated as close as possible to live performances of small scale chamber music or small jazz ensembles in limited scaled room conditions. Here the acoustical resonant corpus of the performing instruments (i.e. cello, brass horns, piano, etc.) is quite similiar to the resonant corpus of the performing transducers (loudspeakers). My definition and further undertakings can be understood by the most of yours within this model in mind.

Typical Tannoy Lancaster cabinet (sealed version for the 12'' driver),
these generation cabinets are well made from lumber core plywood, excellent material.
Some month ago at the beginning of the design process I did not know, with what sort of cabinet I will come out at the end. I did play through in my mind many possibilties, a combined back/front loaded horn design, a vented port cabinet with 200 liters volume or even a bigger sealed enclosure, working as a resonant chamber. I definetly wanted to leave behind the limitations of the common known vintage cabinets. Instead I was very energetic to find new ways to the naturalness arising from a newer understanding of the loudspeaker to be a resonant musical "instrument". In the last decades my understanding of "true fidelity" in conjunction with single audio components has been widened by a general respect of each components resonant properties, where the speakers show the most suggestible influence of all of them as to be the final transducers.

There are the well known designs of similar speaker cabinets made in the past: some Altec designs like the VotT-line, the japanese Onkens, JBL, EV, Jensen and some other professional small scale pa-addressed designs for 15'' diaphragm sizes. They all have one thing in common, to be originally designed for a different speaker type in mind than the Tannoy Dual Concentric. The uncomparable design of the Tannoy offers opportunities other speakers don't show and these should be respected to find a perfect matching solution. And finally I did want to share my experiences with other Tannoy addicts, because those don't have a lot of choices of cabinets in our culture (may be in Asia, foremostly in Japan there are options for after market enclosures).

Tannoy Amesbury with 15'' Monitor Golds
I think nearly 90% of all vintage Tannoy 15'' Dual Concentric speakers are installed in the typical 120 liter volume ported box. In history it all started with corner cabinets for monophonic reproduction, the huge ones were horn designs the smaller acted like vented port enclosures. Both types used the backward radiated energy of the cone to be conducted as a supplementary part to the air. The horn used the flanking walls to extend  its development. Bot design principles are made to reduce the inherent limitations for the lower frequency response of a boxes loudspeaker. With the need for stereo pairs, the range of enclosures was expanded to rectangular versions like the GRF, York and the Chatsworth. These could be better placed in the room for a improved stereo illusion. Additionally Tannoy started in the 1950ties a small universal cabinet line to fulfill the needs of their customers to smaller cabinet sizes, used for the 12'' and 15" units simultaneously. This design got widely sold for decades as Lancaster and ended up in the mid 1970ties as strengthened Berkeley of the same size. A vented port in the beginning and a true reflex after Thiele&Small at the end was the most well sold cabinet design for Tannoy of all times. With a size of 85cm height to 52cm width and and a depth of 28cm, the success of this enclosures represents for lots of people already a huge speaker. This size seem to be as well a maximum dimension accepted as a piece of furniture in living rooms from its users. This enclosure limits the performance of a 15'' chassis a lot, in particular with the hard edged versions (Gold, Red and Silver) the backwarded compressed air cushion show a extremely limitation of possible dynamics. A few of us have got luck, their partners do even accept the little bit bigger versions, the Rectangular York, i.e. Amesbury which ended in the late Arden enclosure. With a useful volume of 180 liters, this cabinets support the technical conditions of the chassis much better, but are still more a compromise than a solution for listening pleasure. The hard edged drivers have a theoretical Qt which will lead to a ideal volume of 350 liter for a 30 Hz response with -3 db fall. With this parameters it starts that the speakers are getting almost invisible in acoustic terms and show a good dynamic performance down to a low end with fast transients. The most users cannot accept two wardrobe sized cabinets in their living room in order to match these ideal conditions for the drivers.

The biggest enclosure of all vintage Tannoy back loaded horn designs, the Tannoy Autograph Professional with two 15'' drivers in parallel, very poor material choice: chipboard
Mr. Ronnie H. Rackham followed another theoretical ideal for optimized sensitivity and improvement in  response of loudspeaker cabinets. Horn designs use the backside radiated energy from the cone in order to transmit it through its development to an opening as addition to the complementary other half from the front side. It acts like a mechanical amplifier for the conducted frequencies and adds on the second half of the wave, so the sensitivity will be increased. The very early variants have been designed for the corner position in the room in order to use the flanking walls for the horn extension. Only the GRF Rectangular and the Autograph Professional were made for the plain wall position. The Rectangular was a quite small sized cabinet. Here the ideal horn development (around a lenght of 3 m with a continous opening to 2 x 2 m for 40 Hz) has been cut to be anymore unrecognizable sizes. With a length of 1,50 cm and a opening of 40 x 60 cm the horn acts like a lower middle frequency horn, with a cut off end around 400 Hz. This was my first 15'' Tannoy speaker and I never liked its response. With its hefty frequency belly around 400-500 Hz, this cabinet has set a fundamental dubiousness about horn designs in my very early experience with 15'' Tannoy speakers.

Inside the Tannoy Autograph, the complex development of a back loaded corner horn shown at a set of japanese after market copies (plywood).
The today operation of the less compromised horn designs (Westminster, Autograph, GRF Professional) makes a dramatically increased acceptance necessary, as to be the speaker a room dominant piece of furniture. Beside the Westminster I do know almost all vintage Tannoy enclosures very well, since I have or had the most of them myself, or some of them are installed at close friends audio set ups. To be honest, not one of the bespoken designs matches my current expectations about a natural sounding music transducer. They all show a unacceptable part in the lower frequencies were folded horn brings a quite uneven response. The positve benefit of all horn designs is the undistorted way the driver can act like in free air resonance, without limiting air cushion and its fast transient response.
Ideally I want a performance with realistic and fast dynamic transients, a huge and holographic soundstage, with refined and detailed smooth Hf-response (without any phase shifts and resonant knots), a similiar performance like a natural wooden instrument of comparable size. A horn design at it best comes very close but will be extremely huge and room dominant. The other possibilty to leave the limitations off a boxed speaker is the folded baffle principle. To make it work, it needs a lot of acceptance as new approach of understanding of the role of cabinet (new was meant to be connected with Tannoy speakers – Western Electric and Klangfilm did incorporate such design principles about 70 to 80 years ago).

Chinese copies of the Westminster for 12'' and 15" drivers. They do copy everything.

I definitely search a solution to use with the superior hard edged chassis from the Monitor Gold, Red or Silver line in conjunction with low power tube amplification. These hard edged drivers need naturally a bigger enclosure to work superior to their later derivates from the HPD line. The limitations of the early cones depend hardly to the physical parameters shown at their low Qt of 0,26, but their sonic advantages are a close mirror of these facts. The nominal 15 ohm (at 1000 Hz) voice coil (Red, Silver and Black) was the preferred VC-impedance when tube amplification was the standard. This impedance matches the plate resistance preference of a pair of tubes and even more of a DHT-Triode better, the different coild at the output transformer to match are only a little help, since impedance shifts over the total frequency spectrum of the speaker can not be covered here. In particular in the lower frequencies the hard edge surrounds have helped tube amps a lot to control the cone movement. All this results is a increase of fine dynamic details and a better resolution of finest overtone harmonies. The light weight paper cones have a much lower mass to be driven and can therefor much better controlled by a given tube power amp, resulting in a improved sensitivity. The heavy HPD cone (double weight through the stiffing back support brackets and the three layer high power voice coil 85W) does not only make the double power output possible, it needs it it to be adequately driven.When the Monitor Gold was changed already for the establishing transistor amplifiers, the highly maneouvrable HPD cones are a clear reminiscence of the adaption to the high power output transistor amplifiers of their time. When used with tube power amplification, in particular with low power DHT tubes, the HPD drivers show mirrored characterics of the former chassis. All the live, color and speed in lower mid frequencies is gone, to me it sounds quite uninspiring and retarded comparing it with the earlier drivers. Within this drivers the front loaded funnel cannot add any extra quality to the soundstage.

The well known front loaded funnels from the Autograph and Westminster cabinets are a perfect extension for the 15'' dual concentric driver. Such a design helps fundamentally to conduct the cone radiation to the air of the listening room. In theory it works like a pantograph with a adjusted transmission ratio. The finer physical resolution of the stiff light weight cones completes the full potential of this design feature. A clearly listenable quality advantage of wider spread tonality and much improved micro dynamic response are the obvious benefits. In a horn design principle the cone almost works at its physical optimum, since it is not retarded by the air cushion of a closed cabinet. A further fine adjustment of the crossover design will complete this positive effects.
My personal experience was once initialised by the classic 12'' chassis (Monitor Red and Silver), where Ronnie H. Rackham set the Lf-cone as a fullrange unit. Later with the Monitor Gold line (1966) Tannoy limited the 12'' inch chassis performance with a 12 dB filter cutting above 1500 Hz. This intervention brought a flat measured response in the 1000 Hz region, but it can be easily approved, that it takes out a lot of micro dynamic detail. To my taste it sounds slower and a bit uninspiring, so I do like the more lively presentation in full range mode a lot better, even if there might be some little uneven inaccuracies in the measured response. Starting from this experiences and accustomed over the years with every day use, I missed the benefits of the full range driver when I restarted to listen to the 15'' chassis (Gold, Red and Silver) some years ago. Together with my first test of the front loaded funnel I changed here the crossover into full range mode. This intervention is a basic principle for the following incorporation of the front loaded funnel with greatly improved success. The Westminster and Autograph have as well verified (lower) crossover points in conjunction to the front horn opening. I tested both filters as well in my set up and decided to stay with the unfiltered full range mode for my 15'' Monitor Red drivers as to be a superior solution.

With the rejection of the filter for the Lf-cone even with the bigger 15'' units, two important advantages come together. First the sensitivity gets a better ratio. I am sure that the cone gets into trouble at the upper end of its physical ability. It will show a good portion of deformation in the measured response curve, this starts around 4000 Hz and peaks around 8000 hertz with already 6 db or even more loss, so it does not have a fundamental effect to the overall sound. On the other hand the uncontrolled cone plays so much better in terms of dynamics and speed in the important 1000-2000 Hz area, that I can accept the effect as almost completely positive.
As already said in other articles, the concentric high frequency horn is cut at 1000 hz with a 6db filter in the ordinary crossovers. Listening with the front loaded horn funnel shows a dramatic better distribution and dispersion of fine detail and micro dynamics in this most important tonal range around 1000 Hz, due to its acoustic coupling from 400 Hz on to the higher frequencies. It gives a 100% better front radiation of the cone and helps the high frequencies to be supported into the lower registers. Here almost every instrument or any voice will be covered with finer micro dynamic abilities. The overall soundstage is dramatically improved in its illusion of width and depts and the impression of air is noticeably extended, so this change has a fundamental impact with extremely positive effects for my new design.
Another word about measurements. They can help to find some problems, they can shorten evaluation proceeds, but their graphics doesn't say anything fundamental about sound qualities and their harmonic structure. If you look to graphs of measured natural instruments, they show a tremendous deviation from the idealized flat response. It is almost a opposite fact, the most colorful tonal presentation with the best harmonics in overtones, show the most degraded graphs. I don't think that the publishing of graphs shows any content about musical response, so I don't show them.

"Copy and Paste" in China. I do not know what these copies will cost, nor do I know where to get them. I do not know if they will even match my high expectations for tonality and natural musical response...but they are made from plywood.  I wish to have a chance to listen to a pair of these?!
The original two versions don't differ in size but in material choice of their boards and used drivers. The Royal (with HPD derivate driver) is made from plywood, since the TW (Tulip Waveguide, speakers with horn exposed dome tweeter and with ferrite magnet) is poorly made from chipboard. 
I would state, that without the support of the front loaded horn the Tannoy does only do half the job and is a different speaker. After two years of implantation in my set up, I don't find back to the plain ordinary response with typical turning point filter at 1000 hz in the classic crossover. I have tried several times to switch back (with different cabinet designs), for me it is very easy to do, I have built a switch into my network to be operated from the outside of the enclosure. I tried again and again with different equipment and in different rooms – I always tried with and without the funnel – no way, I cannot accept anymore the classic approach.
It is now a different loudspeaker to go. Try yourself, the intervention into the network, its easy to be done, just bridge the capacitor and the coil at the Lf-rail with a crocodile clip wire, – done. For the funnel to test, I can recommend a simple version made from 2mm grey card board as a first stage. This will show almost all the benefits with your existing speaker enclosure. If you have Lancaster cabinets, remove additionally the back panels and position the speakers almost 1 m (4 ft) as minimum distance in front of the backing wall. I swear, you never have heard such a good sound from your Tannoy speakers, if your chain is able to supports it. Don't fear this step, it will be reversible in 5 minutes... And if you do, please ... let me know what you think about!

Read on soon about constructing the new open baffle enclosures in the Christmas holidays, Volker

All photographs shown from Google with respect to their  unknown original resource.

Saturday, 7 December 2013

Musical Instruments in Audio – The Headshell

Everybody who has driven down the hifi road for several years knows immediately what I mean if I talk about the sound influence of different materials. In analog audio components mechanical energy is stored and as a result the ability to damp this energy has a profound influence to its sound character. In the earliest stages of a analog amplifying chain this influence is a lot more obvious and listenable, because the signal is very small and the proportion to the resonances can be quite big. In later stages the ratio gets better in favor of the signal strength. In reversal to this fact it means that materials with different resonant abilities will have at the beginning a more massive influence than in later stages.
The earliest stage of a analog audio chain is the pickup cartridge and its mounting to the tonearm, the component were the electrical signal is created. Any sort of cartridge will be exposed to tremendous mechanical energies arising from the excursioned grooves, a process which inserts energy through the diamond to the cantilever to be introduced it into the arm wand, together seen as a complex compound. In an article published in the early 1990ties in the Swiss magazine Hifiscene the energy at the cantilever was figured with almost 5G at a 33 speed and a 30 Hz peak. I do not know if this is right, but if you have listened to a diamond in the groove without any electrical amplification, just the mechanical resonances, I believe the energy must be enormous. At this point it starts to be understand, that a higher mass (of the arm) and a lower compliance might have positive benefits to handle this energies. A pick up cartridge with low compliance of 8x10-6cm or lower handles naturally the bigger mass of a stainless steel tone arm wand better than a high compliance cartridge can do, since the whole systems has much more damping mass. Therefore the resonant energies are a lot better controlled than a low mass system can do. In the 1970ties it was understood that a lower mass does not support such resonances thoughout. This misinterpretation have created thousands of high compliance cartridges and high tech light weight tonearms in order to bypass that handicap with a lower mass (and less dynamic soundstage as result).
Today we know better, this handicap is as well a big chance towards a more natural response. A wider spread tonality, by far better dynamics and a deeper and wider soundstage are the benefits of a good implementation of a low compliance cartridge into an a heavy mass tonearm with controlled resonances.

A range of headshells I did evaluate within the last years, from top left: Denon original broadcast headshell (plastic); 2nd row: Ortofon Gold aluminium G-headshell; Diy thick-walled headshell zebrawood; standard lw-headshell; 3rd row: vintage Ortofon bakelite G-headshell; diy zebrawood A-headshell;solid lightweight headshell;  4th row: diy G-headshell zebrawood; casted zinc Lenco headshell.

Outgoing from these facts I would like to talk about my experiences with different headshells and their materials in combination with such a converted SME 3012 high mass version. The heavy and stiff stainless steel arm wand will bring cartridges with less than 8x10-6cm compliance into perfect physical balance and its internal balsa wood damping helps further on to prevent ringing which is always obvious in tubes. So these cartridges can produce their best possible fine and coarse dynamic soundstage combined with the highest stage of musicality. Cartridges like the Ortofon SPU, the Denon DL103, the EMT, the Fidelity Researchs, the Koetsus and the Ikedas will profit enormous from the heaviness for damping the arising resonances. So far – so good. I started decades ago to evaluate several of these cartridges and decided like a lot of other people to use a classic Ortofon SPU (with sperical stylus tip) as my standartd pick up cartridge. At these times Decca FFRS and Denon DL103 were in competition in my home system. A lot of my friends did use as well Platine Verdier turntables as I do till today, but in these times they all did use the Shindo modified Ortofon tonearms, which have a slightly different geometry than the classic SMEs. They used the SPU in the shorter dedicated A-type headshell, I did use of course the classic G-type headshell with my standard 3012/II. My friends always stated the A-type to sound better. I could not compare both versions in these days in my set up. To me it always arised a main question: will a square shaped closed box design, like the Ortofons have a principal advantage to the open standard light weight shapes (or its perfect derivate Orsonic)?

Typical vintage Ortofon G-shells, left (hardly corroded aluminum), right bakelite

In the middle 1990ties I got a first vintage SPU with elliptical stylus tip which I did like better than my quite new one with spherical tip. The all around warmer character of the older cartridge I preferred in almost every aspect of presentation of sound. Some years later a friend of mine brought a SPU gold (limited edition from 1980ties with elliptical tip and silver coiled generator instead of the ordinary copper version) to my house. I tried it and I liked it as well a lot, it had a bit better resolution of the higher frequencies than any other SPU-version I did know. I thought it must have been due to its silver coils of the generator. With ebay in the middle of the 1990ties it got very easy to find used SPUs online, mostly in the UK. So I got the next vintage one with elliptical tip. I tried it out and indeed it was very nice in a different way, very warm and with fine resolution and with perfectly integrated extended higher frequencies.

Very untypical, the SPU Gold in the bakelite shell on top, and the standard SPU in the Gold shell. I added a extra weight into the bakelite shell to compensate different total weight for direct exchange.

I compared both vintage cartridges to each other and I realized a good portion of differences. Looking at both cartridges in my hand, I realized one had the typical casted metal G-headshell and the other came in a earlier version made from bakelite. To make it safe, I switched both cartridges in their headshells. It was absolutely obvious, that the bakelite headshell made the difference of a smoother presentation. We made the same test with the A-type cartridge of my friend (the A-type headshells are always made from bakelite), he had now as well the adapter to compensate the length difference for the SME arm. The same result, the differences between both types of bakelite headshells was to negligible. It is not the smaller size, i.e. stiffer design, it is just the material itself, which creates the difference. Now I did understand why the A-type is so much higher rated. I would go as far as to state, the headshell material has a bigger influence to the final soundstage of a SPU than the shape of its diamond.

But this experience brought me to the next question about other materials to be used as headshell instead the bakelite. Obviously the bakelite material and its stronger wall size did damp the resonances of the cartridge better than the casted metal type. It seemed to resonate in the higher frequencies parts and creates a all around lighter and a bit harsher soundstage. My arising question was: How would wood change the sound of such a headshell? For the widely spread Denon DL103s there were already some after market products available made from ebony wood. For the SPU in these days there was nothing made from wood, just the original three types from Ortofon. I decided to make my own headshell from wood to test it. Best material would be some northern coniferous wood sorts, but the long fibers with lots of resin is mechanically not a good material to be milled to that fine wall sizes. Instead I did use a long fiber tropical wood to test it out, african zebra wood. I would have liked ebony, but I could not get rough sticks of that size. So I milled almost three headshells which I ruined by doing. The fourth was the first one with thin enough walls (almost 1mm thickness). I started with the classic G-type design. When finished, I was trained enough to make as well a shorter A-type shell in order to compare both types with their bakelite equivalent. As in the original Ortofon design I used for connection details inside brass parts and screws.

The first impression was quite good, but by far not that good as I did expect before. I tested the G-type first. It produced hefty resonances in the important middle frequencies, I would appreciate around 1000 Hz. This is the by far the most difficult part of the tonal audio spectrum. It is the region were almost every instrument and voice will be covered. I did stop very soon and decided to make a second try with a approved design. This time I milled the shorter A-type design in the hope that the shorter body will not give the same resonances than the long bodied one. I did understand that typical Ortofon design to work like an wooden boxed instrument with its four sided walls. So I tried to mill out the inside more than the first one and with respect to thinner wall sizes of 1mm. I thought as well about constructing a chamber from 0.8mm panels instead of milling a massive piece out, but decided for a increased connection design. For me it was a real mechanical challenge to get it made.

But the new shorter type did showed almost the same resonances. To be honest the difference to the thicker longer version was not listenable. I was really sad, because I did like the look and feel of the wooden headshells a lot. But my ears did tell me a total different story. By far the bakelite headshell was my favourite one, a lot smoother, refined and still more dynamic than anything else.
I did do another series of competions with the original professional plastic headshell from Denon, the heavy casted metal headshell from vintage Lencos and finally the very solid open frame types from the 1970ties. To make it short, the bakelite headshell from Ortofon is the thing to go for. It is in every respect a lot better than anything else. The box type design is stiffer than any later design (skeleton, light weight, etc.). I missed out any tests with C-37 laquer, as I did not set a golden clamp at the arm wand for further improvement... ;-).

Because I like the SPU Gold with its smooth fine extended resolution of the higher frequencies as best SPU pick up, I transfered it into a vintage bakelite headshell for my everyday use. I have owned almost every classic low compliance moving coil cartridge in history (as well the rare early Grados), I did try several moving iron types (Neumann DST, Decca FFRS), as well the early low compliance moving magnet types from Fairchild and Elac, but I have settled down with a SPU Gold in bakelite case. I have stopped thinking about other pick up cartridges, even if I would like to listen to a selection of different cased Koetsu cartridges made by the passed away master Sugano himself. He must have made very extensive experiences, otherwise I cannot explain to myself all the different materials he did use with his cartridges? Or was it just a japanese sort of attracting people with some bling bling? I might survive without knowing exactly...?!

Read on soon, Volker