The Aa Line Preamplifier III – The Completion of the Amplifier Part

Hello to everybody,

today I want to show the completion of my amplifier chassis with the constant current filament regulator boards. As already stated I did use the predecessor of this preamp for several years with different battery types, since conventional dc regulation showed a lot of problems and did not sound as good as batteries. So I had to struggle instead with contact problems, broken cables and dying batteries for years, which was a real pain. I had started with lead batteries, later did I use conventional AA Nimh's, a pack of three makes 1.5 hours of listening possible. So did use several packs, the everyday use and charge cycles made life for them short, almost every year I had to exchange the most packs.
In 2010 I did learn about Rod Colemans Constant Current regulator boards, which have been designed for this particular dedication, the filament supply of DHTs and for the use in pre amplification stages as special option. These boards can be configured for almost any triode type, even the big ones like 211, GM70 or 845 with high current draw figures can be used. For each triode one board is needed separately, which means here in this case with two Aa's running in parallel mode as couple will be fed by one regulator. They don't run very hot, so they are quite easy to use in the amplifier enclosures.

The Coleman regulator boards are mounted to both chassis sides to dissipate the heat and to be very close to the filaments of both Aa couples, here shown with one board.

The regulators are dead quiet and don't show any deterioration of the sound structure, comparing them to batteries. They will be available though Rod Colemans web page and are a great help for everybody using directly heated triodes in audio amplifying devices. They need to be implanted with a raw power supply each, which should be designed to match the final preferences set by the tubes itself. Any extra power will be burnt down into heat by the regulators itself. As example for the Aa with 3.8 volts for their filament a transformer with separate windings for each raw supply with minimum 11 volts output is needed. Each Aa draws 0.5 ampere of current, together it is 1.0. The boards allow the exact setting of the current to match the variations of such old vintage tubes.

Since the Daven attenuators  are extremely difficult to find nowdays, which means it is almost impossible to find them as stacked stereo units in values like 100K or 250K, I did use one mono type for each channel. With everyday use of such a preamp, separated attenuators for each chanel would drive me crazy. With any control of volume you need to match the stereo balance again, a night mare if the amp is not positioned exactly in the middle of the speakers. In order to make the use more comfortable, I introduced a coupling system. With a o-ring both shafts are coupled together by wheels from a toy steam engine. The o-ring keeps both attenuators in balanced mode since I need to adjust one of them. If, I can hold one since I turn the other one where need. We will see if that system will do comfortable within everyday use, otherwise I have to design a spring supported clutch system…

O-ring coupled shafts for the Daven attenuators.

The back shows several sockets for different dedication. From left there is the power input socket (6 pole) where both raw voltages for the Coleman regulator boards will be supplied. The other two contacts are for the filtered anode supply. Next to this socket are two output xlr-sockets, the two main output terminals of the amplifier, these can be switches for the two corresponding rca sockets as alternative outputs at the other end of the back panel. All paired rca sockets in-between are four different input contacts, which are connected to the source switch, operated from the front panel. Four inputs should be enough nowadays, since the most sources are fed through one dac, like web radio, streaming clients, computers and similar. So there are three inputs for other sources like phono equalizer or a recording unit and here the second set of output sockets will be helpful.

After mounting the two potted chokes on top of the amplifier case and after connecting the tube sockets with four Aa tubes, the amplifier chassis is complete and is waiting for its complex dedicated power supply. When the power supply is completed and will work with the dedicated smooth anode supply of 200 volts and the two raw supplies for the regulator boards, I need to adjust these with a dummy load instead of the real tubes to prevent an overload of their filaments. But till there is quite a long way… As almost everybody knows, a good power supply is by far more complicated than the amplifier part. I will show it with an option of two different versions, a quite simple tube rectified supply with the three different voltages to keep this preamp a simple stand alone solution.

For the aficionados the series of articles will be continued showing a quite unusual pre-amplification concept, which will have the future in mind. Similar to german broadcast preamplifiers of the 1950ties I will show the build of different stages with different amplification factors. A gain amp (+50 db), a catch-up-amp (+25db) for compensation of losses and the already shown line amp for impedance matching to the power amp.
With these modules and a dedicated power supply almost any use in a modern audio set can be managed. For example a typical dac output stage will need roughly a amplification of +50 db, almost the same than a good phono stage before RIAA equalizing. When equipped with a input transformer with different windings and different ratio, like 1:10 or 1:25 (just to mention the extremes), the same amplification stage can be used for both sorts of applications. Since the former digital signal is now strong enough for the impedance amp (line), the phono signal needs further equalization with a RIAA filter with typical loss of -25db at a following stage. So another amplifier with +25db gain is here needed for compensation of the losses to level up for the line stage.

A multi voltage power supply will be needed for such a amplification chain. Such complexity needs to match highest standards and components, potted oil filled transformers and chokes would be first choice, but it is already difficult to find this stuff nowadays. The anode supply develops with tube rectification at the beginning, ideally made with a classic mesh anode rectifier tube lie RGN1054 or 1064 as perfect partner of the Aa tubes, to be continued with several chokes for HV and LV: 1. a well filtered B+ for the DHTs in the line stage; 2. two well filtered low dc-voltages for the Coleman Regulators; 3. a further filtered and tube regulated anode supply for the gain amps, and finally 4. a well filtered dc-supply for their filaments of all indirect heated triodes. I assume the weight, complexity and size of a well made power amp to get an idea about the case.


Read on soon,
Volker

The Aa Line Preamplifier II – The further Completion of the Amplifier

Hello to everybody

interested into the completion of my Aa-DHT-Preamplifier. As already stated, this line amplifier is a perfect solution for the mainly digital based systems, as it can be a exceptional supplement for any analogue chain with separate phono equalization. Implanted into a system with advanced dynamic attributes and with careful set up to harmonic structures, this preamplifier can open a window into the finesse of advanced audio performance, which I never have been able to obtain from commercial made line preamplifiers. A typical variety of incomparable attributes accompanied with directly heated triodes in small signal amplification stages are the base for such a extreme statement. DHT's for small signal output are very linear in their whole operation spectrum. They have a extraordinary refined character, sometimes show up with unique tonalities and exceptional dynamic abilities. Exactly like their more powerful sisters in power stages, but with a much deeper scaled effect because of the smaller signal ratio. The unbelievable attitudes of the Aa-Triode give a extra portion of refinement, linearity and tremendous wide open transparency, combined with harmonic detail I do not know second. Commercially made tube preamps could and can only be designed around available types of tubes, it was almost impossible to find bigger amounts of exceptional tubes since the renaissance of the tube amplifier in the 1980ties for hifi, nor it is possible today. The exceptional icons of indirect heated tubes for small signal amplification, independent of mu characteristics and impedance values, are mostly tubes made for professional dedication, like the WE 417 and 437, the red RCA's like 5691 and 5692, all the Telefunken special series like EF804s, EF801s and the red tipped types of all ECC types, the D3a's, C3-series, from other makes like Bendix, some former Soviet brands and uncountable lots of rare others tubes not named. All these exceptional quality tubes are not to be found in commercial audio amplifiers, where they could show their incredible qualities. But even these exceptional tubes cannot tame up with the same audible benefits of direct heated tubes, they are able to perform tremendous other benefits but rarely with such finesse of dht's.
The tungsten thoriated filament of directly heated tubes is acting as cathode in the signal part and creates very special peculiarities. On one hand responsible for such incredible aural benefits, but as well well for very delicate conditions in everyday use. Everybody common with DHT's in the power stage might be experienced with the typical sensitivities of such tubes for hum and vibration. In reverse to the amount of signal to ground ratio current, these sensitivities are ten times or more higher. This can make the use of such tubes very uncomfortable or even more, – it can be a real pain. I am using such tubes since almost ten years by now in such implementation for every day, within that time it has come sometimes to a point, where I just switched off my stereo, because I was unable to locate some reason for apparent hiss or hum. Completely exasperated after some time of search I decided to find reasons for the problems another day… In particular in the first years, when I did use flying batteries for the heating of the filaments, contact problems with broken cables, clips, battery containers, – flying batteries create here a permanent conflict zone. With a fixed and permanent installed power supply solution (constant current source) the most of such problems are now history. For those which are already on a shortcut, a  common or even complex regulated voltage supply is unable to support the aural qualities in the signal loop. It needs a complex constant current source with own complex (highly filtered with common mode choke) power supply per tube!It has to be said with impertinence, a direct heated triode is not a plug and go installation. If you want such a ease of use, you better should go for something else than tubes and in particular for directly heated triodes in general. Those respecting the extraordinary outlay will get gifted with the most colorful natural soundstage possible.

For those undaunted here a new life with audio might start soon. The Aa-Line Preamplifier its a fantastic solution for the digital chain. In combination with a good dac all the quite new benefits of digital stored music (i.e. better recorded standards, storage and organization improvements, a wide spread program of sources: world wide radio stations with lossless compression, cloud based streaming, etc), will find a exceptional natural sounding input stage, able to perform with a perfect holographic soundstage, if the following components (i.e. power amplifier and loud speaker) are able to support such a level of resolution. All regular readers of my blog have got already certain ideas how to get close to such a rare and uncommon performance. For me the exceptional resolution and the incomparable micro detailed dynamics are a base to operate a huge cone speaker like the Tannoy with wide medium frequency performance to a higher degree of resolution other designs can not support.

Today I will try to show some more completing of the amplifying enclosure. Now the rubber isolated perspex board has been mounted to the chassis, a distance of 20 to 30 mm between board and case is a quite good value since the Aa-tubes have a solid dimension, more known from typical power tubes of the 1930ties like coke bottled 6L6 types or similar. So the tube will be hidden with the socket inside, wile the balloon shaped glass will show out. The tube sockets are mounted at the perspex board with  some turrets to find place for the very few components and their connecting wires, which are necessary for the design of the line amp. This version of the DHT-lineamp is the "short wire version" of this topology. Since it incorporates plate chokes instead of output transformers (the long wire), the physical signal length from input to output sockets is less than 40 cm wire, with just a tube system (plate-grid-cathode/bias resistor, tubes in parallel mode), one oil-paper cap in-between. It is almost impossible to do any shorter design and this explains the tremendous influence to the final performance of the Aa-tube.

Solid silver wire with cotton hoses customized made near to the unwired socket board

Used components

To bring these 40cm to the perfect resolution I did decide to use solid 4-p silver wire (99.99%) for the signal path. I made up the wires myself from solid silver wire (0.5mm or 24 ga) and did isolate them with natural cotton hoses. The negative loop/earth path is made with thicker blank silver wires (1 mm or 18 ga) per stereo side, which get at one point together. The few resistors are carbon comp types of minimum 2 watts heat dissipation and 3 watts metal oxide types for the cathodes. The attenuators are classic potentiometers from Daven with switched 21-step carbon comp resitors for both sides. All capacitors (4 pc.) are oil-paper types, the chokes are Lundahl LL1667/10mA both coils in series (400 H  for 15 K at 30 hz), potted with wax into aluminum enclosures. The chassis for the preamp and the power supply are from the steel 14xx-series from Hammond. The used tubes are nos Valvo Aa's from war production in 1944.

Amplifying chassis from underneath: at top all input and output sockets; left and right Daven attenuators with input source switch in the middle; next level left and right coupling oil caps and b+-support capacitors; the board with input voltage devider, cathtode resistors and all silver wires; knobs with extension shafts for the front panel.

The used parts and components reflect my final selection for this amplifier type, I will definitely use the built sample for the next coming years. I did decide about the rare and expensive parts, till it might be my final line preamplifier and this is going to be a very important component in my audio chain as a result of increased digital format use. It can be made with similar parts and components (chokes, attenuators, resistors, switches, etc.), which are more easy available at a level of 95% of the same performance at the half of the costs. It might depend to the interest out there, may be I decide to make a kit with this design...
Within my next entry the amplifying part of the design will be finished with the inclusion of the regulator boards for the filaments. After this I will start to show the more complex design of the power supply for both pre amplifying stages, the line and the phono stage. Both stages need very different supplies, till the Aa tubes run in pure class a, so they need a quite simplified anode supply together with exceptional complex heater supplies per tube. A class b operated phono equalizer will benefit enormous from a complex filtering chain with chokes and a integrated tube regulation for the anode supply, combined with a simple dc heater design. If you want to follow its realization 

read on soon, Volker

Incredible close to music VI – A Evaluation of Foreign References

Hello

to all interested reading on about further experiences with Line Magnetic and Shindo amplified set ups. Today I want to make a short report about a visit in Frankfurt some days ago, where a very advanced and experienced audio chain with Shindo amplifying devices and Line Magnetic components is in use. The owner Claus is a long term follower of advanced audio concepts with triode and horn amplification. He started his interest into audio during the early beginning of the european triode movement in France with Jean Hiraga at Maison L'Audiophile as initial. It is obsolete to mention that Claus has owned already a tremendous amount of equipment during that time of 30 years. He always stayed or sold back his components convicted to find paths behind the curtain of the typical superficial audio presentation into a more harmonic and natural representation of music. One example might show his behavior quite well, the shown Shindo 300B Mono amplifiers in my article: Incredible close to Music I – The System Matching.  Exactly this pair has been part of Claus installation til the early 1990ties, when he did sell them presumably with his typical words: "I don't need them anymore". This quote shows a rare attitude: the ability to concentrate to the essential qualities, where a lot of us others would stay with components as proud ownership in mind he gets rid of for him anymore useless components. After one more owner these amps harvested 15 years ago at Mikes set up, just to close the circle.

A listening room were walls are covered with shelves containing records, lots of records (may be 2000), books and CD's. The positive benefits of such surfaces and their physical masses for room acoustics are known and a lot of audio enthusiasts use their record collections for that sort of effect as well. But this time it was the first time, that there was not anymore a dedicated record player…?! As I could hear he had a Platine Verdier player (what else?) and EMT turntables for years, now he uses streamed digital data, deliberated from a pure audio computer into a Line Magnetic dac. ("I don't need them anymore".)

Claus Line Magnetic horn set of LM22/597 is extended for low frequency support with dipole enclosures. Customized made from solid german oak, the enclosures are made similar in design to the "755" speaker from Auditorium 23. Inside he uses a fantastic delicacy, a pair of Microtecnica 15'' field coil speaker units. These are the most beautiful made low frequency drivers I have ever seen. They have been manufactured in Torino in the 1940ties by a company which concentrated to different precisely manufactured micro mechanic product lines, one line covered several products for the cinema industry like complete installations of projectors and sound equipment. Originally these wonderful speakers might have been used some time ago in a Italian cinema, presumably installed very similar to the well known Siemens Klangfilm Bionor sets, assembled with a front loaded integrated horn funnel in a huge wooden baffle board, together with high frequency multi cell horn dispersion on top.
Italian products of this particular time mostly show up with a typical exceptional attitude, where the finalized form follows highest ingenious standards in combination to a exceptional aesthetic expansion. This attitude has been rarely cultivated with mechanical produced components in other countries at this time. In the post Bauhaus era of the 1930ties other values did decide in wide parts of northern Europe about the form finding process in industrialized productions. "La bella macina", the underlying philosophical principle behind typical northern Italian (Piemont and Lombardy) industrial designs before war, was as well a cooperation between swiss immigrants of advanced technical expertise searching work in the most industrialized region of their culture. The term states the perfect combination of functionality, crafts and form. Exceptional motor designs, like made by Alfa Romeo or Gilera, with espresso machines by Faema, typewriters from Olivetti or bicycles made by Bianchi in these days, might remember of what I am talking about, even if a typical German arrogant purely ingenious based understanding of machines, neglects these facts persistently.

15'' Microtecnica Field Coil cinema loudspeaker in solid wood dipole enclosure

The Shindo 64B PP-Mono amps on top, left beneath the Mag-Amp beside at right the DBX active crossover. In Foreground the Shindo line preamp on top of the Line Magnetic DAC.

In difference to Mikes set, Claus positions his LM22 horns at the stereo base close to the center with the low frequency dipole enclosures mirrored to the outer sides. He uses a pair Shindo 64B push pull amplifiers in combination with a Mag-Amp by Lundahl for the active low frequency support. Each sides signal get devided by the use of a active Dbx 24dB filter unit, since the LM 22 and the LM 597 are cut off with a passive network. A rare and expensive paper capacitor from Western Electric supports the performance for the wide tone spectrum of the medium and high frequencies to a higher degree of refinement supplied to the field energy of both speakers.

Passive filter network for the medium and high frequencies, made up as flying installation with rare expensive paper capacitors from Western Electric (behind LM555W telephone).and some ordinary paper caps.

We did listen to a variety of Claus digitally stored music, with a concentration to contemporary jazz, but as well some large orchestral classical music. With good 30°C room temperature or more and high humidity it was not the perfect day to listen to tube amplified audio sets. Well, I didn't know at the beginning of the listening, – was it me, the climate or the set, I did hardly find into the music. For compensation I did drink a good liter of water during the first three tracks. The music did show all the signs, which are so typical for the projection of the wide frequency LM22 horn, but it was a good bit to dry for my taste and it was a bigger bit dryer than I do know the components already from Mikes or Hans sets. It was like with a exceptional wine, which was some years stored to long in the cellar. Like a Tignanello of 12 years age, of a well known year, it might take a good while to oxidate and open up, before its shows its exceptional complexity together with a refined harmony in the foreground. As well here, everything was there, it was just a bit to tight and dry… I do know these horns in the meanwhile very good and I know them better balanced. After a while Claus stopped the audition and asked: "Now I would like to change to a different power supply for the field coils of the Line Magnetic horns?"
It took a while to change all connections and we started to talk about several topics. I started as well to make some photographs of the set. A good hour later we came back again to listen to similar music and I thought: If I will be able in a foreign set up after a hour time to realize any difference of a power supply?
It did not take long, may be two minutes and I tried to evaluate, if we do listen with completely different settings, I had the feeling it was set with a lot higher volume level than before. But it was even more than volume settings, the whole soundstage had lost all the dryness and its shortness of breath. Instead the well known wide open dynamic soundstage performed with incredible detail, harmony and transparency. I did ask, is it true that there is only a different power supply for the field coils? And is it set to the same voltage? I could not believe the difference. I started to tweet my feet and started as well to like the music, which always points the major difference. Just a power supply, … for the field coils, unbelievable. There is not even some direct connection to the audio signal, it must be a foremost interaction between magnet and voice coil? Nobody can really explain this effect...

Now the chain had shown up with all the unique advantages the Line Magnetic horns are known for. For me it was really amazing to realize how small the differences of sets in the final performances are, even when whole parts of the chain can be different or the surrounding room is absolutely different, the general performance shows the absolute same advantages.
Here the only little difference in Claus set is the active 24db cut for the low frequency path. As a result the frequencies from 300 to 500 hz are less prominent, comparing it with Hans and Mikes set. Their 6 db passive filter brings a mild support in this particular frequency range. But these differences are far beyond qualities, they have to be seen with respect to different ideas and taste, performed harmonics and preferences of different owners.  As different power amps, like the Shindo 300b Mono blocks of Mikes set would have a influence to the presentation here, the Shindo 64b amps would do in reverse with Mikes set. At the end I could find completely back to what I already know about this speakers. As well here again the Line Magnetic set up confirmed my understanding to be one of the most transparent speakers for audio use. They are able to produce almost natural dynamics together with a refinement in harmonic detail, were other systems will be judged by. So they can offer the most advanced insight into well recorded music and can make the listener to forget about its origin. A pitty that the beloved Microtecnica speakers were on such a level of perfection, that I could not really hear them in the set, they just acted perfectly to be true invisible…

Later in the evening I had the chance to listen to the new A 23 loudspeaker "Hommage à Ken", made as a homage to the shortly faded away master Ken Shindo. Equipped with a totally new designed LM755 chassis, which in difference to the first LM version with field coil magnet, is exceptional close in all details to the rare an expensive WE755A. It incorporates as well a w-shaped alnico magnet like the original and a extremely similar made cone structure. Out there is a quite huge community relying to that first version to be the best full range speaker built ever. For me it was a first time to listen to such a alnico version, and it was the first time to evaluate such a speaker not to be operated in the classical baffle board.
Two things are remarkable from the first sight. This 8 inch cone can do real "full range" and it shows a exceptional refined resolution of musical harmonies together with all necessary dynamic abilities. Coming from Claus LM set, it was a very similar experience to find into its presentation. It is of course not a "full range horn", with all benefits of a little aluminum diaphragm, but it has a quite small cone and performs without any crossover on the other side. It brings out a similar tonality, so that the shallow listener would not see any argument to get such a complex system like the LM22/597 with LF-support, if a simple cone can do the same…?! Almost the same, to be honest….


Read on soon, Volker

The Aa Line Preamplifier I – The Mechanical Construction of the Enclosure

Hello to everybody reading my blog,

now after the end of the soccer world championship it might be time to start a new series of entries about the building of a DHT preamplifier as central component of a future orientated system. Several times I have quoted my extremely positive experience from my Aa Line preamplifier, which I do use since 2004. This was my first realized preamplifier incorporating directly heated triode tubes in the small signal section of my chain, namely the line stage of my set up. When I realized this concept almost ten years ago, I did not expect to be so much convinced one day that such a preamp will go to be my final word in the line amplification stage.
At the beginning it formed a extremely well sounding approach towards refinement, but in 2004 my chain was not in that developed stage, where it is today. The first remarkable side effect came when I started to rediscover my digital signal sources again. For more then a decade my Meridian CD player was into storage. With my Platine Verdier Record Player and my time living in the US, created a concentration into vintage vinyl as foremost signal source. But around 2005 the digital storage of music attracted my attention. I did start to record my vinyl for digital storage at harddisks. The combination of "lossless" storage and Apples hard- and software (Airport Express w. digital out, lossless format to be supported), formes a easy access to digital systems within my analogue tube amplified audio set up. Together with my new Aa-line amp it created a extremely refined sounding system, with lots of merits I didn't know from my analogue arm. In these days I did use my audio mainly to listen to my analogue jazz record collection, from time to time I made some recordings from vinyl just for storage issues. I didn't take the digital side to serious, I was a lot more shaped by my early experiences from the 1990ties, when early digital recordings and cheaply made transcriptions from vinyl to CD created my worse experience with digital and formed the decision to leave it for the "consumer".

When I had to move my studio in 2010 I had to adapt new listening conditions. At the beginning I did start just to set up a digital streaming chain as first set, in order to have some music by hand. It came as is always happens, new room acoustics did create new courtesies, I started to like the digital arm of my set up quite well. Together with a new interest into actual and therefore newer recorded music, I realized a unknown conservated audible quality. It was very obvious that in the recording part of audio in the last decade a huge quality step was realized. Completely digitally recorded, mixed and finalized takes showed up with a remarkable close and accurate preserved soundstage, in a way of perfection I rarely didn't know from vintage vinyl. All the typical aural fingerprints, made by every analogue component in the recording chain, the microphone, its input transformer, the preamp, the mixer, the tape recorder, the amplifier and serveral other chained components seem now not any longer exist in a conspicuous way. Instead a much more homogenous and digitally corrected sound image seem to be the new standard of actual audio preservation today. A better focused staging with unknown lots of captured air is the typical side effect of modern well made recordings. All the former unavoidable phase shift effects seem to be gone with digital shaping, instead a wide, dynamic and refined window to lively recordings seem to be now some sort of standard. With the exceptional resolution of my line preamplifier, these qualities were the foremost sensual facts to be experienced, which I rarely did only know from a handful of my best analogue recordings. The DHT tubes combine a extreme musical coherence with absolute linear resolution in a way, indirect heated tubes don't show. The Aa Weitverkehrsröhren are exceptional top performers within the common known DHT's for small signal amplification. I did try other tubes as well like the widely used 26 tube ore the TM2 with similar success, as well with transformer coupling, but I will stay with the German Post Tube, since I like its extremely open, transparent and dynamic sound better than any other. They are made once for 10000 hour service in professional installed telephone relay systems and have some other mechanical advantages the most other DHT's don't show up with, because these typical US-american tubes once were made as consumer products for radio receivers in the 1930ties. The availability of German Post tubes is far better in my culture than any US-DHT and there is the variety of three different brands with different properties to find. The rare and expensive original early (from 1927 on) tube from Siemens (with tip and glass tree inside), the common Valvo type (globe type with mica spacers) and the last version made in the former East Germany by Neuhaus Röhrenwerke (with brass socket and coke bottled glass shape and ceramic spacers).

So I started after almost 20 years to buy again some CD's, giving me a new unknown listening pleasure on the first hand, but as well as streamed data beam digital sets a comfort and usability I never could establish with vintage vinyl recordings. Vintage vinyl is still unique in different fields, it wonderful large size covers, the printed informations and a typical liquidity in the timing of their sound, digital formats do not cary. Today I use both systems side by side with mating success, but the operability of streamed data sets the pace for the years to come. So the quality of the line stage is the key for that kind of use and needs to be of exceptional ability.

First  evaluation stage of my Aa-Line preamp in 2004, equipped with battery clips for the heaters and here showed with rare Siemens Aa tubes, identified by the tip.

Solid mechanical construction with complete relying at oil caps and solid silver wire for the signal path. On the left: the variacs for the lead batteries and a stepped attenuator for volume control.

But I will not conceal that there are some problems with the use of thoriated tungsten filament direct heated triodes, other tubes don't show. With directly heated triodes the cathode acts as heating element for the tube, which means the heater is part of the signal path. The most people know this problem from power tubes, where it creates sometimes hum problems, which can be solved quite easily, because of the higher signal to ground ratio. But at a lower signal levels and following further amplification, any little hum sign will be amplified up to solid levels. Here the problems needs to be solved completely. To get it work, it needs advanced solutions for the heater supply. In the beginning I did start with classic regulators (LM317), these bring a lot of radiated heat to the amp and don't sound very good. After burning my fingers at the chassis of my preamp I did decide to look for other solutions and ended up with a very uncomfortable solution, I did use lead batteries first. Now I had to charge every day my batteries in order to have enough energy for some hours of listening pleasure. I did try several different battery types, since the cheap Chinese lead batteries didn't last very long, after 100 loading cycles they lost  energy to be stored. So I switched to nimh-batteries. I got a quite good sound but only for two hours time with one set of batteries. So I had to buy several sets, which needed to be exchanged after a good year of use by charging them every day. I liked the sound qualities a lot, but hated the charging practice and the all around contact problems in practice. Always some hiss or hum happened needed some helping hand to fix the contact problems for further listening. Not comfortable.

In 2010 I switched to Rod Colemans CCS boards, which make life a lot easier. These constant current supplies are sounding as good as battery power and do not burn tremendous amounts of heat like other regulators do, when well implanted. These can be used with almost any DHT triode, independent of current amount with good success. So they are as well a good solution to be used with power amps.
Now after almost 10 years of use with this preamplifier and after final evaluation comparing it to other options with my new speakers, but as well in other chains, I decided to bing this concept into the next level and final stage. This will be accompanied with several blog entries.

It needs a well made mechanical design to find the long term usability. 

Now, in the final stage the line amp is going to be the switching center for all types of sources and needs several in- and output options. Only the best components are prefered for the job to be a final preamplifier, here with Lundahl iron, NOS Daven stepped attenuators and a Elma switch. Classic WE components are a good guide how to make a well organized amplifier.

For my new approach the Line amp becomes a central position in my chain. Beside the analogue system arm with my vinyl record player, the dac will feed the line stage with digitally streamed music using the comfort offered by wlan and with the iPad as a remote system, since all data are stored at the hard disk of my computer. For the future this is a important and foremost feature to be extended as main source? As well a recording option has to be kept be in mind, which will create other problems to be solved with tube amps.
I did try to listen again to some conventional line amps in the last couple of month. After this exceptional evaluation with very different amplifier concepts of advanced stage I was restless convinced about this preamplifier and therefore I did decide to bring it into a final state. For absolute perfection it needs a much lower output impedance to work flawless universal with every tube amp. With the high impedance of the Aa (30 K) it is almost impossible to match this preference, so some tube amps are not happy with the high load and connecting cables are getting a difficult choice. So, staying with the Aa tube and relying to its extreme unique sound qualities make a fundamental change of the implementation necessary. Cutting the internal resistance into half as a result of the doubled tubes into parallel mode, might be the way to get half of the output impedance. It should sound as good as before with much improved load into the most input stages of tube amplifiers.

Read on soon about the next steps, Volker

The Tannoy 15'' Dipole Enclosure – The Evaluation of the Known I

Hello to everybody,

interested into my Tannoy enclosures. In the last three to four month I did cover several articles about different Line Magnetic sets, assembled from LM22A, LM555W and LM597. I started the successful line from my conviction, that this horn array completed with dipole enclosure for the low frequency support, is one of the best speakers I have ever listened to.  I will cover more articles in future about similar audio chains, but it depends as well on the occasion of access to them. Through the evaluation of Mikes and Hans sets, it got manifested that the electronic components carry a remarkable part at the final aural result, in a way of execution, the owners didn't believe before. As already extensively reported, such a horn array, driven by a Shindo tube amplification chain, together with dedicated transformers, generators and other components, can work in a stage of harmonic holographic audio transparency, which I do not know a second time. It can, – it is not a inevitable result with such components or a result of other possibles recipes, it needs the educated ear of the holder to make it real.

In the past three years the described carefull setting up of both chains had a tremendous influence to the decisions about the design features of my enclosures. This decisions have been made about the acoustic principle of the enclosure type (dipole), the radiated wave front (front loading) and the general audible preferences (materials used). As already widely covered in my former articles about the enclosures, without the experience of the LM-set up, I never would have been able to realize the cabinets with such a incredible success. The physical performance of such huge medium frequency horns like the LM22A, covering a tremendous part of the frequency range (300 to 6000 hz) in combination with a dipole for the low frequency support, have given me a true new perspective what a loudspeaker is able to perform at its best. So I accepted some major changes during realization of my 15'' Tannoy enclosures and got rewarded with the by far best response I have ever listened to with Tannoy speakers.

But it has to be said as well that under permanent real impression of the LMs, with such advanced perfection of a almost holographic sound stage, together with all other favored properties, like harmonic micro detail, fastness and general naturalness, the Line Magnetic horns have created in a sustained way my precisely defined sense for the performance of such a audio transducer. Every time back home the listening to my Tannoys was a quite difficult experience with lots of aftermath work. It came several times to a point where it was hard for me still to believe into the unique properties of a 15'' paper cone speaker, covering the important frequency range of 1000 hz, like my Tannoy Monitor Red. I did hardly question the listenable results and the staging of my personal chain and its ability to follow on the described route in direction to a similar result close to the LMs. At the beginning I made the mistake to require the absolute same physical performance from my speakers and their driving chain. In the early stage of comparison I was not able to admit my set a own physical performance, with own peculiarities and unique individual qualities. I wanted it to perform similar to the bespoke LM set up. Of course I do know that this is in fact absolutely impossible, but my ear forced me to follow on… Comparing a 2'' aluminum diaphragm with a 15'' paper cone at the execution of middle frequency response is like comparing a truck with a sports car. This comparison would get better, if the mass of the cone will be reduced, may be to a third like with a Altec 755 full range speaker. Still this mass of the cone is several times higher, comparing it with the 2' aluminum diaphragm. Both cone masses create their individual conditions, which need to be featured and compensated by the driving electronics. Both cones create their own typical fluent rich tonality in particular with the important medium frequency response. Since the small mass of the aluminum diaphragm needs less driving energy and control, but it can tend to sound to thin or very technical, since the large heavy cones need some sort of the opposite compensation. One reason why the typical full bodied sound of the direct heated Western Electric 300b tube matches perfectly the demands of the Line Magnetic 22A metal horn. A perfect team mate.

For me it was as well a chance for perfect evaluation of my own components, their particular abilities and their competence to operate in a foremost natural inconspicuously way. Since I never could work out the level of experience like the ingenious mastermind of a Ken Shindo, who was able to conduct every audio component to a perfect match of his personally favored attitudes. I have to proof and readjust every amplification stage for its individual input of peculiarities. All my components got verified over decades and matched together to work in a good evaluated balanced mode. With my new speakers everything needed to be checked again, their new profound abilities made a advanced sort of coupling to a higher degree of definition necessary. During that time it came to a point where somebody offered my a LM22A/555W set as part of a attractive deal. It was a really hard test mode for me at that time, but I decided to stay on with my Tannoys, even if I did know that the final result can not be the same. I still believe into the unique properties of my enclosure design as a rare alternative option for the few Tannoy users, which want to get a speaker of highest expectation and refined expression. A speaker which can leave classic original Tannoy concepts far beyond, if naturalness, musical involvement and perfect refinement are the most sought qualities instead of superficial hifi attitudes.

My phono stage works on its own with extremely liquid naturalness, lots of harmonic detail and very refined overall tonality with quite good outer dynamics are the major qualities. I do use this design (5691 SRPP to 5691 OP, tube rectified and regulated PSU), since 10 years. It works in every respect and discipline better than anything I could compare it with, and this was a whole lot of commercially made tube phono stages. Big names, tremendous amounts of money, clever designs have been in comparison, I decided always sound wise, – but I did it with different sets and rooms with different speakers! Sometimes if one of the surrounding parameters is in minimal change, it might be necessary to check such decisions again. This phono amplifier had always some sort of a more self evident attitude than other options, – rounder with deeper insight into the musical fluid – with one word more natural sounding than others. I did built this type in the late 1990ties as a typical test approach after lots of discarded designs. It is very ugly realized from a US-military speech amp for the enclosure, the PSU transformers and the sockets, the amplification design is built up on a Kondo M7, but I did incorporate my beloved 5691 RCA red base tubes, a high mu equivalent to 6SL7 designs with unbelievable better sound properties, as a result of their sturdy mechanical construction. Till today I do not know a better sounding tube in the first stage of amplification of phono equalizers, the prices for them always have been very high, but with the web they have skyrocketed to the top of their range.



























After this phono amp I did try again several other concepts, with inductive elements for equalization, different tubes in completely different arranged concepts, I always came back to that provisionally built sample shown in the image with the idea in mind: one day I will do a perfect made phono stage. Till today it did not happen.
For my actual evaluation the RIAA filter of my phono amp needed to be checked at a professional work bench, I never did that before, but I had the feeling that my low frequency filter gave me a bit to much punch. The filter was realized completely with paper-in-oil-caps and everybody with some experience in RIAA designs knows exactly what I want to say. High tolerances versus unique sound properties are in question with oil caps of such small values, in former years the exactness of the RIAA was not my foremost trial, I spend much more energy to get it singing in general, to difference out, if it is more tenor than baritone was not my major aim. But now it needed to be evaluated a bit more precisely. My friend Klaus has well equipped test bench with uncountable W&G components for every reason, so it came out that I had a good mismatch in my RIAA filter by typical 10% variants of caps. After selecting pio caps for better matched values, I got my filter into a less than 1% tolerance, which is very good comparing it to the variations pressed into the vintage records. The first active amplifying stage in a chain has a tremendous impact to the final result, every little detail which gets here included in perfect shape will bpassed through the coming stages with audible success. So I still cannot accept anything else than oil caps for the RIAA filter, even if its getting really difficult to match.

My line stage pushes the general performance towards a highly transparent holographic audio image. In combination with a unknown spectrum of musical harmonies and rich open dynamics it shows all the very typical attributes of Directly Heated Triodes. The holographic attributes of my line stage make it a perfect companion for compensation assignments in the important medium frequencies, when a huge paper cone speakers will be the transducing element. Directly Heated Triodes with thoriated tungsten filaments are in small signal amplification stages a unbelievable formng element. By far more important than incorporated as power tubes. It can not be said enough, in earlier stages their same aural benefits are much more effective shown. My line stage uses the Aa Weitverkehrsröhre, one of the most holographic sounding tubes money can buy. But…, if there will be not their "archilles heel", the high internal impedance (Ri), which makes the use of this tube a bit tricky. As a result its output impedance is quite high and it will not be a universal match for any tube amplifier at planet earth, transformer coupling is impossible, shortest connections are a must to get them work best.

Finally I do use the well known Leak TL12 Point One power amplifiers, since these a simply one of the best tube amplifiers made ever. They are early push pull designs, with all positive and negative attributes such a (Williamson derivate) principle offers. Push pull designs emphasize at the frequency extremes, but as well are characterized to have by far a better control about speakers, with 15'' paper cones this can be a very sophisticated property smaller speakers don't need. More common push pull  examples from other brands are mainly characterized with thin tonality and limited middle frequency response. Leak did a time typical oversizing of their transformer designs, together with a relying on oil caps in all sections make this mono amp a major design in history and they are as well highly sought after. These early Leak models (1949) cover the rare and important skill to keep the musical content in a comprehensible flow, a attitude which only a handful of brands have been able to perform, – independent of the virtues of push pull or other design strategies. Their extremely complex output transformer design (Haddon) with 8 independent inlayed coils at the secondary, typical (2, 4, 8, 16, 32 ohms) for all early Williamson designs, may be as well responsible for their elaborated and refined performance, which any other later Leak model could not hold. A complex extra benefit which has been given up first in the early 1950ties as a result of already cost cutting issues tamed to growing productions figures of a beginning audio market.

I do know my chain very well, after readjustment of my RIAA the whole set works with a remarkable similarity to both described Line Magnetic sets. It works with minimal lower resolution in the important frequency range between 500 to 1500 hz. Of course the resolution of a 15'' paper cone can not show the same attitudes like a big horn development driven by a small diaphragm of minimal mass. But the overall insight into the music, the dynamic abilities, as well the eminent importance of micro dynamic detail of higher frequencies is extremely similar throughout the front loading and the dipole principle. Listening to them just leads to forget about other sets like Line Magnetic, they can induct their listener in a way only a few speakers are able to. A benefit of the 15'' Tannoy Monitor Red Dual Concentric speaker is its perfectly match of high and low frequency timing, as a result of physical perfectly arranged coupled units. Here the long horn development of the LM22A creates a profound difficulty, but it can be perfectly reached and even better without digital support.

Read on soon about my future tries of integration of completely different amplification concepts like a 300b amp, which will change completely the sound structure again,
Volker

Incredible close to music V – The Ear of the Holder

Hello to everybody,

after the series of articles about the Line Magnetic products which are made to resemble modern equivalents of the extremely rare vintage Western Electric products from the 1930ties, like the WE555 receiver, the WE 22A horn unit, the WE 597A telephone, extended with the TA7331 dipole like enclosure, the feedback to this articles was more than resonant. I have got some requests from interested people worldwide into such setups, but as well from users of similar equipment. My series of articles was introduced to take care about the incredible rareness of such fine performing chains in the audio world and to find bases why it is so difficult. Within these first articles I did try to describe an aural rarity, were natural tonality, refined resolution of detailed micro dynamics together with almost realistic dynamics, form the base for listening ease as a sort of harmonic presentation. Reading the feedbacks on the one hand and my own long time experience with audio sets at the other hand, it seems to be extremely difficult for others to find such a level of performance. Almost every mail which reached me during that time, described difficulties or even a real lot of problems with similar sets to the far extreme impossibility to make it work in a reasonable way. How can this be?

The Line Magnetic LM22A/555W/597 with dipole enclosure here shown is the speaker combination which has impressed me most within my 30 years with audio, by far. How can it be, that a similar set up somewhere in the world does not seem to work at all? How can it be, that this combination of the most transparent audio response, with the fastest and most harmonic medium frequency response I personally do know, will not work together with some of the best triode amplifiers available today? How can it be that a similar set with digital dsp and active amplification is not able to show any harmonic content, being far away from musical insight, even with such a technical implementation will allow so much more "advantages"? Only a few questions are quoted here to show the catalogue of contradictions, but they all point to the same basic problems. It is a damned task to bring a highly complex audio chain into advanced mode.

Platine Verdier Turntable with Shindo Merseult tonearm and dedicated Shindo pickup

In todays audio world we are looking back to almost 80 years of technical "advancement". A actual professional studio monitor with integrated dsp and 800 watts power amp can perform with a tremendous advancement, just by its own. The audible difference to the former named Line Magnetic set driven by extremely refined tube gear in terms of quality difference is small, if namable. Of course tubes and such ha huge medium frequency horn adds some extras to the final performance, due to their special physical forming of the signal.
I know that I will open a new "barrel" with that thesis, but some sort of discussion seem to be on need about compability. It looks that for the most people the actual active studio monitor might be the better solution, it is a lot smaller, cheaper and causes less responsibility to set it up with a decisive ear. With a highly variable chain of different components and accessories, in particular with vintage or similar tube gear, the mismatch is a inevitable program, but it guarantees a good cash flow for this business. Widely varying impedances, highly different sound performances of varying brands, components and accessories, create a infinitive wide field of scopes. So almost everybody well experienced with the variety of such mismatches, keeps on running to plug components by "try and error", sometimes for years, decades or even a whole lifetime.

Double page spread from japanese audio magazine showing a installation with two WE16a/WE597 and two LF-baffles

Another typical and inevitable problem is the abstraction, generated by the human brain in comparison with audible impressions. Since generations the typical "blind listening test" brings out surprising results, showing that a lot of people do hear what they expect from what they see. The same trick happens with what they believe to know. I only have met a very few people, which are able to trust their listening impression and are able to difference out what they hear and how they feel with it. Another problem is the high rate of forgetfulness of the human ear in order to transcribe impressions and emotions from one set to another for comparing reasons.
A continuous experience with natural music performance with nonamplified performed instruments, like world-, jazz- or classical-music is a perfect school for the ear to internalize the fine differences. If you just rely to electrical amplified, mixed and performed music program, it will be difficult to work out the character of natural tonality. The regular experience will create a sense for the finer details and the atmosphere of micro dynamics, as they are a important part of a natural impression.

The rare gift or skill of true listening ability is absolutely necessary to bring a complex audio chain into  improved stage of performance, since the educated human ear can be the most refined instrument for detecting any errors in a final sound stage of audio performance. 

Since three or more decades some payable measuring equipment is available to support the listening impressions with technical evaluated data and printed graphs as visual equivalent. To my understanding such a equipment just can help to confirm the subjectiveness of impressions, but true relying to such technologies brings the most people out of the track. Furthermore digital DSP with its virtual cockpit of possibilities will add extra options to be disguised and finally spoil any remnants of naturalness. Of course the proponents of such technology will reply that aural coherence without measurement is just some sort of illusion ...
It might be fact that the foremost crowd of audio aficionados will cut into two contradictive groups, the one relying to the logic interning of technology and the other group hardly believing to the superiority of the human senses. Manifested knowledge vs. "fishing in the dark", the jin and jang of mankind.

I think the most people reading here do know what I want to explain. I have spend almost 10 years till I found my first real anchor in my audio chain. In my case it was the Platine Verdier turntable, from were almost everything else in my chain got evaluated further on. Now after 25 years I have found some components (or made them) which might work out together in a improved way. I never have counted all the energy, money and time to find out about and even today I am far from save within every component I do use. But independent from components I did learn within that 25 years to listen – it was a expensive lesson.

LM22A/555W/597 on top of a TA7331 influenced dipole enclosure

So if you are interested to get one of the most expressive speakers ever, a Western Electric original like WE13/15/16, a Line Magnetic replica or a Sato horn array, you need to be save that you will be able to tame these exceptional magnifying glasses into musical performance. They can be "hell or heaven"at once, just another component can be responsible either or. These horns can show a tremendous perfect insight into the music with naturalness and perfectly refined harmony, as they can dramatically explain any imperfection with impertinence and sustainability.

When Mike did start his journey with his LM set he did absolutely not know where the train will stop or how long the trip will be. With his own words he did state, that he was several times at a point within this four years to give up and sell the set. He did not know anymore further or even back, he luckily had his close friend Hans, who tried on his own and could push him back into lane. Today both are absolutely happy with what they did work out: "the first time in 30 years that we have got a system working".

The most relevant findings from this process were:

1. The Shindo chain takes a tremendous part of such incomparable matching qualities. It is the perfect impedance matching of the different amplifying stages, their exceptional tonal coherence from the pick up trough the arm, over the matching input transformer, followed by the RIAA stage and perfectly conducted from the line stage (output transformer coupled) to the power amplifier. Here the typical warm, refined and full bodied sound of the WE 300b directly heated triode in perfect implementation is a significant part of the final result.

2. The Line Magnetic LM22 horn is set with a 6 db crossover to the range from 300 hz to 6000 hz, the LM597 is set with a 6db filter above till its physical limit. The dipole enclosure uses two Siemens KL405 units in parallel to get a better efficiency with 4 ohms comparing the horns, this makes the autoformer redundant. The crossover is set with 6 db filter at 300 hz. This is another most important feature for the aural superiority, since it will let the woofers play beyond the 1000 hz range. Even if they are not very loud here, they do bring a important subliminal support of the LM22a into business. I did listen to them separate and it is fascinating that they act almost a bit like a full range speaker, as a result of the property that the KL405 is normally used as full range unit as solely speaker for the tone of a film projector.

3. The room treatment brings out a very musical damped room with conducted reflections to make such a degree of performance possible. Even when the horns do peak the radiation in direction of their mouse, the treatment helps a lot to keep the wandering reflections in control and make therefore a foremost listening of the directly radiated waves possible.

4. It is Mikes and Hans ability to work out the complete panel of properties combined with a true sense to avoid almost all deformations coming by, created by the rare opportunity to tune such a set for improved demands. They restless tried to question every aspect again and again. So he shortly did reevaluate again a DSP with active amplifying devices for each unit, just to make sure, that the decision from 2011 to ban this technic from his setup, was the right one. He did come back to analogue filtering with 6 db crossover a second time, now completely convinced that a DSP might create perfect measurements, but is no solution if harmonic audible structures and homogenousity are the requested values for the final sound. As Mike tried to resemble the Shindo 300b amps with other tube amps of exceptional quality to find alternatives for rocketing tube costs. As well here he has to complain, that there is no real alternative for him in sight. He relies completely to the typical aural skills of the original WE 300b tubes and exceptional abilities of his Shindo amps. In some restless sort both guys always try to find better solutions, at the moment they will not be happy since they have tried the last big mystery for such a installation, a selenium rectified or a historical tungar power supply for the field coils of the LM speakers. Since the beginning of this year I do tell them, that there might be other options to spend time, energy and money with than some further audio tweaks, like sailing, food …

Passive crosser for the medium-high frequency path show impressive simplicity

Dipole enclosure with Siemens Kl405 woofers underneath the LM597 telephone

I now have had several chances over short period of time to inspect Mikes set in almost every detail. I can agree that there is no part or component to be changed without impunity. The receipt follows on the foot with some sort of deformation if you try. This audio set impresses with a absolute uniqueness of balance, a incomparable performance with tube audio components and horn speakers. I would be interested to learn about another set at the same degree somewhere realized, but with different components to widen my horizon. ...


Read on soon, Volker

The Perfect Ensemble – A Bronze Body for the Denon DL103 to match my SME Tonearm Kit

Hello to everybody. After a longer period of entries about complete audio sets and about the making of my Tannoy enclosures, I will continue with another entry about my SME tonearm conversion kit and its extension with a matching cartridge. Several customers do have confirmed my statement, that the converted SME 3012 with its heavy stainless steel tube outperforms almost any other available 12'' tonearm, when equipped with a low compliance pick up cartridge. The range of typical cartridges bringing out the highly improved dynamic abilities of such a mass-spring-system are today the Ortofon SPUs, the Denon DL103s, the Koetsus and some exotic brands from Japan. In this group the Denons are in a outstanding position, since these cartridges are by far the cheapest alternative.

The LignoLab bronze case, the only housing at the market which is closed from the underneath generator side. It features real bronze and not brass in a perfect matte blasted finish as optimized material.

The DL103 was once designed and exclusively made for professional broadcast use in 1962, right in the past time when stereo recordings with Long Play Albums did take the market. Several other brands tried to introduce competive cartridges (Fairchild, General Electric, Grado, EMT) in these days to follow the Ortofon SPU been the first stereo moving coil cartridge in history and dedicated first for this professional use, introduced in 1958. Four years later the Denon was exclusively handmade for the Japanese broadcast industry NHK, to be identifiable by its black bakelite body. Since 30 years it is machine assembled with a thin plastic body for common distribution to a general audio market. Denon produced the commercial DL103 series like its european paragon without technical change till today, but with several variations over the years to keep the interest up.


Denon DL103 Technical Specifications

• Stylus: 16.5 µm diamond spherical tip
• Cantilever: Aluminum
• Frequency Response: 20 ~ 45 kHz
• Output: 0.3 mV at 50 mm/s
• Output Impedance: 40 Ω
• Load Impedance: 100 Ω
• Channel Separation: Over 25 dB at 1 kHz
• Compliance: 5 x 10–6 cm/dyne (100 Hz)
• Tracking Force: 2.3 ~ 2.7g (± 0.3g)
• Weight 8.5 grams
• Stylus: 16.5 µm diamond spherical tip
• Cantilever: Aluminum
• Frequency Response: 20 ~ 45 kHz
• Output: 0.3 mV at 50 mm/s
• Output Impedance: 40 Ω
• Load Impedance: 100 Ω
• Channel Separation: Over 25 dB at 1 kHz
• Compliance: 5 x 10–6 cm/dyne (100 Hz)
• Tracking Force: 2.3 ~ 2.7g (± 0.3g)
• Weight 8.5 grams

The perfect moulding of the housing with thick walls to conduct resonances and their harmonic proportions within the pick up process

The Denon DL103 always had a extremely economical pricing, a important attitude for this worldwide longtime success. But as well its unbelievable good performance and its unique technical standards made this cartridge to one of the foremost values today to be used with twelve inch tonearms and broadcast transcription turntables by the vintage hifi scene. I would estimate that 70 % of all Garrards, Thorens 124, EMTs, Rek-O-Cuts, Commonwealths, Fairchilds and similar type of players use a Denon DL103 moving coil cartridge. So it is no wonder that in 50 years of production a broad aftermarket product range has been established. So several case modifications are offered by audio dealers and are worldwide sold at Ebay, made from wood, stone, aluminum, brass and composite materials. All these mods follow a very early modification schematic, published by Maison de L'Audiophile in the late 1970ties, showing a lead trimming of the enclosure to minimize the ringing of the thin plastic type. Together with a heavy cabling mounted outside of the arm tube, the mass of the unit did grow so high, that there was almost no alternative other low compliance cartridge available beside the SPU, to balance such increased masses. With a compliance of 5 x 10–6 cm/dyne (100 Hz) the DL103 is some sort of  extreme. I do remember my own making of such a lead case in 1992 for my first DL103, mounted with a SME 3012/II at a Garrard 401 on a 30 kg plinth. In these days I did not have the advanced experience with heavy arm tube materials, which I have today. I did not know that a silly light weight aluminum tube like the SME SII was a less than a perfect solution for such a modification. Even the later thin steel wand ( 0.25mm material thickness) of the stainless tube from the last series R, was made to allow the time typical high compliance cartridges to be driven, but it was not a optimized solution for a cartridges like the SPU or the Denon DL103.

My following years have been in a way a research time about the perfect matches of compliance to tonearm combinations. At the end of this research I had the reason to make my conclusions affordable to other users of such systems with my conversion kit. Now with the LignoLab bronze housing the kit has got a perfect extension with a modified DL103, excessively well made by Norbert Gütte and his company. In difference to all the other after market bodies, his case is a perfectly exact copy of the original. This means it features as unique and important technical difference to any other metal housing,  –  a closed underneath side. Near the generator almost all resonances have their origin and this means to be the most delicate region of the body in terms of resonances. The cubic closed form creates really a tremendous difference by its resonant absorbent abilities. The case is by far more stiff, with remarkable thicker walls comparing it with other cases, to prevent the ringing abilities to a unknown level with highly improved harmonic anticipation by real bronze as material. Since all other aftermarket products are open frame designs, which are a lot easier and cheaper to make, will have a more decorative intention than technical improvement in mind. These are mainly meant to be a optical revaluation of the outer appearance as material and design issue of the common and ordinary thin plastic case. They create a nicer and more expensive look, much more than to be meant a mechanical improvement of audible properties.

The cartridge slips in a perfect sucking manner into the housing, a effect of its advanced CNC moulding and manufacturing process. This perfection is a typical feature of all LignoLab products.

With the Lignolab body the Denon gets into another stage of refinement and dynamic property, where the standard cartridge is not able to follow. Unmodified it is a simple basic construction, a piece of thin moulded plastic holding the generator in place with two drops of glue. This detail is the "achilles heel"  of its basic design. With the new bronze housing the Denon playes in a new league, where only the very best phono cartridges gather. With a smooth but extremely dynamic extension to both ends and a highly integrated harmonic presentation of the middle frequency response, the Denon is now a unique cartridge. And even independent of its pricing, it is a top class moving coil cartridge for long broadcast tonearms. For myself it is grown to be real a alternative to my longtime favorite, the Ortofon SPU Gold. At the beginning of the making of my conversion kit, I had the very first SME 3012 tonearm in mind with its heavy weights (220 g) for the SPU. So I produced a good amount of this balancing weights, but subsequently it happened that the most cartridge/headshell combinations of my customers appeared to be to lightweight, so I needed to produce a second weight (160 g) exactly like SME did in 1959. The LignoLab housing with its extra weight of 25 g is a perfect match to my kit in combination with the heavy balancing weight. This extra high mass of this combination makes a extra sturdy armwand necessary to perform in a highly improved state. All other twelve inch arms beside the rare original SME 3012 MK1 are generally to lightweight built for such a mass and work much better with lower masses. No version of the standard SME 3012 weights will be able to balance this extra weight. As well here my heavy weight is a welcome extension for technical improvement and higher aesthetic claims at classic SME tonearms. Otherwise a typical additional rider weight with very unoriginal look will be necessary to make it work. With the 3012/R version the vinyl saddle will create additional problems and can be worn out soon. But as well the aftermarket brass versions of this saddle, as a typical replacement for the vinyl type, are acting far beyond their physical limits, when used with a extra weight of 150 grams. It definetly needs to be a steel saddle to prevent excessive wear at the fine blades with such a high mass and to take the advantage of a wide improvement of dynamic abilities.

The Denon with bronze housing mounted in Ortofon bakelite headshell balanced free to zero  in a converted SME tonearm with the large 220 g balancing weight.

As a conclusion of my evaluation of the LignoLab housing I did decide to dedicate my last 30 weights of 220 g solely for the use with this combination. Either the weights can be bought with LignoLab together with a bronze housing for additional 100 EUR (fitting physically to any SME 30XX tonearm).  Or the complete kit can be ordered together with the bronze housing and the 220 g weight for a limited special offer here. Both offers will be strictly limited to altogether 30 pieces, either or! Just inquire here at the mail template beneath or at the LignoLab web page. 

Read on soon, Volker