Wednesday 17 August 2022

Revisiting my Favourite Sounds again

Hi everybody,

today I come back to an installation that I last discussed in 2017. Having described this chain as exemplary and outstanding several years earlier, it was at this time that its owner began attempting this set more linear qualities to educate. I would like to remind you once again that a classic analog tube amplified Shindo chain with a typical Monbrison tube preamp, a pair of the early legendary 300B single-ended power amps and analog three-way crossover with historical components such as oil-paper capacitors and auto transformer in combination with the LineMagnetic 22A/597A and WE7331A speakers. In these days changing from smaller dipole housings each equipped with Pushpull Klangfilm KL405 14'' basses had ensured outstanding results. I have described this chain in detail and also looked up for its variants in other places for comparison, everything is well documented in this blog within the past years.

In this last stage of expansion at that time, dipole bass enclosures got exchanged to larger and more solid made enclosures 100% comparable to the vintage originals from Western Electric in terms of material and design here manufactured and additionally fitted with LineMagnetic 14'' field coil drivers. In this last article, I did describe in 2017 that the original quality and restrained sound structure with the new, much more powerful and heavier paper cone bass speakers was no longer able to deliver the homogeneity and natural unobtrusiveness, that I value so much in favor of a more typical PA tuning.

New Location and first step towards a new set up, still LineMagnetic 22A, but equipped with ribbon tweeters.

A lot has happened in the meanwhile of five years, especially in all of our lives. We are now familiar with numerous corona virus variants as with their medically correct names, for a few months we have been able to correctly decline all weapon systems of the German military and their NATO partners and we are happy that as a result of all this the inflation values ​​​​in our country measure our quality of life in the low double-digit range. 

But also in this audio set up numerous stages of evolution were declined. First, the entire tube electronics were replaced in favor of a fully active DSP-supported digital amplification terminal. So it brought the possibility to switch from three to four and five-way systems. The LineMagnic midrange and tweeter horn systems were also exchanged for larger, similar horn system. Instead of the 22A snail horn, a Susuma Sato interpretation by a friend, LignoLab owner Norbert Gütte, was used. This means a completely double-walled construction with a resonance-reducing quartz sand filling. 

Norbert Gütte offers both curled necks and straight necks of different lengths for the sato-typical square meter opening. So it makes sense to evaluate different sized and different driver systems. From the classic 3/4'' pressure chamber driver to the 6.5'' paper cone driver, everything can be adapted to a dedicated straight horn throat in a mechanically optimized length. One after the other, modified Atlas/Klipsch drivers from Dietmar Hampel, JBL / Selenium 405, Celestion AXI 2050 were used. Modern PA drivers like the latter are of course no longer made with Alnico magnetic materials, but ceramic materials are used to achieve optimum efficiency in the PA dedication. With the 3/4'' version, the straight horn neck extends backwards over a distance of 2.40m and has to carry a solid weight. This requires a support system made from 12 meters for each side from typical Bosch/Rexroth structural aluminum profiles 40x40mm. The entire unit, consisting of the 7331 dipole bass enclosure, Satohorn and Mundorf AMT 197PP27R-740-452-CDH tweeter horn built into it from the Pro Series, is reinforced with these profiles and movably mounted on castors. One unit therefore easily reaches 1.00x1.72x1.80-2.40m (WxHxD) variable in depths by the preference of the middle tone driver size and a weight of 150 kg.

Sato with long straight neck, adapted with extension neck to match D. Hampels modified 3/4'' Atlas Sound driver

Sato with 6'' driver and recessed neck

After many attempts with different bass drivers, such as the Altec 416B/A, the Sonido 12'' driver is now being used in the dipole bass enclosure as final solution. The comparatively small 12" cone only works satisfactorily in combination with a SW Becker B1000 subwoofer with 18" bass drivers per channel, which are actively used below 80 Hz.

In this chain, the loudspeakers described with active crossover (Xilica XP4080) are used with DSP support. The crossover frequencies are therefore:

Subwoofer 28 < 80Hz; Bass / Sato > 180, or 200; Sato / AMT < 900 to 1000 Hz

Actual set up, three ways plus stereo subwoofers

Initially, a Butterworth filter characteristic was used, but in the meantime it has been switched almost exclusively to a Linkwitz Riley characteristic with 48dB/octave. This not insignificantly complex structure is controlled by the STA-800D or STA-400D power amps, depending on the power consumption required. The settings of the DSP have been subtly integrated to counteract the typical room modes. In this way, undistorted levels of at least 110 dB can be reproduced. At medium levels, the distortion factors are around 0.1 percent, and at high levels it is still below 1%.

Amplifier and crossover/DSP rack

It's all hard core technical and well complicated. Such complex and expansive installations in the past have repeatedly shown very similar soundstages, very dynamic, tonally very complex with clearly noticeable properties. In the past few years I have often had the opportunity to listen to such large horn installations. The tonal properties were usually extremely different. They mostly impressed with an extremely present and fanned-out midrange reproduction, so one believed to hear details that other sound transducer principles are not able to reproduce, including electrostatic transducers.

In addition, the space-consuming structure with its physically extremely large distances between the individual sound transducers and the clear expansion length of the respective sound generation is hardly manageable in the sense of a point source. This effect additionally supports the interpretation of a tremendously extended reproduction of the stage space. It is not uncommon for this sensation to become the originated problem after a short time of listening. The first thing that strikes you is the typical fatigue of our sensory perception. Later, one also notices that the supposed sensation is a result of typical inhomogeneities of such large three-, four- and five-way systems and turns the underlying sensation into its exact opposite, namely making listening increasingly an emotional stress.

It was exactly the same in 2017 in my report, when in the more solid and larger WE7331A replicas, 14'' field coil-driven LineMagnetic woofers supplemented the setup at that time. The originally extremely refined homogeneity, which was achieved in the bass section with two 14'' Klangfilm KL405 in push-pull operation, became so noticeable due to the significantly stronger cone structure that it suddenly got in the way of effortless, natural listening.

Intermediate installation with mixed amplifying devices, here still rolling tubes

Other Sato horn installations or similarly large horn systems that also work four-way with large passive or partially active bass systems sometimes also involve four-segment midrange horns, like the original installations in the 1970ties by Susuma Sato. In these days it was supposed to improve the linearity of the overall frequency response in the upper mids, but examples I did listen to, do play so little homogeneous that it seems possible for the experienced ear to identify all drivers as single sources at the same time, like a large orchestra to be heard separately with insane runtime differences. 

The experience trail shown here is also about tracing the complex path of the various ways that such a structure enables. Here the effort was increased to the extreme that is feasible, as many variants in the pictures impressively are shown. And this complex path of various tests has really paid off for an exclusive refinement at all.

With the usual scepticism about such overexpenditure and also about the technology used here, I did listen to this installation calmly and impartially. Despite a four-way structure (HT-MT-TT-SW), it has been possible to achieve a completely seamless and extremely homogeneous sound pattern with the finest tonal reproduction quality. Over the entire tonal spectrum, i.e. between about 40 Hz up to the limit of my hearing ability in the high-frequency range, an extremely dynamic but never conspicuous sound spectrum is projected into the room with unbelievable ease, which with such cogency I have never heard of such a large-scale installation. One is able to recall approximately a live performance, or to put it another way, the playback is incredibly close to the characteristics of a very good pair of open space headphones, such as the AKG K1000 with near field equalization. Especially with extremely difficult tutti passages of large orchestra recordings, i.e. music that can hardly be reproduced realistically via normal loudspeakers, the set impresses with a huge stage that makes an exact spatial staggering comprehensible, but above all the most important thing of such a reproduction, the unbelievable amount of moving air makes playfully realistically tangible. Other challenges such as smaller jazz ensembles, chamber music or voices, on the other hand, are almost a side exercise. One can enjoy listening to music for long passages without any signs of fatigue, and after all, that's exactly what we should all be aiming for. Even if this is often lost in pointless technical debates, here it shows that it will be possible with almost contradictive conceptions of audio response.

Half of the actual set up, 2022

This chain consciously relies on currently produced technology for the large-scale public address use, so it is completely free from the usual hifi terminations of a "beautiful sound", like exalted tube technology, "certain rare old components without which the earth would not continue to turn". Go then...

So if you are striving for something similar, in words a "walkable headphone", you might want to take advantage of the moment. The actual savings discussions might set your mind to convert existing inhouse swimming pools, indoor squash courts or the like in the generally sense. With a room area of less than 50 square meters it becomes difficult, the integration of such an installation into normal family life will probably inevitably lead to opulent maintenance payments. And if you were equipped in younger age with a pronounced play instinct addiction, which might have in your earlier life led to basement-sized H0 model railway installations, you can certainly think about a similar way of presenting such amounts of fun with music reproduction into your life.

Read on soon, Volker

Wednesday 15 June 2022

Back to stage – a PSU for a known singing bird

Hello everybody,

in loose sequence I am posting articles about vintage audio equipment. In the last couple of month I have spend my time more with listening to music and with the support rearing of songbirds, in particular of black birds,  than with building audio equipment. To listen to the very different sound of birds is as well a exceptional training for the educated ear...

Today I am talking again about building a power supply for a British tube preamplifier with RIAA-equalizer stage. A familiar customer asked me a while ago if I will be able to make him a power supply for his Concordant Exelsior preamplifier. He pretended to have a schematic for it and as well the schematic of the amplifier itself. I said that it would not be to difficult to make one. Next he asked me if I will be able to make one with tube rectification and better components. I said I need to check, because some components are hard to find in the meanwhile and that I would need to check my stock of parts. The schematics turned out to belong to a completely different version of this preamp. As the most people might know mains transformers with split balanced HT-output and two different filament windings "don't grow anymore on trees" as it would be needed for this! A quick look in my storage gave me some overview to pulled transformers from old equipment, foremost from old radios, some were missing parts, others where winded for 4 volts filament, etc. I didn't find the right part to do it well. Next question is to find new parts, Lundahl might here the right solution, but nothing under 200 €, which was expected a lot to expensive. Next problem would be to find a matching case for all, matching in visual terms, but as well big enough to harbor all components. Not easy, but I decided to get forward with a black painted Hammond casted aluminum case of the same height and depths of the Concordant. My customer limited the cost range for all to 250 €, which is an almost impossible sporting competition to stay beyond. A rough calculation showed immediately that such amount will pay the needed parts but not the work making it. On the other hand this guy never had a chance to listen to this preamp before, since he bought it without power supply. This person normally listens to a Shindo Monbrison and other well priced and established products, so he does not know what he will become at the end, just to explain his tight money framing. To be honest with this limit a simple PSU with silicon rectification and simple filter stage for the anode rail and silicon 12 volt IC regulation will be the solution to bring the package back to life within such financial limitations. I told him about and he pleaded to get something better, smoother sounding. I told him, that there will be no guaranty that even a perfect made PSU will bring this preamp to the level he ideally might expect.

Ok, I started some research at the internet and opened the Concordant case with the result that I realized that this version is equipped with ECC82 in the output stage and ECC88 in the RIAA-filter stage. This means with ECC88 it needs a 6.3 volts filament supply – no way make a cheap silicon based regulation with penny parts only ugly rails of hated caps and resistors to drop the voltages. 

So it gets back to the start with tube rectification with EZ81, choke regulated loading and filter stage for the anode supply. I looked again into my storage list for mains transformers, where all transformers are listed, which are useful for power amplifiers with their exact output data. The most of the transformers are collected as pairs, I am always afraid to use one of them for a single project, so still a lot of them is untouched since years. So I found the right type with the right taps, just a little bit oversized for such a project, but otherwise perfect. I decided to use it because I am not getting younger and the future projects might get countable. Now I needed to order a Hammond 157G 30H/40mA smoothing choke and I found a supplier who offered a bunch of NOS double capacitors 2x100uF/400V of ideal physical size to match my selected case. The Concordant sports a luxury, a mirrored double filament support for each channel, so it says at the front plate double mono preamplifier. At the back it has two identical unusual German DIN three pole jacks for this reason. I found in my storage the matching plugs, otherwise nowdays hard to find. So I collected all necessary parts from my storage together, – switch, fuse holder, cables and wires, resistors, tubes, silicon rectifiers, oil caps, supports, screws, nuts, bolts and more. When I first time tested the size of the case with the real components, I realized that it will get tight, – exceptional tight. At the end there was not the space for one more resistor inside. I needed several times to regroup the components inside to make it work!

At the end of the day all parts were in place and the case could be closed without pressure. Before I needed to isolate delicate exposed contacts. For example the tip of the EZ81 just matched the close case because I drilled ventilation wholes into the cover, the middle whole takes the tip, underneath the octal socket I needed isolation, because there was only 1mm air left between HT contacts and the base plate!

When I connected the new preamp with PSU to my setup, I was really astonished. The sound was exceptional refined, with wide open smooth and liquid soundstage, exactly so I do like it a lot. Of course I don't have any comparison to the original version, but I must say this combination is very very good. Yes the PSU uses some basic ideas which have been established in my equipment for years. For example the push-pull choke for the filament, the low oil capacitance in the loading stage for the rectifier tube to make it fast and smooth. 

I am looking forward about the ruling of the owner when he does the compare it with his Shindo Monbrison. It might get difficult... This is definetly under all tube preamps which had a chance to listen to one of the rare singing birds.

And who is now going to pay my work? 

Friday 21 January 2022

Revisiting own History – The classic Leak TL12+ amplifiers

As already widely shown in my earlier articles I collected in the early 1990ties during my London time a whole lot of classic Leak tube amplifiers. Foremostly I remember one visit in London in 1992 when I did buy an exceptional lot of amplifiers from London dealers. On the way back to Germany my car got stopped from French custom officers because of its obvious visible overweight in its trunk, the rear wheels already were deep hidden in the chassis with an extra 15º camber. I will never forget the officers face when I did show him the tight stacked amplifiers, he had no idea what he was looking at. I don't exactly remember, but it must have been around 6 to 8 pairs of this model TL12+ and several Stereo 20 and as well some pairs TL10.1  and TL12 point one's. I tried to explain that these are historic audio amplifiers, but he hardly could believe my words looking at a wall of golden chassis.

The classic late 1959 Leak TL12+, here already with RCA-socket and input pot.

The shown pair is one set of this batch. I did restore all of them to my highest possible standard these days. In particular this pair got the best care because of the rather rare color "champaign" and with the aim to keep them for my own collection. As regular treatment I replaced the electrolytic filter caps to oil caps. Here the old electrolytic content needed to get emptied in order to reuse their cans for originality and color with new caps glued in. Generally all coupling caps where replaced to oil caps, a expensive step these days because the only modern source for such was Audio Note, who cared about the distribution of Jensens Audio Caps, a good 20£ investment for each value which added alone to 200£ for a set. All carbon composition resistors got exchanged to new German Beyschlag 2 watts carbon composition types, each around 2 € only available in 10er belts these days. The cathode bypass capacitors generally got changed to bipolar tone frequency caps, which mainly where used as crossover parts in speakers. The religion in these days was the use of triodes in all stages, so I always changed the input stage from EF86 pentodes to ECC83 triodes in order to refine the soundstage and to reduce the input amplification factor, which is with all Leaks extremely sensitive. I brought generally the power stages of these push-pull designs to semi triode operation of the EL84 tubes. All these steps were introduced in order to achieve with this little amps a much more sophisticated and smoother operation, in contrast to the impressive, but a bit too cheaky performance of the original version. The reduction of output power from 12 watts to hardly 4 watts in pseudo triode operation emotionally perceived with efficient speakers (better than 96db) as to be a even better drivability. 

Close up of input stage in foreground, in background whole lot of modifications at the filter stage with smoothing choke (at left) and fuse holder, switch (at right) and power cord.

As some might expect the days weren't far that I decided, with almost every Leak model in daily use, the most of them in several versions, to get rid of some doublets to save space and money. Some friends of mine got within this years involved into my passion and became interested as well to use tube amplification in combination with Tannoy speakers. So I sold some amps from my collection to them. As reported in my last entry a Leak Stereo 60 of my early collection revisited me unexpected end of last year. This example found a caring new home in the meanwhile. Shortly before New Years Eve another friend visited me and brought another former pair into service, which acted for 30 years a long term companion to his Tannoy Lancasters with 15'' Monitor Golds for him. When I started to inspect this pair, I realized what 30 years of rough use with several house moves and more or less permanent plugging and unplugging can do. They were completely rocked down. Loose contacts, open wires, leaking capacitors, wax dripping from transformers, tubes run down to 20%, in one an almost black ashed rectifier tube showed the remnants of an unexpected firework, – he had treated them almost to unusable wracks. My friend decided to spend good money for another life and a total revision. At my first restoration in 1992 these amps were already 35 years old, now added on to another 30 years. I will try my best to give them another third life for the next 30 years. Maybe these little wonders will find one day when I already will be passed away the next owner who might bring them into a fourth period of living  –  this is what I will call sustainability – not the highly acclaimed class G digital amps to be so.

View of the complete mainboard, just at top edge underside of pot and the filament symmetry element

For this reason to open up for a new future I decided to change some principles I had 30 years ago. I always took extremely care to keep mechanical originality of the amplifiers, which was meant not to drill wholes or remove unused components, like the octal sockets for chaining further Leak- or other components. Today or even better tomorrow nobody really will use a Troughline tuner or a Varislope preamp, so contemporary preferences for practical use are getting more important instead of originality. A better control of the input signal, in particular with modern high output components (min. 2V or more) like preamplifiers, computers or digital streaming clients, – more or less hum- and hiss free operation and of course still the smooth and dynamic soundstage are relevant for the aficionado.

So I needed to find mechanically and electrically matching filter capacitors as paper-in oil types, not an easy job even with eBay within such sizes. Pots, switches and simple things like fuse holders are more and more difficult to be found in well known high quality, foremost made for military use in the 1970ties.

Knob inlay made from real embossed calf leather matching luxury expectations...

The Leaks got now smoothing chokes (8H/100mA) in the filter stage, NOS mil spec input potentiometers, perfect RCA-sockets, switches, optimized AC-cords and of course a set of best possible NOS tubes in every stage. So equipped this little pair will do a perfect job in the coming years and play now in the same league where best handmade tube amplifiers like Shindo, Thomas Mayer or others are bought for in difference to modern chrome monsters made to match Asian expectations. 

60 years of technological time shift to play music

Now this little amps are ready for the time which is already there, a time were music streaming has overtaken the music market and digital components are feeding their playlists into such ultra analog audio chains. After 10 years of wireless music stream into my own chain from my notebook as to be the 'jack of alle trades'. I did spend at the start of 2022 myself an actual iPad with 1Tb storage to be solely my comfortable music juke box to play from cloud services as well from my own digital collection at a finger touch. 

Stay healthy, it might find an end sooner or later, Volker

Monday 11 October 2021

Collection Resolution – Leak Tube Amplifiers – Addendum

 Hello to everybody,

after my successful sale of my tube amplifier collection, fore mostly several Leak models, I have to make a curious addendum. A very old friend offered me after 35 years a rare Leak Stereo 60 back, which I did sell him in the early 1990ties. I had completely forgotten about it since I wasn't in contact to my friend over all the years. As the most people know which do read here such tube amplifiers have got rare and even more rare is such condition. He did not use it a lot, just enough to keep it flawless running over the whole period of time. So I got it back (home I would say) and was a bit astonished about it. I did overhaul it in the 1990ties with even than expansive Audionote (Jensen) Paper-in Oil Caps, which did cost through the luxury distribution a good lot of money in these days. I now did replace all electrolyte capacitors, in particular the original ones, more than 60 years old. I was astonished that I already did change the design to triode mode by shortening the suppressor grids with a 100 ohm resistor in order to improve the sound attitudes. When I connected this amp I was more or less speechless about it enormous sound qualities and its solid driving qualities, which did make my standard set with single ended topology completely superfluous. A exceptional natural fluid sound stage, which is a lot better than any modern produced tube amplifier I do know.

The amp is equipped with used tubes, all in very good condition. The ECC83s are Mullard - Blackburn production, the power tubes are early 1970 Sovtec 5881.

The coupling caps are "Audionote"-Jensen made oil-paper-typres,
even in these days an expensive  upgrade

This rare item will be sold to somebody who might take a good care about this exceptional amplifier. I will be able to demonstrate its perfect performance here to anybody interested who wants a  good tube amplifier for the rest of his life... With its triode connected push-pull design the amplifier is able to drive a quite wide range of speakers from 92 dB upwards on to exceptional dynamic open and natural sound stages. 

Thursday 4 June 2020

Faith, Hope and Salvation – The WE91A SE stereo amplifier without 300b tubes – I did it again

End of 2017 I did publish a post about the single ended amplifier designs and my evaluation of power tubes to be more than an alternative of the Western Electric 300B tube. In these days the idea formed from my earlier sound evaluation experience of different manufactured 300B tubes. The audio business focused on tube amplification made single ended tube amplification designs with 300B power tubes for 40 years to be the "cash cow" of growths. As result there are uncountable amounts of makes and brands in the market which explain each as the most original reproduction derivate of the original Western Electric power triode WE 300A from the 1920ties. The major problem here are the extremely developed market values of original vintage rare WE-tubes from all production decades and as reaction to such rareness the market mechanism highly raised the price tags. So modern production tubes create an own market, such are made in different countries but foremostly in China (to keep the quality level high, lol). As earlier stated, if you are not millionaire, able to light your Cohibas with 100$-notes, the modern replacement tubes in the 100 to 600$ range are all more or less crapfunctional in comparison to vintage tubes from the 1940ties in + 2000$/pc range. So relevant amplifiers of the traditional WE91A design topology use on top the WE310A as driver, the WE274B as rectifier, all together the equivalent for stereo in the 10K$ range and if you really want the exceptional finesse of sound, – alternativeless.

Yet, the single ended amplifier topology shows up to the tube audio connoisseur with several advantages if you incorporate a lightweight, fast and fine detailed alnico magnet driven loudspeaker, like horns and full range paper cone speakers (like Altec 755 or similar) or combinations from both principles. To raise the full potential of such systems the amplifier design is in need of radical control about component quality and about its consequent amplification topology. Today almost all decisive vintage components of quality production have disappeared from the market, so it is almost impossible to realize an amplifier design without any compromising cut or ending up in the cost nirvana (known from several Japanese brands reissuing modern Western Electric equipment at a highest possible level). Such set ups easily might create levels of investment in the million dollar range. If you are not the successor in the Toyota heritage or the son of an Arab prince, it might get a bit difficult to follow up such ways to your hobby within the coming years. For all others it needs some intelligent liberation from hardly traded positions in order to find perfect new ways to comparable sound qualities. Here I am going to describe my second sample to a wishless audio happiness with tube amplified equipment, where the tube line up for stereo matches the amount for a well cared piece of organic breeded beef. Yes, 50 $ and all tubes are vintage NOS highest quality production standards long life types or military grade, – and on sale in good amounts.

I am still in the good position to have several of necessary vintage quality parts as spares stored in my cellar, so I am able to realize rarely a design with almost ideal components. My first sample of such conception from 2017 earned so much interest that I did decide to realize a second version build on an identical design topology but realized with completely different hardware, a interesting step to find out about resulting differences.

Partridge mains transformer beside modern open frame output transformers, all covered by epoxy resin boards, like several British vintage amplifiers show up with

Here I did finalize an early Ebay finding after more than 20 years, a British Goodsell GW12 Williamson PP design from 1949, which had lost its open frame Partridge-output transformer. I did look for years to complete it again or to find a matching partner for stereo use, which never happened by its exclusive rareness. So I decide in 2005 to break off the originality line with a heavy heart, but at least in order to bring it back to a new functional life as a single stereo ended amplifier. In these days I did experiment with another rare find, the DHTs from Elektromekano S6 in order to resemble the classic 300b out put tube in such designs. I used the Mullard EF37A to be the driver tube and tested several output transformers to complete this concept, but nothing could convince my expectations in these days (and the illustre matching preferences of this extreme tube). It ended up that I stored the chassis back in my cellar and followed up other ideas like DHT tubes in preamplification stages and so the Goodsell SE-amplifier got more or less forgotten.

The Danish 1940ties Directly Heated Triodes from Elektromekano, the S6 and M7  (4V/1A) are some of the finest manufactured power triodes made ever. Even the Western Electric types from this period don't match mechanically their standard. Unfortunately these triodes don't match the ordinary range of output transformers but they are still some of the nicest Tube ever.

at the far right the knob for the global feedback loop, realized with single switchable carbon composition resistors

Last autum I did start a collection sale of all my long time collected amplifiers and other audio collectibles in order downsize my life in a "less is more" matter. So I had several people coming to look and listen to different components of my personal estate. Many of such auditions ended into sales of exceptional sounding vintage valve amplifiers and dedicated components like speakers, preamplifiers, tonearms, etc. But the most respect raised after end of a particular sales procedure when the question came up with which amplifier I am going to listen in the future? When I demonstrated the "bastard amp" in my favored chain, the most people didn't need a lot more than a minute of listening to understand my decision. Within the two gone years of time the interest into such a special single ended tube amp has grown. So I thought about another sample, well knowing that the prototype was some sort of recycling of leftovers on a highest level possible. I did exactly know, that I never will get a chance to make a identical copy and so could not predict the following result, in particular when using 70 year old parts like the mains transformer, choke (both Partridge brand) and other sound determining parts like the output transformers. The open frame design of the vintage parts made the selection of output transformers delicate in terms of authenticity of design. Modern potted transformers like Japanese classics from Tango, Tamura or later Taiwan successor   James aestetically do exclude themself for this project. One of my technically ideal choices, the Swedish Lundahls, were no option since their design makes an open frame incorporation impossible. I had a pair of vintage Philips universal single ended transformers in spare (1/2/3/5K:4/8/15Z). I had no idea for which power output they were made for, but size and weight let rate me them to something like 7 watts (similar to Tango U808). The next candidate were some classic Chinese laminated oriented steel core OPTs with 3.5K:4/8/15Z@20W, such have been sold as entry level transformers in HK as Mars brand are built into lots of typical Chinese made chrome monsteramps, which are sold through Ebay since years for small money. With the Philips transformers the amplifier performed with a exceptional open refined soundstage, wide, liquid and natural, but with a little slim sound fundament lacking the typical natural substance of a single ended amplifier. Switching to the 2,5 kg Mars transformers the soundstage was perfectly well balanced. I did only try them since they measured at a scope very linear between 30 and 18000 hz, but these lack all the subtile refinements, which have been already on stage with the smaller Philips iron. So I needed to find something with good sound attitude and matching design preferences.

Clearly visible the eight pieces of amorphous c-core parts forming the final transformer core

Beside these experiments I was a bit curious about all the rumors about different new core materials and designs. The final sow which had been chased through the tube audio village in the last years was the Hitachi made "metglas" core material, an amorphous nanocristalline alloy formed with extremely high pressure under exceptional melting temperatures of several thousand degrees. This high tech material is known for its lowest loss properties addressed with "never before heard" tremendous resulting properties. Something which is equally important addressed to even more important rise of the resulting price tag in the audio world, a factor up to three times to an ordinary cut c-core output transformer. Vintage (early 2000) made Tango or Tamura transformers containing amorphous core instead of c-cores or even laminated iron are on sale at Ebay for tremendous amounts... and even serious brands like Lundahl have incorporated such cores to keep up in the vanishing markets.

Today the amorphous cores are used in different high tech scientific applications or in mobile web technologies and Hitachi produces a whole catalog of differently shaped cores and sizes. It looks that only the audio nuts are paying the elaborated high bill for the next "must have gadget". Hitachi has found paths to produce this high tech metal somewhere in India at reasonable market prices. Like with all other new technology some people will find fast illegal ways to sell fractions of such production lines at the web. Then is it only a little step and a question of short time that you will find other people there who make a serious business with such cores and produce audio output transformers for the audio aficionado and sell these for a fraction of the price of established brands. So I found at Ebay. different designed tube out put transformers with amorphous core material, one type was matching my primary preferences of 3.5 K/20H/15W, unfortunately with secondary windings interlaced for 4 and 8 ohms. So I asked the seller if a custom version with 15 ohm will be available and the friendly people were happy to make me a customized pair. Visually the transformers are wound in a typical British manner with steel mounting frames, so these OPTs did visually match well with my 70 years old Partridge transformers of the Goodsell. So I ordered a pair with 15 ohm secondary tap in the hope that this transformers will match my expectation set by other brands like standard Lundahls, but will offer a better formal integration with this vintage amplifier. I had no expectation about something special as a result from different core material.

The transformers where delivered by Hermes as a standard parcel, no customs, import procedure – how can this be possible? When I opened the parcel a strong smell of the epoxy resin knocked me out for a second, but this smell evaporated within a day and when I had the pair incorporated into the amplifier, their smell was already neutral. The first listening showed up with a well known sound attitude, so I needed to adjust the feedback loop with the new amplifier. In my first post from 2017 I photographed the amplifier with fixed feedback loop with a 3.2K resistor. Later I integrated two wire wound pots of 5k range to have the opportunity to match different speakers than only my Tannoy Monitor Reds with 15 ohms. Here now I planned from the beginning to have the luxury of a adjustable global feedback loop. After some measurements and finalization by listening I ended up with matching value for this amp, ironically it is again 3.2k!

Underneath oil paper caps ballet and a Partridge choke, all high current wire is original vintage Western Electric wire. Top right corner the switchable feedback resistors connected with blue and yellow wire

The most of yours will or can not believe me, but the new realized single ended amplifier sounds absolutely identical to my first version. Yes of course, the design is to 100% the same, but all the very important HiFi narratives about hardware, the use of parts, in particular output transformers, their quality and branding seemed to be what it is – marketing fairytales. Both amps look completely different, but soundwise I cannot detect the smallest difference, unbelievable but true. I have used the same capacitor layout with the same material preferences, paper-in-oil-capacitors as small values as necessary. For example I use 4µF as loading capacitor and another 4µF as smoothing cap. For 30 years of my life it was impossible for me to get such rail calm, now I know how to do and this amp is dead quiet, like a modern transistor amp, but with a "fresh oiled liquidity" unknown from other tube amplifiers. The only coupling cap between driver and power stage is 0.05µF like it should and not like in 99% of all WE91A copies and derivates wrongly transcripted 0.5µF and so on...

If you are looking for a reasonable priced tube output transformer which shows up with exceptional sound qualities and offers results which are on par with the well established brands for a fraction of the price tag ask the people in HK, they will be happy to serve your needs and HK people need some support anyway, their future doesn't look so bright...

Sunday 20 October 2019

Collection Resolution Part V -– 12 inch Tone Arms

Hello everybody,

today I want to start my final sales with 12-inch  tone arms. As some people may have recognized, within the the last eight years this blog published extensive informations about my Conversion Kit. In 2012 I started to sell such kits in order to convert SME 3009 SII arms into their predecessor, the legendary so called Mark One type. This early (1958) tone arm was a modern masterpiece of British engineering and its market entrance was some purely dedication to the first moving coil stereo pick up cartridge ever the Ortofon SPU (Stereo Pick Up). This remarkable cartridge was made in the tradition of the former monaural cartridges from different makes, all were extremely low compliance types and were optimized for high tracking mass in order to track safely 78-records. With high torque record players  the pick up process was brought to a seer side. In 1958, in the age of micro groove recordings, the most players still were equipped with heavy arms, so the new stereo cartridges were made to match this masses. As everybody knows it didn't take a long time and the mass of typical cartridges made for the audio amateur aimed to another direction, the ultra low mass cartridge and dedicated low mass tone arms. The SME Series Two got lighter and lighter, got improved for further lightweight, got resembled into Series Three with less mass to match ultra high compliance cartridges of the late 1970ties.
In the 1980ties a huge rediscovery of the tube era was synchronized with the esteem of the equipment of the golden time of audio, the 1950ties. The manufactured quality of no equal in these days and the depths of engineering got discovered again. Tube amplification, idler wheel turntables, former professionally used speaker systems, horn systems and all dedicated technology found back for some lovers to be highly superior than the commercial audio products which had flooded the world since then. So the professional tone arms from SME, EMT, Ortofon, all made in quite small amounts for studio applications got back into demand. In Japan these were combined with broadcast cartridges like the Denon DL103 or the legendary Ortofon SPU. In Japan several new made pick up cartridges from Koetsu, FR, Ikeda, etc. took the path to the low compliance to be highly superior into current products. A heavy arm with a low compliance cartridge on a high mass record player reproduces vinyl completely different than the typical high end products of the commercial audio market.

In the last couple of years I could made several aficionados world wide happy with my SME MK1 conversion kit. Additionally I refurbished outworn SME 3009 SII into like new 12 inch tonearms which are assembled with stainless steel arm wand and internal balsa wood damping element, heavier weights and highly improved internal 99.99 % silk isolated silver wire and good RCA terminals in order to find back to the original performance of the legendary heavy SME 3012 MK1 and improve even that.
When I started this idea outworn SME 3009SII were still available in countable amounts, so it made sense to convert these into something superior. But today there is no more stock available in any amounts, so I had sadly to stop my idea. I will now sell my last three converted SME 3012 from my own stock. When these are once sold a exceptional quality item for analog sound reproduction of vinyl will be gone forever or you will need to spend thousand of euros to find a original MK1 in unknown condition without any spares available.

SME 3012 converted to MK1 standard – #I ,  sold

The first arm is in like new condition without any marks. It has been completely refurbished and got the silver internal wire, new damping balsa wood and new RCA terminals with additional ground contact. This arm is like new condition and performs with a low compliance cartridge like SPU light years better than any SME arm available. Wider more refined soundstage, more undistorted and deeper unlimited low frequency performance, far better trackability make such a combination superior to any arm I do know. Read what customers do say about their own experience.

This one comes with anti skating weight and original SME head shell with raised logo.

Additional grounding wire with dedicated socket.

SME 3012 converted to MK1 standard – #II ,  sold

The next one is asthetically in very good condition. It shows very minor spots in its galvanizing, technically like new. To compensate this I put a original SME connection cable on top of that package.

This one has the later anti skating guide with roller, head shell is original SME with raised logo.

SME 3012 converted to MK1 standard – #III ,  1250,00 EUR plus shipping

This one will follow after request since it built into a presentation box for fairs. It is in better than new condition and my last sample of these.

Accos Lustre studio tone arm –  12 inch , SOLD

As next offer I have a Australian studio tone arm, which was mainly used at Technics direct drive turntable at broadcast stations.  It is a extremely well manufactured arm with micro ball bearings and a wide range of additional weights to compensate different cartridges. This feature and the built quality brought me to the idea to convert this arm into a heavier stainless steel version to perform with low compliance cartridges as well. This arm like many professional arms has no cueing option and needs to be operated manually by hand, I have a rest included to make it work. The tone arm has the exact overhang figure like the SME 3012, which means 312mm between center rotation axis and diamond tip.

This arm has got a RCA contact terminal with separate ground contact and cloth isolated ground wire, additional balancing weight. Internally wired with 99.99% silver wire silk isolated. Internal damping of the arm wand is the typical balsa wood element.

This is a perfect solution for those who want a 12-inch arm of best quality with out the price tag of the well known brands. This arm performs on the same level like other stainless steel arms with micro bearing and internal silver wire. You don't know one, Fidelity Research FR66 or some later Ikedas. Yes they feature a lift, but otherwise ten times the price. 

Unknown Japanese make 12-inch tone arm –  SOLD

The next arm is converted from a typical japanese 9-inch record player tone arm, maybe Jelco. It shows up with the same details like the arm before. Precision micro ball bearings, internal 99.99% silk isolated silver wire, balsa wood damping element, RCA terminal with separate grounding contact. Geometry is identical with SME 3012, which means an overhang of 312mm. The unit features a brass base, which will be screwed with two M4 screws from underside and will simultaneously lock the RCA terminal from underside. 

Additional extra is a second lateral balancing weight and a cloth isolated ground wire. The arm features a anti skating mechanism.

The bakelite SPU headshell is shown just for illustration purposes and is not part of the sales package. This offer is dedicated to somebody who might build a own plinth for a idler wheel turntable and who does not want to spend thousands on a tonearm, when the player will cost a reasonable amount. Beside comfort reasons this arm does not limit the audio performance comparing the arms shown in the upper section.