Turn on the radio, Marantz 20B FM Tuner

Introduction

Sitting in front of a great tuner late in the evening, when all the daily trouble is gone and listening to some of the very good broadcasters here in Berlin, like Deutschlandradio and Deutschlandradio Kultur or Radio 1 is something very special.

Those broadcasters are not private stations, they are financed by a sort of tax, we listeners have to pay here in Germany (Rundfunkgebühren) – so they are not overblown with advertisement programs and could search their content which they bring on air more freely.

That means that you are able to listen after 8 O clock pm. on Deutschlandradio some live concerts they recorded themselves with their own very, very fine recording equipment, and you will listen to music never sold on a media like cd or vinyl. You get access to artists, who are not widely known or just the opposite – well known super star conductors and their orchestras, which play for you some music seldom heard. Sometimes they broadcast jazz festivals live or they invite the artists into their studios and record them live which results in very intimate music – in short – you have the chance to listen to very, very good special interest program.

Getting an FM Tuner

P1040339

The only chance to listen to such program in proper quality, is to use a very good FM tuner. As you might guess, I am not a big fan of internet radio – and I hate commercial radio which broadcasts such an extremely processed sound, that there is less than 4db dynamic range left at the end. Very good radio in Germany means dealing with the small stations and mostly no private broadcasters.

Germany has a very narrow FM bandwith were all the different stations are located on – so a proper FM tuner must have the ability of a high station separation, to get rid of all that noise of little birdies singing behind the broadcasted program. A lot of separation means very steep filter design – and steep filter design often generates a sharp synthetic sound – so a good tuner is not something you will find around the corner.

Tubes or transistors?

P1050745

Vintage tube tuners have an amazing warm and detailed sound, but most of them were made in the USA, which do not have the same bandwith – situation we face here in Germany, so the ability to get a strong reception and good separation is a task most of the vintage tube tuners could not achieve. And, if you think about one of the most popular vintage tube tuners – in may opinion the pinnacle of tube tuner design – the Marantz 10B, you need 22 tubes , most of them very, very rare. So a tube tuner is a nice thing to have – but if you judge the complete package it is mostly the second best way to achieve a fine radio tone into your listening room. On the other hand we have the modern synthsizer tuners, some late models with digital converters on board to feed digital amplification systems – these generation of tuners lack the classic, warm radio tone. This kind of presentation, the quality how radio should sound, was formed in my childhood. My dad drove an old Mercedes/8 – and in that car there was a radio installed – a Becker Mexico – which fed a huge oval fullrange speaker mounted on top of the dashboard. This radio sound was intoxicating! Voices sounded warm and deep with all that colourful proximity effect realised via a close up microphone position – music sounded big and bolt with a special wet treble sound – it was amazing. The other event, which formed my view how radio should sound was the purchase of an old Loewe Opta mono tube radio, I found one day at a shop dealing with vintage electronics.

How can I get exactly that tone with the ability to get a little bit more detail in the sound, more resolution – but without a synthetic attitude so often detectable with modern radio sound??

The Marantz 20B

L9991093 (1)

I had to get one of the famous first generation transistor tuners from Mcintosh or Marantz. And I opted for the successor of the famous Marantz 10b, the Model 20.

The Model 20 was made right after the 10b, which nearly ruined the Marantz company, because they made it in such an expensive way, that with every single unit they sold , the company made no revenue – instead they had to spent money.

As the famous Marantz 10b, also the Model 20 was constructed by Sid Smith and Richard Sequerra – both legends in the history of high end audio!

There are two variations of the Model 20 in existence – the Model 20 and the Model 20b, the latter is much more scarce that the Model 20. The difference between both is a modificated front end on the Model 20b and a slightly better output stage!

To find such a 20b is like winning the lottery – most of the examples you will see, are not working anymore – or they are “upgraded” with “nice” things like LED lamps or the circuits were modified. If you want to hunt such a rare piece of audio history, you need time and patience, and not indulging in illusion – these things have to be overhauled and restored to their original specs – you can do that by your own, if you have enough skills in working with some solder iron and in reading circuit diagrams – or you have to find someone who will do that for you. My example I eventually found,  was in a very poor state as I bought it – the front plate was bent, not a single lamp was working anymore, the stereo lamp circuit was defect, corrosion had done its work on the chassis and some internal parts, a couple of cpacitors were leaking….you get the picture. But it was love at first sight!

Restoring the blue eyed lady

I had to bring this thing to its specs and back to a much more beautiful condition as it was, when we first met each other.

P1040264

I needed 6 months of research were to get the parts, getting the circuit diagrams, service manuals and a lot of soldering work. I tried in most cases to repair the unit with its original parts, which is not an easy task, because most of the so called NOS (New Old Stock) Parts of that time might be as much out of their specs as those found in the unit itself. But after 6 months there was a sign of hope – one evening I heard the first sound coming out of that classic tuner. Maybe you can imagine how I felt, as I listened to the first transmitter noise coming out of that old Marantz FM tuner – it was like me, the little Dr Frankenstein made his a dead believed monster to breath again. I am a happy man – because my wife (the most understanding girl in the world!!!) had to face weeks of a half occupied kitchen table with soldering iron, solder, small and large parts and an mazing amount of dirt on it – and she did not  protest nor was she annoyed.

Later I got in contact of an expert who was able to do the alignment of the tuner because I have not the special equipment needed for that job nor do I have any experience with such things. After the alignment was done, there was the first contact with our house antenna and the stereo system!

The tone is back

P1050748

There it was!!!!

This specific classic warm radio tone, which left its mark on me since my childhood, the old Becker Mexico installed in my dad´s Mercedes / 8 which I never could forget during all that years – a sound I adored so much!

The Marantz 20b has an amazing quality in its low end – it is one of the most satisfying tuners in this regard – bass impulses broadcasted not with too much compression are nearly as full bodied as I can reach that with my turntable. The sheer impact is amazing, and till today, I found no other FM tuner capable to produce this quality of bass. The treble is completely open and detailed – not the typical rolled off sound so many FM tuners share – there is a sort of presence and light at the treble region, which is fantastic. Keeping in mind, that broadcasted program is cut at 15Khz, the treble performance made me to doubt for that fact.

In the midband the tuner has this classic warm and realistic touch, I do miss so much with more modern equipment. The whole gestalt of the sound is bold with the ability to create a huge soundstage garnished with a sparkling treble wich is smooth as silk. If you like the sound of vinyl, than this old Marantz FM tuner is not so far away from that aesthetic direction.

My biggest problem was to find the lamps, which Marantz used at this time – 6V/5Watt. You get everything in the 6V category, but not 5 watt…..this type of bajonet socket lamps vanished from the market.

One day I found a shop which sells parts for vintage motorcycles – and BINGO – this ebay shop had exactly what the doctor ordered – and my Marantz 20b struck again its sexy blue eyes.

Last things I had to do was dealing with the poor cosmetics of the device. The front plate has do be fixed, which needs a lot of gentle violence – but I succeeded. One of the biggest problems was the rusty original laquer at the steel chassis. A full repaint would mean to loose all the original stickers which were used on this piece of gear instead of some engravings. I decided to use a very tricky coating technique to obtain all the glued on signs once the Marantz factory had put on that tuner.

P1050739

At the end the tuner got a new rope driving the needle which shows you the FM frequency, a new Telefunken oscilloscope tube and a complete cleaning.

P1050746

To give you a short description of the operation, let me explain the features of that old audio classic.

The Marantz 20b has 2 pairs of adjustable RCA output sockets at its rear side. Beneath those you will find two spindle potentiometers to adjust the output level, as also the output balance of both pairs – their maximum output level will be 1V. Also at the rear side you will find two RCA input sockets, which lets you feed a signal into the tuner to have the possibility to use its scope, measuring that given signal. This comes on handy, if you adjust the azimuth of your phono cartridge for example. To activate any external signal fed to the scope, you have to turn the diyplay switch to its “ext.”(external) position.

Also at the rear side there is a pair of sockets for test purposes and we will find a strange locking pedestal which takes the 3 antenna inputs as also a switch on its backside wich adjust signal damping on the antenna signal. Last but not least we will find at the back a fixed power cable, my unit was officially imported to Germany, which means it is a 220V unit with a proper Schuko plug at the end of the umbilical. The European distributer for Marantz gear at this time was the Swiss company Bolex, who also built some of the most famous film cameras of that day (Bolex 8mm or 16mm cameras).

At the front we face on the left side two small potentiometers which are used to center the focus of the oscilloscope tube. If the tube is cold, after you switched the unit on, the scope will not match with the engraved cross marking at the screen – so you are able to correct that at the beginning of any adjustments done with the other switches or the tuning wheel – because the scope shows you everything you have to know regarding signal strength and multipath performance. So it is a good idea to begin with adjusting the scope. To do that you need to switch the knob called “display” to the point were it hits the “ext” marking (external). The scope shows now a small point, which has to be centered with the two potentiometers on the horizontal plane as also at the vertical plane – both are lettered accordingly.

P1050747

The display switch has 4 more positions. “Audio” will show you the phase relationship between the two channels of your program on the scope. If you listen to a true mono signal, as it will be the case with speech, there is a 30° stroke displayed. If you have a strong stereo modulation the scope will show you more or less a circle with a lot of movement accordingly to the modulation of the music.

The next mode is off – that is self explaining – but I need to ad – off is a very good mode ;-))), because if you are not dialing in a station or observe the phase relationship between both stereo channels – it is a good idea to switch the scope off – because the tube will live much, much longer and to get a new one gets more and more complicated today.

The next two modi of the display switch, show you the signal strength on the scope or the multipath performance!

Next to the display switch we will find the knob for the different muting modes. The Marantz 20b has an adjustable (internal) muting threshold at which the signal will drop in volume, which is a nice feature, if you want to get rid of all that noise between two stations. But you can turn of that mode – and for that purpose exists the bespoke muting switch.

On the right hand side we will find the on and off switch and a knob  labeled with “mode”. Here you can decide if you want to listen in stereo or mono – but there is more…. If you listen to a weak stereo station, the noise you will receive is annoying – so there is a position between stereo and mono called “high blend”. Sid Smith used therefor a special trick in his circuit – it is a high frequency blend which uses phase cancelation of the noise – not a traditional high frequency cut. With that “filter” you will miss on weak stereo stations no treble! – That was a sensation at the time were the Marantz 20b hit the market. What you will loose is some spaciousness, the signal gets more into the mono direction – but is still a stereo signal!

All in all such a fantastic vintage FM tuner is a nice addition to a very good vinyl playback system – and at night, when I am listening to some rare music performance broadcasted in high quality, the wish comes up to record all that great stuff – but that is another story for another day.

My biggest respect goes to Richard Sequerra and Sid Smith, the inventors of the Marantz 20B, may Sid rest in peace, as he died in the year 2000…

Thank you for the music, you two genies….

 

E. Strauss

 

A miracle – Kiseki Purpleheart NS

My story

Those of us audiophiles grown up in the 80ties (last century) may remember: It was the time, were the Stereophile as also the Absolute Sounds magazine were like the bible for us, the time, were Nastasja Kinski showed her amazing curves on the front cover of the French erotic magazine “LUI” and we dreamt about Nastasja and a proper HiFi – system – but could only afford a Sony Walkman to listen to some 80ties stuff like The Cure, Joy Division and Prince or Michael Jackson (I was not a Madonna fan at this time….;-)))

One day my Sony Walkman headphones broke – a catastrophe, but a good occasion to visit one of the high end dealers in our town, instead of pressing my nose against the store window, I had now a proper reason to step into the shop .

So I pulled myself together and entered the shop…..oh my….. Micro Seiki turntables, Fidelity Research FR64S and 66S tonearms, Mark Levinson amps and preamps, a Cello Audio Platte and a Kiseki Purpleheart cartridge, mounted on a SME V tonearm. This little jewel got my attention – a dream, made of brass and a strange purple coloured wood with a tiny needle under its long body – it was so beautiful, that I could not forget about it in all the years followed that day. I promised myself – one day such a Kiseki will be mine – not knowing if it sounds good nor what such a jewel will cost. The following decade was stuffed with Rega decks and tonearms, cheap moving magnet carts, Mission amplifiers and tiny British bookshelf speakers – but deep inside my heart was still a purple shine from that Kiseki cartridge.

P1050720

As the financial situation once changed and I eventually could afford such a cartridge, the company had disappeared – CD – players were now the holy cow, and Herbert von Karajan claimed – against the sound of the CD a vinyl record seems to be like gas light – how wrong he was!

Ok – no Kiseki for me – sometimes I saw some vintage ones on ebay or other audio selling platforms – Kiseki Agate Ruby, Kiseki Blue Goldspot and Kiseki Lapislazuli – but never was there a Purpleheart on offer.

Here and now

P1050025

In 2010 I spotted some new old stock Kiseki Blue – and recognized that Kiseki was again back on track – the man behind that brand, Herman van den Dungen, coming from the Netherlands, decided to participate at the upcoming vinyl revival and used old parts from the 80ties to built a brand new Kiseki Blue. Since I was totally aware of that new situation – the complete series of these NOS (New Old Stock) Kiseki Blue were already sold out….

OK, again – no KIseki for me….

Van den Dungen realized that there was a growing market for his Kiseki cartridges and did a very bold step – he recreated the brand, now with new parts, a new design – and he called these cartrdges NS – which stands for new style.

Exploring the miracle

P1050723

One day I found a little package at my doorstep – and my pulse began to rise. Inside the package I found the traditional round wooden box with the myterious Japanese writing on its top. Van den Dungen created the Purpleheart NS (New Style) in a different way he did with the Blue NS cartridges – the new style Kiseki Purpleheart had its traditional long body and looked like the vintage original which I was fascinated about since the middle of the 80ties. Oh, what a gorgeous looking pice of audio gear it was….nothing of its beauty had vanished in all those years – it was like I had a time machine, and was again in 1984 together with my old Walkman, the LUI magazine with Nasti on its front and all the great audio gear of that time – the only sign which tells me something was different, was the colour of my hair!

The new style Kiseki Purpleheart is a moving coil cartridge with an internal resistance of 42 Ohms, which means, that I could use it with a Denon DL 103 compatible step up transformer. The electrical output is a healthy 0,48mV – so a mach with a 1:10 Step Up transformer will give us clearly more gain, than with the classic DL 103 used with the same step up transformer. The cartridge has at todays standards an unusual long body made of the beautiful purpleheart wood. With some headshells or tonearms there might be a problem with space, as I intendet to use a Frank Schröder Reference tonearm, there was no problem with the size of the cart.

Mounting and adjustment

P1040896

But there was a serious problem with the weight of that audio jewellery – the cartridge might look big and heavy but it is not – its weight is just 7g – to bring that into some perspective – a Lyra Kleos weights 8.8g and looks much lighter and smaller. There was no chance to get the optimal tracking force of 2.3g for that cart with the standard counterweight of the Schröder Reference – so I had to call Frank, praying, that he was in town and would have time to make me a smaller and lighter counterweight for my Reference arm. To my surprise Frank was at home, and offered me to come over the next day to pick up my lighter counterweight. Thank you Frank!!!!

Adjustment of the cartridge is not an easy task because you cannot see the tip of the stylus without making some Yoga exercise in front of your turntable. At the end I could have used the straight angles from the body, because the stylus of my Purpleheart was mounted with 100% precision – so no correction in geometry nor azimuth was necessary.

To get the most out of this cartridge I would advice you to use 2.3g VTF, which is a tad under the official figure – and a straight VTA, so that the top plane of the cart is parallel to the record surface. You could use a full active phono stage with up to 1 Kohm internal termination, but I think the best sound will be achieved with 400 Ohm. Or you can use  a step up transformer in the range of 1:10 or 1:15 – i opted for the latter – and connected the Purpleheart with the Hashimoto HMX trannies in my Air Tight ATH2A using its high impedance switch. The transformer will give us 23db of gain, and the cartridge “sees” around 210 Ohm.

The sound

The first thing I recognised was the silent ride of that cartridge – you wont get much noise from the grooves, which means, that we have a larger dynamic window for all the small details. The Purpleheart needs less than 20 hours of playing time to come to live – that is something I cannot stress enough – because today some cartridge manufacturers tell us – you need 150 – 300(!!) hours to judge the sound of a moving coil – which is ridiculous. What we can expect after round about 20 hours is a bit more openess in the treble region and a more fluid sound in the midband – but it is not a dramatic change.

Kiseki means miracle – and the name could not be better chosen – because the sound is like a miracle. Out of a very black background we get a fast and articulate sound, with bold colours and a silky smooth top end with an amazing amount of detail and resolution. The bass section is sinewy and reaches into the deepest octave – this bass performance is fast, and has a lot of tone – not that typical one note deep bass with slow action. The stage the Kiseki is able to render has a slight up front gestalt – a singer is not on level with the speaker plane – instead he is placed a good portion in front of the speakers, which gives us a very intimate vocal performance. From the mono center toward the sides, we get a very good rendering of recorded space with a lot of detail and an amazing resolution. The space between the instruments is also very good – not on par with a Lyra Kleos SL – but there is not much missing. The kind of projection is a mixture of pin point accuracy and a sort of wholeness, which makes it very easy to get the whole picture of a recording, while also being able to listen to a large amount of detail.

In comparison with the Lyra Kleos

L9990234 (1)

As the price of the Kiseki here in Germany is around €3000,- it is fair to compare it with one of the best cartridges in this price range, the Lyra Kleos SL. Both perform in a wide margin above its price class, you have to spend nearly €2000,- more to get really something more. And this “something” is not another class or a whole different picture – differences are shown in the amount of resolution and attack pureness, as well as the blackest black in bass of the really big boys. As you spent such a serious amount of money for a moving coil cartridge, it gets difficult to gain more sound quality for the developer of those high end gems. So do not expect a complete different sound quality if you spent €6000,- or more – as I said – you will gain performance in some single aspects of the reproduced sound. A Lyra Etna for example puts a better resolution on the table and has a tighter and deeper bass register with a good more portion of dynamic shades, than a Kleos SL can give us. What I try to explain is – from a certain price range on, you have not a linear function between your investment and a better sound quality. There are some “jumps” in that function between price and sound quality which take place from under €1000 – to the limit of €1000, and there is another bigger gap existent if you double your investment to around €2000,-. After the 2000,- mark it gets much more complicated – so the next little jumb will take place at €4000,- but it is much smaller, than everything till that point.

P1050020

The Kleos offered in my comparison a better pronounced leading edge. The Kleos has the ability to start and stop immediatly. The speed of this cartridge is astonishing – the Purpleheart in comparison is a little bit slower with not so much accent on the rhythm of the music. The story behind the Kiseki is more about the tone – and in this category it is more beautiful than the Kleos. The latter might be more neutral more transparent, but the Kiseki gives you a more emotional picture of the music. There is a certain emphasis on the lower midband, which renders the body of instruments and vocals with greater impact and a greater sense of authenticity. Both share a nearly equal ability to render recorded space, the Kleos is doing that in a more pin point kind of way, the Purpleheart shows us the soundstage in a broader more bolt style, which makes it sounding a little bit bigger and greater. In the treble area the Kleos is more refined and more open with a greater sense of resolution and detail, the Kiseki is a little bit on the warm side of neutral at this point, which can be an advantage if the engineer or the mastering facility cut the treble slightly too hot, which is often noticeably with the sibilance S or T or SCH. On the other hand the Kiseki is not rolled off – it renders the highest treble with a slight drop of energy – and while doing this, there is a very sophisticated quality at the treble – it sounds wett and three dimensional.

The Kleos is a bit dryer in that area and misses some of the plasticity of the Kiseki. The Midband of the Purpleheart is one of the best I ever heard – it is so colourful and real, with a huge dimension – a dream! The Kleos is fleshed out with an ever so slight cut in the upper midtone spectrum – which gives it the ability to render a very clean and structural sound, even if the record gets more dense and highly dynamic. Both are amazing cartridges – I would vote for the Kleos if you are a kind of listener, who is consuming music in a more intellectual way – the Kiseki touches more the heart and soul of the listener. And the Kleos is more about rhythm, while the Kiseki is more about tone – so both will be a perfect complement to each other.

There is a certain tendency to have more than one tonearm mounted on a record player…..

Relax and enjoy your music

E. Strauss

Introducing a Legend, Telefunken ECC83 Smooth Plates

Introduction

If we think of music reproduction, 90% of the whole information in a piece of music, even more with spoken words, takes place in the audio midband. As we were young dance club visitors the most important thing in sound reproduction was bass – more bass equals better reproduction and greater fun – we had to feel the energy right in our chest. With getting a little bit older, things changed and today I cannot stand 10min of reproduced sound, if something in the midband sounds wrong or coloured.

Where everything began

OLYMPUS DIGITAL CAMERA

The best example of the human capability to hear the slightest variations in the midband of the audio spectrum is the voice. If we have our girlfriend on the phone, we can hear in less than 3 seconds in which emotional state she is, and we can also identify a known voice after seconds, even if we haven´t spoken to that person for years . In this example we are using a telephone not a high end audio system – just a simple telephone. The ability to remember the character of different voices we once heard and to recognize even the smallest nuances in them is frightening. If we think about the evolution of us human beings, the ability to listen at such a high level, has something to do with our existence on planet earth, and the sound of our mothers voice was  familiar to us a long time before we were born.

The Goal

Thinking about serious sound reproduction means to deal with the midband. And dealing with the midband is much more complicated than with bass or the treble. Do not misunderstand me – bass and treble are also complex in their own way – but the diversity of the midband, the amazing amount of different shades and the ability to detect them, makes us to real “midband gourmets”. To get more information about the hearing of the human ear, we have to look at the findings of Fletcher-Munson, who manifested in 1933 the famous curves, in which we will see how loudness levels and the ability of our ear to her different frequencies is described. If we take this curves as a fact, we have to get the highest quality in that frequency range in our sound reproduction system we can afford – and – to tell you the truth – it is not cheap nor is it easy to achieve that.

The Midband

L9991119

One ticket to heaven in the difficult midband area is a very good tube amplification system. That does not imply that transistor technology is not able to reach an outstanding quality in this regard, but to get there via a transistor driven amplifier or preamplifier will be even more expensive than with a tube amplifier.

But a tube amplifier needs tubes – and there the whole story begins to turn. Today we face a growing number of tube suppliers mostly located in russia and china, which give us the most common types of our so urgently needed glass – but how good is the sound of these brad new constructions? If I put brad new JJ or Electro Harmonix tubes in all 12AX7 positions in my preamplifier, the sound  gets more of that specific colour I will find in a cheap transistor preamplifier – sometimes even worse that that. Gone is the complexity of the midband, gone is its smoothness and the grain free gestalt, what I get is a sparkling treble and a nice sounding full bodied bass, but the midband is flat and lifeless, with a clear cut in that frequency range. In other words, if someone will steal all the great old tubes from my stach – I would by tomorrow a very nice and expensive transistor preamplifier – and get rid of all the tube procurement, all the tube rolling, the fine matching to the amplifier – and at the end I would probably save some money too. I cannot tell you, why it is not possible in 2018 with all the computer technology, the materials we have today and the indsutrial possibilities to make tubes with the same sound quality it was the standard in the 30ties, 40ties, 50ties and 60ties of the last century. Maybe computers and all the modern technology we have today are able to create the newest I phone – but are useless to built a tube like the Telefunken ECC83 – who knows.

Meeting a Legend

L9991103

The Telefunken ECC83 is one of the most important tubes in its class – maybe the most important one. It was made in the Telefunken plant in Berlin – and has some distinctive marks which we have to talk about later. The Telefunken ECC83 is maybe the one and only tube in the ECC83/12AX7 range, which behaves is such a neutral way with its sound characteristic, that we are able to hear the quality of a given circuit. That makes this tube for some of us boring – you plug a Telefunken ECC83 into a line stage and the big miracle you will have with a Mullard, Amperex, or RCA Black Plates is seemingly missing. But that is just half of the whole story. A Telefunken ECC83 smooth plates has not the typical shining light to any frequency range or a special dynamic behaviour in the spectrum – nor has it any obvious coloration, but it has one of the most complex midband abilities of all ECC83/12AX7 tubes. You will get a highly neutral ultra complex tube sound, a sound, which needs your attention – it is not a sound were you can read a book, while listening to some music. A Telefunken ECC83 sucks you into the music – and it challanges you.

Together with its neutral full range sound, you will also get an outstanding quality in reproducing recorded space – the smooth Plates Telefunken will render the slightest amount of reflections once captured by the microphones. If you put the RCA Living Stereo with Haifetz´s Interpretation of Sibelius Violin Concerto D minor Op.47 on the platter of your turntable, than you will recoginze after the first movement – it´s all about tone. Hot and cold shivers coming over you while listening to this violin tone – reproduced with a Telefunken ECC83 smooth plates it is so frightening real, that you nearly can touch the instrument. The ability to show the whole spectrum nearly uncoloured and especially the complex midband, makes this concert a very intense experience! The smooth plates Telefunken ECC83 is one of the biggest legends in the ECC83 class of tubes and it´s status there is completely justified!

L9991112

A trip to the past

The Telefunken ECC83 was used in countless legendary amplifiers of the audio or recording industry, it helped a lot of companies to gain their specific sound, which we adore even today. To name just a view….what happens, if you throw out all 6 Telefunken ECC83 of a Marantz 7C preamplifier – what if you do that with a Mcintosh C22 or with a Telefunken V72 microphone preamp??? Marantz and Mcintosh are more or less the inventors of what we call today High End – and both companies used wherever it made sense at their 12AX7 positions Telefunken ECC83 tubes. The whole US hifi scene in those years used them, Fisher, Scott, Harman Kardon and so on….sometimes they got from Telefunken tubes with their brandname printed on the glass – so it might be possible, that you have seen Telefunken tubes with Fisher and Rogers as also Mcintosh logos on their glass. As Germany was forbidden directly after the second world war to build any arms, the recovered German tube industry concentrated on civil usage of vacuum tubes and one of those fields was the reproduction of sound. Maybe that´s the miracles behind the sound of a Telefunken ECC83. Telefunken had not to deal with constructive details imperative,  if their tubes were used in supersonic jet fighters or bombers which can fly at the border of the stratosphere. Strangely enough, the Telefunken is inspite of their civil purpose, a very rugged construction.

L9991099

What about noise?

The smooth Plates are one of the very rare tubes which have nearly no problems with noise, nor have tey any tendency to get microphonic. Both attributes make them predestined for the use in very sensitive applications, as we will find them in phono and pre amplification stages of our sound reproduction systems. Imagine a phono stage constructed with two gain stages which will amplify the signal up to 40db – every bit of microphonic behaviour of a tube will cause an earthshaking noise coming out of your speakers. Once you reached a certain quality level of vinyl reproduction – it is the signal to noise ratio, which divides the boys from the man. As blacker the background will be, as much details and recorded space you will get – any tube hiss will weaken the ability to show the dimension in space of the recording. In a phono stage a tube can´t be quiet enough – and with the Telefunken ECC83 smooth Plates we can achieve a level of quietness no one would think is possible using a vacuum tube.

How to spot the original

L9991109

There are 5 different versions of the Telefunken ECC83 in existence – the oldest ones are called ribbed plates. The anode plates of this tubes have on their flat sides a certain pattern, which could be described as a ladder – or ribs – which gave them their name.

The smooth plates share 4 different variations – all of them differ in the numbers and positions of the holes at the side of the plates – and of course the smooth plates misses the ladder structure on their anode plates – which made them – the smooth plates!

Type 1 of the smooth plates have two rectangular holes symmetrical arranged on top and bottom auf their plates structure.

Type 2 has 4 rectangular holes at the side of their plate structure.

Type 3 has 3 rectangular holes on the side of the plate structure.

Type 4 has again 2 rectangular holes in the plate structure – but this time the holes are more centered – not as far away from each other as it is the case with type 1.

P1050738 (1).jpg

All original Telefunken small signal tubes have the diamond logo at the  bottom of the glass  between the contact pins – that is more important as we might think – because at the end of the tube era Telefunken stopped making their own tubes and sold re labeled tubes from the east german supplier RFT. Those RFT – “Telefunken” banded Tubes do not have the diamond logo between their pis. The great thing is – no one can fake this sign in the bottom of the tube – because it is a structure casted in the glass.

All Telefunken ECC83 have a code on the opposite side of their logo, which begins always with a capital B – which stands for the plant in Berlin/Germany. Telefunken had also a plant in Ulm/Germany, were they made all the power tubes and their special high grade signal tubes(Telefunken “S class”) – in such a case there will be a capital U at the beginning of the code.

The Logo itself changed over the years – very old ribbed plates Telefunken had a small diamond shaped Telefunken logo printed on the glass – later dated smooth plates have the more common large and thinner printed logo.

On the left and right side at the bottom of the logo you will find the writing “Made In”…………”Germany”. At the bottom of the tube you will find the type – in this case ECC83. If the tube was made for export purposes, there will be both type names – the international /US type 12AX7 and the European type name ECC83  separated through a slash.

Some Telefunken ECC83 have numbers, normally three digits, on their getter mirror on top of the tube – this was a special numbering of internal batch matching processes.

If the customer needed special selected tubes, as we will find them in medical or industrial applications, there might be a coloured tip – mostly in red or blue on top of the tube.

Some special grade Telefunken ECC83 have a bank wrapper around their glass with selection informations and names of the company for which they were made – like Tectronics for example.

And there were also Telefunken ECC83 tubes, which were made for the German Post and telegraphic applications – those have in addition to their normal logo a coloured code around the glas. I have such a pair with a red code index for telegraphic applications – but there might be also yellow codes or other coloured codes as well.

All Telefunken ECC83 are long plate types – Telefunken never changed that construction detail, as most of the other tube suppliers did at the beginning of 1960. They all have a round getter ring fixed with one getter support rod, and they should have, if they are in good shape, a shiny silver coloured getter flash. The glass on the getter dome changed over the years – the oldest smooth plates and ribbed plates have 4 segments on their dome – newer examples have a smooth glass dome.

L9991100

In comparison

A lot of electro technical engineers deny that there will be a sound variation between different tube brands sharing the same category like in our case the ECC83 family. They claim,  that if two tubes share the same measurable data determined with a tube tester, and have the same internal resistance, than both tubes should sound equal.

As I am an audio engineer myself – I am far away from believing in Voodoo, but I must say that the sound differences between different tube brands in one given class are dramatic. A Mullard ECC83 long plates, square getter, wrinkeled glass (MC1) sounds completely different, than a Telefunken ECC83 smooth plates – soon we will discuss that more in depth.

In this case I wanted to know how a modern tube would perform in terms of sound quality against an old Telefunken ECC83. So I did some investigation at the internet to inform myself of the possibly best modern 12AX7 and got as many nominees as there are tubes on the market – but one specific tube stood out of the mass – that was the New Sensor made 12AX7 Gold Lion.

I bought a triplet of those, perfectly matched from a well known tube supplier in Germany and wanted to compare them with a equally good matched triplet of the legendary Telefunken ECC83 smooth plates type 1 with equal production codes.

As we all know, tube rolling is not a game were we can directly compare the sound of two different tubes – because we have to switch the amp of, we have to wait till the tubes cool down before we can pull them out and plug in a new set.

In the professional sound engineering  world, we claim, that our memory dealing with sound will be fooled after 30 seconds – so I decided such a comparison has to be done in a better way. I decided to record the music rendered by the two different tube settings, using a professional 24bit, 192Khz digital hard disc recording system.

After I finished recording of 4 different types of music using the exactly same records, the same cartridge, same turntable, same cabling – everything being as equal as possible, I used a normalize algorhythm  to bring both files at the exact same gain level to get rid of eventually existent gain differences – and listened for a couple of days to the recorded files via headphones and via my Quad ESL 57 and a pair of vintage Chartwell 1 LS3/5a. Later in the test procedere I made blind tests with both tube settings.

And what was the outcome???

In comparison to the Telefunken the most obvious impression you will get with the Gold Lion 12AX7 is a more pronounced bass – it seems to gs a little bit deeper and had a greater sense of dynamic, which gave the bass range a greater impact.

On the other side of the audio band you get the impression the Gold Lion has more sparkling treble with a pronounced roll off in the highest range of the frequencies. This character of the Gold Lion 12AX7 has its origin in a compressed midband – which makes the bass frequencies stand out – as also the treble spectrum. It is the typical – “hello – I am a great HiFi sound” tube character, which so many people fall for it.

With the treble character it is not so easy to describe the difference. An old audio engineer rule says, high frequencies mask lower frequencies – if you cut of the highest spectrum, you get a more pronounced presence in your sound. And that was exactly the case with the Gold Lion 12AX7 – the frequency range was comparable to some MP3 files, were you will not find much signal anymore above 15Khz  – but in spite of sounding dark – you will get the impression of more presence. The Telefunken had the complete spectrum – and this is the reason why a vocal does not jump on you – it is placed were it belongs. The Gold Lion made the presence of the treble more pronounced more sexy but it lacks a lot at the absolute top end of the audio spectrum. If you listen to a singer songwriter track it might be nice, but if your next music sample is some Jazz with pronounced cymbal work, you will recognize that something is missing. Also the compressed midband and the pronounced presenc could make the Gold Lion sounding harsh – because all the smoothness of a balanced tone is gone – what is left is an unbalanced sound which should impress you in the first instance. In the area of rendering recorded space the Telefunken could jump over the Gold Lion – it was no comparison – the New Sensor construction sounded flat and two dimensional. The Gold Lion was simpler – more easy to listen to, it draws less attention to the details, less space, less midband accuracy and a kind of loudness curve was detected. The dynamic abilities of both tubes were more than obvious – the Gold lion compressed the midband from 350hz – 1,5khz while the Telefunken sounded completely open in this range.You will get with a recorded violin the whole gestalt of the instrument – every nuance of it was there with the Telefunken ECC83 while the Gold Lion made it more simple, more easy listening.

P1040387

Prices and supply

A Gold Lion 12AX7 costs us with a good matching process around 50,-, the Telefunken ECC83 will set you back around 80 – 100,- – so it is much more expensive. But – you payed a lot more money for your phono stage, your cartridge and your tonearm, as also the turntable itself – if you want to keep the signal chain as neutral and as open for what you feed in it, than there is no other way as to bite the bullet and get some good quality NOS tubes!

And do it now – because every year the things get more and more expensive – we are probably the last generation, who will be able to consume the fruits of a technology obviously forgotten in our modern times. We face much larger demand of NOS tubes than the market can deliver – a proved sign are raising prices. The same Telefunken ECC83 costs 8 years ago 50,- exactly what you have to pay today for a Gold Lion 12AX7 – and I thought that was really expensive in those years.

If you spent such an amount of money for a single tube, you should be certain to get good quality – so I am not a big fan of countless ebay auctions with no tube tester is involved or tube testing equipment is used, were you can not work with the data published at the auction.

Buy from trusted sources – pay a little bit more and forget the story of the dead grandfather with a stach full of brad new Telefunken without any sign of a label on the glass or dark getter mirrors. At the end such an expensive Telefunken ECC83 could be also the better decision in the long term, because such tubes will be durable around 10 000 hours – during that period of time it might be, that your third generation of Gold Lion tubes will be necessary.

 

Great listening

E. Strauss

 

 

 

Quad ESL57, for the closest approach to the original sound. Part 1

Itroduction

So much has been written about the classic Quad ESL 57, that it is worthless to repeat the historical aspects of this famous electrostatic loudspeaker or describe the technical aspects of its construction.

My intention is, to give some practical advice about room placement and how to match this speaker system with an amplifier. How to deal with its shortcomings and how to enjoy its outstanding performance.

Getting a pair of Quads in proper shape

The fist adventure with the original Quads is, to get a fully functional pair. If you are not willing to deal with restoring their panels and working with lethal high voltages inside its electronics, it is a good idea to skip the typical ebay auctions or cheap offerings of old used ones and contact one of the professional suppliers. In my case it was Manfred Stein from Quad Deutschland who got my attention, because the small German company bought all the original tooling from Quad UK as they were sold to Shenzhen China. Manfred Stein was a Quad Distributor during the heydays of the British company and shared a close relationship with Peter Walker, founder of Quad Electroacoutics Ltd, and father of the ESL 57 speakers. As Quad UK had to close their doors, Peter decided to sell Manfred Stein the whole machinery park, so that he is able today to restore the original Quad ESL 57 and its more modern brother the ESL 63 to its  original specifications.

 

So I voted for an old classic 57 with its typical bronze coloured front grilles, which was completely refurbished and brought to the original specs. Manfred Stein gave the speaker, manufactured at the end of the sixties last century, brand new panels and overhauled the complete electronics while letting the original transformers untouched. Most of what you can read on the internet about the efficiency of this old speaker design has to be seen in the context of its state at the moment of listening. Old, sometimes defective panels will not have the performance they once had, which causes the listener to pump up the volume on his amplifier, to compensate for the compromised efficiency. Such action will ruin the speakers even more, because the danger of overloading them with your amplifier rises, which will cause the well known arcing of the treble panels.

Efficiency

A historically correct refurbished ESL 57 will have an efficiency around 84db/1w/1m, which is in the same league as the famous BBC LS3/5a speaker system. That is everything but especially efficient if we look at horn loaded speaker designs or actual modern constructions, so the typical way to go is using a very, very strong amplifier – but it is not! The ESL 57 accept 33V at maximum on its terminals bevor arcing occurs on their treble panels. The amplifier designed for the ESL 57, the Quad II monoblocks, delivered 15 watt to drive the speakers in a safe way. So the ESL 57 will not accept a super strong amplifier which will limit the maximum SPL we could reach with this speakers to around 100db in 1m.

100db in 1meter is not too bad, we could easily listen to nearly every piece of classical music with a realistic dynamic swing, as we can do with Jazz, Singer Songwriter and also modern Pop music – the limit will be Heavy Metal or modern electronic music and also very large orchestral pieces like Mahlers second symphony. But I wrote 1 meter – 1 meter will be extreme close up listening – or better nearfield listening, which is not possible with the ESL 57, because of its poor sound radiation in any given room at this distance. The minimal distance we can achieve is around 2m measured from the treble panel to our ears. Every doubling of the distance, results in a 6db drop of sound pressure level – which means that nearfield/midfield listening with the Quad ESL 57 is a good idea to get enough realistic and dynamic expression in a not too large room.

The impedance

If we look at the 33v maximum Volts the ESL 57 will accept without being destroyed, we haven´t yet discussed the impedance curve this speaker produces on different frequencies. To make things much more complicated, the Quad ESL 57 is a very reactive load for our amplifier, the panels will produce an impedance peak around 100hz – of nearly 40 Ohms – and in the treble around 17Khz we see a serious drop in the impedance curve of under 2 Ohms. That is not an easy load for our amplifiers. To match the original ESL to an amplifier is a task which books were written about. To shorten the story at this point (later on we will discuss this more in depth) – my advice is to use a very good push pull tube amplifier with high class output transformers or an OTL (Output Transformer Less) amplifier – both will work in a fantastic way with this little diva!

 

P1050709

Nearfield listening and a dedicated room

Coming back to our nearfield listening approach we have to think about some more surprises the original ESL has in store for us. The 57 is a dipole speaker – this means it will radiate the sound pressure not only in front of its panels, we also have to face a distinctive radiation behind the panels. The radiation of the sound pressure has the characteristic of a figure of 8, which means there is total cancelation 90degree of the panels. The sound wave radiation at the rear side of the panels is damped with some felt and jute pieces – so we do not have a mirrored radiation in the front and at the back of the speaker. The truth is, that at the rear side we have a lot of damping at the higher frequencies, but nearly no damping in the bass region of the frequency spectrum. If we place the ESL close to a wall, the rear radiation of the speaker will be heavily compromised. With the construction of the ESL 57 we have exactly the opposite behaviour of an enclosed speaker system, which raises the bass frequencies by placement close to the rear wall or even worse by corner placement. With the dipole characteristic of the 57 we have a proper tool to adjust bass performance in any given room to get a linear response. That means as far as we could get the Quads from the rear wall, the more sound pressure level we will get at the low end of the spectrum. Everything depends on the room in which the speaker is installed – a good starting point is to place the panels at 1/3 of the rooms length. This position is nearly unachievable in a living room, if you still want to be with your girlfriend or wife. ;-)) A dedicated room is the best way to get rid of all limiting circumstances, wether it be furniture or just the pure design of the room. The big question is now – shall I put the panels on the long or the short side of a dedicated listening room???

Room placement

In the case of a pair of BBC LS3/5a I would strongly suggest to choose the long wall of the dedicated listening room (a topic I will write about in another article) – with the Quad it is just the opposite – if the short wall is not too short, which will harm the amazing ability of the Quads to show recorded space, we will gain sound pressure level and bass performance with this kind of placement.  Remember, we will listen to the stats in a nearfield placement – so you will need at least a minimum of 4m width of the short wall in your listening room – if that can be achieved, you have finished choosing the wall at which the ESL 57 will be placed.

The distance from the rear wall starts with a minimum of 1m – under this distance you will compromise the sound radiation in such a way, that all the moaning about bass performance in most of what is written on the internet will be justified. My room is 4.5m long – so if we use the “one third” rule, the speakers should be placed around 1,5m away from the rear wall, which is a good starting point. Quad experts will now shoot at me – because that is not enough – but wait – we are talking about a nearfield listening situation – and we are not finished with the placement.

The next step is to adjust the distance to the side walls – as we chose the small wall of the room, we will not have too many possibilities – because the room is not wide enough to get the panels far from the side walls AND achieve a proper stereo base for them. But there is a reason why we chose the smaller wall in our room – and the reason is again the bass performance and the efficiency. If we place the Quad ESL 57 near to the side walls, we will get more bass level from them and more sound pressure level – so we have two screws to adjust bass with the placement of the speakers, distance to the rear wall, and distance to the side walls. But there is no profit without loss – if we would place the ESL 57 nearly in free space – far away from any wall at the sides and behind them, we will have an amazing spacious sound but serious restrictions in bass and sound pressure performance.

On the short wall of our room, with around 30 – 40cm distance to the side walls, and 1,5 – 1,8m distance to the rear wall, we can measure a maximum sound pressure level at our sweet spot nearly 2m in front of the ESL 57 at the maximum 33V coming from our amplifier of nearly 100db spl, and no drop in the bass frequencies up to 42hz. The side walls of our room act like an acoustic amplification system!

As we discussed earlier the panels have no sound radiation 90° of the axis – so at this stage there will be no reflection from the side walls of our room – but the speaker will get an angle in which it will be placed towards us, which changes this situation. This means there must be a certain distance from the side walls if we want to have a breathing speaker and no boomy bass response! It is also a good idea to give the space behind the speakers and the side walls near the panels some acoustic treatment, to avoid too much early reflections.

P1050712

Toeing in

If we put on some music without any toeing in, we will recognize that there will be very poor imaging and a serious drop in the treble performance – the sound will be really bad!!! To cure all these aspects, we have to give the panels a certain angle in which they radiate towards us. To get the perfect stereo triangle placement, we will place our chair at a point were our ears equal the distance between the center of the two treble panels – in my example it will be 190cm. The treble radiation of the ESLs is limited in the horizontal plane to about 30° measured symmetrically from the center of the treble panel axis – and even worse – 15° in the vertical plane. And there is another detail in the construction, which we have to know – the treble panel is not mounted at the same plane as the bass panels are – it sits behind the plane of the bass panels – which is a good thing regarding the time alignment of the whole construction, but you should keep this detail in mind, because at large angles this construction detail causes diffraction at frequencies above 3Khz!

We have to toe in the speakers in such a way, that the very directed high frequency sound pressure level has direct access to our ears – too much toe in, and the sound will become too unbalanced in the high midband and lower presence – the Quad ESL 57 will shout at us. Too little of an angle, and we will miss the highest treble and air. This adjustment will take a lot of time – a good help is to use a noise generator available on the internet, and listen to some white noise trough our speakers. Some of the white noise generators available have the possibility to shape the noise, so that we can drop lower frequencies and listen only to the highest frequency band – you will be amazed how directional the Quad will be in the highest treble range! Our aim is to get a perfect stereo triangle – so if we realise that we will get more treble energy by varying the distance towards the speakers, we have to work on the angle again. We are finished when we get the most treble energy at our listening point in the stereo triangle – it will be achieved at around 15° toeing in of the panels. And do not give up!!!!

At the end of these adjustments, you will crawl on the floor with a ruler in your hand and your ears will distinguish every single degree of angle variation. You´ve succeeded if you listen to a vocal with some natural reverb captured in the recording and the singer is right in front of you, perfectly placed in the center of the stereo image and the reverb vanishes smoothly and absolute symmetrically between the two speakers. Next listening test is a walking base figure played in Jazz music – get different tunes written in different keys and listen carefully to the bass – there should be no bass bump or drop at any tone the bass player performs. If that might be too difficult – get a sinus tone generator from the internet and put some frequency sweeps on the Quads – if there are bass bumps or cuts, you have to vary the distance to the rear wall and maybe also to the side walls. In the end we should achieve an even bass performance, while getting the most treble and spacious sound with pin point imaging from the Quads. If you take great care placing the stats in the room, these speakers are able to vanish completely as a sound source, while throwing a three dimensional sound at you with an amazing pin point accuracy. Do not give up, till you have reached the maximum – every little change has a great effect – it is not plug an play!!!

The height

P1050718

A lot has been written about the original three feet floor placement of the ESL57 and about upgrading this with some higher stands, to bring the panels up to ear level.

The same people will tell you, that you need stacked Quads to gain sound pressure level and bass performance. Peter Walker had a reason to place the ESL 57 as he designed it – and one of his strongest arguments was the coupling of the bass panels to the floor. If we raise the panels we will get around 4db – 6db drop in the deep frequency spectrum. But raising the speakers from the floor also has a strong advantage – you get a very, very good stage and pinpoint performance and the soundstage will be much better, than sitting in a normal chair and listening to the panels on their standard feet. So how can we bring all these things together….??? The solution is adjusting OUR height instead of the height of the speakers. A normal chair is much too high – we must choose a chair or armchair, which brings us to the level of the ESL speakers. A narrow armchair or a chair like the Vitra LCW is as if it’s made for listening to our beloved Quads. Our goal is, to bring the ears below the top plane of the speakers – a sitting height of around 30cm will achieve that, without loosing the bass coupling Peter Walker once designed with his short legs under the panels. To gain a realistic stage, the panels have a slight angle backwards – if you listen to a singer, placed exactly in the center of the stage, you should “see” the voice straight in front of you without having the feeling of looking down to the stage. Now we´ve gained a realistic perspective to the virtual stage captured in our recordings….. and yes, a Magnepan is able to show us that stage in a way, that we have to raise our head – we look up to the stage. With the ESL 57 we look straight, sometimes a little bit down to the music. The difference could be described like this: with the Magnepans we are standing in the first row of a live concert and looking up to the singer on the stage, while with the Quad ESL we are sitting in the third row of an orchestra hall looking slightly down to the performance on the stage.

Why do we listen to the ESL, a design from 1957?

P1050730

As we can see, there are seemingly a lot of disadvantages in using an ESL 57 speaker to enjoy our favourite music…..so why do we choose such an old construction?? Why were they used as a control monitor for (classical music) recording and mixing in a lot of studios around the world and broadcast environments, and why are they still used today by engineers like for example David Chesky of Chesky Records?

If we read the headline of this article, Quad claimed, that the ESL would be the closest approach to the original sound – and this is from my point of view not only some advertisement. Until today the Quad ESL 57 show 95 of 100 modern speakers what a realistic reproduction of the whole midband in the sound spectrum is. The stats are able to produce the human voice in a manner, that we can believe a human being stands in front of us and sings. The string tone of these speakers is so realistic and pure, without any coloration, that we learn a lot of new things about our records and recordings. Even the slightest “mistake” in a given recording or within our audio system is clearly detectable. The Quads act like an audio microscope without being analytical or dissecting. We can enjoy music as a whole experience and we can also zoom into the finest details, and this zooming can be done without the slightest feeling of getting tired or stressed while we are listening. If we place them as monitors in the nearfield and let them sit on their original feet, we get enough sound pressure level and also a bass performance that is more than enough. If we think like a mixing engineer, we must accept that the human ear reaches its maximum linearity around 86db in the sweet spot. If we sit 2 meters in front of the ESL 57, we gain a maximum sound pressure level with my special “nearfield” placement of around 100db at the maximum rate of 33V driving the panels – that is 14db above the average level in which our ear shows the highest degree of linearity. 6db means doubling the volume, so for the highest dynamic swings in our music we have around 14db left to describe the given dynamic. That works perfectly if the room is not too big – and if we are not fans of Metallica live on stage. The bass response reaches down to 40 – 45 hz if we have placed the stats with great care, which means that we can hear the deepest tone played by a traditional 4 string bass guitar or an upright bass. The quality of the bass is phenomenal – no coloration of any enclosure, no boominess, therefore we get a speed and articulation, a toanlity in the deepest octaves, which is so realistic, that it is a great pleasure to listen to music which is produced with good bass performance.

The soundstage which these little wonders are able to throw into our listening room is astonishing. The midband is as natural as breathing and the immediacy and clean attack of percussive elements in our music is sometimes frightening. The feather light foil used inside our stats has such a low mass, that we have nearly no compression at the leading edge of a tone or percussive event. These speakers are amazingly fast – the reaction they will show with a finger snap, piano attack or a side stick hit of a snare drum is incredible. Listening to a pair of Quad ESL 57 with a monitor style placement at nearfield distances is like using a gigantic Stax headphone system without the disadvantage of sound localisation taking place in your head, a typical problem of most headphones.The cleanness and cohenerence of the music makes us listen for hours.

A Quad ESL 57 can be your last loudspeaker.

So, a lot of space on this blog will be dedicated to the Quad ESL 57 and also the LS3/5a, the amplifiers to drive them, the analog frontend to feed them, the tubes, all of which gives you the feeling of being there and much more other fun stuff.

Stay tuned.

 

E. Strauss