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. hk.com 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.

Tuesday, 8 October 2019

Collection Resolution Part III -– Driver Units and Speakers

Tannoy

Within the years I have collected a variety of speakers and drivers, if they haven't been installed in speakers for myself or for customers. The whole period addicted to serious audio I was some sort of married with the legendary Tannoy Dual Concentric Speakers. I had almost every type of every size, which is 10'' with IIILZ-units, 12'' and 15'' with one exception, I never owned a Monitor Black speaker. When I decided some time ago to start my audio retirement, which means I will stay on with my actual set and will get rid of all other equipment for sale. One exceptional pair of Monitor Red in 12'' size will be offered here. This pair is in almost like new condition, the cones are absolutely perfect like new, only little chips at the chassis paint where the mounting screws did hold the units in their cabinets and one dent at the metal caps, that's all. Otherwise this pair is perfect which is today 60 years after their introduction hard to find. So I will offer it to somebody, who looks to find a amazing pair for stunning audio future! I still have a pair quite small cabinets (in size like the Chatsworth) but with opened backside to work optimized like a dipole. I used this pair for 15 years for my everyday audio listening, till I came up to my own design with front loading horn and 15 inch chassis. I do not anymore recommendations about this exceptional speaker, but recently I had a chance again to listen to my former smaller 12-inch sized cabinets again, now with opened backside to improve into dipole mode. I was just amazed how good even such a small version matched all preferences to perform on a improved level of refinement, musical, realism and integrity. This speaker is able to do everything like my much bigger pair, without appreciable differences.



Of course the original solders crossovers are included. Today such set has got quite rare and everybody who uses these will not give them away, otherwise he is getting old.



Look at the screws of HF-units, these are still secured with lacquer!



Here you can see the Ding in the cap of one unit and as well the scratched screw wholes. Please notice the incredible British attitude with top products tu use high glossy chromed screws!


So if anybody is looking for new partner for the rest of his life, here it might be the rare solution.  Sensible offers are welcome!


Vitavox GP 1 pressure units

On offer is a pair of the legendary Vitavox GP 1 units. These were made in the very early 1950ties and were dedicated to different horn extensions, which were designed to match a frequency ranges between 700 and 12000 Hz with different dispersion attitudes. Their magnet is made from alnico and their coil is designed for 20 watts and 15 Ohm impedance. Their outer case condition looks well used with several ships and some surface stains, rust spots. Unfortunately the previous owner was of opinion to improve the performance of this units by poking the security grids inside their threads. Of course this is not dysfunctional, but could be much nicer when intact.





As you can see inside the diaphragms are original and like new.


The new owner will get a third unit without diaphragm free for spare parts like the magnet, grid, contacts, etc. Offers are welcome on eBay.


Bouyer Bireflex

Quite similar in energy dissipation, frequency range and actual size to the above Vitavox GP1 units, but with phenol diaphragms, the Boyer Bireflex units. I offer these as another set of HF-drive units of the french company specialized into public address equipment Bouyer. As well these show some wear at their cases, some chips and stains, but they are still in a technical perfect state, as the meter shows. They are dedicated to a 15 ohm impedance, power rating is unknown.



These much more common than the Vitavox and I believe they are much younger, so the prices are less.


Jensen A-12 field coil

A single Jensen A-12 field coil driver only usable with a separate power supply. The units work between 150 to 300 Volts. These have been used in the later 1940ties til the 1950ties for different kind applications, like public address, organs etc. The most of them were integrated as chokes in the power supply of their dedicated tube amplifiers. Well known is the 2A3 or 6V6 designs from Hamond.



This unit has a repaired cone, otherwise it is completely functional. Offers are welcome.




Wednesday, 2 October 2019

Collection Resolution Part II – Quad

Quad Series II – Sold


The next set of components will be from the famous brand Quad from Peter Walker. I always liked the chassis design of the well known tube power amplifiers called Quad II as the most advanced of all brands. Simple, straight and without any a abundance of parts, these amps are ridiculous small without any compromise ind technical design, comparing them to other brands. They show up with a smoothing choke, well calculated transformers for power and output and well designed housings for all of them. Other brands normally used bell caps instead closed covers.




The dedicated preamps Quad 22 are a milestone in casing design and functionality. Control about filterloops, bass and treble energy, balance and volume and pluggable equalizer filters for phono and tape were oriented at professional studio equipment instead of home audio products. Together with their legendary electrostatic speaker system ESL 57 these sets set the pace for refinement and resolution of recorded audio response in the mid 1950ties. The Company did sell really a whole lot of these sets until the late 1960ties because of its well named reputation, so there are still a lot of these units in use still today. But to be honest, these components are incredible nice designed, but their paints were not on par with other brands. All my Quad components from all series like series II, III and IV show after several years of use (sunshine, humidity, etc.) hefty discolorations and  paint chipped offs. You will see below. The Series II is a single layer gray metal paint without protective clear lacker coating, that shows up with some of them with decent rust blisters. So as well my set is far from perfect, it shows its age but it can be a lot worse than this pair.


Still almost everything is original, only the RCA sockets have been added for better compatibility. Here showed with cloth isolated ac-wires to match their original two contact (earth-free) Bulgin plugs (I have added a separate earthpath which connects to one contact of the Johnson-socket. The tubes are in working condition, but the GEC KT66 are dead and are given just for optical originality. Included is a quartet of very well sounding Russian NOS 5881 long live types. The Mullard EF 86 measure good as the GZ 32 do.



Inside the amps are in pristine condition, restored with the best components available, like Jensen paper in oil caps and Beyschlag carbon composition resistors.





My set contains an original dedicated Quad 22 Stereo Control Unit with their typical connecting wires to the Johnson Connectors at power units, so the preamp is supplied by them. Included are as well two pluggable filter units for phono (MM) and tape equalization. The Control Unit is complete but untested and comes as I got it 30 years ago from a London dealer. The cosmetic condition is fair and can be verified through these images.
The second unit ist the Quad FM 2 mono tuner in quite poor cosmetic condition, technically untested. Both units are included for complement. Both units should be seen as base for restoration.

I own as well a pair of ESL 57 electrostatic speakers. These I do own since 30 years, back in this time I did use them the last. I don't have any idea about their functionality, but normally I would expect the power unit will need new capacitors as some of the foils might need some attention? I do not know and actually I am not able to test them, so I would give these free to a new owner of the Quad II/2/22 units if picked up here. No way to ship them, simply too large.


Quad Series III


The successor of these famous Series II is the logically called Series III. With the first transistorized amp series from Quad, called Quad 303/33/FM3 Peter Walker approached end of the 1960ties again a design masterpiece. Again presented in tiny cases with orange-ivory-brown keys, knobs switches the new series was on top of this time. The Series III was still dedicated to the famous ESL 53 speaker, so the 303 power amp was technically designed to supply the high current requirements of this speaker type. 





Both units are untested and show cosmetically aging and on top some resting spots. These come with ac cords to connect the smaller 5-pin Bulgin mains plug to EU mains.




The Quad Series III introduced first the in Britain so popular 5-pin-DIN-sockets, as well for the preamp unit different filter boards were available to match different pickups and tape equalizing preferences.


Quad Series IV

From this successor series four I only own the extremely nice tuner, which I used over the whole period of the 1980 years in my setup. The Quad FM 4 tuner introduced station preset buttons and a numerically frequency display. Even the Series 4 was housed in quite small sized cabinets with exceptional well designed technology built in.  I always liked the typical simplicity of this excellent tuner, in particular comparing it to the typical japanese "all you can get"- concepts with tausend functions as sales argument from big brands. 
Within the end of the 90ties I got off listening to FM broadcast, so the tuner went into storage for 18 years. As everybody might expect, such a disuse is not very healthy for several components build in. So electrolytic caps dry out, batteries defunction soon and other oxidations might occur further. When I switches last year this unit first time after all this period, almost nothing happened at all. So I decided to give it a complete refurbish. I exchanged all 56 capacitors on the board, some resistors went out of tolerance and the cell battery type needed to be exchanged. It was a nightmare to find in Britain an original spare part but, I was happy. A lot of work spend on this tuner it now works flawless like new again and will give perfect service for another 25 years. The unit has some small chips in the paint and a slightly surface detoriation on the top case, nothing not to be seen in the images, – the unit looks still very good.