Wednesday, 3 June 2015

Vintage Treasuries – The Restoration of Leak Valve Amplifiers, TL12 "Point One", Part I

Hello to everybody,

today I want to start with a first part of a step by step restoration project. The restoration of the well known monophonic tube power amplifiers made by the H. J. Leak & Co. LTD, first issued in 1948 and called TL12 "point one", will be covered with this series of entries. These amplifiers do have reached cult status for vintage audio aficionados within the last 60 years. Some would rate these the best vintage amps made ever. Direct opponent for the throne for the best audio amp of all times will be the Western Electric 91A with single direct heated triode 300B as power tube. A whole crowd of enthusiast for early US american cinema equipment in the western and eastern world will rate these legendary monitoring amps (6 watts directly heated triode) made by Western Electric Co. in the 1930ties, the WE 91A, to be the most favorite amp of all times. They have set the pace for the forty year old single ended audio virus to a hunt to find the right speaker matching such amps. But specially with professional broadcast designs, there is a whole lot of not so well known amplifiers, which work exceptional well too.

My own pair of restored Leak TL12.1, here shown with plugged octal input adjustment modules and NOS tubes. Unfortunately I own a mixed pair of both versions, one early open frame mains transformer type and one later closed mains transformer type. Technically seen identical options of the same design made by the same manufacturer (Haddon LTD.). The closed type came into order for improved humidity protection.

Such comparisons are for real life conditions as useless, as comparing fish with beef, specially if you are already on a vegan lane... Both designs can show tremendous advantages against each other when combined with the right matching components, in particular if the important fact of well matching efficient speakers will be part of the test. The most of us will not be able to make such a comparison anyway with a first hand impression, since both monophonic amplifiers are almost lost without trace as find for a consumer market, since their low productions figures and age have set them extremely rare.
The push-pull Leaks are by far more universal to use and they are exceptional transparent sounding examples of their bread (Williamson design derivate with 12 watts in triode mode KT66). I do personally know no other pp-tube-amplifier which I would prefer in any discipline better than the old Leaks TL12.1.

First I want to do a bit of historic digging about these famous amplifiers. In 1948 these amplifiers were released by Harold J. Leak in order to match as first audio amplifier in history with such low distortion figures of 0.1% as selling argument. Together with ultra conservative specifications for the established transformers (Haddon LTD.), a complex case protection (4 layer zinc grounded enamel to withstand any humidity stain) and elaborated manufacture specifications for long term operation in difficult conditions. Like glass sealed paper capacitors and sealed cathode bypass electrolytics are signs of a purely professional intended market introduction. Harold Leak did travel Britain doing live - versus - reproduced sound comparisons with his new TL12 and RC/PA (pre-)amplifier set. The sound was reproduced via the Leak system using an STC4033 microphone (also known as the WE639A in the USA) and a 15'' Tannoy Dual Concentric Speaker (Monitor Black) in a 280 liter sealed enclosure behind black curtains in order to show that there will not be any difference to the live signal!!






He published a expensivly printed triple tone color (metallic gold as separate tone) 28-pages sales brochure to inform his aimed customers about the realized qualities of these amplifiers, different available versions and optional preamplifiers. The BBC was one of the first customers who made the success of these amplifiers possible and with their continuous orders over two decades they manifested the name for the coming "world class supplier ".  The BBC got the first active speaker units equipped with Tannoy Dual Concentric speakers, where the amplifiers are positioned at a drawer in the base of the enclosure in 1950.

"The New B.B.C. Monitor Loudspeaker,
incorporating a Leak TL12 "Point One" amplifier and a 15'' Tannoy Monitor Black speaker to form a active unit. Underneath it says 731 amplifiers were ordered by the BBC! (mono!)

Till today it is hard to find another push-pull amplifier in history able to fetch up with similar audible qualities. Normally this today more common topography of tube amplifier design (push-pull, global feedback, etc.) establishes in a foremost way a clean technical defined soundstage. With a glass clear superficial aural attitude of more technical expression these designs are not known for their natural harmonic aural performance, not so the Leak TL12.1. Generations of US-american or European KT88, 6550 or similar tubed power horses did set the pace in terms of power, control or drivabilty, but never showed the slightest chance to demonstrate a bit of Leaks natural harmony. Instead they flooded the market in the late 1950ties with cheap EL84 PP designs in tremendous counts, again fast rejected by the even cheaper power ratio of transistor designs in 1960. It needed the delicate intimate knowledge of individual masters from the eastern world in the early 1970ties like Anzai, Shindo, Kondo, Sakuma and lots of others to give path to the understanding of the refinements as stairway to such natural harmonic soundstage of early vintage tube amplifiers like the We's, Leaks, Brooks, RCA's and others.

The Leak TL 12.1 are exceptional well made and harmonic sounding power amplifiers worth to be restored not only because of their increase of value, due to their low production figures and a well named reputation. When I bought a first pair in London around 1990 I had to pay 850 pounds, which was a good amount of money for a 40 year old tube amplifier wrack. A Leak Stereo 20 in these days was 85 £ just in comparison. Today a good stereo pair of TL12.1 is a rare find mostly coming from collectors or dealers which want already 7500 € and more, a single unit might be found for 2500 to 3000 €?
A well restored pair of such amps might give a whole lifetime audible satisfaction and musical performance, so such amounts are still paid by really interested people, who know about alternatives available for such rates. But the high boost of prices came with the early 2000 years, when Honkong based Chinese audio collectors did try to get any offered single Leak amp at Ebay for any price. Some of them are proud to show a whole line of these amps as some sort of new living standard...


Hongkong based line up of restored Leak TL12.1, you will never see a amount like this in real life...

A friend of mine in Sweden has got his pair decades ago, but he never used them or did restore them for everyday use. So now I will take the chance and try to do a experiment and guide him here online through a restoration of his pair as a remote project, so that everybody of yours interested to follow can participate.


This pair will be restored through the next articles in parallel as some sort of a remote experiment?!
The left one is missing its ac plug, no problem to become.


A list of the most necessary parts:


A real problem will be solid hardware defects like broken windings of transformers and chokes, missing parts of the amplifier, like the component board, shields or outer case parts. Original replacements are impossible to find, it needs another amplifier for spending its parts in transplantation. If you know a winding company, it might be possible to rewind the original iron cores (if you need further informations about winding details visit here). The company Sowter offers replacement transformers which are sold as technical copy of the original, but look and feel very different. Bulgin plugs can be found at Ebay-UK. Good Luck!

Exceptional rare tube shields for the input tubes, difficult to find two-pin Bulgin socket for the speaker terminal, the common three pin AC-socket and dedicated plug, both latter are still available as new parts.




First steps


1. First all electrolytic capacitors need exchange, after 60 years of use/storage they are dry out and need replacement. Within these amps they are only used as cathode bypass of the input and power tubes:
C1 = 30mF/32V
C7, 8= 25mF/100V
Several new capacitor topologies and materials (Black Gate, Bamboo fiber, etc. ask your audio boutique dealer) have been established in the audio market resulting in very different sound structures. A classic, cheap and authentic decision would be electrolytic bipolar tone capacitors for crossovers with smooth anode.

2. All coupling caps are oil impregnated paper types. These last a lot longer than any electrolytic designs, but after 60 years it might be time to reset as well here:
A wide range of types is available from NOS suppliers or new brands. Standard is the use of aluminum foil, Jensen and Audio Note are able to supply additionally copper and silver foils with oil impregnated paper. Modern substitute are polypropylene foil types as advanced isolation material for the one who likes their typical sound. Sound wise, smooth and cheap and a good all round decision are the Russian PIO types:

C2, 3, 4, 5 and 6 are originally stated to be 0.25mF/500V, even if the highest voltage at any of them will not be higher than 300 volts.



A range of usable capacitors for the restoration, on top:
Russian 4mF/600V PIO caps for the PSU filter stage;
from left: Russian 0.25mF/1000V PIO with glass sealed wires; two vintage silver mica types;
there different actual Jensen PIO coupling caps

3. In the power supply line the Leak does incorporate as well oil impregnated paper types, which were in these days extremely expensive (and bulky). These are hidden in the black cover left of the output transformer. They are welded as 4 pieces of 4mF/600V in that case. For transistor aficionados the unbelievable low values of 4mF as charging type and as well 8 mF plus 4 mF as filter capacitor rail is set here. The push-pull topology make such low values possible, but the efficiency of such design depends on perfectly matched power tubes for hum free performance.
These capacitors normally last a lifetime, but I have seen several amps with typical oil leaks. Here a replacement has got necessary. It is almost impossible to find matching types and sizes in such amounts (8 pieces for a pair of amps) from NOS stock. The originals are welded into that can, it is a lot of work to dismantle these to keep the metal boxes for some modern replacement capacitors. Several users do refill them with smaller sized electrolytic types, and in a foremost manner with higher values to improve the filtering effect. The result might bring optical authenticity by the reuse of the original metal case, but will be accompanied by technical and aural detoriaton from the electrolytic capacitors.
The common electrolytic capacitor rail will come along with a lost of the incomparable smoothness in sound typical for these amplifiers. It is a must to replace them all with oil-paper types to keep their sound qualities. Another problem is the capacity of the first loading capacitor, which will be charged from the rectifier tube to its ripple limitions and might do complex damages when set to a higher values than 16mF (depending on the tube type) and a short life time period will result together with noticeable sound deformation. I hope to present here soon a perfect replacement solution for Leak TL12.1 users within the next entries...

C10, 11 (two of them in parallel), 13  are each 4mF/600V. These need to that high!! Big cans, look at the image!

The small values C9, 14 are welcome to be replaced as well with highly selected and measured paper oil types for the shown values and perfect soundstage, but silver mica types (original) are another option to keep the tolerances in a low range.

4. All resistors are carbon composition types of high wattage (1 to 3 watts), the so called british bone types have been used. It will be almost impossible to find NOS replacements of that brand. But several other brands are available from different countries like US, Europeen countries or Japan to match here. To my understanding it needs to be carbon composition types of high wattage to prevent hiss and show up with exceptional tonal delicacy.

Look into the schematic for all built values.
The two KT66 cathode types R16, 17 of 600 ohms should be 5 to 10 watts wire wound.

5. Tubes should be NOS types, British brands. Otherwise with modern Chinese or Russian replacements the amplifiers will perform with some sort of withdrawn performance of its original sound abilities. Yes they MO/GEC KT66 are expensive! But to come back to the beginning of this article, a (one) NOS WE 300B tube with engraved base will cost the double amount of two complete sets for stereo use of NOS British tubes for two Leak TL12.1's.


Read on soon,
Volker

Thursday, 7 May 2015

Vintage Treasuries – The Restoration of Leak Valve Amplifiers, TL10.1

Hello to everybody,

today I want to start with a long planned series about vintage valve power amplifiers and their restoration for everyday use. I want to give some advanced help for enthusiasts following here to preserve some rare and incomparable products representing audio history with tremendous skills to perform music in many respects a lot better than later made products. Cost cutting issues were within audio products likely the same than in any other industrialized mass production the decisive argument killing any individual contribution towards quality.
I will start with one of the most famous european brands from the golden age of tube amplification, the H. J. LEAK & CO. LTD.. I want to introduce a bit history of this manufacturer and try to show the adequately organized preservation of early examples with well selected parts and components. Aim hereby will be the historical correct interpretation of the final result in perfect balance with the best possible audible ability in mind. Almost all Leak power amplifiers are excellent audio performers independent of any later built technology (transistor>integrated>classD). They don't shy any comparison with more modern examples of their bread, their exceptional realized superiority has made them to icon of the audio age. So a careful knowledge based restoration make them to be a lifetime investment with exceptional natural capabilties and as lively sounding instruments too, when properly implanted with efficient and expressive transducers.


Leak TL10 "point one", with their typical straight golden appearance with black transformer covers.
I will start the series of entries with a quite common example of the early 1950's Leak models, their last called "point one" amplifier, the TL10 point one. When Harold Joseph Leak started his business in 1934, he first manufactured several amplifiers as contractor for the cinema and recording industry (like Geaumont Kalee and General Electric Co. ). He introduced his first amplifier series, the early triple loop Type 15 four stage KT66 amp in 1945. In 1948 Leak released his most famous model the TL12.1 with 12 watts triode push-pull power and its bigger brother the TL25. The TL12.1 was the first model named "point one", because it was the first amplifier in history with such a low distortion figure as  0.1 percent. This codicil was proudly used for a period of time to demonstrate technical advancement against other competitors in a fast raising business. The TL12.1 was a very successful amplifier in the broadcast and recording business, since the BBC ordered a noticeable amount for their studios around the world. This success did consolidate the name Leak in the professional business as first grade supplier of amplifiers. The TL12.1 will be covered quite soon with a own multipart restoration documentation, shown here online as a work in progress.

The later TL10.1 amplifier was brought into the market to get as well access to the new home audio market, a well decreased lower cost version of the professional outrider TL12.1. These amplifiers are  in every respect a downscaled version of the former heavily oversized designs. Today the TL10.1 models are highly underrated, seen from the today pricing results of auctions. These are from time to time still available in pairs for quite low costs, comparing their built value of quality. Their predecessors are hardly found anymore for sale anymore as single, have almost completely disappeared as later coupled pairs. Their production counts never have been high, in monophonic times less than 2000 pieces, where the TL10.1 has been sold in a lot bigger amounts, even still as monophonic units.

Their later successors from the mid to late 1950ties, the monophonic TL12+, TL25+, TL50+ and their stereo counterparts made after 1958, the ST20, ST50 and ST60 have been produced in tremendous quantities (each model 10.000 to 100.000 expl.) due to their well establishment in the audio market (Leak did make on special request for the BBC special versions of the TL25+ as back up units or as replacement for the TL12.1 in the late 1950ties). All these late types as to been from today represent a wide spread treasury of the best times of audio products made in Britain, the only country in Europe with a similar prosperity and a common targeted market like the US in the 1950 years for home audio products.
Any of these amplifiers is still today a good valve amplifier to show the exceptional audible inherent qualitiy of solid manufacture standards, contrary to the modern built samples of the "tube amplifier revival since 1980". Any of this models is with a little bit care able to fill even highest expectations and in a well suiting surrounding, able to show the foremost qualities of tube amplification in general. So all Leak tube amp models have been collected since their disappearance in the early 1960 years. Their typical gentle style with various luxurious metallic golden paints and their perfect technical realization within open cased designs, have made them together with a whole lot of other British brands, to some sort of incarnation of "the valve amplifier" (AEI, Soundsales, Pye, GEC, Armstrong, etc.). All of them have been dedicated to reach the same luxury consumer at home and as well abroad. Major US brands like Marantz, HH Scott, Heathkit, Fisher, Eico and others shared the same strategy with golden paints, only a view tried different concepts and designs. In the foremost stage here again a Europeen company, Peter Walkers Quad is an exceptional example of a individualized design culture with a typical modernist understanding of formally reduced appearance. Some other US manufactures did try the strategy towards the chromed jukebox appearance to match the taste of a younger generation, like Macintosh or Radio Craftsmen.


Close view of the valve line up and between output and mains transformer a Siemens MKP oil cap for the PSU filtering adapted with golden paint.

A must for this amplifier: british NOS KT 61 valves 


A restauration project always starts with a first check of the capacitor conditions, typically electrolytic capacitors have been dried out after several years of use or even in storage. A long term use might have shifted the resistor values within permanent physical warming, tubes might have run out of order or might show other types of failure (like "gassing", loose parts or broken sockets). For such a first check all valves should be plugged off and the secondary readings of the power transformer might give a first check. If these are in a expected tolerance (without load the figures are higher), the rectifier tube should be plugged back into place. But now, even without load the PSU capacitors are seeing high voltages, so it will be helpful to use a rheostat variable transformer, which gives the opportunity slowly to increase the incoming voltage. Starting with 60 volts for a while, it can be set higher in 20 volt steps every 10 minutes till the final voltage has been archived without failure. Now the other valves can be plugged in with a first test to read the voltages at certain points of the design. First it needs high power resistors of 10 watts dissipation in values between 8 to 16 ohms to give the amp a dedicated load at the exit terminals. Tube amplifiers need a load and should not be used without a speaker or such a dummy load connected.
A first voltage reading should be made behind the last PSU filter cap, than all anode voltages beginning with the first driver stage, second the phase shift stage and finally both push-pull power stages. In the same order all cathode voltages should be checked as second test, as third test ac leakage of all coupling caps might be checked with a multi meter at all secondary terminals of all coupling caps. If all readings are in a acceptable tolerance for a 60 year old amplifier (20%) it might be checked now with a real signal and with loudspeakers connected (check to use the right speaker impedance terminals or the right setting at the output transformer with later Leak models). Hum and hiss are common signs that parts have got out of tolerance and do degrade the performance or may be  falling completely. Normally burned resistors, leaking capacitors can be detected visually by deformations, burning scuffs or wet surfaces surround capacitors. I always would recommend after sixty years of service a complete exchange of all resistors and liquid conducted capacitors.

The TL10.1 needs to be used with the original KT61 valves for best performance, all 6L6 types or similar types like EL33 even with dedicated changes at working points do not match the sonic excellence of the early and rarely used tube due to their higher internal impedance ratio and this matching output transformer.



Rarely seen in real, perfectly matching paints of two originally monophonic amplifiers. Normally they differ a lot since the production fluctuations were high.



Parts

For resistors the classic carbon composition types from different brands are available from different sources are the agent of choice for such classic amplifier. They sound generally better (i.e. more musical) than cheap metal types and are historically seen the right decision. Here the higher power resistance of 2 watt is to be preferred, since these don't show the typical hiss, known from low power types.



Silver mica caps in the feedback line, oil paper coupling caps, 2 watt cc-resistors from Beyschlag and bipolar cathode capacitors from F&T beside Rosenthal resistors for the cathodes.

Coupling caps are widely available now at almost any price and origin. Here plastic foil types are in competition with oil paper insulated types. Generally I do like "pio" or "mp" better than more expensive plastic foiled types. With "oil-paper" you have as well a wide choice to be selected. You might get hand rolled types. made "under new moon" conditions from of long term stored copper foil, or you might find several so called audio caps made from exotic materials like bamboo fibers in your audio boutique available from different brands and with "definitive different sound attitudes",  or you simply go for former Russian military graded pio caps –  nor of them will make you a different amp...


MP capacitors for the smooth filtering of the anode supply are the aim, even if they are a lot big


I was always a believer of long term usability, so I always preferred Metal-Paper-Capacitors (MP) over unreliable electrolythic types as well in the the power supply stage. But the oil-paper types are always bulky and hard to find, in particular if you want to restore a amplifier to look like the original. So it makes the process difficult, to find space underneath to install some extra caps to get it made without compromise. Her in my example the big golden painted type on top of the chassis is such a compromizing type. It is a Siemens 8mF type which resembles the original black container in-between the two transformers, containing three electrolytic types which are after 60+ years leaking anyway. There is no way to get MP-types in that small box with similar values, so I decided to change it and mounted another two caps underneath. The boxes are still in storage for physical completeness of both amps in theory.
The only position in such a power amplifier where I hardly accept electrolytic types is at the cathode of a valve. Here I did use bipolar tone frequency capacitors as to be used in crossover networks with smooth anodes, in these days one of the only opportunities at such delicate position. In the meanwhile several special audio products have established like the Black Gate types and several other brands which show up with a improved abilities, so it depends a lot at the taste of the owner which capacitor here might be used.
Leak amplifiers normally do use silver mica capacitors in the feedback line to match closest tolerances. These are very good and do normally not fail, so they can be reused or if they need to be exchanged, styroflex types are the value if no other mica type is available.


I did restore my pair around 1990, a time when it was already difficult to find the right spare parts for such a project. Carbon composition resistors, oil paper capacitors and nos tube stock had already disappeared within the traditional electronic supplies in 1990. So it needed good researched informations to find New Old Stock parts or even specialized side business products, like Danish Jensen Capacitors or the British Billington Valves.  For example a 2 watt type Beyschlag carbon composition resistors was still in sale back these days, but it needed a minimum order of 10 for each value costing some 30 DM each. For a typical Leak amplifier some 20+ values were necessary, which ended in a 600 DM region just for the resistors. Another 200 DM for the Jensens pio caps (each around 30 DM), some switches, cables, tubes (even than a set NOS KT61/EF86/6SN7/GZ32 was 250 £) together with new contacts and switches it did lead roughly up to 1500 DM base cost for such a restoration. If you take the basic costs of a pair of TL10.1 in GB in account, in these days 450 £, a equivalent of 1400 DM, the cost did add to 3000 DM, which is almost 1500 EUR. This amount will hardly cash back for such a good pair in this restored condition. So it is another example of  typical hobbyist projects, where costs are no option. Today though the easy access to NOS spare parts via internet such a project has got a lot cheaper. As well you can find the original resistors and caps to make it perfect, or alternatively with some former Russian NOS parts you have just to pay the shipping costs...




In order to improve the sound the TL10.1 a smoothing choke (10H/100mA) resembling the original 1K filter resistor is a must. Oil caps for improved smooth filtering in the power supply have been installed for completeness.


Schematic drawing of the Leak TL10.1 together with dedicated "point one"-preamplifier module, supplied from
the power amplifier through the dedicated octal socket.


Read on soon about the famous TL12.1 amplifiers, Volker



Friday, 3 April 2015

Refinements of a Certain Stage  –  Low Frequency Decoupling Dampers

A german text version follows the end of the english text.


JBL 075 tweeter, modified with LignoLab bronze horn, decoupled from the low frequency enclosure underneath with special version LignoLab Niederfrequenzdämpfer DQ148 with support element.

Hello to everybody,

with this post I would like to introduce a new category "with rhyme or reason" into my blog. Here I will report about audio products in irregular sequence, which are made with intelligence, innovation and sense in mind. Such products are getting rare in a world made on top of a chinese workbench.


Today I would like to deal with a tiresome subject that is adequately known to every lover of high-quality audio reproduction – the influence of resonances to decrease the aural abilities within audio components. Too well such influences are treated with "sacred stones", decoupled cable beds foremost finished with massive CNC lathe machined anodised surfaces to be representative relicts in stores for "audio make worse trades", just to be lush money transformers. With profit margins reminiscent of dental technology, consumer products are thereby brought closer to guarantee always one thing: to mark a tremendous listenable difference as selling argument. All these products will have listenable effects, but will not substantially resolve the basic problem of decoupling down to the lowest oscillation frequencies below 10 hz, they just shift the resonances into another register of influence. All depends on the physical operational depth, its effect of insertion will have different effects with speakers in wooden enclosures electronic components or, at the most delicate place, within the pick up process of a analogue record player tonearm. This means the potpourrie of commercial offers is rich, sometimes reduced to simple home made recipes, voodoo and manly fashionable products from a audio boutique, but rarely based on solid physical principles, solutions and applications to master the problem. Naturally, the influence of such resonances in the analogous components of an audio chain is here greatest. Especially when evaluating a record player, where comparatively microphysical factors can produce enormous changes naturally the problem is fatal.

It was not until relatively late in the history of the analog palpation process realized that resonances in turntables have a large influence in this sort of sensitive application. Different it can not be explained why in particular the first division of brands for studio equipment turntables, namely EMT, Garrard, Thorens and Platine Clemént, but as well numerous refrigerator sized units from overseas with arm thick sized driving shafts, driven by bucket sized motor drives, have been mounted completely solid coupled to their studio consoles (the only exception proving the rule was the swing frame for the EMT 930, which was made to decouple the entire unit with a simple spring suspension frame, at least a first attempt in 1956). It started to be issue in 1959 with the first sub chassis player made by Acoustic Research, followed by Era 1962, Thorens in 1965 and later the well-known British players like the subscription project Sondek LP12 from the 1970s, managed to raise awareness of this problem.
These were and yet are still far away from a sustainable solution of the general problem. In order to visualize it in more detail, one must understand the physical preferences with delicate low (arm- / pick up-) mass of less than 50-100g and cantilever compliances from 5 to 25x10-6cm dyn. so that the oscillation frequency is below 10 Hz, better below 3 Hz. This value must be achieved so that the resonant frequency does not adversely affect the sensitive pick up process. This fact shows why a classic light weight sub chassis player of the above named types has a much higher resonance frequency due to the lack of damping properties for the spring suspension, resonances can be much easier develop from the input, decaying lack of mass and weight. This explains also equally sound wise their typical lack of colorrange and expression in the low frequeny response, even if they are well enabled to present all fine resolution within the middle and high frequency range as a benefit of their spring decoupling sub chassis designs.



Cuisine Française

Jean Constant Verdier, who died last autumn, was the unique design engineer of the turntable simply called  "Platine Verdier", which has written history in the past forty years in this regard and solved the topic of this article as much as possible.
Last but not least J.C. Verdiers early work with the company Era has led to a thorough analysis of the advantages and disadvantages of these light weight sub chassis constructions and have thus largely determined the structure and design of his unique first mass player to solve the problem. 
In the context of the French Maison de la L'Audiophile some developers have been in research between 1978 and 1988 about the conditions of the pick up process and around the player technology in general (P. Lurne). They tried extended analysis works with several main topic interests, since the turntable was still the foremost signal source for the audiophile in these years.
J.C. Verdier realized already in his first draft of his legendary turntable Platine Verdier (L'Audiophile, No 13, December 1979), the necessity not only of a precisely measured spring suspension, but also their pneumatic motion damping, so that this feet were damped down for maximum benefit to an oscillation frequency of 1-2 Hz. 
One would think the air damped suspension is a French specialty, because it was a similar pattern for the suspension of a French car maker Citroen (in the 1950s the Citroen 15CV was equipped with pneumatic damped suspension first time at one axis). Here with the Platine Verdier feet too, the combination of a loaded spring damped by a controlled air chamber for decoupling from typical vibrations was the innovation. In many other technical designs hence the more stronger made gas damper with higher frequency damping is used. In some vehicles even a simple torsion or leaf spring system were installed without any damping effect. The comparison may imagine a beautiful picture, where vehicles without damped suspension systems are just bumping over the road ... ?!


Drawing showing the first air damped spring suspended feet design from J.C. Verdier published
in L'Audiophile No. 13, Dec.1979



Together with the unique magnetic bearing design and the mass of 47 Kg for the complete turntable a incomparable "unit to play vinyl records" was invented by Verdier, at least in drawn theory published within three issued articles of the french audio magazine. Its realization is another completely different posting within this blog to follow later on some time. 
As we know today the Platine Verdier is a unique turntable, which did combine unmatched properties to a higher degree of interaction and led finally to a exceptional package of aural properties, which are even by todays standards almost 35 years after its first appearance, are still a milestone to pass. The Platine Verdier is the turntable that is still setting the pace for the today generation of all heavy mass players, oil rig inspired designs and ocean liner dashboard players (namely the ability of keeping the dynamic and musical content in a authentic flow of natural expression), combined to a higher degree with the typical known benefits from the best light weight sub chassis players (namely the finest resolution of micro dynamic harmonies), both welded together with an incomparable tranquility and homogeneity (by the magnetic bearing) in the finalized expression. No less and no more, and studied to date his master.
Unfortunately, this incomparable record players wide recognition success was denied in limited Iinternational scale, due to its heavy and bulky transport weight. In general, at overseas locations far outside central Europe, especially in Korea and Japan within the "audio gourmands" of the first hour, have been remained largely unknown about this design. Well, one can't have always the best...


Three different models are already designed to match almost any realistic mass in audio systems,
from left: Niederfrequenzdämpfer D172, D136 and SQ148, dedicated support element back in the middle.


At this point of the article I would like to focus on to Norbert Gütte, who was a long-time companion of Keith Aschenbrenner at Auditorium 23 from the start, not only as a carpenter of wide developed solutions for their speaker cabinets final realizations, but even as a "l'audiophile confessor". He has devoted all kinds of problems both supportive, as well with the adverse effects of resonances in the audio field extensively. Numerous speakers became addressed to the properties of musical instruments for taking advantage of harmonic skills from wood to be used with speaker enclosures. But also with reversed terms of the full scale avoiding the inherent resonant effects speakers have been designed and realized by Norbert Gütte, like the known component support rack called "Die Bank". This aim was achieved with subtle and complex unconventional material and joining technologies, still aimed to support the positive harmonious qualities in its stored audio components. So it is not surprising that Gütte began to examine the properties of Verdiers damped pneumatic spring principle at the turntable feet, since the Verdier turntable was distributed by Auditorium 23 from its beginning. The component rack "Die Bank" is typically a heavy mass unit, built with complex structures and joints, expanded in 2001 and equipped with Güttes first designed suspension damping feet series D172 for perfect decoupling of the total weight with more than 200 kg. The suspension of the rack can be adjusted to different weight support in order to match the important lowest resonance of 3 hz oscillation frequency. On top almost any record player can be positioned with all benefits known from this suspension/damping principle, additionally all other stored components like cd-players, amplifiers or recorders can profit from such a integrated completeness of decoupling.




The equipment rack Die Bank (100 kg) shown with centered three-feet damping system and security feet at the edges, the LignoLab preferred most efficient system. As well available with four D172 dampers in traditional edged position

Sectional cut through the side wall and carrying tray of Die Bank, shown with one D172 damper edge mounted in order to show the complex inner structure and the tonal best compound wood material for audio furniture, northern coniferous plywood.
Anybody who was not lucky enough to obtain a out sourced decoupling table from a physical research institute at a yard sale will get with "Die Bank" an sound key product for his high-quality audio components with incomparable attitudes to any other component decoupling system known. This is to be assumed in effective depth at least equal value of a exceptional audio component, – and it tops it with length for a fraction of costs. Here not only a extremely prone turntable can benefit, but this furniture also offers enough space much for the rest of the chain, such as pre- and power amps to be decoupled in one unit. The low frequency damper D178 can be equipped with different strong springs and can expand with further two or three dampers to a resonance system interconnected to the weights between 100 kg and 250 kg, decoupled precisely down 3 hz with different sized springs. Such a rack is a lifetime investment, which electronic components can do so?
As a logical consequence resulted from these dampers the complex built turntable bench TT100 (100 kg) is designed, since such a high mass optimizes the physical effect of a air damped spring suspended system. This table enables analog devices, so-called mass turntables perfectly to get into non resonant stage. Thus, these units can now get one of the unique features of the original Platine Verdier, namely their air damped suspension system, which is to my knowledge and experience may be even more important than the magnet bearing, been decisive for the remarkable sound quality of the Platine Verdier. Norbert Güttes TT100 can be impressively seen in action in a little Youtube video. Totally amazing, the entire unit can be irritated to several centimeters in vibration, without any sort of affection to the pick up process.

But amazement alone can not be a selling point, certainly when so little representation factor is associated with a product and since the feet purely functional appearance, then already sufficiently convincing properties have to play the role of desire. It can not be completely described with words, how a analog turntable can profit sound wise from such circumferentially decoupling. Very few have probably a assessed idea of ​​the actual aural signification to the skills of a high-end mass player. But if you follow the theoretical idea of a complete resonance elimination and to its sense of a system with low frequency isolation introduced and alternatively not in comparison the most will be more than surprised by the result and the depth of the effect. With a profoundness that goes far beyond completely different tone arm / pick up- / step up transformer sets, such a player wins exorbitant fine dynamic resolution, dynamic capabilities and allows the natural flow of music to follow a lot more with natural ease. Immediately one no longer recognizes his player back and actually begins now extensively to learn just as you have probably never heard it before. Norbert Gütte has varied the use of the D172 damper within a quartet or within an equilateral triangle as a triplet underneath "Die Bank" and with his newer turntable-bench TT100. Actually this first damper model is extended with two more smaller damper variants for lighter weighted components. The D136 can also be used in different versions with different inserted springs to match a range of three weights between 14 kg to 60 kg and is suitable to be mounted directly underneath a turntable, with built in weight adjustment and balancing option.

Laufwerktisch TT100 with Platine Verdier on top


Norbert Gütte takes the trouble to precisely tare the actually searched weight to adjust the usable range with the help of sample structures from brick stones to ensure a one hundred percent effective product. Thiese dampers can be placed directly under a component and are therefore also suitable for direct isolation of todays typical massive weight turntables. In addition, for lighter designs with plinth like the Thorens TD124, Garrard 301 u. 401, as well all other representatives of the typical idler wheel section, there is the low-frequency damper DQ148 of being able to balance weights between 4 to 25 kg. This damper type was originally designed for the decoupling of tweeters and midrange drivers in critical resonance mounting positions of loudspeaker enclosures, in order to protect these from the influence from heavy low frequency resonance insertion. Originally made for the JBL ring radiator 075 or 2402 may be provided with his own bronze horn, but these dampers can also decouple heavier drivers to the influence of powerful bass drivers in the same physical enclosure set for perfectly resonant freeness. I was not able to test this dedication within my own set up, but I know about such delicate decoupling issues from my own enclosures very well.

The only final word can be, that the decoupling effect and its profound values of refinement are second to none. Once installed nobody will reject such a system after personal evaluation, I swear. The remarkable profit in resolution and dynamic abilties is exceptional and exceeds the known dimension of change between two world class components in a given system by far, even not being cheap such a system can be counted as long term investment at the lower cost side of  the audio world. If you're wondering whether you really will need such a system, please answer the question: Whether you can do without a spring damper system in your car?The LignoLab dampers are the only universal available solution with such technical and audible efficiency and profit worldwide. Additionally all products from Norbert Gütte are produced in small series as pure manufacturing pieces, but deny any manual ductus of the emergence in absolute perfection in its execution, workmanship and finish. As to be typical for any LignoLab product.

For further informations about the LignolLab products you will find at the end of the German text all necessary addresses and links.


Evaluation to match perfectly the given weight of a customer with
3 hz oscillation frequency (here 46 kg).





German Version:


Heute möchte ich mich mit einem leidigen Thema beschäftigen, das jeder Liebhaber hochwertiger Audiowiedergabe hinlänglich kennt, dem Einfluss von Resonanzen in Audiokomponenten und deren wirksamer Isolation. Nur zu gut wird seit Jahr und Tag im repräsentativen Reliquienhandel für Audioverschlimmbesserungsprodukte der Einfluss geweihter Steine, gebetteter Kabel und dies alles vor allem mit massiver CNC-Dreh- und Eloxaloberflächentechnik optisch wirksam geltend gemacht bzw. zu sattem Geld transformiert. Mit Gewinnspannen die an zahnmedizinische Technik erinnern, werden dem Verbraucher dabei Produkte näher gebracht, die eines auf jeden Fall fast immer garantieren, nämlich einen gewaltigen klanglichen Einfluss zu markieren. Häufig werden dazu dehnfähige Polymere, in einfacher oder komplexer Verbundtechnik als Allheilmittel mit wirkfördernder Namensgebung eingesetzt.
Inhärente Resonanzen in ihren unterschiedlichsten Ausprägungen beeinflussen den Klang von Audiokomponenten in gravierender Weise, sie können diesen sogar umfänglich verändern. Jedoch selten gelingt es mit solcherart Boutique-Produkten, den Hebel an die Ursache oder Wirkungsweise und -tiefe anzulegen und die gezielte Beseitigung des Problems zu bewerkstelligen. Häufig verändern diese Produkte die resonanten Eigenschaften oder verschieben die sie in ein anderes Register, in den wenigsten Fällen werden sie minimiert oder gar beseitigt. Dabei ist das Potpourri mehr als reichhaltig, nicht nur einfache Hausrezepte, Voodoo und zahlreiche Mode-Produkte aus der Audioboutique werden eingesetzt, sondern auch auf physikalische Grundlagen beruhende solide Anwendungen und Lösungen versuchen den Problemen Herr zu werden. Naturgemäss ist der Einfluss solcher Resonanzen gerade bei sensiblen analogen Wandlern wie Plattenspieler oder Lautsprecher einer Audiokette sehr deutlich erfahrbar. Beim Abtastvorgang eines Tonabnehmers, wo vergleichsweise mikrophysikalische Einflussgrößen ungeheuere Veränderungen durch die darauf folgende riesige Verstärkung von fast 100 dB erzeugen können, ist naturgemäss das Problemfeld der Resonanzanregung besonders fatal.

Norbert Gütte uses his Niederfrequenzdämpfer within his Sato-Horn installations, in order to
decouple the sensitive wide range horn from the sand filled Double-Onken-type cabinet.

Erst relativ spät in der Geschichte der analogen Tonabtastung hatte man erkannt, dass Resonanzen in Abspielgeräten einen großen Einfluss an dieser sensiblen Stelle nehmen. Anders lässt sich eigentlich nicht erklären, warum insbesondere die Erstligisten der Studioausstattung, nämlich EMT, Garrard, Thorens, Platine Clement und zahlreiche kühlschrankgrosse Studioprodukte aus Übersee (wie Fairchild, RCA und Gates mit armdicken Antriebswellen und eimergrossen Motoren) noch in den sechziger Jahren ihre Tonarme massiv mit den Antriebskonstruktionen verschraubten. Selbst im Verbund als Einbaugerät für Studiokonsolen wurden die Laufwerke weitestgehend steif angekoppelt. Eine effektive Entkopplung fand bestensfalls mit gefederten Einbautrahmen für die Gesamtkonstruktion nur unzureichend statt (Der Schwingrahmen des EMT 930 sollte das gesamte Laufwerk mit eine Federaufhängung entkoppeln, zumindest ein erster Versuch in 1956). Erst mit den sogenannten Subchassisspielern für den Heimaudiomarkt der ersten Generationen wie Acoustic Research 1959, Era 1962, Thorens 1965 und später die bekannten britischen Abonnementkonzepte wie der Sondek LP12 (wird seit Erscheinen in den 1970er Jahren fortwährend mit den gefühlt 56sten Upgrade verbessert), schafften ein Bewusstsein für dieses komplexe Problemfeld. Sie waren und sind aber von einer nachhaltigen Lösung immer noch weit entfernt. Um sich das Problem etwas genauer zu vergegenwärtigen, ist zu verstehen, dass der Einfluss beim sensiblen Abtastvorgang mit relativ geringen (Arm-/Abtaster-)Massen von weniger als 50-100g und Nadelnachgiebigkeiten von 5 bis 25x10-6cm dyn. gravierend ist. Dementsprechend ebenso plausibel, daß die Schwingfrequenz unter 10 Hz, besser unter 3 Hz zu liegen hat. Dieser niedrige Wert muss erreicht werden damit die Anregung sich nicht nachteilig auf den Abtastvorgang auswirkt. Ein klassischer Subchassisspieler der genannten Typen liegt aufgrund mangelnder Bedämpfung des Ein- und Ausschwingvorgangs, aber auch mangelnder Masse sehr viel höher und damit noch sehr deutlich im Hörspektrum. Dies erklärt auch gleichermassen derer Mangel an durchgezeichneter Farbigkeit und komplexer Ausdrucksfähigkeit in der Wiedergabe des Grundtonbereichs, obschon sie allesamt in den mittleren und höheren Frequenzen die Vorzüge einer solchen Entkopplung vorteilhaft zu präsentieren wissen. In diesen Frequenzbereichen funktionieren die weitestgehend ungedämpften Entkopplungsmethoden nachhaltig gut.
Viele vermuten bei Entkoppelungsmaßnahmen vor allen Dingen positive Effekte bei der Trittschallentkopplung von Plattenspielern, diese wird zwar auch wirkungsvoll mit diesen hier vorgestellten Dämpfern erreicht, jedoch geht es in diesem Artikel um weit umfänglichere Einflüsse, vor allem sollen die weitaus weniger wahrnehmbaren geräteinternen Resonanzanregungen beleuchtet werden, die durch feinste mechanische Schwingungskopplungen entstehen und sich unkontrolliert ausbreiten.


Cuisine Française

Jean Constant Verdier, der im vergangenen Herbst verstorbene Konstrukteur einzigartiger Laufwerke, schlicht „Platine Verdier“ genannt, haben in den zurückliegenden vierzig Jahren Geschichte in dieser Hinsicht geschrieben und hatten das angesprochene Problem bereits damals weitestgehend gelöst. 
Nicht zuletzt seine Tätigkeit bei der Firma Era hat Verdier genaue Erkenntnisse über Vor- und Nachteile der leichten Subchassiskosntruktionen verliehen und diese Erkenntnisse haben somit massgeblich die Konstruktion seines legendären ersten Masselaufwerks zur Lösung vorbestimmt. 
Im Umfeld vom französischen Maison de la L’Audiophile waren in den Jahren 1978 bis 1988 einige Entwickler mit Fragestellungen um die damals wichtigste Signalquelle Plattenspieler befasst (P. Lurne) und bemühten sich mit erheblichem Aufwand, Versuchen und physikalischen Messungen den ungelösten Problemen der Schallplattenabtastung beizukommen.
Verdier gebührt deshalb auch die Ehre, das Prinzip der aufwendig bedämpften Federwirkung, hier pneumatisch realisiert, für Plattenspieler eingeführt zu haben. Man sollte meinen die pneumatische Dämpfung ist eine französische Spezialität, denn sie wurde auch ähnlich funktionierend für die Federung eines französischen Automobils entwickelt (die erste hydropneumatischer Federung wurde im 15CV der der 1950er Jahre von Citroen verbaut, zunächst nur auf einer Achse). Auch hier bewirkt die Kombination von belasteter Feder und einer kontrolliert eingesetzten Luftkammer als Dämpfungseinheit den erwünschten Grad der Entkopplung von tiefstfrequenten Schwingungen. In vielen anderen technischen Bauformen wird deshalb der einfacher zu verbauende und härtere Gas-/Öldruckdämpfer mit höherfrequenter Dämpfung eingesetzt. In manch einfachen Fahrzeugen sind oder sogar noch Torsions- oder Blattfedersysteme ohne Dämpfung verbaut. Der Vergleich mag eine schönes Bild entwickeln, Fahrzeuge ohne bedämpfte Federsysteme springen über die Strasse…?!

Niedrigfreqeunzdämpfer D172 set as used with Laufwerktisch TT100 and Die Bank for perfect central alignement of masses


Verdier realisierte bereits bei seinem ersten Entwurf zu seiner Platine Verdier (L’Audiophile, No13. Dezember 1979) deshalb nicht nur eine präzise bemessene Federung sondern auch deren pneumatische Bewegungsdämpfung, so dass diese Einheit nach eigenen Aussagen bis hinab zu einer Schwingungsfrequenz von 1-2 Hz optimal wirken konnte. Zusammen mit der Magnetlagerkonstruktion und der Masse von 47 Kg war ein bis heute unvergleichliches Laufwerk zum „Abspielen von Schallplatten" zumindest theoretisch erfunden worden, dass es dann zu einer Realisierung kam ist eine weitere ganz andere Geschichte, die ich an dieser Stelle sicherlich auch noch vorstellen werde. Wie man eben inzwischen umfänglich erkannt hat, ist erst durch diese Kombination ein Zusammenspiel möglich geworden, welches unerreichte Eigenschaften in sich vereint. Die Platine Verdier ist das Laufwerk, welches die Eigenschaften sämtlicher Masselaufwerke (nämlich die Fähigkeit auch dynamische Musikpassagen mit authentischer Kraft, Ausdruck und Farbigkeit wiederzugeben im Stande ist) mit den typischen Eigenschaften der besten subchassisentkopplten Laufwerke kombiniert (nämlich mit feinster Auflösung mikrodynamischer Harmonien) und beides zusammen mit einer unvergleichlichen Ruhe und einem Fluss (Magnetlager) in der Musikdarstellung verbindet. Nicht weniger aber auch nicht mehr, und das sucht bis heute seinen Meister. Leider ist diesem unvergleichlichen Laufwerk der ganz grosse Anerkennungserfolg im internationalen Masstab aufgrund seines mächtigen Transportgewichts versagt geblieben. In Übersee generell, vor allem bei koreanischen und japanischen „Audio-Gourmants“ der ersten Stunde ist dieses Laufwerk weitestgehend unbekannt geblieben. Naja, man kann ja nicht immer nur das Beste haben....


Component base realized with heavy sand filled platform and three DQ148 Niederfrequenzdämpfer in triangle order for lighter weighted turntables and amplifiers, seen from underneath.



An dieser Stelle möchte ich auf Norbert Gütte zu sprechen kommen, der als langjähriger Weggefährte von Keith Aschenbrenner im Auditorium 23 von Beginn an nicht nur als gelernter Tischler vielfältige Lösungen für Lautsprechergehäuse mitentwickelt und realisiert hat, sondern selbst als l’audiophil Bekennender sich bereits früh für allen möglichen Fragestellungen sowohl der unterstützenden, wie auch der unerwünschten Wirkungen von Resonanzen im Audiobereich ausgiebig gewidmet hat. Dabei entstanden zahlreiche Lautsprecher die die Eigenschaften von Musikinstrumenten zur Vorteilsnahme harmonischer Fähigkeiten nutzen. Aber auch mit umgekehrter Zielsetzung, nämlich zur Absorbierung unerwünschter Resonanzen wurde z.B. das Komponentenrack „Die Bank“ entwickelt. Diese erreicht mit subtil und aufwendig umgesetzter Material- und Verarbeitungstechnik ebenfalls eine Unterstützung der harmonischen positiven Eigenschaften der ihm anvertrauten Komponenten. So ist es nicht verwunderlich, dass Gütte das pneumatische bedämpfte Feder-Prinzip der Füsse Verdiers auf universellere Wirkzusammenhänge hinreichend zu untersuchen begann, war doch das Auditorium 23 von Beginn an der Vertrieb für das Verdier Laufwerk. Gütte hat das Prinzip der bedämpften Federfüße schon seit längerem weiterentwickelt. Die bewusst schwer gebaute "Bank“ wurde dann seit 2001 mit der ersten Niederfrequenzdämpfer-Serie D172 um eine perfekte tieffrequente Entkopplung erweitert. Wer nicht zufällig in den Besitz eines ausgemusterten Kopplungstisches einer physikalischen Versuchsanstalt gelangt ist, bekommt mit der „Bank“ eine unvergleichliches klangentscheidendes Produkt zur Steigerung seiner hochwertigen Audiokomponenten an die Hand, das diesen in Wirkungstiefe mindestens als gleichwertig zu bemessen ist. Hier können nicht nur die generell extrem anfälligen Laufwerke profitieren, sondern dieses Möbel bietet auch noch Platz einen Großteil der restlichen Kette unterzubringen, so können Vor- und Endverstärker gleich mit entkoppelt werden. Der Niederfrequenzdämpfer D172 kann mit verschiedenen Federn ausgerüstet werden und kann somit im Verbund mit weiteren zwei oder drei Dämpfern zu einem resonanzfreien System ausgebaut werden. Mit individuell nach Kundenwunsch bemessenen Federn können dann Gewichte zwischen 100 kg und 250 kg präzise bis hinab 3 hz entkoppelt werden. Als logische Konsequenz daraus ergab sich dann mit diesen Erfahrungen der aufwendig gebaute Laufwerkstisch TT100 (100 kg Eigengewicht zur Masseoptimierung der Dämpfung). Mit diesem Tisch können schwere Analoglaufwerke, sogenannte Masselaufwerke perfekt entkoppelt werden. Somit können auch andere Laufwerke sich eines der beiden entscheidend wichtigen Alleinstellungsmerkmale der Platine Verdier, nämlich ihre Dämpferfüsse nun nachträglich als Vorteil zu eigen machen. Norbert Gütte führt auf seiner Homepage eindrucksvoll in einem kleinen Youtube-Video die nachhaltige Funktionsweise der Einheit vor. Völlig verblüffend kann diese im laufenden Betrieb um mehrere Zentimeter in Schwingung versetzt werden, ohne das der Abtastvorgang davon im geringsten beeinträchtigt wird. 

Aber Verblüffung allein kann kein Verkaufsargument sein. Schon gar nicht wenn so wenig Repräsentationshabitus damit verbunden ist und das in einem Geschäftsbereich, der eigentlich heutzutage nichts anderes mehr als genau diesen verkauft. Dann müssen schon hinlänglich überzeugende Eigenschaften wirken und diese sind mit Worten kaum zu beschreiben. Die Wenigsten haben vermutlich eine Vorstellung davon die tatsächliche Wirktiefe der Niederfrequenzdämpfer auf die Fähigkeiten eines hochwertigen Laufwerks zu übertragen. Aber wenn man den schlüssig physikalisch abgeleiteten Erkenntnissen folgt, ist man immer noch mehr als überrascht über den realen Zugewinn. Die Tragweite ist eher mit einer möglichen Investition in eine höchstwertige Audiokomponente vergleichbar. Dabei gewinnt jedes wertige Laufwerk an feindynamischem Auflösungsvermögen, dynamischen Ausdrucksfähigkeiten und macht es möglich dem natürlichen Fluss des musikalischen Geschehens müheloser zu folgen. Man erkennt sein Laufwerk eigentlich nicht mehr wieder und beginnt damit es nun umfänglich komplett neu zu erfahren, genau so, wie man es vermutlich noch nicht zuvor gehört hat. Norbert Gütte hat inzwischen den Niederfrequezdämpfer D172, der im Quartett bei der Bank oder auch im von ihm präferierten gleichseitigen Dreieck als Triplett auch beim Laufwerkstisch TT100 eingesetzt wird, um zwei weitere kleinere Varianten nach unten erweitert. Der D136 kann auch mit geringeren Gewichten als sein größerer Bruder optimal eingesetzt werden. Er deckt in verschieden bestückten Ausführungen im Dreierset Gewichte von 14 kg bis 60 kg ab und ist somit geeignet direkt unter entsprechend schweren Laufwerken montiert zu werden. Hier kann Gütte vier Gewichtsvarianten anbieten. 
Er macht sich die Mühe das tatsächlich gesuchte Gewicht seiner Kunden mit Hilfe von Probeaufbauten exakt auszutarieren, um eine einhundertprozentige Wirkweise sicherzustellen. Zusätzlich für die noch leichter bauenden Zargenlaufwerke, wie den Thorens TD124, Gararrd 301 u. 401, sowie weitere typische Vertreter der Reibradtechnik, gibt es noch den kleinen quadratisch gebauten Niederfrequenzdämpfer DQ148, der in verschieden bestückten Versionen in der Lage ist Gewichte von 4 kg bis 25 kg zu entkoppeln. Dieser Dämpfer wurde ursprünglich entwickelt um Hoch- und Mitteltontreiber in resonanzkritischen Montagepositionen bei Lautsprechern (s. Bild am Beginn des engl. Teils) vom Einfluss der tieffrequenten Schallwandler zu schützen. Zu diesem Zweck kann man ihn mit einem veränderten Auflageaufbau ausrüsten, wie z. B. für den JBL-Ringradiator 075 oder 2402 der auch mit Norbert Güttes Bronzehorn aufgewertet werden kann. Aber auch schwerere Treiber lassen sich komplett vom Einfluss der kraftvollen Basstreiber im gleichen Gehäuseverbund perfekt resonanzfrei trennen.

Abschließend kann man zusammenfassen, die Wirktiefe einer pneumatisch bedämpften Federung ist in empfindlichen Einsatzpositionen von ungeheurer Bedeutung und ist sie einmal ausprobiert danach schnell auch unverzichtbar geworden. Das diese Dämpfer natürlich auch nachhaltig Trittschallprobleme auf schwingenden Fußböden absorbieren, ist eigentlich nach allem Gesagten selbstverständlich wie naheliegend. Wenn Sie sich jetzt fragen ob Sie ein solches System wirklich benötigen, beantworten Sie sich die Frage: Ob Sie in Ihrem Auto auf eine Federdämpfersystem verzichten könnten?

Erst recht bei analogen Laufwerken und auch bei hochfrequenten Hornlautsprechern (der Wirkungsgrad der Resonanzen und damit verbundenen Irritationen auf die feinsten übertragenen Frequenzen ist einem einem mechanischen Verstärkerprinzip wie einem Horn naturgemäss sehr hoch) ist der tatsächliche Gewinn an musikalischer Auflösungen als ein mehrfaches einer höchstwertigen Komponente jeweils anzusehen. Die Dämpfersysteme und -Möbel decken in allen Varianten fast jede denkbare Möglichkeit zur Entkopplung ab. Die LignoLab Niederfrequenzdämpfer sind das einzige universell adaptierbare Produkt ihrer Art, diese bieten eine einzigartige nachhaltige Lösung der Resonanzproblematik und dies mit absolutem Alleinstellungsmerkmal. Selbst das Original, die mit pneumatischen Dämpferfüssen ausgerüstete Platine Verdier kann bei schwinganfällgen Fußböden in Kombination mit Bank oder Laufwerkstisch durch das gesteigerte Gesamtgewicht noch einmal deutlich profitieren.
Sowohl die Bank, als auch der Laufwerkstisch und auch die Niederfrequenzdämpfer werden in Kleinserien als reine Manufakturarbeit hergestellt. In ihrer Ausführung, Verarbeitung und in ihrem Finish repräsentieren sie allesamt Güttes Auffassung hochwertigster Funktionalität verbunden mit einer konsequent von überflüssigem Habitus befreiten Ästhetik in jedem Detail. Die Dämpfersysteme und -Möbel sind wahrlich kein Sonderangebot, aber deren klanglicher Einfluss auf hochwertige Audiokomponenten ist im gleichen Maßstab derer Kosten als Sonderangebot zu werten und das auch noch mit Langzeitstabilität. So betrachtet bekommt eigentlich auch noch jeder "Geiz ist Geil"-Einwand seine unverdiente Belohnung.


Weiterführende Informationen zu den Produkten von LignoLab:

LignoLab
info (at) lignolab (dot) com
Norbert Gütte
Telefon: 02327 54 66 97
Fax: 02327 54 66 98
Mausegatt 59
44866 Bochum
Germany




Saturday, 14 March 2015

The Tannoy 15'' Enclosure for the Enthusiast Revisited – The First Birthday

Hello to everybody interested

reading further about my 15'-Tannoy enclosure loudspeaker design. A bit more than a year time has passed since the dipole based front loaded enclosure has been finished in its final form and did set place in my everyday audio setup. Today, after that time, I can say this was one of my most important steps in my whole audio life towards a refined, smooth and absolute natural audio response. Since last February these speakers have given me so far the rare present of hundreds hours of inspired musical listening pleasure, were the technical aspects of its origin did step into a background role.
In the former 30 years I have owned several different original Tannoy speakers/enclosures with almost all types of drivers with alnico magnet. All these loudspeakers are quite well known and have several fans around the world. They all show up with similar audible characteristics and attitudes. Their very conspicuous presence of articulation, illusion of space and exceptional dynamic abilities, which are common similarities independent of size and enclosure principle, have made Tannoy to a classic in audio history. They perform in a well known robust tradition where other similar vintage makes from Altec, Jensen, Stephens, University and more are gathering, but were refinement and natural aspects do not play the foremost attitude, instead their typical common habits are more or less similar cheeky frequency ends. The Tannoy typical reflex/vented port cabinet designs (like Canterbury, Lancaster, Mansfield, Cheviot, Arden, Devon and their similar designed predecessors), but as well the highly favored back loaded horn designs (like Autograph, GRF, Corner Canterbury or even both Westminsters) are good examples for more than prominent low frequency response (but unbeatable excellent all-time favorite selling arguments). The latter group extend this spectacular attitude into the region of lower mids as a result of the to short and to small opened backing horns, mixing up with a cocktail of unwanted wooden resonances as a result of large interior surfaces of the horn development.
Excuse me, these classic speakers might be able to fulfill the claims with typical attitudes of electrical amplified performed rock music, but for lovers of naturally performed and articulated music with delicate dynamic structures such designs are are of no use, unable to represent a full spectrum of micro dynamic information. For audio gourmets these classic designs need a lot of work to be a final choice.

A loudspeaker is one of the most important components in a audio set up. As the final transducer of  electrical signals into acoustical waves it has a important function. If it is unable to transform the signals without harmonic relevance and dynamic finesse, other components will not be able to catch up the loss.



My enclosures did lead my long term relationship with Tannoy Dual Concentric alnico drivers into a complete new adventure of unknown land. My listening experience with such "full range" horn installations from Linemagnetic LM22A/LM555/LM597 with TA7331 inspired the dipole woofer idea for my enclosure, as the LM22A did inspire the front loaded funnel for the medium frequencies (to be honest since the middle 1990ties I did plan to add such funnels to a typical Tannoy enclosure, but I never realized this idea before 2014). Within several articles I have honored the "best audio set ups I personally have listend to" and I am still in hope to extend this experience one day with a larger wooden horn like WE15A in a similar refined set up.

My own unique way to follow such exceptional sets uses a Tannoy Dual Concentric speaker in combination of dipole enclosure, where the purposed half is formed to act like a front loaded horn development and the backing part acts like a traditional open chamber. Such a front horn helps to overcome the most difficult fault of the large 15'' paper cone. The medium frequencies response between 500 and 1500 hz will be mechanically amplified and supported, a tonal spectrum where a cone speaker of such mass and size is physically limited in its ability of resolution finer harmonic details. In the same time the funnel does act as a extension of the cone, who itself is already a seamless extension for the high frequency driver. So the horn is enabled to conduct lower frequencies with its wider and longer opening development. Not only to my personal taste the Tannoy high frequency horn is known to be one of the best two or three horn tweeters built ever. It shows up with a exceptional rare attitude, its seems to be unlimited extended in its higher frequency performance, since it is at the same time completely acoustically invisible, as any for hf-horns typical superficially is at the same time completely absent.


Horn development as seen from the mouse, the funnel extends the cone, who itself seamless extends
the hf-horn. Additionally the funnel enables the cone to conduct a larger air mass.

The dipole principle for low frequencies was a early simple invention to obtain fast and naturally sounding low frequency response in early cinemas of the 1930 to 1950 years. Together with the open baffle principle, which is physically seen as a similar design, it was in these days preferred over any closed or ported cabinet design. These came into account when the amplifiers started to be powerful enough to drive small enclosure types to allow complex filter units for massive corrections of low frequency radiation.
The dipole shows some advantages comparing it to other designs, like the fastness of the transients, the completely uncompressed tonal expansion and the non-existence of any wooden resonances, which are typical for all cabinet priniciples. Open baffles mostly fail any acceptance in living room surroundings because of their space consumption (a square meter plus wings is a minimum to obtain some LF below 100 hz). The folded baffle into a such dipole design ends up with a quite room friendly size of typical classic speaker enclosures (here my speaker dimensions are 90 x 55 x 45 cm, HxWxD).

But the backward radiated energy makes a delicate room positioning necessary. The speaker radiates wide parts of the frequency spectrum in anti phase mode, a effect which makes a minimum distance to the backing walls necessary to avoid problems. Anything closer will result in typical phase erasure and adding effects, both can degrade the tremendous abilities of the speaker. I have positioned mine with a distance of 60cm from the backing walls. On the other hand the funnel helps to direct and disperse the forward radiated energy, which is a another welcome advantage, this helps to keep the vagabond room reflections in almost perfect control and limits further room treatment to a minimum.
If you can set up the speakers with such space, you will be rewarded is one of the most dynamic and expressive loudspeakers available, together with a rare freeness of resonances and a exceptional refinement of finest micro detailed harmonies, most other speakers of that league cannot compete with.


My speakers show up with the typical grill cloth at the back opening of the enclosures.



Detail of the backside, the former installed sliding mechanism is completely redundant. So I have removed the rails and fixed the inside enclosure, the shown felt seals are not any longer useful. The former planned blinds to adjust the backward
radiated energy are as well completely redundant.


One of the two best 15'' Dual concentric speakers of the Tannoy line: Here the reconed
Monitor Red with specially designed crossover to complete the enclosure design with front
loading. Later versions show up with higher paper cone weights and less optimal impedances
for low power tube amplifiers. No other duplex speaker design in history makes such a seamless
integration of high to low frequency with front loaded funnel possible.


I am now extremely happy about the behavior of this a phantastic speaker, a result which I didn't expect when I started to built up that concept. More than this the speakers are able to work in a highest possible stage of harmonic audio response with a almost invisible holographic dynamic soundstage other speakers of that size do not follow.
This speaker works so refined that it made possible to detect several limiting aspects in my chain, which in former times I was not able to detect and resolve.

I hope that such design will find some more interest in the coming future,
Volker