Sunday, 5 June 2022

Move the Groove

In consideration of vinyl playback it has long been my thinking that the motor is the heart of the endeavour. It is, after all, what moves the groove and it is the groove's motion against the stylus which creates sound. The nature of this motion occurs on the micron level and is then grossly magnified. A phono preamp for a low output moving coil cartridge will have around 60 decibels of gain meaning a magnification factor of 800 to get it to line level. This is then further amplified by a following line stage and amplifier. Given the very high level of magnification those 1 to 20 microns of stylus movement are under it is natural to conclude that the nature of the motion itself will be readily discernible to the naked ear.

Any cogging, vibration or lack of stability will be subject to the same X 800 magnification. Added to this is the ever changing drag of the stylus in the modulated groove degrading the stability of speed for which the motor and its controller has to compensate. The nature of this compensation is similarly under the scrutiny of X 800 magnification. I have said before it is the inductive compensation of shaded pole motors (and their ample size) found on idler drive turntables which accounts more for their sonics than the type of drive mechanism.

Long ago when a Galibier turntable was driven with a Garrard 301 via a belt and sounded more like a 301 than it did a Galibier the motors significance was made plain. This was true of other motors and turntable combinations. Therefore I propose that the major influence of character in a turntable is determined by the motor, not the platter, bearing or drive mechanism given that any of these are of sufficient quality not to be a grossly limiting factor. This conclusion directed experimentation in motors and this blog is to highlight some of the results of these experiments.

In order to frame the variable of motor influencing audible performance the constants were the rest of the turntable. These motors were all tried with the Foundation turntable combination of platter, bearing, plinths and support - details of which can be found in other posts on this blog. The DC motor controller uses analogue current sensing and adjustment resulting in a what we term "Natural Motion" for speed regulation. It utilises purpose designed motor regulators rather than ubiquitous LM317 types as well as a Schottky fully choke loaded DC supply. I used to have to perf board these until I had a PCB made. 

The motor depicted here is the favourite by a large margin. It is a high precision Maxon unit. More on this later in the post...

Here are some of the motors tried on this sled: left to right, AC on top to DC on bottom.
Pabst KLZ three phase AC, Lenco, Garrard shaded pole - similar to the 301 motor but smaller,
Premotec 18105, Premtotec 16141 (as used by Verdier), Maxon 226774, Maxon DCX

On to the most interesting part (to me) which is the subjective impression left by each of these. As a frame the Premtotec 16141 was the base line as it has a long history of success and I had become very familiar with it over perhaps a decade in the Platine Verdier.

Pabst KLZ three phase:

There is no doubt this is the powerhouse of the lot. I do not believe stylus drag has any influence on it at all. The flywheel effect of the rotating case is enormous and the power is more than obvious. The greatest negative was a mechanical presentation. Capacitors were used for phase provision and this was not the best way to go about its power supply. I had thoughts of creating a controller with signal generators and Class D amplifiers but in the end the high noise level of the motor with the wind it generated as well as the lack of detail and mechanical presentation eliminated it for further development. Its power was not forgotten.

Lenco and Little Garrard:

Having spun several Lencos as well as 301s for years I know these motors well. I find the Lenco more precise perhaps than the Garrard however it does not have the same groove factor. On the Foundation it was clear the Garrard was more organic sounding or more human. Perhaps it is better to say the Lenco was more HiFi and the Garrard more about music. The differences were small and overall more similar than different. This little Garrard is not the same as a 301 or 401 motor. The thinking was that it might be lower noise than these while still providing the shaded pole inductive regulation of speed change however while having the same kind of presentation it was not as dynamic or expansive. 

Premotec 18105:

The little Premotec was a bit of a lark. Some turntable manufactures use it and I thought it might have a chance at lower noise than its big brother. In any case it was a data point. It was the low man on the pole with poor dynamics and not much else to offset this disappointment. I am not a fan of low torque motors although there is a limited genre of them with heavy platters and woefully low torque motors. This provides a very slo mo vibrato. The platter gradually slowing down and speeding up in cycles as the motor does its best being dragged around by a heavy platter. This creates an artificial lushness but the slow speed cycling can be slightly nauseating. 

Premtotec 16141

The Verdier sourced motor is a serious piece of kit with an established reputation. Back in the day many die hard idler devotees claimed the Platine Verdier Granito was the one belt driven turntable to have. I found that with battery power (to assist the poor little LM317 who was having its regulation raped and pillaged by the motor EMI) it had much of the idler dynamics and frame with the lyricism and lovely decays of the other camp. In this comparison it is significantly more dynamic (due to the controller mentioned above) while still notably easy on the ears with depth and tone qualities which engage one to listen for depth and nuance in the music. At its price point it is on its own pinnacle. I have not of heard of anything that can do what it does for its price.

Maxon 226774

If one is willing to spend five times more this motor has a slightly more dynamics and engagement with a shade less lyricism than the 16141. My determination is that it was a push between them - the 16141 slightly more nuanced and the 226774 slight more dynamic. My hat came off to the memory M. Verdier. He found a real gem with good margin for commercial profit. I slightly preferred the 226774 as being brought up with live music I have found dynamics to be essential but the 16141 is no slouch and it had other things to offer, organic, smooth, easy on the ear while having more dynamics than the bulk of belt drives heard over the years.

Maxon DCX

The 226774 was excellent and kept up with the 16141 in regards to the softer side of things. With its 8.62 nMn of torque the question posed itself: "would more be better?" and so higher torque possibilities were examined. In this same series precision began to suffer in larger versions but the specifications of the DCX series offered more torque with greater precision in a similar sized package and same shaft diameter. At 14.1 nMn of torque it was almost double that of the 226774. Sonically this was abundantly clear immediately and it also had everything the 16141 had in smoothness and decay. This was a clear winner in all aspects save price. In order to verify this two motor pods were prepared, identical to each other, including flywheel capstans, with the different motors. - a "mano e mano" combat comparison with the Verdier motor. It was no subtle contest. The DCX motor had it all - far greater dynamics while staying with the 16141 in ease, lyricism and beautiful decays. It is seven times the price but also the best sounding motor I have personally heard. Dynamics are quite pronounced, perhaps because of the quieter background than idlers provide, but none the less quite engaging, even captivating.

Whats next? Well, a bigger brother of the DCX is sitting on the shelf waiting for its own capstan to be completed. Its 4mm shaft needs one of its own size. It will provide 32.9 nMn of torque - double again - and has the same precision as that if its little brother. Cost factor now more than X 10. A follow up blog will be posted of the sonic impressions it makes.

Monday, 18 April 2022

It's not about how much it's about how.

We underutilise our senses and as a result when we do experience nuance - we remember it.

A loudspeaker cabinet has at least as much to do with the sound as speaker drivers. If this does not initially make sense let's consider the phono cartridge. Cartridge mavens understand well the importance of chassis material. From Koetsu stone bodies to the plethora of Denon 103 chassis options the descriptions and discussions concerning the sonic attributes from these chassis are endless. The cost of a D103 can more than quadruple depending on what material the aftermarket chassis is made of. Koetsu lovers compare sonic attributes and differences in stone materials from onyx, jade, coral stone, blue lace etc... each having their own distinguishable sound.

This is concerning the resonance characteristics of a very small transducer's chassis. The difference in the physical amplitude between a phono cartridge and a loudspeaker is quite enormous. I propose that a loudspeaker's chassis material would then be even more critical than a cartridge's. The difference in amplitude will make a loudspeaker cabinet's resonant nature more easily discerned. When we consider that the majority of high end loudspeakers use MDF as the primary material, under glossy veneers,  then we can understand perhaps one of the short comings the industry has accepted in the pursuit of profit over fidelity. MDF sounds like mud if you sit down and do a comparison of it with with almost anything else - even cardboard sounds better.

There is an argument that dampening all resonance is the best approach however this is fantastic thinking. In reality some percentage of unwanted vibration always remains and the most heavily damped materials are most often grossly uneven across the audio spectrum. They give back what they cannot damp in the most unfortunate of ways. Rigidity, transmission and dampening are what I look for in speaker building material. Most importantly dampening must occur in proportion to what is natural to the ear. This is much like amplifier distortion: it is not the lowest amount of distortion which is most desirable but the harmonic nature of what there inevitably is. This concept can be applied in the same way to unwanted resonance in loudspeakers.

Add to the cabinet the additional complexities of a crossover and a horn and we have a matrix which is more influential than speaker drivers by themselves. These interactions are the most complex and difficult to model of anything in the audio chain and thus it has become the most mysterious, misunderstood, and exploited aspect of the audio market. This and the small detail that more than 95% of an audio amplifier's energy is lost within the loudspeaker indicates that it is here the main challenge resides. The endless decisions, experimentations, measurements and litmus listenings - all with the poor roadmap if limited modelling ability - results in the high cost of time, money, thought and effort. Due to the dismaying complexity it is easy to get disoriented and thus extensive and regular experience with live music, along with speaker design experience, are not only helpful but perhaps essential.

Hemingway said about writing that the most essential thing a writer can have is a: "Built in, Bulletproof, Bullshit detector." (I propose P. W. Klipsch would agree - wherever he may be.)

Knowing what to throw away and being willing to throw it away, despite the cost, time and effort, does not come easy or cheap.

With the Hadron we have reached a point in performance where 48 hours of thermal stabilisation is not just readily apparent it is transformational in the speakers performance.

The three dimensionality of the presentation that develops on day two causes customers to routinely contact us concerning the metamorphosis in performance.

Is it the string or the wood which manifests the sound of a Gesú or Stradivarius? 

Saturday, 19 March 2022

A little rotational mass in the right place...

 A flywheel can benefit rotational stability and using one with a turntable is a natural application. Adding size and weight to the motor pulley does a couple of things with no penalty. First, it lessens the amplitude of any motor generated vibration. Second, due to its high RPM, the small mass is has greater effect than it would seem.  There is also no added noise of a second bearing and drive mechanism, belt etc... as a separate flywheel would require.

It took three versions to refine the concept into production.

The old pulley...

... and the new one.

After years of trials with tapes and threads, including, silk, linen, nylon, polyester, 1/8" and 1/4" audio tape, holographic party ribbon, kapton etc..., the easy winners are polyester thread and a lightweight, precisely made, fabric belt. This has no stretch and plenty of traction.

The Pulley is setup for both thread and belt.

Verifying with numbers is helpful. Here we have a wow and flutter measurement less than 0.1% which is getting into direct drive territory.. 

The numbers indicate stable rotation but they do not tell us how it sounds, how it compensates for load variation. This influences the sound significantly and the numbers do not speak to this.

As a refinement of tuned setup the differences were readily apparent sonically.

I will attempt to be neither coy nor enthusiastic. The music flows with greater authority and greater ease at the same time. When big things happen they they happen big and when they are over the space around them in the decay is well depicted. The decays themselves are extended and layered.

Overall the music is more compelling and the music has a life of its own. 

It took two years with three versions of prototypes to reach this performance and now it is ready to to be offered as an upgrade to our customers. Please inquire via email.

Next up are the motors experimented with and sonic impressions of each as well as a little detail of the motor controller developed with pure analogue speed control of a DC motor.

Wednesday, 4 November 2020

Hadron Production Detail

Hadron Production Detail

Here are a few details of the Hadron cabinet production.

The layers are bonded in a hydraulic press under high pressure.

Milling cabinets out of solid blocks of plywood might appear to be overkill however this is a process  derived after a long evolution of building cabinets in various ways, measuring and listening to them at each step. 

This expensive and elaborate cabinet is not a product of theory. After years of trial and error, many versions of various cabinets evolved into this. It was an empirical process.

Braces and supports are not added. They are integral in the layers themselves. This not only adds strength but also provides paths and nodes for resonance distribution within the material.

The philosophy is not to eliminate resonance entirely (which is impossible). Reduction in amplitude and distribution over the entire construction is one step in resonance management. The characteristics of material internal dampening are critical.

The first part is not like a musical instrument which resonates intentionally over a broad frequency band. Here we would like to distribute resonances and lower amplitudes. The second part is to be mindful of the nature of resonance which inevitably remains and are internally damped by the material. This last part is very much like a musical instrument. Since we cannot eliminate resonances completely the remainder must be damped with pleasing qualities. Just like amplifiers - is not as much the amount of distortion but the nature of it which is important.

The cabinet shape is a fundamental and critical aspect of resonance management. Here a Fibonacci arch is implemented which is far more potent in distributing harmonic reflections than a similarly proportioned rectangular chamber.

The port is designed into the layers and milled out of the solid wood.

The result is an annealed, solid wood construction which handles resonances evenly.

With considerations of this kind the material of the cabinet itself is critical. It has been recently been made popular with the Dennon 103 re-housing movement (and others that have followed) that a phono cartridge's performance is subject to the material it is housed in.

Sugano San knew this as early as the Rosewood Supex cartridge production of the 1970's and was further mapped out by him in the the evolution of Rosewood, Urushi laquer coated Aluminum, Onyx and other semiprecious stones the Koetsu line utilized over the following decades.

 The loudspeaker is an electro-mechanical transducer ust like a cartridge however its amplitudes are far greater than a phono cartridge's. It should then be easy to understand that a material's resonance characteristics in a loudspeaker are of great importance.

One interesting aspect of this construction method is that the wood which has been subjected to stresses and pressures in manufacture and bonding processes is annealed in the milling process. Not only is an annealed product stronger but it is also more "at rest" which improves its resonant qualities.

Hadron loudspeakers are now available with shorter lead times.

Please email for sales and further information.


Wednesday, 28 October 2020

Famous Direct Heated Triodes (DHT's) and the Unknown

Monsieurs Slagle and Jackson

Although the legend of the DHT tubes like the 300B, 2A3 and 45 got me into low powered amplifiers these Holy Grail tubes did not continue to hold my attention after a decade or so. It did however open the door to appreciating other low power, direct heated tubes. After hoarding a stock of NOS tubes while trying new production versions, which were often unreliable, it was time to look further. Before powering up a fleet of collectable tubes was the question: "Is it worth a thermal cycle on the tubes for a quick listen?" This is not the way. The enjoyment of music is the pursuit not materialistic and possessive concerns. After years of foraging in the mire for the same truffles everybody wants it became clear that the mind set of NOS tube acquisition was more about curation, trophy collection and possibly fetish than performance. Fact is tubes do not need to be expensive to sound good. Yay, I blaspheme.

Across the industry DHT landmark tubes like the 300B not only dominate - they rule consumers and often do so poorly. The majority of products are cashing in on the publicized trend leaving the consumer slowly to discover, sometimes over years, that the products they purchased, be it amps or tubes, are not at all what they hoped. The US military abandoned tons of vintage PA gear in the wake of post WWII occupation. Intelligent, sensitive ears salvaged and discovered the treats therein and created the seeds of legend with these discoveries. Yet this does not mean there are not others of equal or greater sublimity, in fact it should excite the curious to know what else is out there. Western Electric can sound good but it can also suck. Yay, I blaspheme! Klangfilm, Seimens, EMT and Russian, etc... artifacts are pretty sweet as well. The Eurodyne is probably the finest small venue vintage speaker there is. Yay, I say even better than the 753c or 757a. GASP! Yay, I blaspheme thrice! May lightning strike me if it is not true!

The WE300B can be an excellent sounding tube but they have no monopoly on special sound and to make amps, and replica tubes of them, poorly undermines the expectations that have been set by their mythology. This unfortunately is the market trend. Marketing, as we know, is all about mythology.

It reminds me of motorcycles in the 80s. The Japanese were not yet making decent handling bikes and so the Europeans were the ones to have. The American BMW ads of the time had the slogan: "The Legendary Motorcycles of Bavaria". After I got tired of grinding cylinder heads on BMWs I got into the relatively unknown Italian bikes. After waiting for a buddy a mile or two past an off camber chicane I returned to find him struggling with his BMW in the mud. Once we got it back on the tarmac he said panting: "That is the last time I try to follow a hot Italian bike on a German Myth. We both smiled. Going fast through corners has little to do with ad copy in magazines.

Mercury vapor baby - its hard to beat.

The iconic labels of 300B, 2A3, 45, etc are just popular labels for what a good DHT can sound like. If this is true what then lies beyond the scope of an audio reviewer's limited vocabulary? If they are indeed closer to the divine glow of tubes and share their wisdom across the alter for us to be blessed with must they not disclose the tenets from which they mount their ideology? If another divine glow is found and they do not recognize it does it then not exist? Must we suffer excommunication in order to explore it? What other glows could their be? Ahem, well this is the question but first: "What is wrong with the average big name tube amp out there?"

The 300B is not an easy tube to get working economically and so many implement it with inadequate voltage swing and/or inadequate current and resulting issues - sucky slew rates. etc... Chop it and dice it how you want, unless there is a pentode in there its a three stage program. (a step up transformer input driven by a low impedance line stage is a stage, its just in a different chassis). It is better to have a well engineered and tastefully voiced amplifier with an unknown tube rather than the average 300B amp out there. Blasphemy #1. The output tubes makes less difference harmonically than the driver tube. Blasphemy #2. The circuit design itself has more to do with the sound than any of the parts and tubes are just parts. Blasphemy #3 Yay, I blaspheme thrice, twice! Clouds darken and high voltages range to find a way to rapture me back to the herd - unless it is true - and then there is nothing in front but freedom and fresh air.

The first crack in the mythical facade began when I heard an amplifier which was not anywhere near the divine glow and did not pay any tribute to it at all. It had none of the elements the lore decreed. It used two 25¢ UF4007 rectifiers in full wave with a π filter. It was indirectly heated, it used a common, high gain but wimpy mini tube driver (12AX7, 12AY7 or 5751) with its two sections paralleled cleverly to give it some grunt yet with nothing but a resistor as a plate load, the output tube was a pentode (6CA7, 6L6, 350B, EL-34, or KY-66) run in ultra linear mode. Worst of all - it intentionally used feedback and even had a selector knob for adding this profane corruption! The real problem with it was that it sounded good. Real, serious good. Thus did the candle's flame waver and the shadows on the cave's wall flutter and fail. Light could be seen from the mouth of the cave and soon after the sky and sunlight for the first time. It was not all about the output tube! The amplifier did have unusual implementations which helped it to be what it was but these can be discussed another time on request.

The creator of this amplifier was Dennis Boyle. He lived in an old movie theater full of vintage gear collected over his lifetime. He had been a successful industrial designer before he discovered one day that one audio device could sound different from another after which he lost everything and fell into habitation with aisles of industrial shelving full of carefully collected vintage audio gear. In this closed stack of a humanities museum he lived a solitary life.

Mercury vapor with a damper diode.

Old movie theaters are spooky. They are built for darkness, temporary illusion and the pleasure this provides. They harbor pigeons who leave it everywhere, coo and come flapping out of places least expected. The smell of their guano is sour and makes for headaches. Harvesting vintage gear from these places was like spelunking. It was dark, dirty work which had a bad feeling about it. I would never visit these places without the promise of cheap or free vintage gear and so it was only after Dennis moved out of his abandoned theater and into a metal warehouse, which could hold all of his plunder, that I began to visit him. There was a little mono system which played FM radio through a Scott tube tuner. It was the only system I ever saw him use and it was always quietly playing. He never showed it off or asked anyone to listen to it. It just sat in a stack, speaker, tuner, amp, on the floor against a wall in the warehouse. Dust covered shelves held gear piled beyond reach row after row. After collecting all of this treasure in junk yards, craig' list, military salvage, and endless internet searches, after decades of study and pursuing the rare and precious flotsam and jetsam in pursuit of magical audio properties this modern day tube shaman, self confined hermit monk of audio listened to nothing else. This amp he called the Ace.

I spent some time there on and off over years becoming fond of Ramble, the Timber Wolf. In greeting he would put his snout between my legs and lift me off the ground, easily. It was just an affectionate nudge on his part which instantly lifted my feet off the ground. The first time he greeted me thus I wound up on my hands and knees. Dennis just commented that Ramble did not take to people like that often. Point being that the sound of that amp went into my comparator database unconsciously. Over time I became less happy with most 300B amps I heard. When I hosted a demonstration of the Axiom 300B amplifier brought out from Florida to Texas. This was Dennis' and Bob Hoekstra's (Nascar Engine designer) all out pursuit of a 300B amp done right. It made abundantly clear the tube itself was never to blame for comprised performance but these amps were huge and stupid heavy. They required two men to carry each mono block. With gobs of custom iron, three tier stacked supplies, ten tubes per channel and metal Deco styling from Dennis they looked like something out of Metropolis. (A modern day version of a 300B done right might be Ale's foray into the fray which became quite an amplifier. Ale's 300B)

The Axiom had 20 tubes to ignite for a stereo listen, the Ace had 4. They had things in common however, they were both alive, muscular, ultra clear and still had the inner lifelike clarity that is was what tubes are all about and few deliver. The similarity in sound demanded attention. One was easily an everyman's amp while the other a statement piece and yet they both broke, without even noticing, many of the decrees, laws and tenets of magazine audio. My conclusion? Tubes are not the problem, it is the commercialism which surrounds them. The 300B and its kin are like Merlot - it can be good but usually it is not. Nothing wrong with the grape but its commercial appeal created commercialized production and its sea of mediocrity. Want something better than Merlot? Learn about other grapes and wines.

It is to this venue I extend an invitation. Let us enjoy a little freedom and fresh air away from the marketplace, the ad men's hypnotic distortion field and amplifiers built into MDF cabinets with vinyl veneer to make them look like wood while costing more than a car. If you have not figured it out by now there is no hot, admiring house wife ready to hang on your every word just because you bought the shiny thing in the advertisement. MDF is dust - toxic dust. Let's make real stuff out of real materials with real design work. This means opening the design criteria well beyond the 300Bs of the world and using our ears to determine the value of music. It is after all our ears we are trying to please is its not? This is the way.

An all DHT amp with tubes not so heavily publicized.

Friday, 15 November 2019

ETF 2019

Arrival Thursday evening in lovely Belleme

What is this?

A Magnetizer - get your magnets energized right here.

Test gear

Now that is a triode.

And some steampunk...

Plaster horns and amazing woodwork

And this is a platter...
The cork is 12” LP size.

Greetings from Belleme with more to come...