This is the third instalment in our collaboration with Jean Nantais of www.idler-wheel-drive.com. Enjoy the in depth essay with great photos...
Up there in the flea markets I picked up an idler-wheel drive to serve as the basis for a decent budget system for our apartment, though I didn’t know it at the time. It was a Garrard SP-25 record changer, didn’t work, and when I removed the platter to see why I was astonished to find what appeared to be hundreds of small brass parts and springs, and of course an idler-wheel instead of a belt or DD circuitry. At that time, no audio magazines did reviews of idler-wheel drives as belt-drive was king.
I was forced to improvise, so with no hope of repairing such a complex mechanism (this was before the internet), I simply threw out everything excepting the motor, the switch, the wheel and the spring which held it in place, thus modifying it (i.e. throwing out everything which rattled and vibrated). I soldered a decent cable to the tonearm and mounted a decent cartridge. At that time, back at home, I owned an Audiomeca record player and a Maplenoll, and I had a reputation in my home city for adjusting and improving the Maplenoll, which was making huge waves in the North American audio scene thanks to TAS and Enid Lumley. The Maplenoll was superb, very musical, with incredible dynamics, bass, imaging and timing (once you had corrected its weaknesses).
I hooked up the little Garrrard to a NAD 3020i (which you could still buy new in Helsinki in those days) and a pair of Boston A40 MKII, and was astonished at the amount of sheer speed, clarity, dynamics and bass which emerged, which even via that little system seemed well beyond the abilities of either the Maplenoll or the Audiomeca!! I knew, given the low quality of the Garrard chassis, main bearing, tonearm and platter, that it could only be explainable by one thing: the drive system, including and especially an important increase in torque.
I did the research, could not find a Garrard in Scandinavia, eventually tripped over a Lenco, and eventually returned to Canada to start my campaign on Audiogon to have what I considered to be the superior drive system for spinning LPs recognized and brought back from the dead.
Though most in the world, including many of my/Lenco followers, argued against the drive system being responsible for the unbelievably high level of sound quality (attributing it to what?), I stood my ground, and eventually went my own way, focussing on both the speed stability/torque aspect and also the benefits of wood (which both allows Direct Coupling and has certain sonic benefits) and metal (which has sonic benefits).
To prove the potency of the drive system and the potency of wood to the world (as certain exotic materials/gimmicks swept the world), I proposed a wooden-plinth Lenco to Salvatore, who had already approached me to commission one, with the Lenco itself largely stock (certain minor-but-important modifications and the only new part a new bearing sleeve) so as to derive a fair idea of what the drive system could do. Salvatore agreed. I decided to turn to the principles of lutherie by embracing certain dangerous (in terms of colourations) solid woods (highly researched and tested), which I would incorporate into the plinth in such a way as to benefit from the intrinsic abilities of wood (i.e. tremendous sustains, clarity, speed, warmth, balance, etc.), but also keep them under control (i.e. keep them accurate and tonally neutral). I also made standard what had previously been upgrades: a metacrylate platter mat permanently bonded to the platter, and Bearpaw footers. Finally, I made standard custom hardwood exteriors rather than the previous Classic rebuilds which were either lacquered or veneered. The resulting rebuild I named the Reference Lenco, and Salvatore proclaimed his conversion via his eloquent in-depth and detailed analysis of the Reference Lenco’s sonic abilities, and by giving it his highest accolade, an Upper Class A rating.
To begin, the Reference Lenco MKI had two features (other than coupling to a high mass) which improved speed stability over stock: 1) the Reference main bearing and 2) the Post Mod, to be discussed.
Over the two years since developing the Reference Lenco, I began to inspect the Lenco’s parts more closely, in order to remove weaknesses which interfered with its already-stellar speed stability and torque, my main focus as always. I first developed the TJN Mod, which swept the world and which proved the role of torque (i.e. sufficient torque to overcome stylus force drag) in absolute sound quality: the greater and more stable torque brought about by the TJN mod, was clearly audible as better imaging, greater detail, better separation, improved dynamics, more extended highs and lows; which brings up the issue of not only speed stability, but torque stability. I made the experiment, with photos, public, and as with the Lenco, set it before the world jury for them to judge. As with the Lenco itself, conversion was near 100% (100% agreement on anything is impossible due to various human foibles).
Having proven, once again, the role of torque in sound quality, I then followed the TJN Mod up the chain to the slider upon which the idler-wheel arm rests and travels. I had long ago publicized, via my "Building high-end 'tables cheap at Home Despot" thread on Audiogon, what I called the Post Mod. In a stock Lenco the original post on which the idler-wheel arm sat was deliberately set up so that the post itself rocked back and forth in a 360-degree arc, thus incurring speed instabilities (i.e. the wheel itself shifted back and forth on the tapered motor spindle, which sets speed). The Post Mod consisted simply of using washers to tighten the post to the slider so as to defeat the spring washer which allowed the rocking. The sonic effect of this simple and cheap mod (two washers) was to greatly increase speed stability, and so focus, clarity, detail, transient speed.
Having proven, once again, the role of torque in sound quality, I then followed the TJN Mod up the chain to the slider upon which the idler-wheel arm rests and travels. I had long ago publicized, via my "Building high-end 'tables cheap at Home Despot" thread on Audiogon, what I called the Post Mod. In a stock Lenco the original post on which the idler-wheel arm sat was deliberately set up so that the post itself rocked back and forth in a 360-degree arc, thus incurring speed instabilities (i.e. the wheel itself shifted back and forth on the tapered motor spindle, which sets speed). The Post Mod consisted simply of using washers to tighten the post to the slider so as to defeat the spring washer which allowed the rocking. The sonic effect of this simple and cheap mod (two washers) was to greatly increase speed stability, and so focus, clarity, detail, transient speed.
Having already had made the Reference main bearing and the TJN Mod itself (a hollow screw with brass weight and attachments), I decided to design and make a new slider from scratch, using my talented Swiss-trained machinist. It is very large in comparison with the original, and machined to extreme high accuracy from solid blocks of aluminium, including the post which is not screwed in or bolted on but part of the same block. The post can thus be bent backwards slightly to give free rein to and so optimize the TJN Mod (i.e. if the wheel is canted higher, then the brass weight better pulls it over for more secure engagement of the wheel). The slider body itself is much wider and thicker, and so, like a sumo wrestler with his legs spread wide provides a great improvement over the Post Modded original slider by being far more stable, the idea being it gives even greater speed stability, as it is relatively immovable. Given the much greater surface area in contact with the chassis, it also acts as a much more efficient sink for motor vibrations, which travel along the arm, into the slider and back into the wooden plinth thanks to Direct Coupling. The sonic effect of this new slider is very great: a great increase in separation and detail, while at the same time a great increase in naturalness, a big rich enveloping soundscape, but even more accurate. The slider has another feature worked in: after shipping internationally, the range of speeds can easily be adjusted from above by the proud owner, to ensure optimum operation regardless of voltage swings anywhere in the world. The bottom half of the slider is not visible, those secrets will be kept for now.
Since the slider worked so much better to tap into Direct Coupling, I increased the amount of Direct Coupling already in use, via various means, to optimize this facet of the new slider's performance further. This done, it allowed me to address an improvement to the original chassis, which I still favour sonically over the alternatives (as with the platter). I call this a Reinforcement Ring, a ring of metal which sandwiches the chassis between itself and the main bearing sleeve underneath, thus eliminating resonances to a much greater degree (bear in mind that the original Lenco chassis, resonances included, is far more musical and sweet than aftermarket alternatives, given a certain amount of modification, such as the pouring of glass epoxy into the voids and, of course, Direct Coupling to a wooden plinth). This results in far greater accuracy, focus of detail, separation, and so on, and works without extra brightness or emphasis due also to the increased Direct Coupling. As with the Reference main bearing itself, I had several prototypes made of various metals to to test my theory of which metals sound best, and chose the winner (which was indeed the metal my theory predicted).
I then addressed the motor, by means of a very simple experiment, as with the TJN Mod itself which used string, Saran Wrap and pennies, proving that the best laboratories begin with the human mind: I used a Reference main bearing with zero viscosity oil in order to eliminate the bearing's contribution to speed instabilities (i.e. with no drag whatsoever, to make visible, by means of a strobe disc, what, if any, contribution the motor made to speed stability). To my surpise, using a strobe disc, I found that the motor itself generated speed instabilities internally. Keeping to the zero-viscosity bearing, I experimented with various techniques in motor rebuilding until I hit one in which motor-generated speed instabilities disappeared. This reaped the usual gains whenever speed/torque stability is improved: greater detail and separation, more clearly focused bass and highs, better soundscape, etc. This done, I also perfected the motor's existing suspension, which also resulted in a dropping of the noise floor, which itself resulted in the usual improvements in separation, detail, and so on.
Finally, I turned to the Lenco idler-wheel itself. I found that the Lenco idler-wheels, stamped from sheet metal and with a pressed-in oilite bushing, were off-centre, causing not only “thumping” in extreme cases, but also leading to speed instabilities as the wheel travelled more on one half of the revolution than the other. I found that aftermarket wheels were also off-centre. So I designed, of course, a new Ultra-High-Accuracy idler wheel whose design brief,tbased on perfect concentricity and lateral accuracy, was first of all to increase speed stability. It is also much beefier than the original wheel, being machined from solid, and has special bearings and other features which not only greatly increase speed stability and so sound quality, but also drops the noise floor. The effect of this wheel is SO dramatic that it is evident the original wheel is acting as a cork in the Reference Lenco abilities: remove the cork, and the Reference Lenco MKII potential is realized.
All this work done, with some icing on the cake to boot, these changes, each profound and each contributing to a much greater whole, indeed warrant a “MKII” designation. To match this internal design/improvement, I changed the external visual design, also so by its distinctiveness my work would be instantly recognizable, and had an industrial designer design a TJN logo (Turntables by Jean Nantais) for me to be inset as a badge front lower left on each of my plinths (there are two tonearm/cartridges in the logo: the "J" and in negative along the top). The new design was inspired by vintage high-end Japanese electronics with their wooden side-cheeks held by four bolts, each plinth being made of two woods, to be selected by the commissioner, with matching dowels/bolts made of the contrasting wood, and each "signed" by me with an inset dolphin of the contrasting wood, as I wrote in the first part of this series, "The totality of all this - especially the dynamic freedom and amazing PRaT - are symbolized by the leaping dolphin, an iconic representative of freedom and joy, in this case a freeing of the music, and its power." All of which is indeed part of the monoandstereo design brief, but using for this collaboration the extremely rare and striking Yellow Cedar Burl from the Rocky Mountains of British Columbia. In the meantime, here are photos of some of the various Reference Lenco MKIIs I have already built, unveiled publicly here for the first time.
Matej Isak
Mono and Stereo ultra high end audio magazine
All rights reserved, 2012
www.monoandstereo.com
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