November 30, 2016 1:46 pm

The TJN Mod/Replacement of Spring for Torque/Speed Stability

I posted the following explanation on Audiogon January 31st, 2011, specifically for the benefit of all Lenco admirers and to further ensure Lenco performance worldwide, regardless of implementation:

WHAT I DID WITH STRING, SARAN WRAP AND PENNIES

I was sitting at home during an extreme cold snap (similar to today’s extreme cold snap which is why I’m writing this  ) which made it impossible for me to work in my workshop, and so I decided, FINALLY, to address the issue of that damned Lenco idler-wheel spring.  Pay attention now y’all as I’m about to provide the Keys to Paradise, a MAJOR upgrade to the Lenco’s sound and overall performance regardless of implementation/flavour, to all Lenco afficionados, DIYers and client/buyers alike.  The “competition”, already living in fear of the Lenco, will have the bar raised – overall performance – quite a bit further, heh-heh.

So let me tell you about the TJN Mod (named pithily in remembrance of the fab Twl Mod for the Rega tonearms which was popular back at the start of the original Home Despot thread) which you can either fabricate/cobble yourselves extremely cheaply (as I’ll explain in some detail), or simply order entire as a kit later (dependent on availability/time). It’s been at the back of my mind for years, but since the Lenco is so amazing I never got around to actually testing it out, thank the cold spell.

As I’ve written since the beginning in the Long Ago and Far Away (i.e. since my first attempt to start the Idler-Wheel Revolution), the reason the Lenco is such a sonically-amazing record player is not Magic Lenco Fairy Dust as some seem to want to believe, but simple engineering: torque from the combination of a powerful motor married to an amazing flywheel-platter via a delicate idler wheel and the resulting speed stability, a great resistance to the braking action of the stylus in the groove, friction, otherwise known as Stylus Force Drag.

BUT, this whole scenario depends on that damned little spring (the motor too, but that’s not at issue here).  Now, I’ve rebuilt some 100+ Lencos (and others) over the years (remember I rebuilt quite a few in a variety of ways/styles/materials before ever starting the A’gon Home Despot thread) and very often any problems which come up are due to that damned little spring.  Usually the issue is a tired spring, meaning it has lost its force and so the Lenco’s overall torque is severely compromised and, as demonstrated to and verified by Salvatore, leads to a serious loss of detail, SLAM, PRaT, dynamics, and so on (even imaging!).  It can also lead to serious “wobbling” at higher speeds, like 45 rpm, where the wheel simply doesn’t engage reliably.

The fix to this was to snip off a few loops of the spring to make it tighter, but one had to be careful, because if the spring was shortened too much then all sorts of weird noises and grindings and bindings would occur: the force of the spring needed was pretty exact: not enough, and a serious loss of performance, too much and various problems.  Add in to this that it is very likely, after all these years, that ALL Lencos are performing sub-par due to tired springs (unless NOS).

Then armed camps will rise up and the X-weighters will oppose the Y-weighters, and the thing will go the way these things always do, in an increasing fracturing of the Brotherhood I had naively in mind when I started on A’gon

Furthermore, looking at how the spring operates on the Lenco, it is evident that, even given a spring which has all its original force intact, that it draws the idler-wheel arm closer to the motor shaft the higher the speed chosen.  Which means that the higher the speed, the shorter the spring.  Which means that the spring is not drawing with as much force at 45 rpm as it does at 33 rpm.  Which means that the performance/sound, given “perfect” spring force at 33, will be lesser at 45 rpm than at 33 rpm.  And this is assuming that the exact amount of force needed for 33 rpm actually exists.

Finally, let’s admit that the spring is a spring, which means that it is spring-Y.  This means that, being a spring, it is always springing, i.e. stretching and contracting.  Can you see where this is heading?  It is behaving exactly like those rubber belts in belt-drives (which consequently many now replace with thread etc.) I started attacking back in the beginning, meaning that the performance, regardless of an optimized spring, is always, to a certain extent, as verified by Salvatore, being compromised.  Now it is obvious that the Lenco spring DID work as the Lenco’s speed stability relative to pretty well everything else is clearly audible in transient speed, bass power, reach and detail, dynamics macro and micro, detail period, etc.  Which is why the Lenco, essentially unknown, unrecognized and reviled only 6-7 years ago, now stands high along with the Garrards, EMTs, and top belt-drives of today.

So you can see why I think of it as That Damned Little Spring. Especially given the heights to which I’ve brought the Lenco, which made that Damned Little Spring all the more galling, since my end results depended so much on it, a major weakness and so problem (i.e. in almost every case – not all – a problem with the Lenco can be traced to That Damned Little Spring).

But what if we could ensure optimal performance of the Lenco, all the time, at every speed, with utter stability and dependability, forever!!??!!

So, up opened the Mighty TJN R&D Laboratory.  I took out scissors, Saran Wrap, pennies (being in Canada, Canadian pennies) string, and a drill bit.  The intent was to measure the force of the spring, which I measured in grams.  I needed a cradle which had no weight, hence the Saran Wrap (this message brought to you by Saran Wrap TM  !!!) and string.  Doing some research, I discovered that all Canadian pennies minted between the year 2000 and today weigh in at 2.35 grams.  So, I cut a square of Saran Wrap (doubled for strength), poked a hole at each of the four corners, knotted string at each to form a weightless cradle, and suspended it from the spring.  I started to pile in the year 2000+ Canadian pennies until I reached an amount which seemed not to drag on it too much, but enough to cause it to stretch comfortably. I counted the pennies, then multiplied the amount by 2.35 grams.  Ta-Da, a precise amount, double-checked via a postal scale.

I took out scissors, Saran Wrap, pennies (being in Canada, Canadian pennies) string, and a drill bit.

I then drilled a hole in the Lenco, beyond the motor in the same general direction as That Damned Little Spring post but in a place where it would not interfere with motor or plinth, and inserted one of the brass, rounded inserts which originally held the on-off switch, to ensure the string was not catching on any edges to give me a false reading.  I then ran the string through the brass insert and, cutting off the spring so that only one loop remained (so no springing), hooked the string to the loop/idler-wheel arm so that it was tied to the idler-wheel arm, the other end hanging below the motor.  The Lenco itself was sitting high above the floor on stilts so I could have access to the cradle (see photo of the experiment under my “System” page).

I piled the pennies in and turned the Lenco on.  BAM the platter started up, and the silence was astonishing.  That Damned Little Spring makes noise too; The Glorious Little String does not  .  I checked the torque by hand as I always did when optimizing That Damned Little Spring and the torque was amazing.  I added pennies and subtracted them to test torque at various pressures, even pulling on the string/cradle to add pounds of force weight to see if I could increase torque/speed stability.  The end result of all this was that after a surprisingly small amount of weight/pressure/force, there is no increase in torque.  Not enough and there is a very definite decrease in torque.  Too much and not only is there no increase in torque, but there will be undue wear on the wheel and strain on the motor.

If there’s something I’ve learned in my years of participating in and reading internet forums, it’s that for every idea/result someone will rise up to say Nay, and someone else will rise up to Defend, regardless of the worth or not of the idea.  So, I’m not going to give anyone a hook to attack and criticize my results by publishing the optimum weight I’ve arrived at, as I know from experience someone wanting attention will say “It is not enough, I’ve come up with better weight” and someone else will rise up and say “It is too much, I’ve come up with a better weight.”  Then armed camps will rise up and the X-weighters will oppose the Y-weighters, and the thing will go the way these things always do, in an increasing fracturing of the Brotherhood I had naively in mind when I started on A’gon (I gave up on that idea as, evidently, impractical nonsense).

So I’ll give pointers now on design of a cheap DIY TJN Mod, and leave you all to it.  To those who want a finished kit-form TJN Mod, with threaded insert for secure bolting to the Lenco chassis with rounded lip which raises the string to the level of the arm (so pulling at a perfect 90-degree lateral angle at X-gram force) and which extends to below the motor so there is no fouling of the string/weight possible, machined brass weight with hole, measures string with hooks at both ends and template so you find the exact position on your chassis, contact me, I haven’t yet decided on a price, but it will be about $60.  For those who will inevitably rise up and scream WHAT, so expensive???!?? I remind you I don’t use 13-year old children in sweat shops in Asia, but a locally-based European machinist who has made reality my exacting and precise and practical and simple design, using real and pricey metals, then there’s my own time an materials.

So here’s the instructions to the TJN Mod, look at my photo too.  I had first contemplated plastic fishing line for the thread due to its low friction, but decided that plastic, being hard, would transmit vibrations, and given the extreme silence and “mushiness” of simple string, decided on cotton thread on the same principle (I rejected polyester thread based on this same principle).  Find the spot on your Lenco which doesn’t interfere with your motor or scrape against the inner platter.  I used the brass insert which comes with the original Lenco on-off switch due to its rounded/smooth edges, it’s a 5/16th inch hole, so small and easy to drill (I use this same diameter for my kit for this same reason), but you can use something along the same idea somewhere else, have a blast.  Cut the spring to the last loop so that there is no longer any springing, it’s convenient and easier than stringing directly to the idler-wheel arm, it only has to pull with a certain force expressed in grams which, being a weight subject to gravity, it will do with Supreme and Eternal Reliability (WARNING: do NOT take the Lenco into outer space and expect the same results).  I use fish hooks at both ends which I snip so that there is no risk of blood spilled,  After finding the weight you like best, simply hook your weight (which can be glued-together pennies, or a bolt and nuts or or or…, just be sure it’s not scraping your plinth or motor) from the other end.

The end result of all this was that after a surprisingly small amount of weight/pressure/force, there is no increase in torque.

Even if certain of you don’t agree, for whatever reason (as is almost certain to occur) that the TJN Mod is a sonic improvement, be aware of the other issue, that being that That Damned Little Spring will be gone, to be replaced with something which will NEVER wear out or get loose or tired and will ALWAYS work with exactly the same force you’ve determined is ideal at every speed, FOREVER.  Now THAT’s peace of mind  .

In MY current set-up, which is, for the moment, a Koetsu Black mounted to a Triplanar mounted to my Reference Lenco with spring already optimized (prior to the TJN Mod), I noticed the following things: first of all, the utter silence of the mechanism itself, which now always works.  Sonically, previous to the TJN Mod, I had found this set-up a tad on the polite side, both the Triplanar and the Koetsu being on the more polite/rolled-off-highs side of things compared with other tonearms and cartridges.  But, after the mod, suddenly the Triplanar/Koetsu combo sounded much more incisive, with even quicker transients and more extended and aggressive – in a GOOD way (more defined and forceful) – high frequencies.  The bass gained in power and detail in the bass is amazing (it was already excellent via the Triplanar/Koetsu combo). PRaT/timing has become much more exciting still (already very good), an album which I had worn out in terms of interest – Kraftwerk’s Electric Café which I had indeed played previously on this combo (one of my test records) – became once again rivetting with much more SLAM and excitement, in fact it was SO good that for the first time in years I had to sit entranced through the whole album.  Finally, and since the Triplanar/Koetsu combo is relatively recent  I can’t be sure, but while listening I realized that there seemed to be no surface noise from LPs I knew were noisy: I suddenly sat up and thought “Where the heck did the surface noise go??!!”   Did it disappear the moment I set up the Triplanar/Koetsu, or did the TJN Mod do it? Further testing and results ahead.

Needless to say, all my Lenco reconstructions will from now on include the TJN Mod.  Those who want a nice kit ready to go with all issues already addressed contact me via my website at www.idler-wheel-drive.com.

All those who have had various Shootouts and have come to certain conclusions prepare to seriously revise upwards!! Enjoy the Mod all!!!!  And for the Gupper: Vive la Lenco, Vive la Idler-Wheel!!!!

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