Building high-end 'tables cheap at Home Despot II

Hi Chris,

It’s an honor for many of us to have you post to this, the 2nd iteration of the “Home Despot” idler discussions, as well as your consideration of the possible candidacy of the Lenco as a platform for the Verus motor.

After reading the Teres promotional material about this motor and drive system, a couple of questions have occurred to me that I hope you can elaborate on. At first blush, they may seem to be “challenging”, but be assured that the purpose is one of inquiry into the discipline of what drives a record, and drives us all in this pursuit.

Unlike a true idler, the tire of which can take wear without affecting the speed relationship between motor and platter, the Verus motor’s direct drive wheel will have a direct effect on speed as it wears (quite correctable, no doubt). Should Verus owners hang onto those stroboscope discs, which they are encouraged to discard in promotional literature, for just such an event? Is there a way to recalibrate the “speed lock” for anticipated wear?

Secondly, is a general question on the area of variable torque. Coming from a camp where hard-cranking, big idlers are often the “quest”, it seems curious that Teres would put engineering effort into a low-torque optional adjustment. The promotional material leads one to believe that this option allows for a smoothness in listening playback. Is this smoothness, in fact, the “wow” of imprecise speed?

Many thanks for your continuing contributions here.

All best,
Mario

Boy, lots going on in just a few days!! I've been off-line over the weekend enjoying the last "summer" weekend (temperatures in the mid-twenties Celsius when they are ordinarily 10 degrees cooler), hiking the provincial parks and watching the amazing Perseid meteor shower (we're talking fire-balls with smoke trails).

BIG Kudos to Teres for so bravely turning their backs on the belt. As my Vintage Guru would say, FINALLY, the industry is waking up, the charge led by Teres! I confess I never thought I'd see the day when the War for the Idler-Wheel/Wheel/against the Belt would actually lead to a change in the industry, so I'm caught entirely by surprise, having adjusted to eternally being consigned to a rebellious fringe element.

That said, Teres is a commercial company, and it's wise to take pronouncements with a grain of salt, and to separate advertising from truth and facts. I refer here to the following lines: "An idler setup suffers from cogging effects but to my ears it's a better compromise than the smearing you get from the greatly increased isolation resulting from a belt. But it is a still a compromise." Now, there is a LARGE difference between a large idler-wheel drive simply bolted to a plinth, and one which has been Direct Coupled to a large high-mass plinth. Furthermore, as I am all too aware of right now (working on a bunch of TD-124s by coincidence), rubber mushrooms, rubber gaskets and so on act like springs (not to mention actual springs), allowing the very powerful motors in these old idlers to actually move the 'table, leading to the claimed speed instabilities and cloudiness.

Now Direct Coupling to a giant plinth not only improves speed stability, but it also drastically reduces noise, drawing away and eliminating everything from the 'table's own noises (motor included of course) to simple surface noise. I would love to hear the effect of the Verus motor on a Giant Direct Coupled Garrard, perhaps one will show up in my area. Looking more specifically at the motors, these old induction motors are brushless like the Verus, and are essentially cogless, once one gets rid of the suspension which amplifies various motor energies, as they spin at an average 1500-1800 RPM, eliminating/smoothing out their own speed imperfections. Being coupled securely via a rubber wheel rather than a belt, the platters themselves act as flywheels to the motors (this design philosophy being expressed most of all on the Lencos), regulating and smoothing out speed imperfections in purely analogue fashion with no need for electronics. The trick is Direct Coupling to a Giant plinth.

Finally, there is more to this whole issue than mere silence, there is the issue of the amount of torque. These old idlers have MASSIVE torque, and the question is: does the Verus provide an across-the-board improvement with no sacrifices in transient speed (a function of torque as well as speed stability), dynamics (ditto) and bass reach, SLAM and detail? I am especially aware of this facet of idler design, as European Lenco motors do function in NA (but not the reverse) and are actually quieter than the NA variety (can hold it in your hand and feel/hear nothing). But their torque is significantly less, as is the SLAM, transient speed and PRaT. So, how much of the perceived improvement to the Garrards is simple silence (addressed by Direct Coupling to a Giant plinth) and “smoothness”, with PraT, SLAM and transient speed being ignored; and how much is across-the-board improvement? I hope to hear a Verus soon, and perform yet more experiments!! Be very interesting to see how the horizontal orientation of the motor works out if a Lenco version is released. FINALLY, the Lenco gets some serious consideration, and thanks for that!

Hi Lew, I found the article on the Garrard 501, and the main improvement is indeed to the motor, which, given the current discussion, is crucial and fundamental. If the magnetic cushion removes the noise while retaining the torque, then this indeed is a very large step. Loricraft have also resorted to electronics to further control motor speed, who knows how much this contributes? I'd love to hear one of these as well.

On the issue of direct drives, it is well-known what I think of quartz-locking and how this too leads to a form of audible cogging (dryness and dynamic constriction): I find the servo-controlled variety thus much more musical and fluid. The Sony 2250 has an absolutely superb main bearing (makes me think of the Roksan’s superb bearing), and extracts astonishing amounts of information (this tested with a smaller plinth, simply bolted). So I will be rebuilding this into a Giant Plinth and going the Direct Coupling route, and testing out a power conditioner to see how this affects the servo-controlled speed stability.

Have fun all, WHAT developments, and thanks again to Teres/Chris for waking up (as my guru would put it), smelling the roses, and stepping forward, and most of all for joining us on our journey here on Da Thread and posting!!!

Dopogue, thanks for heads up on the vertical extrusions. Back to the drawing board...

Jlln, I do not expect that flat spotting will be an issue. The o-rings we use are fairly hard and also very durable. Much more durable than materials that were available in the 60's. Also the pressure is quite small. If I am wrong replacement o-rings are about $0.50 and are readily available.

Lewm, I have no idea if there would be an advantage to driving the underside of the plater rather than the rim. From a theoretical perspective there would be slightly more "scrubbing" with the Lenco approach since the driven surface is not moving in a straight line. At first blush this would seem less effective, but who knows. I do like the elegance of the approach.

We may be able to come up with a way to use a Verus motor to drive the underside of the platter. Constant pressure would not be a problem but it may require too large of a drive wheel. I need to think about this.

Mario_b, good questions, thanks for asking. You are correct, as the o-ring wears the speed will change. However, as I noted before the o-ring material is quite durable so it is unlikely that after even years of play that the overall diameter of the drive wheel will change more than a few thousandths. So the speed change will be very small. The controller has switches that provide precise 0.16% speed adjustment steps. So maybe it will advisable to check and possibly re-adjust the speed every year or two.

The Verus controller has a torque adjustment. First of all using the term torque is not strictly correct. This adjustment controls the voltage to the motor which in turn affects the maximum torque that can be delivered. However, the actual torque delivered is a function of load. The load is always much less than the maximum torque so the extra energy is just converted to heat. My point is that the adjustment never actually changes the torque. What the adjustment does change is how rigidly movement of the rotor is controlled by the magnetic field in the stator. The effect is very similar to adding compliance between the motor and platter, but on a much, much smaller scale. Higher voltages are analogous to more rigid coupling. A higher torque setting results in tighter more precise sound. But you can go too far with the sound becoming analytical and dry. I am sure that it is all about precision of speed but I do not think that the lower torque settings are necessarily less precise.

Chris

Johnnantais,

A few corrections. While we no longer produce belt drive motors I do still think that they have a place in the industry. But that place is not at the top.

Induction motors are indeed brushless but they are not coggless. Any single phase AC motor by definition will exhibit nearly 100% torque ripple (or 100% cogging). The incoming power is essentially cycling on and off at either 50 or 60 time per second. When the AC voltage crosses zero then the torque produced by the motor also must be zero. When the AC voltage peaks the torque also peaks.

The RPM of an induction motor is determined by the AC frequency and the number of motor poles. More poles increases the frequency of cogging but in no way diminishes it.

While flywheeling from the platter and/or motor does aid in speed stability it is not a cure. Otherwise the heavy belt drive platters would womp on idlers with relatively light weight platters. Experimenting with a 70 pound platter we still found that subtle changes affecting cogging were clearly audible.

Cogging is always detrimental to good sound. What can be debated is if cogging is better or worse than common fixes. A rubber belt is very effective at reducing the effects of cogging. But it introduces it's own problems that many, but not all, find worse than the cure. An idler wheel is far less effective at reducing cogging effects and also introduces a lot less negative effects. It's all about compromises. But if you start with a motor that does not cog then everything is a lot easier, and better.

I am total agreement about the detrimental effects of "quartz-locking". Thats why we don't use any sort of servo circuit in either the Verus or Certus motors.

Johnnantais,

Is there a link where you explain this mod, so I don't have to read 500 posts?

Also, is lenco 85 a good model for this?

Thanks a lot in advance...

I am looking forward to this.