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Again, men love to restore then tweak things as long as it involves dangerous tools and marking the outcome with their signature as a form of ‘Joe was here’ olfactory stamp. It’s thus no surprise that many men took an old idler wheel turntable to the tool shed and started to revitalize the crusty old spinner. Soon it appeared that mounting the overhauled mechanics of an idler wheel deck onto a much more inert than original plinth turned such vintage players into incredibly good-sounding machines. Word spread like wildfire and decades after the alleged expiration date, restoring old Thorens TD-124, Garrard 301, Dual 1019 and Lenco L70 and L75 decks became hot stuff. Of course the analog audiophile church quickly segregated their believers into various camps organized by holiest make but the core belief remains united - idler wheels are heaven.

So what is an idler wheel and what makes it so special? An idler wheel is well comparable to a gearbox. In a turntable it sits between electric motor and the platter which is driven by said motor. By varying the transmission ratio between the motor’s constant RPM by means of its spindle diameter driving the idler wheel, the speed of the platter can be altered. In idler wheel turntables the motor is asynchronous to not rely on the incoming voltage of the connected AC power but the line frequency. Thus even if the voltage is subject to fluctuations, the motor keeps to a steady pace because the power-line frequency never changes. It is always 50 or 60Hz depending on locale.

In an idler wheel configuration there are two popular ways to link motor spindle to platter. One has the motor’s spindle sit vertically like the idler wheel’s plane. From this perspective it is easy to drive the platter by running the idler wheel against the platter’s rim. That’s how Garrard and Thorens idler wheel tables get spinning. Another method is to mount the motor horizontally which more or less forces the idler wheel to sit vertically and connect the motor’s spindle to the bottom of the platter and not rim. Speed adjustment can be done by operating a lever that shifts the idler wheel’s position relative to the spindle steps. Each step is associated with a fixed platter speed. A small diameter step on the spindle makes the platter rotate faster than a step of a larger diameter. Using a tapered spindle enables variable speed control.

All idler wheel designs use a sturdy relatively high-revving AC motor with plenty of torque. That torque has to overcome drag from the needle which depending on playback frequency works like an anchor. Enter terms like stylus drag, groove resistance and friction. In terms of cars an idler wheel motor is a bit like our Defender. No matter the terrain, it won’t stop. The LP’s terrain varies indefinitely with musical content and so does stylus drag. Modern multi-motor belt-driven microprocessor-controlled turntables correct speed alterations after the fact. No matter how fast they react, it’s by definition always after the note has already set. Our ears are very sensitive to minute variations. If there are no variations to begin with, there is no need for countermeasures and hence nothing to ‘overlook’ or disregard.

Many if not all DIY idler wheel projects and even more commercial endeavors like Loricraft concentrate on their plinths. As part of the motor mount it gets ruggedized, air suspended, sand filled and the like. Common to such mods is that the top plate or chassis, however nicely re-sprayed, remains in place.

Here one Peter Reinders of Dutch PTP Audio introduces a radical wrinkle. We were thus very pleased when Peter contacted us for a review of his version of an idler wheel project.

First off it seems that Peter and his PTP Audio are quite well-known in the DIY turntable world and all its fora which to us are terra incognita. That made us the perfect virgins on the topic. When Peter contacted us he’d just received a new Thomas Schick 12" tone arm perfectly fit for his Solid12 Lenco L75-based turntable. He could fit it with an upgraded Denon DL-103 cartridge and deliver the complete set. As we run our Dr. Feickert Blackbird with Zu’s version of the DL-103 we would have common ground to start with and have somewhat of a reference or base line.