The Platter and Platter Sheet

 

The L-07D platter is a resonance-canceling composite, just like the rest of the deck.  The main platter is a three layer sandwich of Aluminum and Duralumin.  The platter mat is a sheet of precision machined stainless steel.  While the standard platter sheet was made from precision-machined stainless steel, an optional ceramic platter mat (TS-10) was also available for use on the L-07D.  The platter sheet is non-resonant and non-magnetic.  The platter and sheet combination will neither vibrate nor ring.  The 5mm thick stainless steel platter sheet is made from non-magnetic stainless steel.  This thick disc shields the pickup cartridge from the magnetism of the motor below.  Total rotating mass of the platter and sheet is 5.5 kg/ 12.1 pounds.  Add the weight of the rotor and the total rotating mass becomes in the range of about 6.8 kg/15 pounds.  Add the optional DS-20 Outer Disk Stabilizer (1.4 kg/ 3.0 pounds) and the optional DS-21 Inner Disk Stabilizer (0.5 kg/1.1 pounds) and the total rotating mass goes up to 8.7 kg/ 19.0 pounds.  Also, the optional TS-10 Ceramic Platter Sheet can be used on top of the standard stainless steel platter sheet with the stabilizers, adding an additional 1.2kg/2.7 pounds to bring the total rotating mass up to 9.9 kg/ 21.7 pounds. 

The L-07D brochure states:

A vibration-proof triple layer platter with non-magnetic stainless steel platter sheet

Another unique feature incorporated in the L-07D design is the structured platter.  The massive die-cast aluminum platter is reinforced beneath by a 4 mm thick, duralumin layer.  But on top of the platter is a second layer of 4 mm thick, vibration-proof stainless steel.  The two surfaces are interfaced by precision machining to prevent ringing, while the non-magnetic nature of the steel sheet serves as a barrier to magnetism generated by a moving-coil type cartridge. 


Top view of deck showing 13 inch sub-platter, 12 inch platter sheet and supplied standard Plexiglas platter dust cover.


Platter and platter sheet shown above.


Side view showing relative thickness of platter and platter sheet shown above.


The center of the platter sheet and spindle shown above.  The two threaded holes on the sides of the label depression are for using the platter sheet screws to capture the platter sheet for removal and replacement.


The platter sheet screws shown mounted to the platter sheet in the photo above.


Platter sheet removed from the platter shown above.


With the platter sheet removed, the massive composite sub-platter is visible in the picture above.


A close-up of one of the platter thumb holes is shown above.  The platter is a three layer sandwich of aluminum-duralumin-aluminum.


The platter was factory balanced and a red mark signifies the best balanced position.  A corresponding red mark would be visible on the platter mounting plate of the motor, but it is covered by the platter in the photo above.


The extra-length spindle is useful for mounting accessories such as the 45 rpm adapter and record clamps.


Optional DS-20 Outer Disk Stabilizer flattens the record and adds mass to the rotating periphery, which increases moment of inertia. 


Optional DS-21 Inner Disk Stabilizer


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