At new deck - Technics SP 10 mk II
10 kg Flywheel for my "Monster
   

 
My old all (now completely dead!) DIY deck were made as a sandwich construction using several layers of black acrylic and lead plates. It employed a Pabs direct drive motor operated by a 12V battery supply - same motor as the Goldmund. Total weight approx. 30 kgs.

The platter on this deck were cast with among other things epoxy and lead-powder. Please note that there is no spindle. The record is centered by a top spindle integrated with a center tightening weight.

 

The carbon fibre airborne tangential tracking arm is also DIY. My brother did most of the metal work and I made the design, as well as the carbonfibre parts. The cartridge is a Benz Ruby. Note that the headshell is made from briar root just like the cartridge housing. Internal wiring is Audio Note silver but will soon be replaced with silver wiring from Tom Fletcher.

The small airhose on the top of the slider supplies compressed air from a big pump placed in another room. The tube is made of very soft silicone rubber only 2 mms in outer diameter. 

 

 arm2.jpg (14689 byte)VTA is adjusted with the large top dial, which also works when playing a record. The dial on the front (just to the right of the arm) locks the up/down going base to the fixed base when VTA adjustment is finished. 

The lift is entirely mechanical. The large lever is mounted in a rubber bushing and pushes down the bar running behind the arm.

The small compartment that now contains the counterweight was originally designed to hold two Lundahl MC-step up transformers that were to have done the job. The idea was to place them as close to the cartridge as possible. It worked fine, but since then the transformers have been dropped and I now use an active MC/RIAA amp.

Why Tangential arms should differ in vertical and horizontal mass.

There is only groove modulation in the horizontal plane at lower frequencies, below about 100 Hz. Any unwanted disturbance from warped records exists only in the vertical plane (approx 0,5 Hz). To get the best possible transient response, the frequency response in the horizontal plane should be as smooth as possible, with a soft 6 dB/octave rolloff down towards 1-2 Hz, so that the only disturbance from eventual record excentricity can be eliminated.

In the vertical plane the goal is to achieve the best possible rolloff of the warp frequency below 10 Hz. This means that the arm resonance (like normal pivoted arms) should be between 12 and 16 Hz, and it can very well be undamped, so as to make the roll off as steep as possible.

In real life this means that the effective mass of the arm in the horizontal plane has to be 25-50 times greater than in the vertical plane, where in a light arm it's typically about 10 grams. The total effective mass of the moving system in the horizontal plane will then be in excess of 250 grams, and depending on its distribution, the total mass can get very high.

 
 

You may know my MC/RIAA as the DACT CT100. Here in Denmark it is known as the NLE 17. NLE is Niels Larsen Electronics. I have known Niels for many years, and it is amazing what this smal company has achieved. At the moment I am building a new preamp employing the new NLE 19 lineamps/buffers and eventually the MC/RIAA will share the same box. The powersupply will be lead acid batteries.
Here the 2002 version of my TD124 with the FR64S and Ortofon MC200 cartridge. May be oldfashioned but it certainly plays music.

   
Remember the old Ortofon arms? This is one of their forefathers made in Denmark somewhere arund the 40'ies or 50'ies. A 12" with monowiring and no antiskating. The mono cartridge is a moving iron (VMS-principle) but the rubber is hard as cement It says "Walchris Supersound FWM" on the top and "for microgroove" on the bottom. I have approx. 100 of these cartridges, but none of them are working. The arm will be rewired and fitted with a fixed house when I have the time.

 
The Van den Hul Condor ... not mine, but a friends. I helped to mount it. A really fantastic cartridge