KAB PS-1200GX

   The PS-1200GX is designed to replace the internal power source of the Technics SL-1200/1210 MK2, 3, 5 and M5G series turntables.

    The PS-1200 provides a very clean, quieter than a battery DC voltage. This eliminates three sources of sonic contamination: The electromagnetic field and mechanical vibration of the internal transformer; and the large peak-to-peak ripple voltage of the internal powersupply.

Since the PS-1200GX is external and no transformers of any kind are used, all original sources of mechanical vibration and low frequency EMF are eliminated. The 'table plays quieter. Sonically this enhances low level resolution and intertransient silence.

    The KAB PS-1200GX meets the latest standards regarding power supply efficiency. It is a green design that consumes less than 0.5 watt in standby mode. It works in any country, on all standard line voltages.

To eliminate the last vestiges of EMI it is highly reccomended that you install the SX-1200 strobe disabler as well. The Strobe circuit produced substantial current pulses at 100hz and 137hz depending on speed selected. The 'table is not truly quiet inside until all major sources of EMF are eliminated.

Note: Installation of this product requires basic electronic skills including soldering. You should refer to qualified personnel if this is outside your comfort zone..

Price & Purchase

SPECIFICATIONS

• 28V Regulated Output Voltage
• Choke Input Filter
• 4000 uF Reservoir Capacitor
• Dynamic Shunt Noise Filter
• DC Supply Line Noise: < 200uV(10-100Khz)
  
• True Over Voltage Protection With Full Relay Disconnect.
• SENSE Line For Power Switch Detection
• Weight: 2.75 Lb.
• Dimensions : 4.2" X 4.9" X1.7"

    The 1200 original power supply has very little reservoir capacitance, 470 uF. The bulk of the supply filtering is performed by the DC regulator, doubling as a capacitance multiplier. These circuits are common, but they are not optimum.

   By incorporating a choke input, large reservoir capacitor and dynamic shunt noise filter, the DC leading into the 1200 is now a clean source of power. This lets the internal regulator do a better job of regulating the motor load.

Also, since the internal power transformer, is deactivated, an additional source of EMI and mechanical vibration is eliminated. The turntable plays quieter.

    The PS-1200GX uses no transformers of any kind, eliminating all sources of low frequency EMF. The kind that can cause audible hum.

• 1 Year Warranty
• Totally Green Design
• SENSE Line For Power On-Off
• 120V- 240V Operation
• Meets all International Regs.

   To gain international approvals, I wanted to use a high quality switching power supply as the front end of the new design. Switchers are economical, fully certified and very light weight. The only purpose of the switcher is to provide a fully regulated 28 VDC input to the DC conditioner. The real work was to come, developing the DC power conditioner. The challenge is, how do you produce a practically noise free source of DC and keep the series voltage drop to below 0.25V? The solution comes in 2 parts. Choke input with large capacitor resevoir and a dynamic shunt active filter.
The choke input filter reduces ripple to under 2mV, then the dynamic shunt uses a unique active bridge cancellation circuit that cancels the residual noise and reduces it even further to less than 200uV. This is one third the noise from a battery! And this is all done while dissipating less than 1/2 watt of energy. That handily beats the more common LM317 whose noise is typically 10 times greater, steals 4+ volts from the circuit and dissipates 3+ watts of heat.

Since the PS-1200GX is external and no transformers of any kind are used, all original sources of mechanical vibration and low frequency EMF are eliminated. The 'table plays quieter. Sonically this enhances low level resolution and intertransient silence.

    The SENSE line detects the original power switch in the turntable. This way you turn the PS1200GX on and off just by using the original power switch.

Notes On Power Supply Design

If you are planning on building your own power supply, here are some hints.

1. Be sure to keep one regulator close to the motor circuit board. Some designs locate the only regulator with the AC components in a separate chassi and then connect with a cord. The inductance of just 2 feet of wire will defeat the hi frequency performance of the regulator and could cause all sorts of noise problems deep inside the table.
   
2. Never use a non ferrous chassi. Using an aluminum chassis lets the EMF from the power transformer bleed right through. A toroid transformer will radiate up to 20 Miligauss. A steel chassis reduces that to below 7mG, aluminum however lets all 20mG pass right through. If you must use an aluminum box either internally shield the transformer or, mount the PS at least 1-2 feet from the turntable.
   
3. Batteries are not the most quiet source of power and they do not have good internal impedance properties. Further the impedance rises as they discharge. If you must use batteries, always follow them with a good electrolytic storage capacitor, a small bypass film capacitor and a regulator to ensure a low impedance drive to the motor. The easiest way to do this is to keep the internal regulator that comes with the table. If you want to use a different regulator, that's fine, just be sure to place that regulator inside the turntable. (refer to 1 above)