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Preserving
the Sounds of a Lifetime |
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KAB PS-1200GX
EFFICIENT DC POWER CONDITIONER FOR TECHNICS SL1200 MK2-5
& M5G
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..
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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"
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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. |
GREAT FEATURES
- 1 Year Warranty
- Totally Green
Design
- SENSE Line For Power
On-Off
- 120V- 240V
Operation
- Meets all International
Regs.
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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.
- 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.
- 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.
- 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)
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KAB PS-1200GX REGULATED POWER SUPPLY FOR SL-1200
KAB ELECTRO ACOUSTICS P.O.BOX
2922 PLAINFIELD, NJ 07062, USA PHONE 908-754-1479 FAX
908-222-3442
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