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Ypsilon PST 100 MK II Preamplifier


Most manufacturers develop a circuit for their power amplifier

and then use the design for their preamplifier. The job of a power amplifier is to amplify the signal and drive the loudspeakers. That of a line preamplifier is to draw together the various source

components; to attenuate the signal in order to achieve "volume control"; to have low enough output impedance in order to drive the cables; and finally, to provide gain if it is required. It performs totally different duties to those of a power amplifier and needs to be designed in a totally different manner.

Conventional wisdom suggests that the most critical part of a

preamplifier is the active circuit design. Ypsilon, however, believe that the means of signal attenuation (the volume control) is the most critical to the overall sound of a preamplifier. Most

designers use resistor attenuators for volume control. Ypsilon

themselves have used resistor attenuators with high quality

resistors (Vishay, Holco, tantalum types etc.) in the past, but that was before they developed a very special transformer as the

means of attenuation. It was immediately apparent just how

grainy and discontinuous resistors sound, even the best of them. The short explanation of this observation is that the series

resistor transforms the constant voltage into current and the

parallel resistor the constant current into voltage. The materials

used in resistors are far from ideal as conductors... they sound

much worse than pure copper or silver... and they do a lot of

harm to the signal.


In a transformer, however, the magnetic circuit can be ultra linear when the very best core materials are used. The sound of such

materials is much more musical and detailed compared with the best resistors. So Ypsilon produced, in-house, a special transformer attenuator with 31 taps.


The active gain stage is a no – feedback s.e. triode, transformer

coupled. The power supply uses valve rectification and choke

regulation. Wiring is made with custom made pure silver wire.

The transformer attenuator is placed after the valve stage,

preserving the purity and micro details of the signal.


The maximum attenuation is 52db and maximum gain is 12db.

Output impedance is 150 Ω max. PST is the pinnacle in

preamplification. It is a must have component for building a “no

holds” system.



PST100 is also available without the valve stage for systems that don’t require additional gain. This version is equipped with the

transformer attenuators and is called PST 100 TA. Notice that it is fully upgradeable to the full version at any time by returning to


"The Ypsilon PST100 MKII is the Best Preamp I have ever heard, Also the Best Component I have ever heard"   ... Michael Fremer, Stereophile

Product Specifications:

5 Hz - 100K Hz / -3db

Output Resistance:

150 Ohm

Input Resistance:
50K Ohm

x10 (20db)   (PST 100 MKII)
x1 (0db)  -  (PST 100 TA)


Power Consumption:
150 VA max

Input Tube:
Siemens C3m (x2)

Rectifier Tube:
6CA4 / EZ81 (x1)


15.75 x 16.15 x 7.1"  (WxDxH)



55 lbs.

Ypsilon PST 100 MK II Preamplifier

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