The Passive Preamplifier series by Audio Synthesis

The original and best selling PASSION controller now has a one input dual-mono partner!

ProPASSION is the high-end controller for single source systems. It can be supplied with top quality WBT RCA sockets for unbalanced use or with Neutrik XLR plugs, sockets and additional attenuators for fully balanced operation. The original 3 input PASSION was enthusiastically reviewed (HiFi News April `93, September `94) and is now regularly used with ProPASSION by England's most respected authority on high-end audio products.

A PASSION controller has no gain but otherwise performs all the functions of a conventional preamplifier and with practically no audible degradation of the source. This is why we continue to refine and expand the PASSION range - no other form of input selection and volume control offers such breathtaking transparency or natural performance.

PASSION passive preamplifiers are produced using only top quality audiophile components with no compromise. The signal path consists entirely of Teflon insulated, high purity silver conductors, precision bulk-foil Vishay resistors with necessary connectors and switches chosen specifically to minimise damage to the delicate audio signal.

With components of the highest quality it is essential to employ time-served, expert craftsmen for the hand assembly of each and every ProPASSION. They ensure that all joints are cleaned and exhibit a metal-to-metal contact before being perfectly silversoldered. Switch mechanics have to be checked for alignment and monitored for consistent lubrication and low resistance. Only with such meticulous attention to the building process can a ProPASSION be guaranteed to significantly improve upon even the most wildly expensive active preamplifiers whether solid state or valve.

Compatibility - Sources
Two specifications of the source are relevant when using a passive controller. One is the output impedance, which should be reasonably low (ideally 600ohms or less). The second is the output voltage from the source since this (together with the power amplifier and speaker sensitivity) will determine how much volume is available in the room. The higher the output voltage the better. We recommend greater than 1V rms. The 3.5V output from the DAX series of d/a converters (7V rms with the balanced output options fitted) is a perfect match for ProPASSION.

Compatibility - Cables
Due to their minimal design nearly all passive preamps exhibit an output impedance which changes with attenuation and which is sometimes higher than a conventional active preamp's. Consequently the cable used between the passive controller and power amplifier should have a low capacitance (the shorter the cable the better) and may need to be screened. We highly recommend SilverBlue (120pF/m terminated in WBT or XLR plugs) and SilverBlue Locap (80pF/m).

Compatibility - Power Amplifiers
When used with a passive preamp a little more gain may be needed in the power amplifier, we recommend 30dB or more. An alternative way of specifying this is as the power amplifier's sensitivity for full output, a figure of less than 0.775V for maximum output is fine.

The amplifier's input impedance is also relevant due to its loading effect upon ProPASSION's output impedance and hence the source's load driving capability. A minimum input impedance of 20kohms is a good guide. The Audio Synthesis power amplifier, DESIRE Decade, with an input sensitivity of 0.5V and impedance of 440kohms is a perfect match.

- One stereo line input and stereo listen output

- Left and Right dual mono attenuators with off positions

- 31-step, all Vishay attenuators, 1.5dB steps (low level 6dB steps)

- Less than 0.05dB error in Left to Right tracking or step accuracy

- WBT connectors, Teflon insulated, 24 carat gold plating & isolation

- Or Neutrik gold plated XLR plugs & sockets for balanced version

- Pure silver (>99.99%) & Teflon insulation used for internal wiring

- Fully comprehensive 2 year guarantee components & workmanship

- Size (w x h x d): 110mm x 65mm x 130mm

- Weight including packaging: 1.75kg

2010 Audio Synthesis