Perfection is a passion - The Passive Preamplifier series by Audio Synthesis

The original and best selling PASSION controller. Enthusiastically reviewed (Hi-Fi News April '93, September '94) and now regularly used 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 PASSION. 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 PASSION be guaranteed to significantly improve upon even the most expensive and respected active preamplifiers, whether semiconductor or valve!

System compatibility is the key to successfully installing a passive preamp.

Compatibility - Sources
Two specifications of the source are relevant when using a passive controller.

One is the output impedance of the source which should be 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 is perfect for use with PASSION.

Compatibility - Cables
Due to their minimal design nearly all passive preamps exhibit an output impedance which both changes with level and 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 be screened. We highly recommend SilverBlue (120pF/m terminated in WBT 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 1V for maximum output is ideal.

The amplifier's input impedance is also relevant due to its loading effect upon PASSION'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, with an input sensitivity of 0.5V and impedance of 440kohms is a perfect match!

- 3 stereo line inputs, tape output, main listen out and mute facility

- Tape output may be used as a Direct In, by-passing all input switching

- Stereo, 31-step, all Vishay attenuator, 1.5dB & low level 6dB steps

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

- Absolute simplicity - a classic 'L' pad only 2 Vishay Bulk Foil resistors are ever in the signal path at any one time

- Signal and ground of all inputs are switched for total source isolation

- Coin silver self-wiping switch contacts

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

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

- Fully comprehensive 2 year guarantee on components & workmanship

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

- Weight including packaging: 1.9kg

2010 Audio Synthesis