Tel: 02 9427 6755

Plessis - Model A

$3,995  Was $4,999

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The Plessis Model A is an integrated valve amplifier, that is to say it has both the pre-amp and power amplifier sections in the one chassis. There are four line level inputs and two sets of differentiated speaker outputs, with 8 ohm and 4 ohm options. The pre-amp valves are 2 x ECC81 and 2 x 12AT7.
4 x EL34s provide the drive, and the amplifier can be switched into either triode mode (for ultimate purity at 20w x 2) or pentode ultra-linear mode (more grunt, 40w x 2).
The chassis is a super-heavyweight casting which nothing much short of a large hammer or dropping it onto concrete paving is going to dent. The casual observer will notice this, but might miss the meter dial and four small adjustment screws and chrome toggle switches set into the top panel. These make it so easy to keep the amplifier in proper trim – they are the bias adjustments, one for each EL34. These enable you to check and adjust the bias of each valve, any time at all. Set each one to the recommended 42mw and you’ll have a perfectly balanced left-right setup, with the added benefit of maximizing valve life.
Most valve amplifiers drift off the right setting over time but have to go back to a technician to have this adjustment done. If any of the valves drift far enough they can run too hot and burn out prematurely. Uneven bias is not just a maintenance issue, but affects the sound quality too. Pinpoint imaging relies on both channels being critically matched. In a class-A solid state amplifier this is done by carefully selecting matched output transistors for each channel. With the Plessis Model A, keeping the bias trimmed is really easy for the owner to do any time the amplifier is operating. There is also a readout to tell you how many hours you've run the amplifier since the last valve change!

While a lot of focus from the public is on what types of valves are used, the real secret to high fidelity in valve amps is the transformers. Without a top-class transformer you are not going to get the bandwidth for proper high fidelity, whatever the valves are. Needless to say, the Model A has this covered, and much more. There’s no wonder that the Model A won Sound & Image’s 2006 “Amplifier Of The” Year award. Another good thing: unlike surround sound amplifiers, these never go out of date! They’ll keep on making a comeback as long as there are people who actually listen to music.


Contact Len Wallis Audio

Address: 64 Burns Bay Road,
Lane Cove NSW 2066,
Telephone: (02) 9427 6755