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  Pure Class A Push-Pull Triode Monoblocks

The VPA is a pair of mono block vacuum tube power amplifiers. Equipped with symmetrical and asymmetrical inputs, they offer a power output of 50 Watts through a pure class A output stage with no feedback. Using a pair of matched and individually selected 845 output tubes the VPA offers a clarity of sound second-to-none.  Since its introduction in 1998, the VPA has set new standard for vacuum tube amplifiers, won prestigious awards and, more importantly, became a reference for a tremendous number of audiophiles all over the world.

Constructed in machined-aluminum towers, its highly sophisticated design is based on Nagra’s simple rule: only the best components, no compromises on quality. In addition, the VPA uses fully balanced circuitry from input to output to minimize intermodulation distortion and phase shift as well as decreasing the need for internal feedback.
 
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As a result, the rise time, slew rate and overshoot characteristics of the Nagra VPA are uncommonly good compared to other amplifiers, and simply extraordinary for one based on vacuum tubes. These performance characteristics are constant whether the VPA is delivering minimum or full power.

Difficult Speaker Loads and Zero Negative feedback
Vacuum tube amplifiers seldom drive difficult speaker loads with success. Using electrostatic or low-impedance dynamic speaker designs with these amplifiers often yield unpredictable results. With the VPA, implementing a zero negative feedback design renders matching difficult speakers much easier. In addition, the VPA offers 4, 8 and 16 Ω outputs so it can accommodate even the most demanding loudspeakers.

Fast, Deep and Low with Nagra Output Transformers
Proprietary Nagra output transformers are used to avoid low-frequency saturation and high frequency ringing so common in other transformer-coupled output states. Bass notes are delivered with absolute authority and sound-stage scale delineation is simply superb.

Choice of 845 Tubes
The 845 tubes go through a 24 hour burning and numerous measurements before computer-assisted matching by pairs.

Inputs
The VPA features both balanced and unbalanced inputs on XLR and RCA connectors.

Monoblock design
The monoblock design offers the advantage of providing one power unit per channel, this contributes to the channel separation and thus respects the signal’s integrity. The amplifiers should now stand close to your loudspeakers, enabling shorter speaker cables to be employed and thus allows a better damping factor.

In addition, the tower configuration allows an optimization of the floor space.

Precise System Matching through the Nagra Load Match Meter
The high precision, illuminated Nagra Load Match Meter on each monoblock amplifier offers a unique function: it allows the owner to check the perfect operation of the 845 output tubes and to match each VPA's output precisely with the speakers. By indicating both the peak DC voltage and current drawn on the output tube anode, it is easy to spot speaker mis-match and suggest corrective action. It is our attention to details like these that ensures complete installation success and ultimate enjoyment of your favorite music.