A pioneer of high-fidelity

The 300B tube has a long and rich history. Invented in the laboratories of the Bell telephonecompany in 1938 for telephony applications, it enabled the development of more powerful relay transmitters to support the rapidly developing network.

The characteristics of this tube are proven without doubt and drew the attention of engineers in the cinema industry who, with the coming of sound to motion pictures, were looking to equip theatres with high quality sound installations. The innovation did not escape pioneering HiFi engineers either who, in turn, adopt it to create amplifiers until now unseen.

An attraction still current

The 300B triode was such a good development that it remains, even today, an unbeatable component for building exceptional amplifiers. Its linearity, low distortion and natural harmonic response close to ideal leaves modern transistors in its wake.

Other excellent triodes, such as the imposing 845 placed in honour on the Nagra VPA amplifiers, appeared later. However they never managed to dethrone the mythical 300B. It has traversed generations while maintaining its attraction. Integrated into high tech electronics, such as those developed by the Nagra engineers, it offers more than ever the pinnacle of musicality and audio performance.

Time defying creations

The integrated Nagra 300i and 300p power amplifier are not only a homage to one of the most mythical components in audio history, but is also Nagras’ way of underlining its attachment to his timeless creation on the occasion of its 60th anniversary year.

Like the “King of tubes”, Nagra equipment benefits from a range of time defying qualities. Employing the most advanced everlasting solutions, they stand out through their ability to deliver music in such a sovereign manner with no artefacts and with complete transparency.

The 300i integrated model aims for optimal compactness by uniting both a preamplifier and a stereo power amplifier in the same chassis. Remote-controllable, it is equipped with 4 inputs
and having all the different audio controls grouped on the front face.

It is at the conception stage that the potential of the electronics is determined. It appears to be an aspect where Nagra differs from mass-production for over 60 years, with innovative and original solutions.

The integrated 300i and the 300p power amplifier do not deviate from this approach. They benefit from hybrid circuit topology allowing the 300B tubes to be perfectly exploited in a Class A push-pull mode.

Equally for the preamplifier stage of the 300i and amplifier and driver stages for both versions, everything has been done to handle the signals
with integrity. End-to-end coherence, the circuits achieve such precision that no feedback correction is needed on the output: thus the stability is perfect
and all load types can be driven without any risk of oscillation.

The care with which the power supply circuits were dimensioned, regulated and filtered also contributes to the exemplary performance while maintaining operation free from parasitic noise, or mains interference.

Extraordinary listening

With a bandwidth ranging from 14 Hz to 56 kHz and a signal-to-noise ratio exceeding 105 dB, the Nagra 300i and 300p have nothing to envy from the best transistor electronics available today. However figures are just one aspect: it is while listening that these units reveal the rest.

The transparency and the neutrality are the first imposing qualities. The legendary  musicality of the 300B triode takes a new dimension, with exquisite treble and mid-range. The soundstage offers a three dimensional and vibrant realism. The bass management at very low frequencies is also remarkable, out of the ordinary for a 300B tube stage.

Quality maintained with all types of 300B

Today, the 300B triodes are manufactured by several different companies of differing origins and are available at very affordable prices. Some users take pleasure in making comparative tests between the different types available, which could provoke undesired audio artefacts. The Nagra 300i and 300p lend themselves well to such tube changes as their circuits always  ensure a high performance in all configurations.

Manufacturing to match the engineering

The more the electronics result from high quality engineering, more their implementation needs to be faultless to the finest detail so as to avoid compromising their potential. Built in  Switzerland in laboratories fit for watch-makers, Nagra equipment benefits from a manufacturing quality of the highest possible standards.

The strict production procedures, choice of components and their definition, the assembly precision and the measurements and tests made unit-byunit, all come together to give a homogenous characteristic and an emblematic lifetime synonymous with the Nagra name.

Transformers wound by hand

Typical to this uncompromising approach, the transformers used in the 300i and 300p are handwound by Nagra, on specially built machines, according to an in-house procedure. This delicate operation, that few manufacturers in the world are able to perform, is critical as to the high performance of tube electronics, as the quality of the output transformers determines the overall global performance that can be achieved.

Tubes scrutinised

The same severity applies to the selection of the 300B tubes, that undergo stringent long duration trials on a specially designed test-bed, so as to eliminate any potential influence on the performance or reliability at the outset. A high percentage of tubes are rejected outright. Each set of tubes is then matched according to their specific measured characteristics which assures an optimised performance.

Protection of the mechanical integrity

The Nagra 300i and Nagra 300p are delivered with a double set of shock-absorbing plates Nagra VFS which contribute to the overall integrity of their operation. These solid aluminium plates are fitted with special Alpha-gel© feet, efficiently isolating the electronics from any mechanical disturbances or vibrations. They are specially recommended for tube electronics, particularly susceptible to such disturbances.

The shock-absorbing characteristics are completed by four conical feet on the amplifiers themselves. These feet are made from Arcap© with Delrin© resin tips, that sit precisely in the cups machined in the upper plate of the Nagra VFS.