Learn more about e.One amplifiers

e.One Amplifier Technology

Overview

e.One amplifiers are designed using the latest analog controlled switching audio amplifier technology. This topology is based on a single supply, fully balanced architecture. All e.One amplifiers use a single pair of N-Channel power MOSFET switches in each output phase. This balanced output section drives a 2nd order optimum-phase balanced LC output filter. There are multiple correction feedback loops to insure low levels of all distortion, both continuous Total Harmonic Distortion (THD) and Transient Intermodulation distortion (TIM). The low TIM insures a sweet, clear sound, without any of the transient artifacts that plague many transistor amplifiers. The low THD insures that the amplifier remains very transparent to the signal, with very low coloration and true reproduction of instrumental timbres.

Switching Power Supply Architecture-Smaller is Better, Much Better!

The e.One amplifiers use an advanced Switching Power Supply (SPS) architecture. This power supply is vastly superior to the traditional line frequency (50/60 Hz) power supplies used traditionally in domestic audio power amplifiers. The e.One switching power supply architecture consists of an input filter, AC-DC rectifier and a high frequency (>100 KHz) switching power regulator stage, high speed rectifier, and output LC filter.

The superiority of the SPS lies in the fact that the final DC power supply voltage is precisely regulated and largely free of the line frequency related noise artifacts that are present with traditional large, heavy, power supplies. Because the SPS architecture first converts the AC line voltage to a rectified and filtered DC voltage it is not sensitive to residual DC on the AC line and we also can reduce the supplies and amplifiers sensitivity to typical AC line problems, such as:

1) High or Low AC voltage
2) RF line noise
3) AC line distortion components
4) AC line droop

The power transformer for the e.One amplifier is running at very high frequency (>100KHz) where the magnetic materials are vastly more efficient than magnetic materials are when running at 50/60 Hz power line frequencies. This efficiency means that the power transformer is many times smaller and uses both less magnetic material and much less copper wire.

Indeed, this efficiency means that the transformers in the e.One amplifiers are less than a 2 inches (50mm) cube while performing better than a 50/60Hz transformer which would be upwards of 10 inches (250mm) cube and weigh 50 lbs (25Kg). Even if the larger transformer could supply the same power there would be much more copper winding resistance that limits the regulation of these types of power supplies to no better than 5%. The regulation of the e.One power supply is at 10 to 50 times better than this while the transformer is 100 times smaller, an improvement of at least 1000 times in performance. This kind of performance improvement can only be had by the use of an SPS as in the e.One amplifiers.

The power supply performance defines the absolute limit of how well an audio amplifier performs. The remarkable performance of the e.One power supply leads directly to the remarkable sonic results that these amplifiers can achieve. The solid foundation of the e.One power supply translates directly to the solid musical foundation that the e.One amplifier provides to the sonic picture.

Further, because of the inductor input filtering at the output of the e.One power supply, there is very little AC residual signal at the output and virtually none of this AC residual lies within the 20-20KHz audio frequency band. Traditional 50/60Hz power supplies have a host of rectified noise residue extending up through the midrange audio frequencies, colouring the critical midrange and obscuring musical detail. You will note the remarkable midrange clarity and expressiveness of the e.One amplifier. This is largely because the power supply is devoid of these midrange residual frequency components.

e.One Power Amplifier Stage- Smaller is Still Better

The key advantages of a well-executed analog switching amplifier lies in the remarkable compactness and elegance of the amplifier. Both the 150-watt and the 500-watt amplifier architecture share the same basic schematic and topology, with changes primarily to the output stage MOSFET device, driver stage and output filter components to allow the 500-watt power capability. Topologically they are virtually identical, even though able to supply 300 and over 1000 watts of audio power the output stages use only 4 power devices, the entire circuit for each amplifier takes up only about a few square inches (20 square cm) of circuit area, no longer are high power audio amplifiers required to utilize banks and banks of large output devices spread over many square inches of area with each output device playing its own tune.

The result of this elegant and efficient design is superior performance, the communicative magic that people find in simple Single Ended Triode amplifier topologies is found in the comparable elegance of the e.One amplifier, however, levels of distortion, coloration, and noise are greatly reduced and the ability to hear through the amplifier to the original recording is unmatched.

Low noise input circuitry provides high dynamic range capability, starting at 111dB for the 150-watt amplifier, and going to 120 dB for the 500-watt amplifier. Indeed, noise levels of these amplifiers are lower than many amplifiers that produce much less than 100 watts of power. This low noise insures that subtle inflections of dynamics and timbre are reproduced with breathtaking realism.

Signal distortion is reduced to very low levels through the use of multiple nested feedback loop correction circuits, including one loop around the output filter components. This reduces output impedance to a minimum and insures that the influence of the output filter stage on the sonic quality is minimized, leaving the purity of the original signal intact.

Multi-Layer PC Board Layout for an Optimum Operating Environment

The sophisticated PC board design uses multiple layers of copper to insure that the high-speed circuit operation is optimized. Multiple star grounding and shielding of critical lines keep radiated noise to a low level and insures that the audio band noise of the amplifier remains at absolutely minimum level; this allows full development of subtle musical cues and insures that your music isn’t hidden by a falsely elevated noise floor. This precision layout approach uses devices on both sides of the PC board, to keep the operating board area to a minimum. Indeed, even the REF1000 amplifier stage occupies less board area than the input stages of typical class AB power amplifiers. This keeps the actual circuit path length to a minimum, further enhancing the low-level signal resolution of which the amplifier is capable.

Superior components complete the performance picture for the e.One amplifiers. Precision metal-film resistor devices are used throughout the analog signal path and application of high performance Polypropylene filter and decoupling capacitors is used to insure the best signal quality. Critical amplifier components are chosen for low noise and distortion in the input and control stage sections and the output switch devices are the latest technology for highest switching speed and minimal on-resistance, closely approaching the performance of an ideal power device.

Superior Performance and Reliability

Along with the superior performance of the e.One amplifier architecture there are equally effective and audibly transparent protection circuitries to insure that the e.One amplifier continues to deliver its superior performance under all conditions. These protection circuits monitor the amplifier and protect against output short circuits both to ground and across the speaker terminals of the balanced output section. Circuits monitor operating temperature and capacitive loading to insure that the amplifier will not be damaged by abuse, there are also DC monitors to insure that excessive DC voltage is not present to damage the loudspeaker connected to the amplifier.

Soft clipping circuitry insures that even if over-driven the e.One amplifier will overload gracefully, much like a well designed tube amplifier.

Conclusion

With the e.One amplifier, Bel Canto steps resolutely into the future of audio amplification. The mix of advanced technologies and elegant design insure that the e.One amplifier reaches rare heights of sonic and technical performance.