Design Features
•High efficiency Digital Power Processing output stage for cool operation
•Analog signals are processed at small signal level, all large signal power is generated using the switching output stage
•700 watts of continuous power output capability in Balanced Mono mode
•Optimized balanced and single- ended input stage
•THD and IMD <0.05%
•Damping Factor >100
•High thermal stability in all stages
•Regulated, low noise supplies for all analog stages
•Audio Grade decoupling capacitors and resistors used throughout
•Soft clipping insures graceful over load
•High efficiency ‘green’ amplification
•Comprehensive protection circuitry outside the signal path
The eVo Digital Output Stage and Digital Power Processor
The Bel Canto Design eVo digital out- put stage is of unique simplicity. The output uses 2 N channel MOSFET switches switching between the power supply rails. These switches turn on and off within 30 billionths of a second and provide an onresis- tance path to the supplies of a few thousandths of an ohm. These switches switch alternately between the supplies at a rate over 600,000 cycles per second (600 kHz). When no audio signal is present, the ratio between the time at the positive sup- ply and the negative is balanced to provide no audio frequency output. The switching stage is isolated from the loudspeaker by a single LC filter stage. This 80kHz second order filter is used to reject high frequency ener- gy and maintain linear phase response.
Furthermore, the digital power processor adds small levels of high frequency dither to insure that an inherently linear output stage charac- teristic is maintained from very low to very high output levels. The audio frequency information modulates the output stage by changing the time relationship between the positive and negative supply rails. The critical timing information is controlled by the digital power processor and the effective switching frequency is changed over a 200 kHz to 1500 kHz range. This spreads the digital ener- gy created by the amplifier over a wide bandwidth, greatly reducing the energy at any one frequency. This permits using a simple LC filter to remove the high frequency energy and maintains excellent phase response.
© | page 3 | eVo User’s Guide 042104 |
