To achieve 75 Watts power into an 8 Ohms load and >110 Watts into 4 Ohms, the mains transformer has to be big. The Evolution 2 uses a 250VA toroidal transformer, which will provide enough current to almost double its output into 4 Ohms. To achieve high-end sound quality, no expense has been spared.
Separate windings are used for each of the high current high voltage and low voltage, analogue and digital circuits. A high capacity power supply using 20,000 micro-Farads of multiple smoothing capacitors are used to power the left and right power amplifiers and provide a very dynamic performance.
The Evolution 2 uses a high quality, Burr-Brown PGA2311, digitally controlled analogue volume control. This allows the user to adjust the volume accurately, from 0 to -80dB. An analogue style rotary encoder, with 40mm solid control knob, is used to alter the volume from the front panel and display the relative level on a large blue coloured VFD. Position 80 is the loudest and 0 is mute. To amplify the signals into the volume control circuit, a high grade Burr-Brown OPA2134 Op-Amp is used as a pre-amplifier. Signal switching is performed by gold contact relays, which are digitally selected from a microcontroller, similar to the Destiny Integrated Amplifier.
The Evolution 2 is configured with higher open-loop gain, using a double differential input and driver stage plus discrete Darlington power output stage, using high current bi-polar transistors. High grade polypropylene capacitors, bypassed with large value electrolytic capacitors, are used to couple and decouple the signal into the power amp.
To keep the amplifier safe, it is monitored by discrete transistor circuitry to protect against over-current demand, short circuits and DC offsets. Relays mute the input and separate the loudspeaker output in the case of faults.
The Evolution 2 operates conventionally with rotary controls for input selection and volume control and buttons for Tape selection and power On/Off. It has four inputs plus tape – including a new feature Direct AV, which bypasses the pre-amplifier and volume control to allow the power amplifier to be used in a 5.1 surround system. Input selection is via the SRC3 remote handset or the rotary input selection control. The display brightness can be altered from the SRC3 remote control handset.
Gold plated input and output sockets have been chosen to provide a good connection and appearance for a product at its price point. Loudspeakers are connected with 1 set of 4mm terminal binding posts, with plastic touch-proof covers. The amplifier also has a headphone socket which is becoming an increasingly rare feature of modern amplifiers.
Here is a list of things we have done to improve of change the mk2 amplifier.
- External, the front panel product designator now says EVOLUTION 2 Integrated Amplifier
- Functionality the pre-amplifier now provides a separate AV input. Selecting AV switches the input signal direct to the power amplifier. This allows the front channel of a 5.1 Receiver to be amplified by the EVOLTION 2 conveniently.
- The power amplifier section has been upgraded to provide better sonic and measured performance.
- The power amp’s open loop gain has been increased by more than x2. This has been achieved by altering the current through its input and voltage gain stages to improve the high frequency gain. Therefore, negative feedback has been reduced, to allow the amplifier to have a higher closed loop gain. The effect is lower distortion and noise.
- The preamplifier has been modified to remove a gain stage after the volume control. This has reduced unwanted noise, improved signal handling and lowered distortion. The distribution of gain in the pre-amp and power amps is now similar to Creek’s higher-end Destiny model.
- Unwanted or unnecessary capacitors have been removed from the signal path, in keeping with standard Creek practice.
- Signal paths have been shortened or rationalised to make improvements to cross-talk and interference suppression.
- The power supply has been optimised to improve speed and timing of audio signals.
- Mains transformer size has been optimised to improve performance.