High Voltage & High Current

You will find Pure Class A and exceptional quality Class AB equipment mostly at “High End” (High Performance) audio stores, and some at the large home electronics chain stores. You should listen to as much of this equipment as you have time for – disregard the price for the moment – before buying anything. There are many excellent brands to listen to. Most are separate components (preamplifier, power amplifiers in separate chassis), but a few are integrated. In general, separate components perform better than integrated units because the circuitry from one section (power amplifier) will have its own power supply, and will not cause electrical interference with another section (preamplifier). This is particularly so with high powered systems. When evaluating amplifier power output, the numbers to look for are watts continuous (RMS or Root Mean Square) per channel from 20 Hz – 20 kHz into 8 ohms. If it says 6 Ohms, this value will be a little higher than it would be at 8 Ohms. If it says @ 1 kHz, this is not as good as stating the value at 20 Hz – 20 kHz.

A good power supply is extremely important, and can be one of the major factors which distinguishes the quality of two amplifiers that have the same specified output. The main components in a power supply are the power transformer, rectifiers, and some large capacitors. If the power supply is inadequate, then distortion will result when high power demands are made, such as during loud passages in the music. Whereas one amplifier rated at 100 watts per channel may “clip” (go into high distortion) at just over 100 watts, a different 100 watt per channel amplifier with a better power supply may give much more than 100 watts, at low distortion, for short bursts (a kettle drum thud in a musical passage, or a gunshot in movie, for example). Well built power supplies not only provide noise free electrical power to the amplifier parts, but are capable of delivering high voltage and high current. You will see why this is important in the section on speakers.