What size (power) of an amplifier should I use?
Updated: Aug 24 2018
The power amplifier is one of the most important elements in any A/V system, as too little power will not allow your system to live up to its full potential. In general, we recommend an amplifier with 100 to 200 watts per channel for most applications. Probably less would be adequate for our smaller hybrids or when used in home theater where a subwoofer is employed. Our hybrid designs will perform well with either a tube or transistorized amplifier, and will reveal the sonic character of either type. However, it is important that the amplifier be stable operating into varying impedance loads: an ideally stable amplifier will typically be able to deliver nearly twice its rated 8 Ohm wattage into 4 Ohms and should again increase into 2 Ohms.
That said, you should consider both your musical tastes and the size of your listening room. What type of musical content do you prefer and what listening level do you like the best-ambient, loud, or somewhere in between?
For instance if your listening preferences lean more toward chamber music, solo, or acoustic performances, then a smaller power amp will be adequate. On the other hand, if you enjoy symphonic music or rock-particularly at live listening levels then you will need a larger power amplifier. This is because, for the most part, chamber music doesn't require the extended volume range that symphonic or rock music performances do to fully reproduce the performance. Another important consideration is the size and character of your listening room. Character refers to its acoustic qualities. Does your room have a bright (reflective) or dull (absorptive) quality? Bright rooms are distinguished by their large flat hard surfaces, and dull rooms by their draperies and wall-to-wall carpeting. As a general rule larger rooms and duller rooms require more power to get the same live performance level.
Also, most multi-channel home theater/music systems incorporate amplified subwoofers (the .1 in 5.1, 6.1 and 7.1 channel home theater) which rely on your processor's bass management calibrations to reproduce the lower bass and sub-bass frequencies (80-100Hz and below). In this case, a portion of the power amp's output will be handled by the subwoofer amplifier, leaving more power available to the rest of the system. This allows the use of more moderately powered amplifiers while maintaining high levels of performance.
Your amplifier should also be capable of stable operation into a varying impedance load-delivering more power into lower impedance loads. This is because most musical content presents a constantly varying load to your amplifier with power requirements tied to the frequency of that content-as frequency rises, impedance drops and power requirements increase. The main idea is to have enough reserve power to handle transients like explosions, cymbal crashes, and other loud passages without overloading your amp.
Your MartinLogan specialty audio retailer has experience with a wide variety of amplifiers and receivers and can recommend the best components for your particular room size, listening habits, and MartinLogan speakers.