This information is intended for newbies in the hobby. For gurus, just offer corrections where necessary. I apologize for the long post ahead.
Investing in audiophile-grade home theatre systems is not only costly but also prone to many mistakes. We all know that in Kenya, price doesn’t guarantee speaker quality, considering that budget systems are sold at a premium (with the excuse of taxes). Below are the things you need to consider before sinking your hard-earned cash into this hobby.
Sensitivity is arguably one of the most critical specifications in speakers. You will find this spec measured in Watt per metre. Sensitivity in speakers means the amount of sound energy produced at a single watt of power for a distance of one metre. If, for example, a speaker is rated at 98 dB at 1W/M (sometimes presented as 2.83Volts per metre if it’s an 8-ohm speaker), it means that it can produce sound energy of 98 decibels with a single unit of power kwa metre moja. This energy decreases as you move away from the speaker.
The reason sensitivity is essential is since it determines whether you need to invest in an external amplifier or not. Primarily, the lower the sensitivity, the more the power you’re likely to use to drive the speakers at higher levels (or at longer distances). You should note that for every 3 decibels increase in sound energy, power doubles. Hence, if your speakers are rated at 86 dB, to listen to them at loud levels (maybe around 108 dB to impress a lass), you will need to use 160 Watts of Power. Here is the math:
108-86=22dB ==> 22dB/3= 7.33 ==> the number of times power has to double for every 3 dB to reach 108dB is 7.33. Thus, if power doubles exponentially for seven times, it means 2^7.33= 160.8977 watts!
If, for example, you underbudgeted in your receiver department, your cheap receiver is likely to max out at 70 watts per channel when driving all 5 or 7 channels. When the receivers cannot supply enough power to speakers, it leads to what we call clipping. Mainly, clipping means that a part of the frequency is cut off at peaks, leading to distortion. The main issue with clipping is that speakers remain at high power for longer, which could easily damage them. Check [U]this PS Audio video[/U] on dangers of clipping.
The best way to avoid the dangers of clipping is investing heavily in highly sensitive speakers or buying an amp for external amplification. Klipsch has some of the most sensitive speakers I have seen at a “budget” level, especially their RP line (around 98dB @1W/M). Most midrange receivers supply around 100 watts of power when driving only two channels. For cheap stuff delivering around 50 Watts, please be content with “low” volumes or invest in an amp to drive the front stage.
FYI: Sensitivity does translate to quality sound. Quality in speakers is subjective in many cases. You might prefer those with dome tweeters or those that are horn-loaded (like Klipsch).
Timbre refers to the tonal aspects of a sound. These aspects are unique to each speaker and are pronounced when moving from one brand to another. As a newbie, never mix your front stage when investing in speakers. This means sticking to a single brand for the centre, front right, and front left channels. The front stage is the most critical part of a home theatre, and mixing brands here could result in sound imbalances that you won’t enjoy. Kama you’re buying Polk, make sure that the front stage speakers are timbre-matched by the manufacturer (the same line of speakers, in SVS, you can either pick Ultra or Prime line). It is also vital to pick speakers with the same driver sizes at the front stage. If the centre channel has 6” drivers, the front R&L should also be the same. Check [U]this Polk Audio article[/U] for Timbre-Matching speakers.
Frequency response refers to the sound output spectrum that your speaker can handle. For example, you will find speakers labelled 30-25,000 Hz. Make sure that this frequency response is within +/-3 decibels range. If it’s within this range, it means speakers have a relatively flat response and unlikely to exaggerate some parts of the sound.
A good subwoofer is essential in any setup. While there are many opinions out there about a subwoofer, one thing you should know is that subwoofer response is an objective rather than a subjective thing. This means that you cannot cheat your way into low frequencies. One of the most critical features of a good subwoofer is its ability to maintain flat response in low frequencies. Further, a good subwoofer should be able to reproduce sounds from around 20Hz even at low volumes. In my opinion, don’t get a subwoofer if it cannot dig 20Hz within +/-3dB. A subwoofer that cannot dig low frequencies effectively is likely to exaggerate sounds at around 30Hz to convince you that it’s fantastic. That’s when a sub sounds too boomy like mathrees :D.
I always recommend getting SVS PB 1000 (digs down to19Hz +/- 3dB) if you’re on a budget or live without one until you can afford it. Front stage speakers can dig down to around 30Hz, and using them alone is allowed.
Double subs are also highly recommended in the home theatre setups. Other than increased response, doubles are critical in addressing nulls in sound waves. Low frequencies have a very long wavelength, which means that some spots are likely to be “empty” in a room. Having double subs eliminates this issue and makes it almost impossible to localize where the BASS is coming from.
Enjoy your Weekend