Invented by Henry Kloss, the founder of Acoustic Research, bookshelf speakers came about when the development in technology made it possible to create smaller speakers with the high sound quality of the large, standing, floor speakers of the past. They are used extensively in home theatre systems, which require five speakers, as opposed to the two-speaker systems that were the norm before the 1990s.
Bookshelf speakers are often combined with wall speakers to create a sleek modern design. Wall speakers are mounted into walls, and they are ideal for people who do not want their speakers to take up floor or shelf space. They can create very low profile high fidelity audio environments and are commonly preferred to accompany flat screen TVs.
Before choosing which bookshelf or wall speakers to use with a particular amplifier, there are a few important considerations to be taken into account. Buyers should also be aware of the most characteristics of speakers and the technical specifications that should influence their decision.
Wall vs. Bookshelf Speakers
As a rule, wall speakers offer lower sound quality due to their lack of cabinet space. While there are excellent in-wall speakers on the market that do not have this problem, they are generally twice or three times as expensive as bookshelf speakers of the same quality.
A very good option for home theatre systems is to use bookshelf speakers for the fronts, where the best quality is needed, and in-wall speakers for the surrounds in the back.
Matching Amplifiers and Speakers
The power of an amplifier is commonly mistaken to be directly related to perceived loudness. In fact, power output is relevant for speaker efficiency and dynamic range, and it is affected by speaker impedance.
Impedance is one of the most relevant characteristics of a speaker. It is measured in ohms, usually measuring either four, six, or eight ohms. A lower impedance places more demand on the amplifier. For example, six Ohm speakers connected to an eight Ohm amplifier would overload the system, producing a less clean sound. Mismatched combinations between speaker and amplifier can cause shutting down in certain instances, for example, after loud scenes in films.
Expressed in decibels, speaker efficiency measures what the speaker’s output is like for a certain amount of amplifier power. It is commonly measured using a microphone placed at a one-meter distance from the speaker, using a level meter that measures the output volume in decibels when the speaker receives one watt of power.
A very efficient speaker has a range of 105 dB, while a rather inefficient speaker would have 85 dB. Speaker efficiency is not, however, directly related to amplifier power. A speaker with an efficiency of 88 dB requires ten times the amplifier power to achieve the same output volume as a speaker boasting an efficiency of 98 dB.
Dynamic range refers to the range between the softest and the loudest moments in a sound track. When music grows louder, there is a demand for more power. While soft passages in music may require little power, crescendos and loud passages can require a lot. The ability of an amplifier to deliver these outbursts of louder sounds for a brief period is called headroom.
Matching Power Ratings
Sometimes, manufacturers list the average power rating and sometimes they list other kinds of power ratings. Therefore, matching what the manufacturer says is the power rating of speakers and that of the amplifier can sometimes be misleading.
Amplifiers’ output power for each channel is connected to speaker impedance, which is expressed in Ohms. An amplifier rated at 100 watts for an eight Ohm load is rated at 190 watts in the case of a four Ohm load. Thus, it is always key to check speaker impedance in order to evaluate power rating.
The main focus for avoiding speaker failure must be the relationship between the amp’s maximum capability and the speaker’s power rating. When the listed power rating for the speaker is RMS or average, this can be compared directly with amplifier ratings. Generally speaking, a speaker rated at 100 watts RMS is usually right for an amplifier that delivers 100 watts per channel. Nevertheless, when one plans to play music with heavy bass sounds or hard rock, the speaker needs to be rated at double the power of the amplifier, in order to be able to handle high distortion levels.
A good general rule for matching speakers to an amplifier is to give them 10 percent more power than they are designed to handle. If the amplifier does not need to work that hard to drive the speakers to the full of their capacity, the sound is cleaner and increasingly dynamic.
Important Speaker Characteristics
Regardless of what most people tend to believe, large speakers do not necessarily imply a louder sound. There are many aspects of speakers that play an important role in the quality and power of the sound output.
Frequency range measures how wide a range of sounds a speaker can reproduce, from the lowest to the highest frequencies. Speakers that can reproduce very low bass sounds with fidelity tend to be expensive, and this often has to be sacrificed when one is on a budget.
Sound-staging, or imaging, is very important when buying a pair or a set of speakers. It refers to the speakers’ ability to create the right sense of width, depth and height. Sound-staging evaluation can only be done by testing the system, preferably with simple, acoustic music.
While some speakers only sound good at loud volumes, the main aspect to consider in terms of volume is the ability of a system to sound good at both the lower and the higher volume ranges.
People who prefer rock may favour losing a bit of accuracy in order to gain bass range. Those who are more inclined to playing acoustic tunes might similarly give up some bass range in order to obtain clear and smooth midrange frequencies.
The room where the speakers are placed has a lot to do with the quality of the sound. As a rule, the best sound can be heard from a point between the two main speakers. Certain things like windows or wood floors commonly diminish the quality of the sound, regardless of how much money one chooses to spend on a great sound system. However, good carpeting and curtains can usually help with this kind of problems.
A speaker’s cabinet plays a major role in the device’s sound. While plastic can be used for computer speakers, serious speaker cabinets must be made of either wood or MDF. Cabinet material and cabinet design are equally important, as it is design that determines where sound waves can go and how they interact inside the speaker.
How to Buy Bookshelf or Wall Speakers on eBay
You can find hundreds of great bookshelf speakers and in-wall speakers on eBay. They are generally listed with full specifications, which allows you to match them with your amplifier. To find them you can use the search bar at the top of every page. Simply type in relevant keywords, such as “stereo speakers”” or “bookshelf speakers””, and then click “Search”. For standard home theatre options, you can search for the keywords “5.1 System speakers””, which means you receive all the results for five-speaker surround systems. To narrow down your search in order to find speakers matching your amplifier’s specifications, you can also input extra keywords such as 100W RMS. However, the more specific your keywords, the fewer results you receive.
If you are buying new speakers from a brand you are familiar with, you can count on being sure about what you receive. However, when buying speakers you have never tested before, especially when they are used, seller reputation is one of the most important aspects to consider.
Used speakers can be damaged in subtle ways that can only be perceived when listening to music with certain characteristics. Therefore, when buying used items, it is very important to ask the seller some questions, in order to make sure there are no surprises.
While bookshelf and wall speakers do not tend to be extremely heavy, they may require pricey shipping due to their dimensions, therefore, it is always important to check shipping costs and delivery times before purchase.
Buying a good set of speakers for a home theatre or for music listening requires a certain degree of technical knowledge. The wrong set of speakers may become damaged when used with a specific amplifier, and the power ratings of both devices need to be taken into consideration to ensure safety as well as best performance.
It is more important to buy speakers that are well-adapted to the user’s personal preferences than an expensive set of speakers. Loudness is not directly determined by wattage, and it takes a lot of power to double the output volume of a system.
Bookshelf speakers are comfortable in that they can be easily moved around, whereas in-wall speakers have to be set in one place. Moreover, wall speakers sometimes offer poor sound quality due to their lack of cabinet space.
It takes a bit of planning to find the right bookshelf and wall speakers for your amplifier, but the results can be very rewarding.