Thursday, January 30, 2014

Can someone explain speaker systems to me?




jl_0517


I'm interested in purchasing a speaker system (preferably 4.1 or 5.1). Can someone explain to me what exactly what makes a good speaker system? I looked at some high end speakers and low end speakers and what sticks out to me the most is watts. Can someone give me a detailed explanation of all the ins-and-outs about speakers? Things like RMS, total watts peak power, the different length drivers, satellites, etc.. Best answer goes to the most explanatory and helpful! Also showing me some deals would also be helpful. No need to explain sound cards to me though. Thanks! :]


Answer
Power ratings tell you absolutely nothing about a speaker system's sound quality. Besides, most big-name retailers sell systems with inflated or flat-out dishonest power ratings anyway.
But, since you asked, I'll tell you what the terms mean.

Power is how much power (electricity) a speaker system can handle without being damaged (and contrary to what xxxnullifierxxx said, power ratings actually rate how much power it can have sent INTO it, not how much power it puts out). RMS power is how much power it can handle continuously, and peak power is the absolute maximum amount it can take, even if for a short amount of time.

Now about the different types of speaker systems. There are 3 different types of speakers you will hear about: subwoofer + satellite, bookshelf speakers, and floorstanding speakers.

Subwoofer + satellite speakers are composed of 1 big speaker for bass (the subwoofer) and smaller speakers for midrange and treble. Advantages: take up less space. Disadvantages: sound quality often suffers, since many of speaker manufacturers try to make their satellite speakers as small as possible (more about this later).

Bookshelf speakers: speakers where all the sound (bass, treble, etc) come from 1 speaker rather than a satellite and a subwoofer. This design is advantageous because the sound quality is often better than subwoofer + satellite designs. So, instead of having 1 subwoofer and 2, 5, 6, or 7 satellites (depending on whether you have stereo or surround sound) you just have 2, 5, 6, or 7 bookshelf speakers. These bookshelf speakers can range from about 1ft x 0.5ft x 0.5ft to about 3ft x 1.5ft x 1ft.

Lastly, we have floorstanding speakers, which are similar to bookshelf speakers except each speaker is bigger---big enough to stand by itself on the floor, hence the name.

Now to talk about drivers and crossover frequencies. The driver is the part of the speaker that actually produces the sound waves (tweeters, woofers, etc). Generally, the larger the diameter of the driver (and generally, drivers are circular, though there are some exceptions--some woofers are square, for example), then the lower the frequencies (pitch) it can produce. For example, a driver with a diameter of 3 inches generally can't produce frequencies below about 200 to 250 Hz. This is where the problem lies with many subwoofer + satellite systems: many manufacturers are trying to make their satellites smaller and smaller and thus they can't produce the lower frequencies as well. So now, you will hear a gap between the bass that the subwoofer produces and the higher frequencies the satellites are producing. Some speaker systems try to compromise for this by making their subwoofers produce both bass and some higher frequencies also, but this introduces another problem into the sound: these slightly higher frequencies are more directional than the bass. So, if the subwoofer produces only bass, you can place it in various spots in the room (in front of you, behind you, etc) and hear no difference. However, if the subwoofer produces bass and some higher frequencies too, then you can hear a difference in sound depending on where the subwoofer is located. In fact, this problem has become quite widespread: a few manufacturers are actually trying to make satellite speakers using multiple tiny 1" speakers (THOSE SPEAKERS SOUND HORRIBLE!!!!). For example, many subwoofers sold in commercial stores (Sears, Walmart, etc) actually produce so many of the higher frequencies that, if you were to disconnect the satellite speakers, you could still hear all the voices in a movie or TV show; that is, you could still follow the dialogue with the satellites unplugged. This is quite inconvenient, since originally these systems were designed to allow you to have only small speakers in sight and allow you to stash the big subwoofer almost anywhere without affecting sound quality.

Bookshelf speakers, meanwhile, usually have (depending on the model) either 2 or 3 drivers inside. Unlike the subwoofer + satellite design, however, each speaker is intended to be treated sort of like a satellite speaker (meaning that you place it to the left or right of you instead of just placing it out of sight like the subwoofer). Thus, the directionality thing is not an issue.

Floorstanding speakers work basically like bookshelf speakers, except they are larger and taller usually.

Lastly, there are some other things to keep in mind when buying a speaker system:

~ Sturdy cabinets/enclosures (the things that house the drivers). Heavy, thick wood (MDF, HDF, plywood, etc) is a good thing. Plastic, especially thin plastic, is a bad thing. You see, as the drivers produce sound waves, they produce them both in your direction and they also produce them inside the speaker's enclosure. If you have a flimsy plastic enclosure, the vibrations produced inside the enclosure will make the speakers' cabinets vibrate too, thus adding extra, unwanted sound waves. By the way, most computer speaker systems and most home-theater-in-a-box systems you see at major retail stores are very poor in this category: thin, flimsy plastic for the satellites and thin 3/8-inch particleboard for the subwoofer. Many floorstanding or bookshelf speakers sold in major retail stores also use the poor-quality 3/8" particleboard for speaker cabinets.

~ Distortion. Thanks to the laws of physics, speakers can't produce the sound waves exactly as they are supposed to be produced. Even the highest quality speaker systems in the planet introduce a few extra artifacts into the sound that weren't supposed to be there and still can't produce every single little sound in the sound recording. There is a way to measure how much the speaker changes, or distorts, the sound when it produces it, and this is called THD (total harmonic distortion). There are some other measurements as well, but I don't know much about them (plus you don't need to worry about them) so we'll stick to the basics. THD is expressed in percentages. Aim for less than 1% when buying a speaker system; any more and the added imperfections in the sound they produce will become quite obvious. Here is where many speaker systems deceive you: as you force them to take more and more power, thus forcing them to play louder, they add more distortion to the sound. Right now, many of the systems sold at major stores base their power ratings on 10% THD, meaning that if they are rated for 1000 watts, they will really be producing 10% THD at that power level (that is A LOT of added imperfections in the sound and it will sound atrocious). If you were to measure how much power they could handle while still playing with a reasonable amount of THD, the power ratings would be much lower. Additionally (and here is yet another reason why power ratings are meaningless) many manufacturers measure these ratings in more deceitful ways than just the THD issue. Many systems nowadays come with a built in power supply that can only supply a certain amount of power to the speakers. If you have a surround sound system, that limited amount of power may have to be divided up into 7 or more speakers. Now, in the real world, if you are using your surround sound system to watch a movie, you're probably going to have sound playing out of all 5 speakers at once: some dialogue in the front speakers and some background sound effects in the back speakers, for example. However, many manufacturers calculate their power ratings when only ONE speaker is playing at once, meaning that the system's power supply does not have to divide its efforts up between 5 to 8 different speakers. Then the manufacturer multiplies that number by the number of speakers, thus achieving an extremely unrealistic power rating. Additionally, if you want to play your speakers loud (I know a lot of people do--and unfortunately, volume seems to be the only thing people care about nowadays) then power rating tells you nothing about the volume levels the speakers can produce. Some speakers are very efficient and can put out over 100 decibels (dB) of sound, easily enough to cause permanent hearing damage, when fed less than 10 watts of power; other, less efficient speakers can't produce that volume level when being fed 100 watts of power. And lastly, neither power ratings nor volume are an accurate way to judge how high-quality a speaker is or how good it sounds. There are some speakers, both high wattage and low wattage, that will sound bad at any volume, and some speakers, both high and low wattage, that will sound good at any reasonable volume (meaning any volume that isn't absurdly high). So there's really no way to judge whether a system will meet your needs based on its power rating.

And lastly, to warn you against that idiot xxxnullifierxxx--the Logitech system he references is not a driver free system. Drivers, remember, are the actual components that produce the sound waves. So a driver free system would not produce any sound. And trust me, that system is not high-end. It's a computer speaker system, the satellites' enclosures are made of flimsy plastic, and I have never met any computer systems (Logitech or otherwise) who use sturdy materials for the subwoofer enclosure.

Sorry, I think I explained some topics better than others, but you get the general idea.

I need help buying a speaker system?




lala


So I'm planning on buying some new speakers.
I currently have some BOSE Companion 2 Series II, my problem?
The sound is horrible. The Bass etc.
I was like 12-13 when I bought them and I had no clue on what to look for.
I'm looking for some speakers, studio speakers, theater system. Anything.
Something with a good amount of bass and will play crisp sound yah know?
I dont have a limit right now so anything goes.

~~ I play games, and make some music here and there, and listen to a lot of music.
** The speakers will mostly be used with the computer or an iPod.
~ Shelf systems are cool to.

Either give me links to some speakers or lecture me on how to choose the right ones.

Thanks~ :D



Answer
One thing is certain, when it comes to home theatre, "Creative" is not best! You already have toy speakers with your Bose, you don't want an even crappier toy.

It would take volumes of books to explain everything there is to know about this. I would suggest you start by finding and visiting a high-end home theatre or audio shop. I'm not talking about a Best Buy with a Magnolia, you need to find a real audio shop. Listen to some nice B&W's or similar in the $5000 to $25,000 range. I know that's out of budget but you need to first get an idea what a real audio system is. Step up your understanding of sound reproduction and of listening.

Unfortunately no speaker company supplies you with useful specifications so it's almost completely pointless to even look at these. Maybe with a high-end speaker you can at least get relatively accurate on axis frequency response data but that is only about 0.05% of the information you need. They will not supply you with detailed non-linear distortion data probably because they don't have it, maybe don't even know how to measure it. In fact they won't supply you with any distortion data, non-linear or linear. They might supply you with some off axis frequency response data but probably only to about +/- 30 deg. You really need 360 deg data but the results much beyond +/- 30 will typically be so bad they will not want you to see it. This is an inherent problem with conventional speakers, it's not a quality issue, it's just an inherent design flaw that doesn't change from the cheapest to the most expensive mono pole speaker designs. To avoid it completely you have to go to some sort of true omni directional speaker like the Duevel http://www.duevel.com/Produkte/EBLdia.shtml but this isn't necessarily optimum either since it maximizes room excitation. Dynamic dipoles like the Linkwitzlab Orion http://www.linkwitzlab.com/ do not have the power response uniformity of a true omni but they are far more uniform than a conventional monopole with less room excitation than conventional monopoles.

As for conventional designs, one of the big factors that degrades sound quality is the cabinet or box. You want to listen to the speaker cones, not to the cabinet walls. If you feel the vibration in the cabinet walls while the speaker is playing then you also hear the cabinet walls. Some cheap speakers actually radiate more acoustic energy from the cabinet walls at select frequencies than from the cones. This contaminates the sound making it sound very garbled. That's why better speakers are made from 3/4" to 1" MDF with internal bracing in an effort to reduce cabinet resonance. This is an advantage of speakers like the Orion because it has no box.

Poorly designed crossovers also make a major difference. Most inexpensive speakers use inadequate crossovers frequently with nothing more than a capacitor or a capacitor and inductor on the tweeter and nothing on the woofer. Cone resonance in the woofer must be eliminated to reduce the harshness of the speaker. A simple 2nd order crossover on the woofer can reduce this problem significantly but to do it properly requires notch filters. Especially modern drivers using various metal materials for cones need to have special attention paid to this. Unfortunately a lot of manufacturers brag about these metal cones and use them improperly without the proper equalization. Some metal cones break up so violently they produce high Q +20 dB or greater peaks that can only be completely eliminated with active equalization.

Subwoofers are a really good idea. If you really want decent bass you need to forget about going for bigger main speakers, just go for small to medium size main speakers and put the bass load onto a subwoofer. You can find a lot of good measurement data on subwoofers here... http://www.hometheatershack.com/forums/subwoofer-tests-archived/6015-index-subwoofer-tests-manufacturer-model.html If you study these measurements and understand them, it will help you to understand what to look for in a sub. Notice that non linear distortion is very high on pretty much all of them at very low frequency. It's really difficult to make a low distortion subwoofer and I do not know of any commercial offerings that are even close to good enough. You can look for those that have less distortion than others and you can look for those where odd harmonics are lower than even harmonic components. Odd harmonics are more destructive to sound quality than even. Sometimes a little even harmonic content can be a good thing if it helps to mask the odd harmonics.

Study the data on the subwoofer site and study the information on the linkwitzlab site. Also, go listen to some high end stuff so you know what's possible. Stay away from toys like Bose and Creative.

mk




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Title Post: Can someone explain speaker systems to me?
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