When I was much younger and living in a dorm I’d saved up to buy and lugged along a pair of speakers to plug into my record player (remember those?) that stood three feet high and had twelve-inch woofers along with a couple mid-range and one small tweeter. I was bummed because I couldn’t afford the ones with fifteen-inch woofers, never mind eighteen. It replaced my childhood player with one speaker built into the base holding the changer and the other that served as a lid when the player was being toted somewhere. No crossover networks, no nuthin’ but two small speakers. Even to my kid’s ears the sound was… adequate but least it was stereo.
Today, I’m installing a sound bar under my flat screen with a couple of speakers smaller than the tweeters in the old pair plus a sub-woofer that’s in an eight-inch cube — no telling how big the actual speaker is. To these admittedly old ears it sounds great, better that I remember the old dorm pair (and that’s with, um, rose-colored earphones).
Now, speaker sizes back (mumble-mumble) decades ago were pretty much like the watt wars prevalent at the time, Bigger is Better, so maybe they didn’t have to be quite so big, but what advances in materials and circuitry were made that can push way better sound out of a couple speakers a quarter the size of my kiddie speakers?
I have wondered that, too. Perhaps since much listening now is done with I-pads and other small devices that can’t drive larger speakers.
I’ll hang around for an answer.
Size matters, but it’s not really all that matters.
The material has not changed all that much in the last 20 year, but higher quality speakers are cheaper than they were 20 years ago.
A 12” woofer with 200W at 2ohm or 4ohm is not as loud/powerful as a 12” woofer with 200W at 8ohm.
The more ohm your speaker has at the same wattage rating, the more powerful the speaker usually is.
Wattage breaks down into:
RMS – that’s the level your speaker should works comfortable without getting stressed
Peak – that’s the level your speaker can go to before it goes bust
Program – basically similar to RMS
Since just saying 200 Watt only tells you so much about the speaker, there is also the quality of the speaker e.g.: the membrane material, the magnet & workmanship of the speaker.
…and then there is the amplifier.
They became way more efficient and better in the last 20 years.
What makes it loud is the amplification. Your little handheld, doesn’t have the power to drive big speakers by itself - neither did/does a cassette player, record player or CD.
An amplification is always needed, those docking stations have their own amplifier build in.
“bigger was better” way back in the day because amplifiers only had a few watts of power to deliver. so yeah, you needed high sensitivity (read:large) multi-way speakers to get reasonable acoustic output and fidelity.
nowadays, amplifier power is so cheap you can make smaller speakers and offset the low sensitivity by just throwing more power at them.
but no, loudspeaker tech hasn’t really changed much. there are different cone materials to try to smooth the frequency response above the breakup point, alternate shapes of voice coil wire to try to get more turns of wire in the gap, and some novel magnetic circuits, but at the end of the day most speakers are still a coil of wire inside a magnet, pushing and pulling on a cone.
I currently have a set of quality bookshelf speakers coupled with an 8" subwoofer. In the early nineties I had a set of much larger floor standing Sony speakers that had 12" woofers.
Now those bookshelf speakers probably make better highs and lows than my old Sonys, but my current subwoofer (which alone probably cost as much as the old Sonys) is just not the same.
Those old Sonys with 12" woofers could shake the room in way that the subwoofer cannot.
Longer answer:
The diameter of the bass driver is only one part of the design choices, and it only affects how loud the deepest frequencies can be reproduced, and even then is not the only determinant.
If you are not reproducing low loud notes there is no need for a large bass driver. It has no effect at all on the quality of sound at higher frequencies, and indeed trying to reproduce higher frequencies with a large diameter driver is almost always a bad thing, and leads to much poorer outcomes.
In order to reproduce low frequencies you need to move a lot of air. As the frequency drops the volume of air you need to move increases. You can reproduce low frequencies with a smaller driver, but the maximum loudness is limited - and that limits the maximum loudness of the entire speaker. The maximum is determined by the amount of air swept by the speaker cone - this is the area times the distance the speaker cone can move. Cheap speakers designed to look great often used large bass drivers that actually had pitiful excursion limits, and could not actually deliver. Further, the actual efficiency of a bass driver is a complicated beast, and is dependant upon the diameter of the cone, stiffness of the cone’s suspension, the cone’s mass, the magnet, resistance of the voice coil, and voice coil geometry. The final efficiency and bass reproduction characteristics are a mixture of the driver characteristics and the box design, which includes the box volume and the design of any port used. This is all covered by the Thiele/Smallparameters, and there is a (now) well understood design regime.
No matter what, if you want loud deep bass, you need large expensive drivers. The advent of home theatre and the need for an effects channel (the .1 in 5.1 and 7.1) added the pure subwoofer as a component, but before then the idea that you could have two small speakers and separate them from the bass reproduction had taken hold. But a further complication is often overlooked. The location in the room of the bass driver makes a massive and critical difference to the bass reproduction. Bass frequencies are long, and in any room you get significant interference patterns, and these change massively as the bass driver’s location is changed. One subwoofer is very difficult to locate to provide satisfactory bass performance, and when it does, it tends to only be in one listening position. (This of course is also a limitation with conventional speakers). More bass drivers in a range of carefully chosen locations makes a big difference.
There have been many advances in understanding and design of modern speakers, but good quality old speakers can still often hold their own. The physics has not changed.
I’ve opened the box and the sub-woofer is about 4½ inches in diameter and pointed down at the carpet. It’s ported though. The instructions say to simply “put it in a corner.” It’s connection is Bluetooth but I’m guessing at those low frequencies, compression isn’t a concern.
Now I’m puzzling over the best way to connect up the sound bar. I was expecting an HDMI port on the bar but it hasn’t one. Instead it has an optical port, a coaxial digital audio port (orange) and good ol’ 3.5mm and RCA jacks. On the BluRay player there’s a port marked “coaxial” but it’s black, not orange. I’m still looking for the player’s manual but, assuming that’s not a digital audio port would it be better to feed off the flat screen (which has optical out) or just go from the player to the bar with the analog RCAs?
I probably wouldn’t be able to tell the difference anyway.
The trick with setting up the inputs to the sound bar are going to be in working out what device has ultimate control of the switching and volume. The trouble with a lot of modern devices is that they all they they should. Usually the choice is either a central home theatre receiver, or for more simple system, the TV. Usually your blu-ray player is one a a number of possible sources - even if the only other source is a receiver for free-to air transmissions in the TV. This means you need to get the sound to the TV (so over HDMI) and thence to the sound bar from the TV with whatever it can provide. This means that the TV remote can be used to select input sources and control the volume.
The bigger the room, the more important it is for the woofer to become bigger, since it has to move more air in the room.
If the speaker gets more powerful, its very important that the amplifier gets more powerful as well.
What most likely the case in your situation is that your sub-woofer is not powerful enough (size and amplification) and also not properly located to get what you want or can out of it.
Also depending on how certain things are programmed/mapped in a 5.1 surround system the sub-woofer does not get properly driven or gets no signal to produce bass and since the satellite speakers are in most cases not able to produce bass as such, you’ll hear very and feel very little of it.
Some DVD’s just have Stereo and then your sub gets no input or very little, whereas a stereo system would still produce bass for the two speakers.
Subwoofers for 5.1 sound systems don’t have a very demanding job; they just put a lot of oomph into the very lowest-end, often submusical range. Two hundred watts and a smallish cone of modern, stiff, lightweight material will do the job fine - just as well as our 75W systems driving 15 inch stiffened paper cones did back in the 1970s, or better.
For most people frequencies below 100Hz have very little musical value - that is, they can’t distinguish between a really pure, undistorted note and one that would be evidently ratchety up in higher ranges. So “pretty damned good” is enough for most people’s use of most LFE speakers and amps. And audio gear is one of those things that has gotten pretty damned good across the price and performance spectrum.
The deep heavy bass is more about felling than hearing it or the kick, at least for me. Below a certain frequency you can’t hear it anyhow.
Here’s a 20hz to 20kHz Video on YouTube… my PC sub only started to produce anything at 45Hz, it just was not able to produce or amplify anything below.
Either way, most people are happy with the “pretty damned good” stuff anyhow.
When we talk about power, we can talk about average power and peak power. Strictly speaking, there is no such thing as “RMS power.” (Well, not quite… you can compute the RMS of a power waveform, but it wouldn’t have any meaning or utility.)
When someone talks about “RMS power,” I think what they really mean is that the average power at the speaker is determined by measuring the RMS of the voltage waveform and the RMS of the current waveform and then multiplying the two numbers. Of course, this would actually be apparent power, not real power. Measuring real power for complex (non-sinusoidal) waveforms requires a power analyzer.
Yeah, I meant to add that that’s why it doesn’t matter much where you put a subwoofer - it handles frequencies below the ability of human hearing to echolocate, and since the purpose is more physical resonance than hearing, shoving it in a corner is just as good and putting it in the center of the room.
For low-range musical reproduction, it’s a little more sensitive to location, but not for Gojira stomping through your living room while being nuked.
Nope. You’re thinking of a resistor. A speaker is not a resistor.
Let’s say I apply a 10 VAC RMS voltage sine wave to an ideal resistor; it will dissipate a certain amount of heat (power in Watts), and the resistor will come to a steady-state temperature (depending on a number of other variables). Applying 10 VDC to the same resistor under the same conditions will result in the exact same power dissipation and the exact same temperature. The resistor won’t know the difference between the 10 VAC RMS sine wave and the 10 VDC.
You can’t do the same with a speaker, since the complex impedance of a speaker is a function of frequency. And speakers are never operated at 0 Hz.
Again, we can talk about RMS voltage and RMS current. But there’s no such things as “RMS power” - only average and peak power. We can also talk about real, reactive, and apparent power.
Different speakers have different efficiency ratings, which is in terms of dB SPL (Sound Pressure Level, usually A or C weighted). I do not believe efficiency correlates to impedance (ohms). Furthermore, watts are watts: power is power. At the same efficiency, it doesn’t matter what the impedance is. For example, say I have an amp that can deliver 100W at 8 ohms or 200W at 4 ohms. If I plug that amp into one 8 Ohm speaker, I get X dB SPL. If I plug another identical speaker in parallel, which changes it to 4 ohms, I get twice the power, which is a 3dB increase in SPL.
Nope. RMS just means “root mean squared”. It’s a way to convert average AC voltages to equivalent average DC voltages. Covered better above.
Correct.
Well, it’s what you gave as the definition above, but it’s not RMS. For the kind of speakers I use for live sound, peak is typically four times program. Peak is to provide headroom for percussive / transient sounds; “program” is for how much power on average it will handle.
Program power ratings are based mostly on dissipating heat from the voice coil. Peak power ratings are based on that and any physical excursion limits or material fatigue (though hopefully not the latter).
… not to mention the efficiency. Watts by itself will not tell you how loud it’ll be. That’s like trying to convey area by giving only the length and omitting the width. However, it’s still often used as a rough guide, because the range of efficiency isn’t that huge for a given type of speaker. For example, for speakers for a smallish PA (such as for a typical small to medium pub) the efficiency is usually in the 90 - 100 dB SPL range, and for studio monitors, the typical range is closer to 80 - 90 dB SPL.
Note that 10dB louder is reported by most people to be twice as loud. Some people report 6dB to be twice as loud. It takes 10 times the watts to get 10 dB louder, though, so a 100 W speaker with a 100 dB SPL efficiency is as loud as a 1000 W speaker with a 90 dB SPL efficiency. So, watts really aren’t a very good guide!
No kidding! Great post.
To clarify:
We can’t tell the direction of low frequencies. So, the direction from the seating area to a subwoofer is unimportant. However, due to room nodes, the location of the speaker can have a dramatic effect. Location is actually very important! But the rule of thumb to stuff it in a corner minimizes most of the problems and is an easy one to follow.
Alternatively, you can download RoomEQ software, get a calibration mic (which is cheap, fortunately) and then spend considerable time learning the details and measuring your room to find the ideal location.
Which is probably a waste of time anyway, with a typical boomy little subwoofer. Adjust the bass EQ control until it sounds best, and you’re good to go. This is especially true when it’s used for TV/theater rather than audiophile stereo.
