Bring over some of your old Motown records
We’ll put the speakers in the window and we’ll go
On the roof and listen to the Miracles
Echo to the alley down below
– Rod Stewart
This will be the second last article in my expensive stereo series. (Maybe…)
And here you thought that turntables were expensive…
Some would argue that the two most important components of a hi-fi system are the cartridge and the speakers. It may not be as simple as that, but as you will see, there is a staggeringly large amount of complexity that can and does go into speakers.
The loudspeaker was first invented as a component of telephony. Basically a speaker is a way of converting electrical signals into mechanical vibrations; i.e. sounds. The first real speakers as we would recognize them today were developed around 1925. In general terms and for the purposes of the discussion here, we will define a speaker as one or more ‘drivers’, possibly some electrical crossover circuitry, and an enclosure.
Drivers fall into types, based upon the frequencies that they are emanating. Low frequencies are handled by a woofer (50hz – 1kHz) or in the case of very low frequencies a sub-woofer (20hz-50hz) Most woofers are comprised of a magnet, a voice coil, a frame, and a cone. A wide variety of materials and construction methods of frames and cones have been employed, but all have their pros and cons and there are inevitably trade-offs. Sub-woofers typically are active designs, employing their own on-board power amplifiers.
Tweeters are drivers at the other end of the spectrum handling frequencies at or beyond the range of human hearing. (20kHz and beyond) Tweeters often times have a similar construction to woofers, but also lend themselves to more exotic designs. And as with woofers there is no single design that is best.
As one can imagine there is a third type of driver known as a mid-range. (250hz-20kHz)
When multiple drivers are used crossover circuitry is utilized. This is a type of filter that splits the signal into different frequency ranges. Two basic types exist. Passive and active. Passive are the most common. The term indicates that no additional power is required by the circuitry. Simple, but usually low performance, and they suck a lot of available power from the amplifier. High performance passive crossovers are out there, but they are difficult to make, thus expensive. Active crossovers on the other hand require the use of additional amplifiers in the circuitry. Complicated and expensive, but usually delivering higher performance across a variety of parameters.
The other main component of a speaker is the enclosure. This is the cabinet or box that holds all of the drivers and associated equipment. But it is far more complicated and involved than just that and is really integral to quality sound reproduction. There are many variables in play when it come to enclosure design…. The main function of the enclosure of course is to physically support all of the drivers and other components; but also to prevent the sound waves emanating from the back of the drivers from interfering with those coming from the front. The rearward sound waves are out of phase with those emitted to the front. Without some form of enclosure they can cause cancellations which degrade the level and quality of low frequency sound. The shape(s) and material selections can get pretty bizarre and eclectic as we shall see.
These days there are a variety of computer simulations that allow for fairly complete modeling of speaker design that includes the combined effects of drivers, crossovers, and enclosures. This can even take into account listening room dimensions.
One other type of speaker design that I will briefly mention is the Electrostatic. This type of speaker has three main components: Stators, Spacers, and a Diaphragm. The Diaphragm is usually an ultralight and thin plastic membrane impregnated with electrically conductive material. This is in turn held taught between the stators which are two sheets of perforated steel. The insulating Spacers separate everything ensuring that the Diaphragm doesn’t touch the Stators. The Stators are connected to the amplifier; which through a transformer supplies a high voltage signal of equal but opposite polarity to each Stator. These rapidly changing charges cause the Diaphragm to move backwards and forwards thus generating the actual sound waves. If memory serves me correctly the good ol’ Desert Mountaineer owned a pair of KLH9 electrostatics way back in the day…
Like with all of the other stuff in this series… you can go from the sublime to ridiculous.
Starting near the lower end of the ’good’ spectrum here is a nice speaker in a more or less classic design.
Made in Arkansas. There is an amazing amount of attention paid to the detail of the enclosure. Crafted from over 100 panels. Book matched wood to ensure that each enclosure pair is virtually identical to one another. That said it’s still made of plywood. Although it comes in either Ash, Walnut or Cherry finish. Claimed to be the only fully horn-loaded speaker in the consumer market designed to operate in a corner. It sports a 15” woofer, 1” tweeter, a 2” midrange driver, delivering a frequency response of 33Hz to 17kHz
Next in line is the only electrostatic speaker that I will highlight.
U.S. / Canada. These are one of only a few serious and good electrostatics on the market today. They stand almost 2m tall and weigh in at 175kg ea. Frequency response is 23Hz to 22kHz. Bass is supplied by a forward facing 30cm sealed mid-woofer and a rearward facing 38cm ported woofer. The curved electrostatic panel is designed to overcome the stereo dispersion limitations that flat panel electrostatics have. The actual electrostatic diaphragm in this speaker is only 12microns thick. These speakers will accept up to a whopping 1300w per channel. The frames are made from a phenolic resin polymer and come in 7 colours.
For those with a little bit more discretionary spending money in their pockets…
From Estonia. Space age baby. The enclosures are constructed from a proprietary marble based composite. That along with the cabinets shape help to virtually eliminate any unwanted internal resonances and diffractions. These are 1.7m to 2.1m tall; adjustable to suit listening space acoustics and users preferences, and weigh in at 250kg each. They are a 4-way passive system with: 2 x 250mm woofers, 1 x 250mm mid-woofer, 1 x 168mm midrange, and 1 x 25mm tweeter (vapour deposited diamond membrane). 20 – 500w rated, with a frequency response of 25Hz to 60kHz
If you want something that will also look really good on the deck of your starship check this out
Hand crafted in Germany. You had better have a large and sturdy listening space. These baby’s are 2.3m tall and weigh in at 250kg. Frequency range is 22Hz to 22kHz. Thanks to the ’bass-jets’ they can produce bass waves 10m long! The mid-range horn is powered by a 500w MOSFET amplifier. This thing is chock full of filters and electronic wizardry which allows the sound to be optimized to the listening space. Don’t worry… they are custom made so you can have any finish your heart desires.
Chump change you say?
Made on the Isle of White. If you really have some money burning a hole in your pocket, then this is the speaker for you. Cast out of gold! Yep. Really. The shape of the enclosure, plus the fact that it’s solid metal contributes to the cabinet being almost completely silent, and the energy from the drivers all goes into the listening space, and not into vibrating a cabinet. This is a 3-way speaker, with a bass/mid-range driver, a tweeter, and a ’super tweeter’. Frequency response is 47Hz to 37kHz. You can always cheap-out and go for the silver or bronze versions.
But when he plays with the bass and guitar
They holler out, beat me daddy eight to the bar
– Raye / Sheely / Prince