Loudspeaker Types

Intro

There are many ways to distinguish loudspeakers, by enclosure / by speaker drivers type ➡ dynamic, electrostatic, horn (compression drivers) / by amplification type needed ➡ passive, or built-in active, etc... but in this post we will focus mainly on the most common commercial types of speakers that you will usually encounter when searching to buy or build one.

Note: Almost all speaker types that we will explain below can be either passive/active or mixed (active subwoofer with passive satellites with external power amp for example). ↪ Check the Crossover section in our This is the (loudspeaker) way... post for more.

Bookshelf 📚

A compact loudspeaker used for stereo pair or home theater applications, intended to be placed on a raised surface (speaker stand/desk) or mounted to a wall or ceiling.

Check our FS-LT 10 tilted stand here.

Usually the woofer drivers in bookshelf speakers are small 5,5"-6,5", so they need to be compensated in the low end, to reach the lowest octaves (below 50Hz) by a single 8"-10" subwoofer at least.

When to choose

If the space that you intent to dedicate for your listening setup is confined, but you want a good baseline, which in the future can be upgraded to a "basic 3-way" setup, by adding a dedicated subwoofer module.

Check our BB4 2-way example for more details & specs about bookshelf. ↪ In this example no sub is needed because the frequency response is sufficient:    38Hz - 18Khz, - 3db / 30Hz - 19Khz , -6db

Anything that goes down to 30Hz, relatively flat and until at least it's -6db  point (if not earlier at it' s -3db) should do the job. More db points in our frequency response diagrams ➡ here.

db points semi-unsuccessful artistic illustration...

Floorstanding/Tower 🗼

Floorstanding is a speaker that stands on the floor with no need for a speaker stand & usually occupies a larger footprint than a bookshelf.

It features multiple drivers from 6,5" and above (up to 10"-12" usually) & ideally has a dedicated mid-range driver. Its tweeter height should usually be close to the listening point/height of your ears when you are sitting, close to ~1m from the floor, so by default it inclines you towards a more serious listening session.

It has a larger cabinet & baffle size, usually offers better low end response with less diffraction issues and if the woofer driver is large enough (8"-10" and above) there is no need for a dedicated subwoofer module because the speaker can cover a wider frequency response range than a bookshelf speaker (can & should be able to reach at least down to ~30Hz).

When to choose

If you are determined to build a hi-quality (Hi End) sound setup & you are ready to compromise (in some degree) on the usability and space of your room over the listening experience.

Check our floorstanding section for more models, details & specs.

Example 4-way floorstanding

(Lab Acoustics future project)

Subwoofer, Satellites 📡 & multichannel setups

The most basic option here is the 2.1 setup, it consists of 2 satellites (they can be considered as 2 small-versioned bookshelves) and a subwoofer usually with a single 6"-15" diameter driver. This setup can be a good starting point that can be upgraded in the future by adding a center &/or surround speakers.

The small satellites & woofer (small volume cabins, with light material, Focal Sib Evo 5.1.2, etc...) are more convenient and easy to move around for multichannel setups (space-weight-wise) but results are far better if we replace the 2 front small satellites & woofer with 2 bigger bookshelf mains (even with a ~30Liters Heavy braced Cabinet/6.5" woofer) or floorstanding speakers with 8-10" drivers ideally.

2.1 basic setup example ➡ check our sub & sat's section for more.

Sub

Subwoofers usually have built-in amps (active) with a fixed crossover slope & a knob that can modify the crossover frequency from 60-120Hz. They also have a polarity switch (helping in minimizing cancellation in the crossover point region) which helps if the position of the sub cannot be optimal due to room limitations.

They can be ported (can go to deeper-lower frequencies) or closed box (have a tighter-punchier bass with more transparent transients) enclosures.

We tend to prefer fuller & lower frequency response over transients so we encourage you to go for the ported version... ported versions always have greater group delay but this is something that our ears cannot perceive, unless it's in comparison between 2 different channels playing simultaneously. Therefore we can't see (or hear) a reason not to choose the ported version subwoofer with the lowest frequency -3db point possible and definitely lower than a closed box sub.

Mains over sub...why? 
Because it is almost impossible to compensate the phase difference of the acoustical centers of the speakers drivers (between sub-satellites) without a custom "tuned" crossover and a fixed position between them. 
Fixed sub slopes in the subwoofer crossover will always have cancellation issues with the satellites, even if you manage to place the sub correctly in relation to the sat's and in combination with the listening position that you'll choose. 
This issue will also be "masked" by room reflections making it even harder to address with REW measurements or even compensate with room correction software completely.

Another reason to prefer 2 mains over one sub, is a more even bass distribution. If the sub is not placed at the middle between the 2 satellites, even if we place perfectly the 3 speakers against each other and we achieve perfect phase relationship (and even when the sub has a downfiring woofer), your brain in practice can perceive quite intensively & maybe more than you would expect, where the bass is located.
  ↪ In theory frequencies below ~100Hz are omnidirectional and in   
    theory you shouldn't be able to notice it at all. 
For the 2 mains this somewhat "minor" problem is practically non-existent. 

Mains
In the case of mains, the crossover slope problem is already tackled thoroughly in the building process of the crossover circuit of the speakers, by the speaker designer. The drivers remain in a fixed position because they are mounted on the same enclosure, so you won't have to worry about the crossover slope , the acoustical centers or the distance between them.

One small win for your ears here ⤵ or not... 

When to choose (2.1)

If you have minimal space to dedicate for your audio setup but you still need a decent quality entry level system, that can handle everything down to almost 30Hz. Keep in mind that, when you choose smaller drivers setups 3.5"-5.5`" mid-woofer for satellites & sub, power handling capability will be significantly decreased. This won't be an issue though, especially in small room setups, because in most cases 1-10 Watt RMS power, is enough dB/loudness to satisfy your ears in any scenario.

The most common multichannel speaker configurations

5.1

• Front (3)

  • Left, Right (22-30° each from listening position)

  • Center (0°)

• Back (2)

  • Left and Right surround speakers (~110-120° each)

• Subwoofer (1)

  • can go in any place that matches the distance of listening position to the right or left speaker (this is for timing purposes)

7.1

Adds 2 extra rear surround speakers to the 5.1 configuration, enhancing the sense of immersion.

• Surround Left-Right (90-110°)

  • shifted forward compared to 5.1 (110-120°)

• Surround Back Left-Right (135-150°)

  • +2 channels compared to 5.1

Atmos (7.1.4 minimum - 9.1.4 or above recommended)

Uses at minimum an extra 4 speakers for overhead/height channels (compared to 7.1) to create an even more immersive, three-dimensional sound stage.

These extra speakers positioned at 45° above the listening position, 2 between the front & surround speakers, 2 behind the surround back speakers.

Center

The center channel speaker is undoubtedly the most important and underrated one, in a home theater surround sound system. Almost ~60-70% of all audio content plays through that channel most of the time, because it mainly handles the majority of dialogues and vocals in movies & music. It is placed at the center of the setup (0°), below or above our screen or projector, pointing directly to our listening position.

Example 3-way ported center speaker

(Lab Acoustics future project)

Ideally, the center channel should be identical to your left and right speakers and designed with a horizontal orientation and multiple drivers which both help significantly to create the fullest dispersion pattern possible.

When voices or effects are panned from Hard Left-to-Center-to-Hard Right for example, these 3 elements combined with careful volume matching between the

3 front speakers, make every sound transition totally smooth & seamless.

Nevertheless any full-range speaker (not driver) can be used for the center channel.

Surround

Surround speakers are typically placed to the sides and/or behind the listening position, creating a more enveloping sound field. 

Their purpose is to extend the sound stage beyond the front speakers, delivering ambient and directional audio stimulus that enhance the sense of realism and immersion. 

They don't always need to reproduce the lowest bass frequencies, which is why you can get away with a smaller size speaker and drivers.

They reproduce a range of sounds, including ambient effects (like background noise), directional sounds (like a car passing by), and even parts of the soundtrack that complement the front speakers.

When to choose 

Surround 5.1 channels or multichannel 7+

If you are mainly interested in watching movies & also your budget permits to go above 3000-4000€. Multichannel solutions below 1000€ for speakers (with plastic or particleboard enclosures) combined with 7.2 channel amps of the same price (1000€ and below) won't quite worth it.

A simple 2.0 stereo setup with the same total price (speakers¹+amp² ~2000€) will usually sound a lot better and if these 2 components are chosen carefully you can always keep the existing setup and upgrade it later, by adding speakers/power amp modules in a future upgrade.

Portable/Bluetooth

This type of speakers work by receiving digital audio data wirelessly via Bluetooth* protocol (& sometimes an extra 3.5mm input) and are consisted of:

• a DAC, to process the audio

• an embedded amplifier (active)

  • which is battery powered

• a small 2-3" full-range speaker driver (usually) or multiple drivers

• passive radiators (most of the times) to extend the low end of the woofer driver at the smallest enclosure possible

*Bluetooth by default means not ideal playback quality. More about codecs & sample rates here & here.

Pros

• Convenience and portability

• Compact size

Cons

• Variable bit rate which is also dependent on the codec

• Latency

• Interference with Wi-Fi frequencies in the 2.4Ghz band

  •  Potential decreased data transfer speed and dropped connections

• Stereo sound cannot exist from 1 speaker. You need 2 speakers, paired and at least at distance 1m between them, so portability is kind of degraded for stereo sound

  
  

When to choose

• Casual listening/background music

• If the alternative sound solution is a laptop or mobile phone speakers

  
  

Some thoughts about its cons

Bluetooth may be good enough for some people and scenarios but you should not expect to do Hi End or critical listening sessions with this type of speaker. Whenever convenience goes up, quality goes down the drain...

It' s simply not the best way to represent high-quality content. Using wired/cable connections for your audio on the other hand, will always be the cheaper way which will also work better with minimum troubleshooting in connectivity and quality loss, even with the cheapest wiring. Good conductivity & tight terminal connections is all you need to "keep it up to the game".

Info: The last 2 types (Horn & Electrostatic) are a bit special & quite expensive so it's not the usual/budget way to go, but we will dig a little deeper to understand just about how they function for encyclopedic reasons mostly.

Horn

Is a loudspeaker which uses one (or multiple) horn-shaped structure(s), which amplifies and directs sound waves, eventually increasing the overall efficiency of the driver(s).

↪ About ~x10 times the sound power of a dynamic cone speaker driver, for a given amplifier output.

The horn is a heavily flared tube, which appears to be like a stretched/extended bass reflex port, but its function is quite different.

It is composed of two parts:

• the throat

  • the narrow part where the compression driver is "mounted"

• the mouth

  • the large flared part which "extends after the throat" & farther away from the driver

Its main function is to direct and amplify the sound waves that are created from the compression driver, which is coupled at its mounted base.

The radiation pattern (dispersion) of the horn is determined by the shape and flare radius of the mouth.

The most common form of horn speakers uses compression drivers which produce sound waves by vibrating a small metal diaphragm (aluminum or titanium) by an electromagnet. The drivers are attached to the horn, which then "guides" the sound waves to open air, acting like an impedance transformer, matching the high impedance of the driver to the low impedance of the air.

Folded Horn

Is another form of horn speaker in which a woofer driver (usually a coaxial) is mounted on an enclosure, which is divided by internal partitions to form a zigzag flaring duct which functions as a horn.

Pros

• Efficiency and Power Handling

• Directivity and Dispersion Control (not always a pro...)

• Dynamic Range and Clarity

Cons

• Large Size

• Resonance and Coloration

  • "honk" effect, specific mid-range frequencies are greatly emphasized, resulting in a nasal sound

  • Uneven Frequency Response

  • Due to their high efficiency and coloration, they need a lot of equalization & have potential for harshness in frequencies around 2-4Khz or above

• Beaming

• Complex Design and Cost

  
  

Electrostatic / Ribbon-Planar magnetic

Last but not least, electrostatic is a type of speaker with a special type of driver. It's actually a floorstanding speaker and the most modern iterations combine the electrostatic panel (mid-high frequencies), with a dynamic (or 2) driver(s) as a woofer or sub.

We will examine briefly its components & how they operate.

Components

• Diaphragm

  • ultra light conductive film which is stretched between two stators

• Spars (spacers)

  • non conductive spacers that keep the overall assembly of the panel stationary

• Stators

  • Steel sheets coated with some insulation material

Electrostatic vs Dynamic Transducer/Drivers

How it works?

These 3 components are sandwiched together so when music is playing, the diaphragm (+positive fixed voltage) moves backward or forward, interacting with the positive or negative field of both stators which are constantly either + or -, but always have opposite polarity between them and are interacting with the audio signal. This movement of the diaphragm translates into sound waves (by vibrating air molecules) in the room, that reaches our ears.

Pros

• Very light diaphragm material

• Very natural (air-y) response without resonances

• 2-way design with one crossover point is enough, no need for multiple drivers for mid-highs

• Fast Transient Response

• Clarity and Detail

  
  

Cons

• Cannot be fitted in an enclosure/cabinet

  • the reason behind: the diaphragm is so light that the stiffness of the air spring created in the enclosure, would drive the resonant frequency sky high with potential risk of damaging the diaphragm by reaching too close to the stators when overly ex-curved

  • Cancellations from the back side of the diaphragm (almost same as in open baffle)

• Lacking bass, membrane needs to be very large or paired with dynamic drivers for bass/sub frequencies

  • the membrane diaphragm also needs to be big to handle power as it has very limited excursion limit

• Poor directivity/dispersion

• Very sensitive/fragile

• Limited power handling capabilities when used for full-range

• Expensive

• Takes up space

  
  

Ribbon and Planar magnetic

These are naming variations of the same type of transducer.

Ribbon speakers are consisted of a thin metal film, wired to the signal which is suspended between opposing plates of magnets. As charge is applied, the film moves back and forth within that "suspension", generating sound.

Main difference between Electrostatic-Ribbon

Electrostatic: the signal is applied to charged stators on either side of the film.

Ribbon: the signal is applied to the film between magnets.

In both cases though, the sound is generated by the movement of a low mass film/membrane with high surface area, which is moving back and forth in a flat plane/setup.

Conclusion

Dynamic drivers in floorstanding speakers is the budget, audiophile way to go.

If you don't know where to start, a simple stereo setup with 2 "mains" speakers will do everything decently with minimum hassle & effort to set them up to your listening position. Adding multiple channels will increase the price & complexity of the overall setup pretty quickly but if you are brave enough and your pockets are deep, you can be sure that you will enjoy it when completed successfully!

If you want to reach a natural sounding result, with similar tone quality & character to an electrostatic speaker, with clarity & huge stage/stereo image, invest in speakers designed and based on drivers with light cone (woofer) & dome (tweeter) materials (carbon, ultra-light carbon-fiber composite TeXtreme, beryllium or diamond) with low moving mass, at least for the mid & high frequencies with braced/heavy enclosures & the biggest woofer diameter you can afford.

The results won't disappoint you...