soundsystems

soundsystems

For this module, let’s use the word “soundsystem” to describe a system that is designed to reproduce sound through speakers — a portable bluetooth speaker, a car stereo, a club soundsystem, headphones, etc.

Let’s think about the standards or typical characteristics of these sound systems. In typical listening environments, speakers are designed to disappear. Good speakers are often described as “transparent” and “faithful”. Today, stereo and surround sound (typically 5.1 surround) are technical standards through which we hear nearly all media and recorded music. Standards are great for a lot of situations. They insure that music will sound similar across any sound system. Surround sound standards provide movie theatres with consistent audio specifications. In general, standards like stereo and surround sound were developed in support of specific sonic ideas and creative requirements (music, film, the stage… but also realism, portability, profit, etc).

overview

Working in this way is not entirely new. Artists have been experimenting with speakers since they became readily available in the 1950s. Certain types of music grew in parallel to their projection formats — dub and sound systems (sound clash culture) in 1950s Jamaica and the acousmonium in 1970s France are two examples of sound systems built for specific types of music, where the speaker design (including visual & sculptural aspects) plays a large role in the experience. Artists have also used speakers in more experimental ways. Janet Cardiff’s 40-part Motet, Tristan Perich’s Microtonal Wall, Pauchi Sasaki’s Speaker Dress, Richard Lerman’s Travelon Gamelon, I-lly Cheng’s Water Tests, Dick Raaijmakers’ Ideofoons, and Lesley Flannigan’s Amplifications are a few examples. Work by Naaama Tsabar, Ed Osborn, and Ellen Moffat use speakers as sculptural elements, foregrounding speakers as functional, aeesthetic, and cultural objects.

questions to consider…

What possibilities might emerge in making sound systems and speaker objects that don’t conform to predefined standards. How might we shift the focus from a desire for transparency and foreground the speaker as an artform? What can playing with speakers tell us about sound? about listening? How does a speaker work? What are the different kinds of speakers? How might speakers change spaces? This project asks you to experiment with speakers as visual, sonic, kinetic, and expressive objects.

some questions towards extending this project…  what is a speaker? can objects speak without conforming to what we understand to be speakers (in a technical sense)? how might we request sound from an object (impact, motion, etc)? how might we attend to an already sounding object?

what types of expressivity are foregrounded and what types are subverted when using a technical standard? For example, We listen to speakers all the time, but what is a speaker actually doing? Like many other technologies, speakers rarely announce themselves unless they are broken or distorted — “what’s wrong with the speaker!”

What if we shift the focus and foreground the speaker as an aesthetic object? What can speakers tell us about sound? about listening? How does a speaker work? What are the different kinds of speakers? How do speakers respond to and articulate spaces? Experiment with speakers as visual, sonic, kinetic, and expressive collaborators.

recommended reading

• Loudspeaker as Musical Instrument
• Foundations of Jamaican Sound

how does a speaker work?

When things collide or move quickly, they displace air and make sound. If you hit a drum with a stick, you can see the surface of the drum vibrate for a bit afterward. That movement displaces air particles which displaces other air particles which forms a pressure wave that eventually reaches our ears. Speakers work in a similar way.

Instead of a drum head, there is paper cone (sometimes called a diaphragm) that is attached to the rim of the loudspeaker. The inner part of the cone is attached to a coil of wire (called the voice coil) that is positioned just in front of a permanent magnet. When you connect an audio signal to the loudspeaker, the electrical signals fluctuate and change the polarity of the voice coil, creating an electromagnet. As the voltage flows back and forth in the cables, the electromagnet either attracts or repels the permanent magnet. This moves the coil back and forth, pulling and pushing the loudspeaker cone, which moves air, not unlike the surface of a drum.

In order to make a speaker work properly, it needs the right kind of signal, a “speaker level signal”.  To condition your audio signal for a speaker, you first run it through an amplifier. There are two main types of speakers, passive speakers (which are simply speaker elements like those pictured above) and active speakers (that have a built in amplifier). Those little bluetooth speakers are active speakers — they have a built in amplifier. The bigger speakers attached to most older stereo systems are typically passive speakers and are connected to an amplifier to boost the signal. Passive speakers can be purchased for cheap at most thrift stores, and passive speaker components can be found online ranging from $1 to well, a lot. If you are building a specialized sound installation or sculpture or wearable sound thing, passive speakers are great because they are flexible and affordable and you can hide the amplifier somewhere else, making the speaker + amplifier option great for custom speaker situations and art projects. 

If you would like another perspective, this animagraff gives another overview of the anatomy of a speaker.

amplifiers

Some speakers have built-in amplifiers — these are called powered speakers and they have an electronic circuit within the speaker enclosure. This type of speakers will typically have a power switch and at least one audio input that lets you plug a source into the speaker. Most older speakers and higher end speakers are called passive speakers and they just contain the moving speaker elements in an enclosure of some kind. You need an amplifier to connect an input like a microphone, phone, or your computer to a passive speaker.There are a lot of amplification options that range in cost from around $2 to $2000. Note that bigger speakers generally require more power than smaller speakers, but some small amplifiers will work well with larger speakers too.

If you don’t have much experience with audio signal flow, take a look at this diagram:

Embedding an amplifier or amplifiers into your sculpture/system will let you connect a phone or computer directly to your project. By using a battery powered amplifier and embedding some kind of sound/media player you can create a piece that is portable, or at least not connected to any external devices.

There are a variety of amplifier options, depending on the form of and power requirements of your speaker. You can build a 386 amplifier kit. I have a few other types of amplifiers to try out, but if you’d like to permanently fix a larger amplifier into your project, you should purchase one.  Here are some options… all of them are available both at Lee’s Electronics and online. I go into them in detail below.

• lm 386 circuit (cheap, lots of sound with small speakers, a bit squawky, runs on a 9V battery, lofi cred)
• amplifier board (inexpensive, a bit more powerful, good sound, usually needs 12v)
• commercial amplifier (~$30, quite powerful)
• loud 8-channel amplifier (talk to me)

a few types of amplifiers

Smallest option (we have a few of these available in the wip lab)

These tiny little thumb-sized amplifiers require a power input between 5-12 volts (a 9v battery works well) and output about 2-4 watts of sound. In order to use this amp, you will need to connect an input jack and power like so…

I’ve made a video on how to connect power, speaker, and input without a soldering iron (for covid)

DIY option (also free)

This is a similar circuit to the tiny amplifier and if you enjoy working with electronics, it is not difficult to put one of these together. I have a detailed video on building these amplifiers and all the components are available in the WIP lab. Again, you don’t need to make an amplifier for this project. The focus is on the sonic and sculptural aspects of your project, but it’s here as an option. I also have pcb versions of this circuit if you’d like to build this circuit in that form.

Medium options (~$12-25)

These amplifiers are a bit larger due to the heat sink (the grill looking thing), but they have a built in barrel connector for power and can output 15W per channel (two audio channels, or stereo).

Larger Options (I have a few you can borrow)

These amplifiers output a lot of power and are great if you are using larger speaker drivers or exciters. Unlike the smaller options, they can easily produce very loud sounds and will be helpful in producing bass frequencies.

another option if necessary

This is an 8-channel amplifier that can drive up to 8 speakers at a time. I don’t think I recommend working with this type of amplifier for this project, but i have one and it is available if you’d like to expand on this project for the end of the term. It is significantly more complicated and requires some additional care. That said, i have one if you’re interested.

speakers

A speaker converts electrical energy into kinetic energy to project sound. Speakers range in size from a few millimetres to many feet across. If you are curious, here is a detailed history of speakers and speaker types. When working with speakers, I often remove the drivers (the moving parts) from the speaker enclosure (the box) and work with them separately, but leaving speakers in their enclosures will often lead to a more conventionally good sounding speaker, as the box itself helps to reproduce and amplify certain frequencies.

In general, larger speakers will be able to produce lower frequencies, but often require more power and a more expensive amplifier. In higher end speakers often contain multiple speaker drivers tuned to reproduce different parts of the frequency spectrum. Each driver will work individually and you can usually free the drivers from their enclosure using a screwdriver. Be careful not to ruin the two terminals on the back of the speaker driver (where the wires connect), we’ll use those to connect to the amplifier. You can also add to / remix a complete speaker without removing the drivers, just try to really transform your speaker into your own sculptural object.

What is a Speaker? How do they work?

When things collide or move quickly, they displace air and make the sound. If you hit a drum with a stick, you can see the skin of the drum vibrate for a bit afterward. That movement displaces air particles which displaces other air particles which forms a wave of displacement that eventually reaches our ears. Loudspeakers work in a similar way.

Instead of a drum head, there is paper cone (sometimes called a diaphragm) that is attached to the rim of the loudspeaker. The inner part of the cone is attached to a voice coil that is positioned just in front of a permanent magnet. When you connect an audio signal to the loudspeaker, electrical signals change the magnetic field of the voice coil, creating an electromagnet. As the voltage changes, the electromagnet either attracts or repels the permanent magnet. This moves the coil back and forth, pulling and pushing the loudspeaker cone, which moves air like the drum skin! Here is a good animated video describing how a speaker works.

exciters and transducers

There is another type of driver called an exciter or a tactile transducer. Transducers work using the same principle but instead of moving a cone of paper, these drivers vibrate whatever surfaces to which they are attached. This method will usually result in lower fidelity sound than speaker cones designed specifically for accurately reproducing sound. That said, they work surprisingly well on certain surfaces (cardboard, thin wood, plexiglass, furniture, etc) and allow for so many material possibilities.