Can you use a speaker without an amplifier and does an amplifier itself make sound?


I feel stupid at the moment, but we have to choose what we do as a school project for next week. The most popular ones are an amplifier and a speaker. What’s the main difference between them? Can I use a speaker without an amplifier?

It’d be nice, if I would make my laptop’s and screen’s speakers sound a little higher. Do I need an amplifier + speaker to do that, or would only a speaker make that? Overall what would you choose to make as a school project from these two?

In: Technology

Speakers need power to make sound. Your laptop speakers draw power from the onboard soundboard. An external speaker can either be powered by its own power supply (it would plug into an outlet or USB port) or by an receiver or amplifier. An amplifier takes a signal and adds power. An instrument “amp” generally has a speaker and amplifier built in.

Hi 🙂

> difference

A speaker is just a coil, a magnet and a membrane.

An amplifier is a device that takes a weak signal and outputs a stronger signal.

Most speaker sets have a built-in amplifier. If it draws power (power cord or USB) it most likely has an amplifier built-in.

> Can I use a speaker without an amplifier?

A audio cable from your laptop runs a relatively small voltage and a bit of current. That’s enough to magnetize a coil of some headphones. The alternating current will cause the coil to become a tiny electro-magnet, switching polarities fast, and hence vibrate over a permanent magnet. This causes the diaphragm and air to move, creating sound waves.

To power a larger speaker, and thus a larger coil over a larger magnet, you will need more power. This is where an amplifier comes into play.

A larger speaker will be very, very quiet without an amplified signal. But it’s safe to try (unlike the opposite, using a beefy amplifier and a small speaker, which may damage the speaker).

> amplifier

The most basic amplifier design would be the weak signal of the audio cable running to a transistor. Transistors can switch lots of power with a small input. It would connect a larger power source to a speaker.

A single transistor amplifier sounds horrible though. Audio signals are AC (alternating current). Transistors can only turn a signal on and off. So you’re basically truncating the signal. It’s enough if you build a small Arduino robot that should play a tune or say something, but not for HiFi audio.

These days there are many cheap (as in under 10 cents) audio amplifier chips, and boards for 1-3 dollars that can drive moderately large speakers. A DIY circuit can be fun but isn’t really practical in most scenarious.


> It’d be nice, if I would make my laptop’s and screen’s speakers sound a little higher.

Unless you want to disassemble your laptop and install an amplifier, and possibly replace the small internal speakers, there is really no way to accomplish this without risking to damage something. Sometimes it is enough to push the audio signal up a bit. But at some point you will get “clipping”. It only works if the audio file / source has low volume to begin with and isn’t using the full range. If you were to install a beefy amplifier and hook it up to your laptop speakers, you might even damage them.


> speaker

What external speaker do you have? Most computer speakers aren’t just speakers, they have an amplifier built-in. Attaching another amplifier in-front doesn’t do much.


> Overall what would you choose to make as a school project from these two?

What kind of project do you have to make?

With a speaker, you can do a lot of stuff.

E.g. display audio wave forms by either attaching a small piece of mirror on the membrane, shining a 20 cent laser diode (or cheap laser-pointer) onto it, and using a signal (tone) generator. It will create all sorts of patterns on the wall. Another method is to put a speaker into a bucket, wrap a membrane over it, and use some sand or grains that will also form patterns.

Don’t know if this is too simple for your project but it’s fun and surprisingly high quality: the flat panel speaker.

Yes, you either need to build an amp, or, buy amplified speakers (they’ll have their own power plug). If you build your own amp, there are several online sources on how to build a headphone amp. The amplified speakers are your safest (and probably cheapest) & often come in ported enclosures.

You may want to see what your school has already for the situation. Check with the AV club (if you have one), and, your schools teachers, principals, and maintenance staff to see what’s already available.

Technically you can make a speaker’s cone move without an amp. If you wire a speaker up to another identical speaker and then physically push on one of the speaker’s cones… will make the other cone move. Why?


Because speakers and microphones are basically the same thing. You have a coil of wire attached to a cone next to a magnet. When you pass an alternating current through the coil, it creates a magnetic field that interacts with the magnet. When the voltage of the signal is positive, the coil will move away from the magnet. When it’s negative it will move towards the magnet.

The cool thing is though…it works the other way too. If you move the coil/cone relative to the magnet, it will *create* a signal inside the coil. (This is literally what a microphone is).

Not sure if any of that helps.