Instructables

Make a simple speaker louder.?

I have a small simple speaker - just the magnet part, with no wires - and i have connected the positive and negative terminals to a simple 3.5 mm audio wire. The speakers play sounds, but at a very low volume even when the volume is max. Is there anyway to increase it?

frollard2 years ago
The audio output jack on most electronics is designed for line-level (low power) output. It's enough to power headphones directly in your ears, but for anything larger there just isn't any oomph.

You need an amplifier. You can get many transistor/circuits/chips to do this for you. Searching audio amplifier, or headphone amplifier will get you lots of projects.
thegeeke2 years ago
You need an amp. Just don't expect a cheap speaker to be able to do a lot, or you will have clipping (see my instructable "audio problems" for more info on that if you don't know what that is) or you may even blow your speaker. On the other hand, stop using that speaker the way you are currently using it, as you could distroy your device that it is plugged into with prolonged use, which also means you need to get an amp that can handle the impedance on the speaker or you will blow the amp.
+1

Take his advice freerun. :)
+1

Amps are there to take the signal and make it useful to the speaker system. Headphones/earbuds, while technically a type of speaker, are meant to be used as very near field listening, as in they are using only the air within the ear and/or ear canal to couple to your eardrum(s). Since that volume of air is so small, very little power is needed to move the air to make sound. Regular speakers must move infinitely more air to reproduce the sound quality and volume, therefore they need to use much more energy to do so, hence the need for amplification.

Qa
As Frollard says ( and Scottie), "Ya need more power!" Plenty of 'ibles and questions on this already. Search for them.

Also, a raw driver sounds pretty anemic when it is standing free - all by itself. You need to put it in some kind of enclosure, even if it is a plastic or paper cup. It will make a big difference. For example, I have an old 6" AlNiCo magnet speaker (properly called a driver) that I use to test my small amps. It sits on top of a plastic Folgers coffee container (the 27-32 oz size) and sounds pretty good. The bonus is that I have a place to temporarily store my current project while working on it. A discussion of why that works is too long for answer boxes, so I'll let you discover this phenomenom for yourself.

Qa
+1. A baffle might help a lot. A baffle keeps the sound waves in the back which are 180 degreees out of phase with the front sound waves from mixing. when they mix they cancel each other out. A proper baffle will either quiet the rear waves or delay them until they will reinforce the front waves.
I guess multiple answer boxes will work. :)

+1 R-d.
Infinite baffles or plain old indiscriminite baffles (those of random, but equal size) will help to tame the back waves from the driver. They work, as you have stated, by delaying the backwave(s) from mingling with the front waves, at least until they can be in phase to reinforce them. Properly designed Infinite baffles are generally regarded as the most accurate type, but they tend to be rather large.

Sealed boxes (acoustic suspension) basically work by containing the backwave. The boxes also are designed to have a resonance (in the bass range) that reinforces the lower frequencies to an extent. However, they tend to be less efficient than other styles of speaker systems. They are preferred for their accurate bass response, though they tend to not have very deep bass.

Vented boxes (bass-reflex) are designed to use a port to enhance a portion of the bass response, generally situated near the free-air resonance of the bass driver. They can have fairly deep bass, but the bass tends to be a bit less accurate.

Transmission line boxes are based on the resonant frequency and size of the driver. It is similar to a vented box except that the "tuned port" is a lot longer and of a specific size as mandated by the driver. This type of "boxed enclosure" is purported to be the most natural sounding / smoothest of the bunch. They are usually larger than the Sealed or Bass-Reflex.

A variation on the transmission line box is the folded horn. As the name implies, the "vent" is in the shape of a horn folded over to fit in a specific box size. The benfit to this variant is that the horn helps to amplify the wave as it goes from throat to mouth, thereby increasing efficiency.

These are some of the most basic forms of speaker systems out there, but are by no means the only ones. Some of the super high end designs out there are works of art and ones I would never have thought of. The web hold the formulae for each of these and many more. Give a search for the ones you are most interested in. Sealed boxes are ususally the ones most beginners tackle first as they are the most forgiving and easiest to build.

Qa