What Metal Is In Speakers?

Audio equipment is constructed using various material. And sometimes its necessary to have an idea of what some these construction materials actually are .

This is useful in times when you need to take apart your equipment to either fix or replace something.

Speakers are built with various components. For the most part, people often wonder how it is they actually come to work.

Knowing the workings of a speaker for some is out of curiosity, other times it’s just to understand their gear better.

One question I came across recently is : “what metal is in speakers?”

In this post, I’ll break down this topic so you get a better sense of the inner Workings of speakers.

Knowing what makes a speaker produce sound is important, because it will help you’ll understand your speakers better.

As an analogy, think of a mechanic that owns a car and knows how to drive it …and think of a person that simply knows how to drive a car but doesn’t really understand the mechanical side of its operation.

Of course, the mechanic in our example, will be better a driver because of the knowledge they have of how the car works, and the mechanics that make this possible.

In relation to our topic, knowing the metal used in speakers is essential in understanding how speakers come to produce the sound that we hear.

With that said, What metal is in speakers?

The frame inside a speaker is made from an aluminum or steel sheet. There’s also a permanent magnet which is a mixture of iron oxide, strontium, and a ceramic binder. Lastly, the cone, surround, and spider are made of treated paper coated with an adhesive.

Manufacturing of speaker components

The permanent magnet housed inside your speaker is constructed by mixing iron oxide with strontium and then milling the compound into a very fine powder.

The powder is then mixed with a ceramic binder and then closed in a metal die. The die is then placed in a furnace and sintered to bond/combine the mixture together.

The frame is usually constructed from an aluminum or steel sheet.

The sheet arrives  preformed.

What then happens is that It is placed on a conveyor belt and transported to a cutting machine that uses a hydraulic press to cut holes in the sheet to allow free air movement from the cone.

The sheet is then formed using an hydraulic press that forces the sheet into a die of the desired shape. Mounting holes are then drilled at their proper locations.

The cone, surround, and spider are individually formed out of composite paper and then glued together.

The voice coil is built by winding many turns of very fine insulated copper wire on a plastic bobbin.

The bobbin and voice coil assembly is glued to the dust cap of the cone assembly.

The frame, soft iron core, and permanent magnet are then bolted together as an assembly.

The cone assembly is then attached to the frame assembly by first manually gluing the spider to the base of the frame and then gluing the surround to the top of the frame.

How speaker materials make a difference

Plastic

Plastic cones are a popular choice in speaker construction given their low production cost and the inherent consistency of build combined with the good sound-dampening qualities that tend to be present in plastic cones.

However, most audiophiles feel that plastic is a less lively sounding material than others, and it tends to make the listening experience rigid or sterile.

Paper cones

Paper cones are a lot expensive for manufacturers to produce. 

Their tonal qualities are often desirable but the paper material itself is susceptible to the absorption of moisture from the atmosphere which can, in time, change the composition and therefore the tonal characteristics of the cones. 

There are also a number of other variables in the paper cones–some manufacturers will treat the paper, which results in a rounder sound.

While other manufacturers use untreated paper, resulting in a bright, wide-open sound.

Aluminium

Aluminum speaker cones are very durable; you likely won’t be accidentally poking any holes in aluminum cones but it’s worth mentioning that they could get dented if not handled with care.

And while their sound can contain great bit of detail, they typically have little dampening which is simply the ability to start and stop vibrations quick enough.

Aluminum can produce what is characterized as audible peaking and sort of a “slappy” sounding bass response.