A speaker spider is a vital part of the speaker’s suspension system. It provides the means by which the speaker cone is able to move back and forth, creating the sound waves that we hear.
Typically, the complete speaker suspension system is made up of two parts, firstly the surround, which is fixed to the top of the cone, and secondly the spider, which is fixed to the bottom of the cone. This speaker suspension system keeps the moving parts of a speaker in place.
The term “spider” is often used interchangeably when talking about speaker suspensions. Here is an image of what a speaker spider/suspension looks like.
Some suspensions, particularly older designs, are round disks with ridges that look like legs. From a top-down view, this pattern can look like a spider, hence why this suspension component is sometimes called a spider. This is where the term “spider suspension” comes from.
n this article I will cover:
- What is a spider in a speaker?
- What is the purpose of the spider in a loudspeaker driver?
- What is a speaker spider made out of?
- What is speaker spider compliance?
- How do you design a speaker spider?
- How do you fix a spider speaker?
What Is A Spider In A Speaker?
A spider in a speaker is the component of the suspension system that attaches the speaker cone to the frame. It is typically made from a flexible material, such as rubber or cloth, in order to allow the cone to move freely.
Some early spider designs were flat discs with ridges or legs, which looked like a spider from a top-down view. This is where the term “spider suspension” came from.
Although most modern speaker spiders no longer look like this, the term has stuck around.
What Is The Purpose Of The Spider In A Loudspeaker Driver?
The spider in a loudspeaker driver is responsible for attaching the speaker cone to the frame. It is made from a flexible material so that the cone can move freely, creating sound waves.
Without a spider, the speaker cone would not be able to move back and forth, resulting in no sound being produced.
Here is an image of what a speaker suspension system looks like with a spider. You can see that the spider is the component that attaches the speaker cone to the frame.
In engineering terms, a spider is simply a mechanical spring. As your speaker vibrates and makes noise, it is the spider acting as a spring that keeps it in place.
The purpose of the spider is to restore the cone (or diaphragm) to its resting or neutral position.
What Is A Speaker Spider Made Out Of?
A typical spider in a loudspeaker driver is made out of rubber or cloth. This allows for maximum flexibility and movement of the speaker cone. If made from a hard material, it would inhibit movement and reduce sound quality.
Some spiders are also coated in metal to increase their strength and rigidity. However, this makes them less flexible and may lead to distortion of the sound waveforms.
Many cloth spiders are made from woven cloth. In addition, they can sometimes be coated with a film or resin impregnation, which will increase stiffness.
What Is Speaker Suspension Compliance?
The compliance of a speaker suspension is the measure of how much it can deform, or bend, under a set amount of force. In a nutshell, it is simply a measurement of stiffness.
Higher compliance means that the suspension will deform more easily, while lower compliance means that it will be more resistant to deformation.
This compliance is often called Cms in speaker parameters and has the unit, Meters Per Newton.
The compliance of a speaker spider is an important factor when designing a loudspeaker.
If the spider is too stiff, it will not allow the cone to move freely and the sound quality will be reduced.
If the spider is too compliant, it may not be able to hold the cone in place and it may move around, causing distortion.
At the end of the day, the suspension spider is just a mechanical spring, and like all springs must obey Hooke’s law, which states:
The force (F) needed to extend or compress a spring by some distance (x) scales linearly with respect to that distance—that is, Fs = kx, where k is a constant factor characteristic of the spring (i.e., its stiffness), and x is small compared to the total possible deformation of the spring.
https://en.wikipedia.org/wiki/Hooke%27s_law
If we overstretch a spring, or in this case displace our suspension spider until it no longer acts as a spring, our spider is no longer linear and can produce distortion, particularly at low frequencies.
How Do You Design A Speaker Spider?
When designing a speaker spider, you need to take into account the compliance of the suspension as well as the weight and diameter of the speaker cone. You also need to make sure that it can withstand the forces exerted on it during operation.
One way to design a speaker spider is by using a computer simulation program. This allows you to test different designs and see how they perform. You can also use this program to determine how much force each part of the suspension system can withstand and how linear the spider design is as it travels over its full range.
Typically, speaker design engineers will produce displacement/force curves, which tells us how linear our spider will perform over a given displacement.
When designing a speaker spider, you also need to consider the impact of the surround as both of these components work together to create the speaker suspension system.
Between the surround and the spider, it is the spider which should have the dominant stiffness.
This is because the speaker surround component is typically non-linear and hysteretic.
Together the spider and surround will determine the mechanical Q, (Qms) of the speaker, which tells us how well damped our speaker is.
How Do You Fix A Spider Speaker?
If your speaker has a broken or damaged spider, you can fix it by replacing the spider suspension system.
This can be done either by taking the speaker apart or by using a replacement spider kit.
Replacement spiders are available for most common loudspeaker drivers and typically arrive as a kit. It can be very difficult to replace just the spider and generally all the “soft” parts of the speaker, which include the cone, voice coil, suspension, and spider.
In the case where the spider has separated from the cone, it is possible just to re-glue the suspension to the cone.
Here is a good video on how to do this:
Final Thoughts
A speaker spider is an important component of a loudspeaker, as it helps to suspend the speaker cone and allows it to move freely.
If the spider is too stiff, the sound quality will be reduced. If the spider is too compliant, it may not be able to hold the cone in place and it may move around, causing distortion.
When designing a speaker spider, you need to take into account the compliance of the suspension as well as the weight and diameter of the speaker cone.
