How to determine the size of my speaker driver?


Active Member
My midrange speaker driver is playing up.. so I was looking at buying a new one. I only need to know what size will fit the case!


Distinguished Member
Having just checked my own speakers, a size of a speaker is measured from outer frame edge to outer frame edge across the center line.

The absolute widest part of my 12" woofer measures 12 inches. The cone area plus surround measures 10-7/8 inches.

Does that help?

Also, if you are replacing a speaker, you need to replace both sides. In you case, you need to replace the midrange on both your left and your right speaker to keep the sound balanced. You need speaker of the same impedance, and new speakers with roughly the same characteristics (frequency response, etc...) as you original speaker. Since it is a Mid-range in likely a three way system, that's not as hard as it sounds.



Active Member
It's a 2 way setup, my tweaters are fine but I play a fair amount of bass-heavy music. I was thinking of replacing both but thanks for answering that!
What should I look for in drivers in terms of specs? Baring in mind the music I tend to play?
Thanks again for your reply:thumbsup:


Distinguished Member
Let me understand this, you are going to remove ALL the speakers and simply salvage the cabinets?

The next question is, are the cabinets ported or vented?

This gets complicated because generally cabinets and speakers are very closely matched. If fact, that is the whole art of speaker design; matching cabinets with speakers.

Here is a link to speaker projects from Parts Express in the USA -

You can get some idea of what is required to create and effective speaker.

Here is a link to the same site and their do-it-yourself components -

Select 'See More Drivers' (in red) and you will see all the available drives. Most likely these same brands of drivers are available from sources in the UK, though I don't specifically know any of them.

As an example, here is a sample listing of all the parameters that must be taken into consideration -

Goldwood GW-6PC-8 6-1/2" Heavy Duty Woofer 8 Ohm

Specifications: *Power handling: 110 watts RMS/150 watts max
*VCdia: 1-1/2"
*Le: 2.1 mH
*Impedance: 8 ohms
*Re: 7.4 ohms
*Frequency range: 46-3,000 Hz
*Fs: 59 Hz
*SPL: 87.2 dB 2.83V/1m
*Vas: .27 cu. ft.
*Qms: 6.31
*Qes: .50
*Qts: .46
*Xmax: 4.0mm
*Dimensions: A: 6-7/8", B: 6-1/8", C: 3-3/8".

These are referred to as the Thiele-Small parameters - for more details see -

Here is a forum that specializes in Do-It-Yourself speaker design.

Be prepared to be stunned breathless by the complexity and subtlety's of this branch of science.

There are several software programs specifically for speaker design and testing, and they vary from free to moderately priced to quite expensive.

Consider this as an example -

though there are many more.

Now, you don't have to make it this complex. You can just by a reasonable quality woofer of the right size, a reasonable quality tweeter of the right size and type, then an appropriate crossover network, and you will probably have nice functional speakers, but I can't guarantee that they will be any better than what you already have.

Also getting the book 'Introduction to Loudspeaker Design' will help introduce you to this particular brand of 'alchemy'. It is the standard starter book in the field of speaker design.


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