Tuning an Enclosure

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#3
2.5 way refers to crossver:

Actually is 2 way: lo + hi

"0.5" means that the low range is reinforced with one more woofer that comes into action parelleled through a series coil in low pass region, also reducing the impedance in the extreme low range.

38 Hz refers to the tuning frequency of the box
 
#9
Now that I understand what it means, how do the different tuning frequencies go into the final design? In other words, how do the different frequencies affect the final product, and how would I choose what I want?

Does that make sense?
 
#10
GrahamnDodder said:
Actually, I was lurking and wondering the same thing. But I am on a Mac platform.
Click to expand...

I use MacSpeakerz from http://www.trueaudio.com/ for modeling sealed & BR. He hasn't done an update in many years and it is getting very creaky under OS X, so may not be considered good value for the money. There are also some spreadsheet based calculators that should run fine under Excel -- maybe even in AppleWorks.

diySubwoofers has a lot of the math.

I'm still working thru T/S parameter measurement (i've done it the long slow way successfully, but am trying to get Mac-the-Scope to do it automagically)

dave
 
#11
squidbait said:
Now that I understand what it means, how do the different tuning frequencies go into the final design? In other words, how do the different frequencies affect the final product, and how would I choose what I want?

Does that make sense?
Click to expand...
Hi Squidy,

The volume of air in the box will resonate at a certain frequency. You can change this frequency by changing the volume of air (size of box) or by adding a port (Bass Reflex, more complex design). The bass speaker will also resonate a certain frequency depending on the design of the speaker. The weight of the cone and voice coil and the “springiness” of the suspension will determine that resonant frequency (fs). All of these design values make up the T/S parameters that are used to design the finished speaker.

How good the finished speaker sounds (bass only) will be determined, to a large extent, by how you match the speaker you have selected to a box you have built. Some speakers work best in big boxes, some in ported boxes, and still others don’t require a box (car rear dash speakers).
 
#13
Thanks Rodd and Dave.

The math wouldn't really scare me. Never met a math course I didn't like.

But I do appreciate the vague, layman's description. Does it boil down to a single horse-choker equation, wherein you know all of the variables except for the one you are solving for?

Or are there different equations for each parameter?

GnD
 
#15
GrahamnDodder said:
Thanks Rodd and Dave.

The math wouldn't really scare me. Never met a math course I didn't like.

But I do appreciate the vague, layman's description. Does it boil down to a single horse-choker equation, wherein you know all of the variables except for the one you are solving for?

Or are there different equations for each parameter?

GnD
Click to expand...
For a closed box design the equation is a 2nd order filter function, as you said, including all of the variables. The solution is the frequency response curve. For a ported system the equation is a 4th order filter function. In either case all of the theoretical response, efficiency, displacement, Q, etc. information can be extracted from these equations.

These equations can be found in an electrical filter book. The trick that Thiele, Small, and others managed was the electical equvilant conversions from the mechanical parameters of the driver, box, and air. Small provide the most comprehensive coverage WRT the inter-relationships between the electrical, mechanical, and acoustical parameters.
 
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