Interpreting T/S Parameters

[fringy75]

I need the help of the collected wisdom of the fullrange guru's.

Is there an easy way to interpret the given T/S values of speakers and to then know what kind of enclosure that these would then suit?

I appreciate that the actual design of said enclosure is another matter, but I wonder if there is a formula that says, if you have T/S parameters in this range, then this is the type of enclosure that would suit that speaker driver.

I hope that you can help.

 

[OscarS]

One basic rule of thumb is Efficiency Bandwidth Product. Feel free to google it. The rest comes from simulation experience.

 

[DrBoar]

A starting point is the total Q, a measure on how well damped the fundamental resonance of the driver is. A q of 0.3-0.4 is a good all round value making the driver work both in bass reflex boxes and closed boxes. Q well below 0.3 really does not give any bass in boxes and are used as horn drivers or as midbass drivers. With Q of 0.6 and above large closed boxes will work with Q of 0.8 and above there will be bass hump

 

[fringy75]

Scottmoose or Chris?

Hi guys.

I don't expect you to spoon feed me on this subject as I can appreciate that you would need to write a few books doing so, but it is an area that I am interested in.

Is there a gold rule of thumb that says (in principle) that if a driver has certain parameters it would suit a certain enclosure design?

 

[OscarS]

Is there a gold rule of thumb that says (in principle) that if a driver has certain parameters it would suit a certain enclosure design?

One basic rule of thumb is Efficiency Bandwidth Product. Feel free to google it.

This is where you need to start. What DrBoar said is correct but it fails to integrate the importance of Fs into the equation. I'm sure it wasn't his intention as I generally agree with what he said about Qts.

 

[DrBoar]

I kept Fs out of the way intentionally to keep it simple.
If I get into the smaller driver, larger Q thing then Vas enter the discussion and then....

I think a better start is a start with a particular driver be it a fullrange driver on sale at Part-Express or something else. With that driver as as starting point tells what happen when Fr, Q and Vas changes.

A really good start, in silico, is "http://www.mh-audio.nl/ClosedBoxCalculator.asp"
Start with Fs= 50 Hz Qts=1 Vas=50 liter and vb 50 L (box volume) this is data typical of a cheap full range driver 6-8" in size.
Then try with stronger magnet system with Q of 0.6 and 0.3
Then try those in larger and smaller cabinets 25 and 100 L

A good system Q is in the 0.6 to 0.8 range. Above 1 you get a bass hump and below 0.5 it declines to early in most cases.

 

[fringy75]

Thanks Oscar and DrBoar.

I did a small amount of reading as suggested via Google and this site and read that many people seemed to dismiss.

I will have a look at the site suggested and see what happens.

The main reason for my question coming up was due to me having 4 peerless 830986 3inch full range drivers and was looking for an enclosure that would work. The only one I found was a plan for the Fostex ff85k recommended enclosure and as I had a mass of 16mm mdf laying around decided to build them which I think was a little ambitious for a first build.

The final result is awesome, great for jazz etc, and they go very low, well into the low 50's with authority and great finesse.

So rather than building an enclosure for different drivers than I may have, I thought I would ask the question.