EBP and QTS

[horus]

Hi,

Let's take for example the RS225(Dayton driver). It has an EBP of ~52.2 and a QTS of ~0.381.

I want to understand why and how do these two parameters(EBP and QTS) affect the woofer's performance in a certain box.
What happens if you put a woofer with a certain combination of EPB and QTS in a variety of boxes(small vented/big vented tuned higher/lower closed open baffle etc)

The 52,2 is a small value suggesting a closed box instead of a vented one. However the QTS is smaller than 0.4(not by much though) suggesting a vented box.

I want to use it in a 50liters box tuned around 26Hz, but first I want to understand how do these parameters(EBP and QTS) change the sound/affect the performance of the woofer and what is the best box option for this woofer.

Thanks! And a HAPPY NEW YEAR!

[sreten]

Hi,

ignore EBP to an extent.

Look at Qts and Vas. Is Vas reasonably low for the driver size ?

Qts tell you (to a degree) the alignment, Vas the box size.

Fs with the above more or lessc tels you sensitivity.

/sreten.

[horus]

Vas is 78,6Liters and Qts is ~0,381.
What do you think?

If someone knows the implications of EBP and QTS into the overall sound of the woofer in a certain box please share it.
I want to understand "how it works". Why do you need to use a closed box with a woofer that has an EBP lower than 50-60 and what happens if you use a vented box instead and vice versa?
Same thing with the QTS.

[pinkmouse]

I strongly recommend you do two things. Buy and read thoroughly Vance Dickason's Loudspeaker Cookbook, and download one of the free box design programmes. The book will give you the theory, and creating your own drivers so you can tweak the parameters of interest will show you graphically what is going on.

[horus]

I have some basis, I'm not a complete noob, it's just that this sort of info is hard to find just by searching over the internet.
I have WinISD and I can work with almost all of its functions, but there are this rules of thumb(with EBP and QTS) that I want fully understand their background.

What happens if you use a driver with a QTS that is inadequate for a vented application? I suppose that there will be some humps in the FR response.
But in RS225's case in a 50L vented box there are no humps. Still there are people that say that this driver shouldn't be used in a 50L vented box and I want to understand their reasons.
What do you have to take in consideration when choosing an alignment for a driver? FR response,GD, max linear SPL,extension, limiting excursion, transient response(how do you simulate it?) anything else?

[Svante]

What is EBP?

[69stingray]

What is EBP?

http://diyaudiocorner.tripod.com/formula.htm

http://diyaudiocorner.tripod.com/dilemma.htm

[noah katz]

"I want to understand "how it works".

I agree with sreten, just ignore it.

I think I have a feel for what the T-S parameters mean, but I've never seen the point of EBP, other than to make it easy for someone who *doesn't* understand to make a rough choice.

Also, I don't know why anyone would reccommend Dickason for actual understanding how speaker systems work.

It is indeed a cookbook, with lots of useful empirical information, but I found it frustratingly sparse on intuitive explanations.

[Svante]

Originally posted by 69stingray


http://diyaudiocorner.tripod.com/formula.htm

http://diyaudiocorner.tripod.com/dilemma.htm

Ah... A rule that helps doing things without understanding why, then. Sort of.

[AndrewT]

Hi Horus,
your Q of 0.38 is close to 0.4 indicating that a final vented box Q of 0.71 can be obtained by making box volume ~=Vas. Then tune the vent to about the driver Fs. This is the "flat Butterworth" response.
Your Q is slightly low so you will aim for a box slightly smaller (about 65L) and Fv slightly higher (about 1.09*Fs) for the closest to flat response. Making the box smaller still will give a hump in the bass response leading to that one note boom boom that I consider horrible.

You can use a box slightly larger than Vas and tune slightly lower than Fs for a shelved bass that can sound nice when room loaded
Your Q is just at the low end of useable in a sealed box, somewhere in the range of 25L to 50L will work. The smaller end of the range giving a bass hump (Qb=0.8)