bass-reflex with 2 different ports?

[andrew24]

Helo everyone, My name is Andrew.

I'm an "avarage DIY guy", I did build a few subs and a few pair fo speakers, none of them where anything special.

I came across a few quite good simulations software, and my interest now is to find out what happens if I have a woofer in a box with more than 1 port.

Supposedly if they are identical then it is an easy task to find out. Actualy the simulation softwares did give a cleart answer.

but.. what if they are not identical?
is it possible to add a secund port to an allready ported box, to introduce a nother resonance in the passband, and reduce cone excursion/extend low freqvency response?


I did allso found a few quite well made excel spreadsheets that can simulate a driver transfer function in a ported box, I guess if someone could help with the math formulas regarding to simulate a box with 2 different ports and a driver I could actualy do a simular thing, so I can see visualy what would happen with that sortha aligment.

I understand that supposedly the 2 ports would interfer, but maybe there would be a passband (I guess a narrow passband) where the aligment could be used. (may require some qute sharp filters to limit bandwidht, and may require a notch filter too..)

well, thats all my question

[chris661]

Multiple ports with different tunings.

I'll let you off, for now...

[andrew24]

WOW!
I don't know how you have done thatone, belive me I did search the board with my keywords.
I guess admins can remove my thread, and sorry for opening it. I'm from hungary, and not a too good english student. I think I might had used incorrect search string...

Anyways Thank You for pointing that thread out, it contains the valuable information I was seeking.

one bit thing, I hope it ain't a problem if I ask it here..
Is aperiodic bi-chamber same as described
here?

[GM]

Well, ideally it would be its own thread, but a search engine will find it regardless........

Aperiodic means 'without period' or in the case of a speaker, it means it has no appreciable impedance peak at Fb, so while that cab is a double chamber reflex, to make it aperiodic would require considerable stuffing to flatten its impedance peaks.

Typically, a true aperiodic speaker is a well stuffed maximally flat alignment TL, but often you'll see a reflex speaker alignment that's been somewhat stuffed listed incorrectly as aperiodic, or more correctly, ~aperiodic, since it only suppresses the impedance peaks just enough to smooth out its response.

BTW, I often have better luck finding stuff on this and other forums by using Google than I do using the various forum's 'search' function.

GM

[andrew24]

hmm, I see.

You surely seem to have a lot of knowledge

Actualy do You see any chanse I could find any material related to dual -chamber ported system shown at the link?

I would be intrested to find some ways to simulate it, with the ability to vary the tuneing freqvency.

from the post You have found for me (thank You again)
I learned that if I only have 1 chamber, with multiple ports it is not going to work as I was thinking it would.

but how about the dual-chamber systems?
I mean.. 1 chamber with the driver and 1 port towards the room, an other port connecting the chamber to an other chamber, and this secund chamber allso vented to the room. I would be intrested in learning how to simulate the response curve of such system, to be able to see what happens if I varry the ports.

realy a shame, but no mather how hard I search, only suitable/related pages I find on the net are showing transfer characteristics of sutch system, and.. basicly they doshow up with an additional peak in the resistance curve.

[GM]

Only this: http://www.claudionegro.com/projects...r/dcr/dcr.html

The only program I'm aware of that can probably sim this is AkAbak, which has a steep learning curve as the price you pay for such programming flexibility: http://www.randteam.de/_Software/AkA...ad-AkAbak.html

GM

[andrew24]

well, I tryd a few of the available simulation software, LSPCAD was allmost close to it, but..
nope, no mather how hard I was trying to I could not get the thing to work as it should..

Too bad I can't find calculation formula anywhere..

anyways might have to do some DIY experiments to see how things are working..