Designing an IB enclosure appears to be relatively easy: find an enclosure calculator, enter the T&S parameters, choose the desired Qtc, press go and, Bob’s your uncle, you’re done!
From what I gather, designing a ported speaker (as a first approximation) appears to follow a similar approach. However, in all the calculators and design explanations I’ve seen, the initial enclosure volume calculation is never discussed, yet I’ve seen it stated that at frequencies above the port tuning frequency the enclosure acts as an IB. If this is the case, then surely the enclosure volume would influence the the slope of the frequency response between (say) 200 Hz and the port tuning frequency?
From what I gather, designing a ported speaker (as a first approximation) appears to follow a similar approach. However, in all the calculators and design explanations I’ve seen, the initial enclosure volume calculation is never discussed, yet I’ve seen it stated that at frequencies above the port tuning frequency the enclosure acts as an IB. If this is the case, then surely the enclosure volume would influence the the slope of the frequency response between (say) 200 Hz and the port tuning frequency?
Yes, box volume does affect the shape of the response above the low corner to an extent.
For this reason, and various others, I would never recommend the simplest online "calculators", but rather suggest a more complete modelling package.
VituixCAD is probably the most comprehensive, but if all you're wanting to do is explore the shape of the LF region in simple boxes WinISD is a lot quicker to learn.
For this reason, and various others, I would never recommend the simplest online "calculators", but rather suggest a more complete modelling package.
VituixCAD is probably the most comprehensive, but if all you're wanting to do is explore the shape of the LF region in simple boxes WinISD is a lot quicker to learn.
Just as Qts' dominates sealed alignments, so goes vented (Margolis-Small basic max flat alignment):
Vb = 20*Vas*Qts'^3.3
[Qts']: [Qts] + any added series resistance [Rs]: http://www.mh-audio.nl/Calculators/newqts.html
[Rs] = 0.5 ohm minimum for wiring, so may be higher if a super small gauge is used as a series resistor and/or there's other series resistance.
Vb = 20*Vas*Qts'^3.3
[Qts']: [Qts] + any added series resistance [Rs]: http://www.mh-audio.nl/Calculators/newqts.html
[Rs] = 0.5 ohm minimum for wiring, so may be higher if a super small gauge is used as a series resistor and/or there's other series resistance.
You may find this helpful. Toward the end he talks about extended bass shelf which is accomplished with larger than typical box size and low tuning.
https://rjbaudio.com/Audiofiles/Speaker Design-Enclosure Design.html
https://rjbaudio.com/Audiofiles/Speaker Design-Enclosure Design.html
The point that many people miss is that there isn't only one possible vented alignment for a specific driver. Nor there is the optimum one. Most if not all the programs and online calculators suggest as optimum is the box and tuning that offers the lowest F3 point in an anechoic condition. Unfortunately the F3 parameter has no special meaning in acoustics, so the whole approach offered by the calculators is flawed. F6 (and F10) are better suited.
You may want to read this (Tuning an enclosure section): http://www.zaphaudio.com/mantras.html
EBS has its own problems, and the kind of alignment suggested in the above link work better.
I suggest you to use a program that offers also driver displacement in order to look at the power handling. I use Unibox, but I bet there are others that can do it.
Ralf
You may want to read this (Tuning an enclosure section): http://www.zaphaudio.com/mantras.html
EBS has its own problems, and the kind of alignment suggested in the above link work better.
I suggest you to use a program that offers also driver displacement in order to look at the power handling. I use Unibox, but I bet there are others that can do it.
Ralf
Thanks for the link giralfino 👍 I’ve not looked at Zaph’s designs yet, but from the link you sent me I really like his approach.
Hornresp plots displacement as well as max SPL with indication of where it is amplifier limited and where it is Xmax limited.