I line the inside of my boxes with sonic barrier from Parts Express. Then I add some recycled denim that I cut into small squares and roll up to the inside of the box. It's important to take measurements without the denim then add it to see if it suppresses resonances. It matters how much you put in and where you put it. You don't want to overstuff the box. But you can make dramatic differences if you get it right.
And that makes 1st port resonance and air speed less relevant? I just dont know what to aim for in winisd.. I know many people say to keep air velocity under 17 m/s under load, but the question is how important it is to look at the 1st port resonance then
Yes I done a lot of speaker in closed box, depend on several parameters to put a driver in closed or bass-reflex.The driver is done for closed / BR ? One parameter very important is the size of the room. Other parameter is the amplifier is capable of bass ? after you can do closed or BR. You can start with a bass reflex and if you have too much bass you can go to a closed box, just close the port 🙂 Note when you build a bass reflex it is very important to tune the port to the right value. The 18W8531 can work well in severals lods Closed/BRPassive//MLTL etc.
My personal taste goes to closed box because the bass is more tight but some modern drivers can work well in BR, with a good group delay near or below 10ms. It is a large subject. You have commercial speaker in closed box, see ATC SCM20 for example, I played a lot with this speaker.
Otherwise agree with @rabbitz 20/22L 40Hz is a good compromise for this driver. Note the @pkitt crossover is a good starting point if you found the box too large. Also see Zaph ZRT
Would like to have your feeling after building the speaker 😉
Thanks for all the helpful information Jerome!
Its going to be used in a pretty small room -15 sqm or something like that. It is not someone who typically listen to a lot of bass heavy music, which is why im wondering if I should just go for sealed.. After all it should be simpler aswell.
I've build a few speakers so far, but I must admit that I don't know how deep i want my speakers to go, to fit certain criteria.. Maybe this will be a good experiment.. But then again, as you say.. If i go ported i can always close it off.
Edit: I was wondering if I could ask you a few questions regarding crossovers etc. that i cant find the answers i want to.
Its going to be used in a pretty small room -15 sqm or something like that. It is not someone who typically listen to a lot of bass heavy music, which is why im wondering if I should just go for sealed.. After all it should be simpler aswell.
I've build a few speakers so far, but I must admit that I don't know how deep i want my speakers to go, to fit certain criteria.. Maybe this will be a good experiment.. But then again, as you say.. If i go ported i can always close it off.
Edit: I was wondering if I could ask you a few questions regarding crossovers etc. that i cant find the answers i want to.
I recommend downloading a program called "Basta!" and watching Scott Hinson's YouTube tutorial on it. It will help you immensely in modeling bass alignments, port size and maximum SPL with any given driver in any cabinet size. Yes, keep air velocity at 17 m/s when modeling but I would worry less about that at this point. I modeled it for you.
Looking at this driver, which I have worked with a lot, you can have a 20 liter ported cabinet. The recommendation for a port is a 2" wide and 8" long. This will eat up some internal space of the cabinet and it means that you need a cabinet with at least 10" of internal depth. I'm not sure if that's feasible. If not, then I would still use a 2" port and get it as long as you can and still have at least 2" away from the internal opening. I recommend using a flared port.
That's a start. I don't personally model any port resonances. I take measurements because that's going to show you what exactly is going on. Then add some stuffing from there.
The picture here is of 2 measurements of a Purifi 6.5" woofer with a port. The green measurements shows the resonances. The purple one shows what happened when I strategically placed some stuffing inside. The resonances were massively suppressed and the low end remained pretty much the same. This is what you're looking for. Don't overstuff. Put a little bit in at a time and measure.
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My port's dimensions and design are correct and appropriate for my design since there are always multiple attributes that have to be considered and compromises to be made. Returning to your comment in Post #18 about the Fletcher-Munson curve, doesn't that apply to everything and to any matter to which we listen. IOW if I go to a live symphony, isn't my hearing affected the very same way as it is when I listen to music at home on my audio system (ignoring differences in the acoustical environment of course)? If so and assuming my audio system is, while not perfect, reasonably good, why would the bass frequencies need to have a higher SPL than the midrange in order to sound equally loud if same requirement didn't apply to the live performance (I'm assuming the bass instruments at the live concert aren't somehow just happening to be playing significantly louder)?
A speaker which can go down to 40Hz is enough for most use.
Yes you can !
This is very helpful! i have 20,1l (23l if you take stuffing in, as some people calculate with?) and almost 9 3/4 inches from the back to the inside of the front panel. - if it is mounted on the backside.
I'll also try to give Basta a go, thank you so much.
Apologies to you for all the basic questions. The more I learn the dumber I get 🙂