Quote:
| That's very nice but we were talking about the low pass. You seemed to make a very big point on the fact that a subwoofer's being ported or sealed or bandpass made an inordinate impact on the sub's upper end extension. |
very simple to wrap your head around acually and is simple physics and a bit of acoustics.
Most speakers needing a lot of bottom end help have a small driver for the bottom end,your typical mini monitor.
These speakers have severe low frequency limitations usually and any appearance of bass is more of the bass hump variety (where just befor erolloff it is a bump to seem to have bass) and not true bass.
A psychoacoustic "effect" to fool your brain.
below this "bump" the actual bass falls off rapidly and so any sub woofer must take into consideration where to overlap the low end of the mains to the high end of the sub.
If the sub comes in too late there is a "suck out' or hole where no driver covers that range.
Too high and the larger cone of the sub becomes the predominant sound coloring the entire system.
This has zero or close to zero to do with crossover slope and more to do with xo
frequncy so the point was made that ported boxes and bandpass boxes are not a good choice for mating to speakers that need to have a high upper cutoof frequency becuase the very thing that makes the speaker suitable for that bass alignment is also the thing making the actual driver unsuitable for high frequency (relative) output.
A sealed or TL box both use the same type of woofer spec wise and this is a totally different animal than the one you would use in a ported box.And becuase of the different alignment usually these speakers also have pretty good upper frequncy reponse and the box itself gets the low notes out of the driver instead of the driver.
Instead of a "humpy" looking response of the ported enclosure where the igh and low end fall off rapidly you will most often see gradual rolloff at both ends of the extremes.Again these are generalities but fit the discussion.
This more easy and gradual rolloff and the extended high end make it way easier to integrate into a mini-monitor based system where more often than not the xo is at or above 150hz.you do NOT want a 15 inch "sluggish sounding" driver reprodicing the same notes as your 6 inch upper bass driver and no matter how steep your crossover slope there MUST be some overlap in the crossover region so both drivers will be making sound there at the very same time.
So if you have a big a*s full range system that only needs some more bass power and extension the ported can be a really good choice (among others) but a poor choice if you need to have a high upper end cutoff unless the speaker has a good high frequency response.If it does,it will not have a good LOW end response because of the type of speaker used in ported designs.Simple man.
but the sealed and/or transmission line use the box to get the low notes instead of the driver and CAN have good high end response for mating to truly bass shy speakers AND good low end response,just less powerful than the ported box.
everything is comprimise and if there was a single right way to do something that fit all systems there would be no need for so many solutions.This is not an accident but designing a thing to fit a need.
first you match the speaker,then you use the crossover to set it up by ear in the actual room it will be used in.The box type is far more important than the crossover in this use.
At least that is my opinion and as always YMMV and probably will
