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Discussion Starter · #1 ·
Hey guys I'm in the researching phase of building a pair of sealed subwoofers and have a decent understanding of the basics and have been modeling in WinIsd, etc. With all of the information (many of it misinformation) around the internet there is one point I'm confused about concerning system Q. I have read that with parametric EQ, which I will be using, you can shape the response to any Q you desire which makes sense to me. But I've also read that the closer you come to the critically damped .5 Q alignment the better the transient response the sub will have and the "tighter" the bass will be. Can anyone help dispel if either of these are myths or if maybe there is some truth in both statements?


These questions are basically driving my decision to either go with the Dayton 12HF or the 15HF. I don't want to go any bigger than an 18 inch cubed which gives about 2.6 cu ft internal before the driver is installed. When modeling each sub the 15 has a slight hump compared to the 12 but it's within 1.5 decibels of it so I'm not sure if it would make a difference in sound quality, especially considering both would be EQ'd flat.


Also are there any other considerations between these 2 drivers I should be concerned with? Would the 15HF for example dig deeper but maybe give up some mid bass performance? Or should it pretty much beat the HF12 in every way?
 

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First off, transient response isn't much of a consideration with subs. 'Tight' bass doesn't mean anything, as everyone has their own subjective definition of what it is. Accurate bass does, and that's not limited to any particular enclosure type. There's nothing magical about a .7 Q, but it does usually represent the best compromise between low frequency extension and overall sensitivity. The main considerations with subs is how low and how loud. In that respect you should be paying particular attention to the maximum SPL chart in WinISD.
 

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iirc that is too small for the 15hf and it may even "oil can" in that enclosure.


ho might be a better choice for a smallish enclosure.


I'd probably back up a bit and ask what you are trying accomplish before specifying a driver.


room, content, level, etc. then work from there...


the biggest offender for the lack of tight bass is actually the room. resonances are the primary cause of problems such as flabby or boomy bass.
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by Bill Fitzmaurice  /t/1521978/sealed-sub-system-q-and-sound-quality#post_24466387


First off, transient response isn't much of a consideration with subs. 'Tight' bass doesn't mean anything, as everyone has their own subjective definition of what it is. Accurate bass does, and that's not limited to any particular enclosure type. There's nothing magical about a .7 Q, but it does usually represent the best compromise between low frequency extension and overall sensitivity. The main considerations with subs is how low and how loud. In that respect you should be paying particular attention to the maximum SPL chart in WinISD.

So let me ask this question, are you saying if I build 2 subs, 1 with a .5 Q and the other with a Q of 1 but EQ them both flat in my room, will they essentially sound identical?

Quote:
Originally Posted by LTD02  /t/1521978/sealed-sub-system-q-and-sound-quality#post_24467115


iirc that is too small for the 15hf and it may even "oil can" in that enclosure.


ho might be a better choice for a smallish enclosure.


I'd probably back up a bit and ask what you are trying accomplish before specifying a driver.


room, content, level, etc. then work from there...


the biggest offender for the lack of tight bass is actually the room. resonances are the primary cause of problems such as flabby or boomy bass.

I'm mainly trying to accomplish nice sounding bass to accompany my mains, and mostly for music, my system is a home theater as well but 90% of the time I listen to music on it and I'm not a bass head by any means. My room is about 17' x 15'. And the loudest I listen is 85-90db.


As far as the room is concerned, like I said earlier my processor does have parametric EQ which I use with REW so either way I go it will have EQ.
 

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Quote:
Originally Posted by aarons915  /t/1521978/sealed-sub-system-q-and-sound-quality#post_24467321


So let me ask this question, are you saying if I build 2 subs, 1 with a .5 Q and the other with a Q of 1 but EQ them both flat in my room, will they essentially sound identical?
Not identical, but very close. Consider the RSS390HF. A Q of 1 takes a 2.3 cu ft box, a Q of 0.5 takes a 29.5 cu ft box. The 0.5 Q is 6dB more sensitive at 20Hz, which is good, especially if you don't have a huge amp. You can EQ the small box to give the same output at 20Hz, but that means you need four times the amp power to do it, which isn't so good.

Now look at the 0.7 Q option. Vb is 5.9 cu ft, and it only takes 2dB of EQ to equal the 0.5Q box at 20Hz. IMO that makes the 0.7 Q box a very good compromise.
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by Bill Fitzmaurice  /t/1521978/sealed-sub-system-q-and-sound-quality#post_24467425


Not identical, but very close. Consider the RSS390HF. A Q of 1 takes a 2.3 cu ft box, a Q of 0.5 takes a 29.5 cu ft box. The 0.5 Q is 6dB more sensitive at 20Hz, which is good, especially if you don't have a huge amp. You can EQ the small box to give the same output at 20Hz, but that means you need four times the amp power to do it, which isn't so good.

Now look at the 0.7 Q option. Vb is 5.9 cu ft, and it only takes 2dB of EQ to equal the 0.5Q box at 20Hz. IMO that makes the 0.7 Q box a very good compromise.

I agree about .7Q being a good compromise in regards to box size. But many times I read that ultimately the frequency response of a sub along with the SPL it's capable of are all that matters and things like "fast bass" and "tightness" are really just a flat in room response. The only detail I'm still not sure of is the behavior of the subs moving mass in these different alignments. If the sub's cone is in more control with a Q of .5 over 1 I'll try to get closer to that but if it's not necessary then I want to stick with the size I think will look best in my room.
 

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If it's a driver you have on hand all you can do is the best you can concerning size and how that relates to Q, power and xmax. If buying a driver, it's pertinent to look first before you buy with your goals/restrictions in mind.
 
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