quick question about 15's and 18's

[KingJay 10+ year member]

Ok i always used 12-15's and i never ran a 18" subwoofer nor heard one close up and personal. How much deeper is say a SOLO X 18/RE MT 18 /etc... vs. the 15" version of the ones that has a 15? I mean how much more deeper does a 18" subwoofer play than a 15 is there a BIG difference?

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[Polecat 5,000+ posts]

in the right box, I don't think they will actually play 'power' per se', if the box is right for a 15", it will do plenty fine, without needing a larger enclosure.

 

[msrpIZtooMUCH 10+ year member]

The best way to figure this one out is to look at the specifications of each individual speaker and compare frequecncy ranges.

Generally, the larger the cone the deeper it will play...all else being equal.

 

[Nukedsodapop 5,000+ posts]

Nah, 8,10,12,15,18's all PLAY the same notes, whether its 80Hz or 20Hz, I think its just a common misconception that just because the larger sizes are bigger, they play lower. An 15 can play a 20Hz note, while the same note on the same speaker except a bigger size (18) would displace more air..

I might be going at this all wrong though, feel free to correct me.

-Blake

 

[msrpIZtooMUCH 10+ year member]

Well, I have several broshures (spelling??) outlining specs for subs and it's a little bit different for each manufacturer. But, generally, as the cone gets bigger, the sub plays a LITTLE bit lower. One exception that I found was RE. The 18 inch xxx wont play as low as the 10, 12, nor the 15. This is just what I see on paper though. In the real world on the other hand I find that the larger the cone area the less "accurate" the bass notes are. The 15s and 18s seem to struggle more in an sq set up...more so than 12s and 10s that is. For spl on the other hand, they seem to shine.

How much deeper will an 18 will play than a 15? All else being equal...little to none. It will just displace that much more air thus making it louder, and be that much less accurate.

Thats the best way that I can explain it based on my experiance.

 

[2lee240 10+ year member]

Well, I have several broshures (spelling??) outlining specs for subs and it's a little bit different for each manufacturer. But, generally, as the cone gets bigger, the sub plays a LITTLE bit lower. One exception that I found was RE. The 18 inch xxx wont play as low as the 10, 12, nor the 15. This is just what I see on paper though. In the real world on the other hand I find that the larger the cone area the less "accurate" the bass notes are. The 15s and 18s seem to struggle more in an sq set up...more so than 12s and 10s that is. For spl on the other hand, they seem to shine.
How much deeper will an 18 will play than a 15? All else being equal...little to none. It will just displace that much more air thus making it louder, and be that much less accurate.

Thats the best way that I can explain it based on my experiance.

from what i have been reading, alot of pple here and SD say that this would be incorrect, that 18's and 15's can produce as good of SQ as 12's and 10's...and they will be able to produce louder lower frequencies...

i donno tho...thats just what i heard...i'd love to see a few more people second you or say the opposite...

 

[squeak9798 5,000+ posts]

The best way to figure this one out is to look at the specifications of each individual speaker and compare frequecncy ranges.

Well, I have several broshures (spelling??) outlining specs for subs and it's a little bit different for each manufacturer. But, generally, as the cone gets bigger, the sub plays a LITTLE bit lower. One exception that I found was RE. The 18 inch xxx wont play as low as the 10, 12, nor the 15. This is just what I see on paper though.

Totally, utterly, 100% ignore manufacturer "rated" frequency response. It is totally and completely useless, especially if you are trying to use it for comparison purposes. Disregard those "rated" frequency repsonse ranges.

In the real world on the other hand I find that the larger the cone area the less "accurate" the bass notes are. The 15s and 18s seem to struggle more in an sq set up...more so than 12s and 10s that is.

Then you heard poorly setup 15's and 18's....blame the install and tuning, not the speaker.

Properly setup, a 15" or 18" can sound just as good as any other subwoofer size.

 

[squeak9798 5,000+ posts]

Ok i always used 12-15's and i never ran a 18" subwoofer nor heard one close up and personal. How much deeper is say a SOLO X 18/RE MT 18 /etc... vs. the 15" version of the ones that has a 15? I mean how much more deeper does a 18" subwoofer play than a 15 is there a BIG difference?

It might not play any "deeper", but it might have more output at those lower frequencies due to it's increased cone area.

Any subwoofer can play down to 10hz...how much output it has down there is going to depend on how much air it can move....

 

[msrpIZtooMUCH 10+ year member]

Squeak, how exactly are those frequency ranges obtained and why would they be useless?

As far as cone size and SQ...if the 15s and 18s have added output at the lower subwoofer frequency range (10hz-30hz), then they would lack output at the higher subwoofer frequency range (35hz-70hz). The 10s and 12s would be the other way around having less output at the lower range and more at the upper end. This is why 15s and 18s are nice when listening to rap or all out bass music, but for more dynamic music they don't seem to do as well. Yeah, they all play the same notes, or close to it, but it's just a matter of where peak output is. Where you want that to be, would be depends on what you listen to. Sure, you could build an SQ system with 18s for subs, but you better have a good front stage to keep up with them...such as 8s or 10s in the doors that can play cleanly down to 40hz (give or take a few hz). I'm not saying it can't be done, but 10s and 12s are more well suited for SQ.

 

[squeak9798 5,000+ posts]

Squeak, how exactly are those frequency ranges obtained and why would they be useless?

They are useless because they don't include the effects of the enviornment or different enclosures. How they are rated varies manufacturer to manufacturer (another reason they are useless)....but many are probably rated in an anechoic chamber.

If a manufacturer "rates" response down to 20hz, but I put the sub into a ported enclosure tuned to 50hz, I can promise you it won't play 20hz well....at all.

Likewise, if they rate response only down to 30hz in an anechoic chamber, then I put the sub in a sealed enclosure in my car, it may have flat response down to 10hz due to the transfer function.

As far as cone size and SQ...if the 15s and 18s have added output at the lower subwoofer frequency range (10hz-30hz), then they would lack output at the higher subwoofer frequency range (35hz-70hz). The 10s and 12s would be the other way around having less output at the lower range and more at the upper end.

Wrong. Low frequency extension (output) is dictated by factors such as Vd (how much air the sub can move) and Qtc (or box volume & tuning frequency, if a ported enclosure).

High frequency extension dictated by Le; or voice coil inductance. A large sub will not necessarily have high Le, and therefore will not necessarily lack in high frequency capability. Don't believe me? Look at pro audio...they have 15" and 18" midwoofers. Just the same, you can have an 8" with very poor high frequency response....why? Because of a high Le.

Sure, you could build an SQ system with 18s for subs, but you better have a good front stage to keep up with them

If you are playing the sub balls to the wall....yeah, maybe. But that's solely for balance of the frequency spectrum..so that the bass isn't overwhelming the rest of the music spectrum. But then again, you could always just lower the output of the sub //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

...such as 8s or 10s in the doors that can play cleanly down to 40hz (give or take a few hz).

Erm.....No. Large subs can play higher frequencies fine (Le allowing, ofcourse). Ask audiolife on here about his pair of 15" IDW's...he lowpassed them at 90hz, and qualified for IASCA world finals with such //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Again, high frequency extension is dictated by Le, not subwoofer diameter.

 

[justsayk 10+ year member]

Squeak, how exactly are those frequency ranges obtained and why would they be useless?
As far as cone size and SQ...if the 15s and 18s have added output at the lower subwoofer frequency range (10hz-30hz), then they would lack output at the higher subwoofer frequency range (35hz-70hz). The 10s and 12s would be the other way around having less output at the lower range and more at the upper end. This is why 15s and 18s are nice when listening to rap or all out bass music, but for more dynamic music they don't seem to do as well. Yeah, they all play the same notes, or close to it, but it's just a matter of where peak output is. Where you want that to be, would be depends on what you listen to. Sure, you could build an SQ system with 18s for subs, but you better have a good front stage to keep up with them...such as 8s or 10s in the doors that can play cleanly down to 40hz (give or take a few hz). I'm not saying it can't be done, but 10s and 12s are more well suited for SQ.

Correct me if I'm wrong, but i'm pretty sure cone size is a very small part of the equation when it comes to what frequency range a driver can play. Someone more knowledgable than me will be able to give specifics, but what about inductance?

edit: Someone with more knowledge like umm...that guy that just beat me to the correct response.

 

[bamaboy 5,000+ posts]

i know my XXX 15 dropped off at around 55-60hz, but it was the design of the sub it was designed to hit the lows, now my MT 18 dosent have a big drop off

 

[msrpIZtooMUCH 10+ year member]

The majority of the 15s and 18s that I have experience with drop off somewhere between 45hz and 60hz. I have never had a 10 or 12 do that though...but I still lowpass at 60hz and have the front stage take over from there.