3 x 12" or 18" woofer ?

SlowcarIX

1 x 12" woofer has ~113in^2 of surface area; 3 of them = ~339in^2, roughly the area of a 20" woofer

an 18" woofer has ~254in^2

Sonically, is there a disadvantage of going with 3 12s vs. 1 18?

engtaz

18" there no replacing size. I have listen to 10"s,12"s,15"s,and 18"s and the 18"s shake the ground and go lower.

engtaz

Early B.

There are too many other variables to consider to answer your question. What specifically do you have in mind?

SlowcarIX

Quality bass - speed and slam

greg2350

2 12" should give you want you want. I have 2 SR124 and they go plenty low with speed and slam most people think I have 2 15's

avguytx

3) 12" = 339 sq in of surface area versus 1) 18" = 254.34. Having done 18" woofers when they first came out in car audio back in the early to mid 80's, I gotta say that I liked the ones that I did. One woofer went a long ways. The unfortunate side was that it too an awkward shaped box to put it in which limited it to certain vehicles....SUV's, etc.

I remember doing (8) Rockford Punch 18" in a 1985 S10 Blazer on a single Power 1000 (the original one) at about that same time frame and it was totally cool. We also did 8 (or maybe 10) Kicker Comp 18" when they first came out in a Chevy Astrovan that used a single Kenwood KAC-1021 bridged on it. It ended up in the Kenwood booth at CES in Vegas in 1988 or 89 I think it was. Man, those were the good ol' days.

ShinAce

The areas you quoted are incorrect, bu their ratios will not change.

A 12" woofer has roughly 87 sq in of area.

The 18" will be roughly 214 sq in.

edit: added precision

avguytx

What, are you taking the surround out of the equation? Maybe so if you're doing that but it theoretically would be a little more because of the downward angle of the woofer cone as we're calculating it as a flat circle area which it is not.

That's been an argumentative point for years on calculating surface area as to if it's calculated using the surround or not or even calculating half of the surround. But since we're only doing this for comparisons sake, I'd say we aren't incorrect.

speakergeek

As for slam, the PB13-Ultra is very capable there (13.5 inch driver). It's made of a very unusual cone material (it sounds almost ceramic like when you flick it). It slammed my PSW-650 right out of the room. Just the driver/magnet alone weighs nearly 60 lbs (more than the entire PSW 650).

speakergeek

engtaz wrote: »

18" there no replacing size. I have listen to 10"s,12"s,15"s,and 18"s and the 18"s shake the ground and go lower.

engtaz

It's not just woofer size, but also box size (tuning), and sensitivty, and damping/excursion capabilty (Xmax). Deeper delving subs will always have larger boxes (enclosures). I'm sure I'm grossly over simplifying here, but it's a start.

ShinAce

avguytx wrote: »

What, are you taking the surround out of the equation? Maybe so if you're doing that but it theoretically would be a little more because of the downward angle of the woofer cone as we're calculating it as a flat circle area which it is not.

That's been an argumentative point for years on calculating surface area as to if it's calculated using the surround or not or even calculating half of the surround. But since we're only doing this for comparisons sake, I'd say we aren't incorrect.

I do not agree. I believe you are wrong on both accounts.

1) The downward angle, or curvature of the cone, does not increase the effective area of the driver. I will not go into the proof; It involves differential calculus.

conclusion: the disk approximation is still useful.

2) I consider the radiating surface as roughly the cone diameter plus one roll of the surround. For a 12" driver, this will be 10.5" . We lose 1 inch to the mounting gasket/flange and another 0.5" from one roll of surround. This gives a radius of 5.25" for the radiating surface for a 12 driver. An 18" driver yields 8.25".

conclusion: the surround does radiate, but how much? The fudge factor is yours to choose.

area = pi*(r^2)
12" driver area ~ 90 sq inches
18" driver area ~ 215 sq inches

1(18") = 2.5(12")

The real test is displacement = area*Xmax

ShinAce

speakergeek wrote: »

It's not just woofer size, but also box size (tuning), and sensitivty, and damping/excursion capabilty (Xmax). Deeper delving subs will always have larger boxes (enclosures). I'm sure I'm grossly over simplifying here, but it's a start.

Sensitivity is important for matching drivers.

Excursion is vital for this purpose. Other than displacement, there's the frequency response to consider. That's about it.

Personally, I'd go with the 3(12") due to flexibility first and performance second.

avguytx

As long as you're clarifying that is the formula you're using, I agree.

And, no. I'm not wrong on both accounts. But it's only in car audio that anyone really cares about cone area. When the "crank ups" went to judging classes on cone area, they calculated it for actual woofer size at first...then apparently modified the rules along the way to suit the whiners...especially on the woofers with the big roll surrounds. Those were always controversial, too. One of the many reasons I'm glad I'm not involved in car audio anymore. It was more fun when I started doing it in 1979 and even more fun into the 80's and early to mid 90's.

engtaz

speakergeek wrote: »

It's not just woofer size, but also box size (tuning), and sensitivty, and damping/excursion capabilty (Xmax). Deeper delving subs will always have larger boxes (enclosures). I'm sure I'm grossly over simplifying here, but it's a start.

I agree. My references were about manufactured HT powered subs not DIY subs.

engtaz

Sherardp

Slow are you thinking Epik Conquest?

speakergeek

Are you already running 3 12s (DSW 600s)?

SlowcarIX

Sherardp wrote: »

Slow are you thinking Epik Conquest?

yes

SlowcarIX

speakergeek wrote: »

Are you already running 3 12s (DSW 600s)?

speakergeek

The Conquest will knock your socks off. It'll look good with your stuff too.

ShinAce

Slow, I like your setup.

Ron Temple

It's an apples and oranges question when comparing a large ported 18 with a high xmax driver vs 3 compact 12s. The Conquest in most rooms will get you > 120dbs from 25hz up, but still can get you 103dbs at 12.5hz with almost no THD (3.4%). The DSWs +/- 3db rating is 25hz. 3 of them might go as loud as a Conquest over 35hz, but can't below that due to they're design. That doesn't make them bad subs. I'd guess the total volume of the 3 subs is still less than the Conquest which also has quite alot more total power. The A7-450 is also a behemoth.

SlowcarIX

Ron Temple wrote: »

It's an apples and oranges question when comparing a large ported 18 with a high xmax driver vs 3 compact 12s. The Conquest in most rooms will get you > 120dbs from 25hz up, but still can get you 103dbs at 12.5hz with almost no THD (3.4%). The DSWs +/- 3db rating is 25hz. 3 of them might go as loud as a Conquest over 35hz, but can't below that due to they're design. That doesn't make them bad subs. I'd guess the total volume of the 3 subs is still less than the Conquest which also has quite alot more total power. The A7-450 is also a behemoth.

the LSi integrates seamlessly w/ the 600s till the point of the ~30Hz roll off...

will the epik conquest integrate to the LSi (xover@80Hz), as well as the 600s considering the 8"/18" cone size difference?

TIA

Sherardp

if you bought the conquest I'd sell the other subs. The only other thing to consider is dual conquest paired with a sms-1. Anything else and youre going to have a hard time getting them to blend. Some others will chime in on this Im sure.

Ron Temple

SlowcarIX wrote: »

the LSi integrates seamlessly w/ the 600s till the point of the ~30Hz roll off...

will the epik conquest integrate to the LSi (xover@80Hz), as well as the 600s considering the 8"/18" cone size difference?

TIA

I really don't know. A buddy has a Conquest and a pair of U13s (not the U12 you just heard). As expected the Conquest was the bomb for HT, but he preferred the Ultras (actually a single U13) for seamless integration and musicality. Partially, I think due to his room not being very large, sealed 2700^3. The behemoth subs like the Conquest and eD A7-450 are certainly going to impress you with impact, extention and pressurization, but I think it's problematic for placement options and tougher to EQ flat (not that I'd say no to trying if given the chance).

SlowcarIX

thanks for the input.

i spoke to chad@epik and he said that the conquest will go up to 130Hz. should have one in my home in 2 weeks...cant wait :D:D

Ron Temple wrote: »

I really don't know. A buddy has a Conquest and a pair of U13s (not the U12 you just heard). As expected the Conquest was the bomb for HT, but he preferred the Ultras (actually a single U13) for seamless integration and musicality. Partially, I think due to his room not being very large, sealed 2700^3. The behemoth subs like the Conquest and eD A7-450 are certainly going to impress you with impact, extention and pressurization, but I think it's problematic for placement options and tougher to EQ flat (not that I'd say no to trying if given the chance).

Ron Temple

SlowcarIX wrote: »

thanks for the input.

i spoke to chad@epik and he said that the conquest will go up to 130Hz. should have one in my home in 2 weeks...cant wait :D:D

Congrats...that will make you the first Polkie that can tell us what that puppy can really do. I've spoken to Chad, several owners and seen a bunch of posts, but first hand experience trumps that. On paper, the Conquest should exceed 2 U13s in output or 3 U12s. I don't think you'll be jonesing for more bass .

speakergeek

That's one heck of a sub man! Lookin' forward to you taking delivery.

Ron, you think it's equivalent to 2 13Us? I'd guess more like 1.5 based on Craigsub's rating ystem.

engtaz

Congrats, that a super sub.

engtaz

mhartman29

Dang, slowcar, way to go for the gold. That thing should be unreal! We'll definitely have to do our get together once our respective subs arrive -- I'm on the hook for dual mfw-15s. Hopefully, they should be here in about a month!

Ron Temple

speakergeek wrote: »

That's one heck of a sub man! Lookin' forward to you taking delivery.

Ron, you think it's equivalent to 2 13Us? I'd guess more like 1.5 based on Craigsub's rating ystem.

Not disparaging Craig's ratings, but extrapolating the AVTalk/Illka measurements for the Ultras 2m GP and the one Conquest LMS 2M GP I've seen, it's roughly 2U = 1C for output. That was Ed Mullen's guess as well.

The Ultra's amp gave out trying to run the 115db sweep, so they are topping out somewhere north of 110db (outdoors). The Conquest from 20hz up starts at 115db rising slightly to around 118dbs from 40-90hz. (check out http://www.avsforum.com/avs-vb/showthread.php?t=885079&page=37 post #1109). I think Illka did slightly better with the Ultra at individual frequencies.

So let's split the difference...the Conquest is between 1.5 and 2 times more powerful than the Ultra13 . To me, it makes little difference. The Ultra 13 is the best sub I've heard and owned. I'm curious about the Conquest and hope to get a listen sometime soon.

speakergeek

Ron Temple wrote: »

The Ultra 13 is the best sub I've heard and owned. I'm curious about the Conquest and hope to get a listen sometime soon.

Amen bro! I absolutely agree:D