1x21" vs 2x18"
Printed From: Speakerplans.com
Category: Plans
Forum Name: Ported Enclosures
Forum Description: Post all your reflex and bandpass and 'other' boxes with holes in stuff here...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=25382
Printed Date: 26 March 2026 at 10:13pm
Software Version: Web Wiz Forums 12.08 - https://www.webwizforums.com
Topic: 1x21" vs 2x18"
Posted By: APMAUDIO
Subject: 1x21" vs 2x18"
Date Posted: 27 March 2009 at 7:45pm
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Anyone had the chance to compare a 1x21" reflex against a 2x18"??
Thinking along the lines of B&C SUB218 or SUB21...
It looks to me like a single 21 will move more air but not generate the same SPL?
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Replies:
Posted By: ceharden
Date Posted: 27 March 2009 at 10:50pm
| The 21" will most likely go lower but the 2x18" will be louder over most of the range. |
Posted By: mykey
Date Posted: 28 March 2009 at 6:11am
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2 x 18, more cone/piston area
2 x 18'' cone area will be 2450 cm2 (sd)
21'' cone area will be roughly 1680 cm2 (sd) ------------- ......just all them hanging there like giant bananas. |
Posted By: APMAUDIO
Date Posted: 28 March 2009 at 10:44am
| True,but an 18TBX100 has an x-max of 9mm whereas the 21SW150 is 15mm so if my maths are correct(?) the 21" moves a little more air than two 18's? |
Posted By: mykey
Date Posted: 28 March 2009 at 11:01am
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2 x 9 = ------------- ......just all them hanging there like giant bananas. |
Posted By: APMAUDIO
Date Posted: 28 March 2009 at 11:11am
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I'm no expert but I calculate the VD of an 18TBX100 to be 1089cm2(x2 for two drivers)=2178cm2 21SW150 VD=2520cm2 Or do I have my wires crossed somewhere? |
Posted By: APMAUDIO
Date Posted: 28 March 2009 at 11:25am
| I do have something crossed as those should all have been cm3!!! |
Posted By: mykey
Date Posted: 28 March 2009 at 11:36am
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wow, that must be a pretty deep cone, I'll have to check it out ------------- ......just all them hanging there like giant bananas. |
Posted By: mykey
Date Posted: 28 March 2009 at 11:45am
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have they changed the code?
I have 21sw152 and 21sw115 ------------- ......just all them hanging there like giant bananas. |
Posted By: levyte357
Date Posted: 28 March 2009 at 11:58am
A few people I know only buy 4 ohm 21"s. They say the drivers drink uber amounts of power, before they start doing anything usefull. ------------- "Who am I? I'm the guy who does his job.. You must be the other guy". |
APMAUDIO wrote:Posted By: ceharden
Date Posted: 28 March 2009 at 1:40pm
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Yeah, they've updated the 21SW150 to the 152 and brought out the slightly less meaty SW115. The B&C ones only come in 4Ohm versions from what I've seen. |
Posted By: APMAUDIO
Date Posted: 29 March 2009 at 1:37pm
| Is it me or have the cab designs vanished from the B&C website again?? |
Posted By: mykey
Date Posted: 29 March 2009 at 1:41pm
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B&C website is so bad, why is that?
is was bad before the updated version, and now seems worse ------------- ......just all them hanging there like giant bananas. |
Posted By: ceharden
Date Posted: 29 March 2009 at 1:46pm
| I didn't mind it before they updated it but it really is sh1t now |
Posted By: APMAUDIO
Date Posted: 29 March 2009 at 3:14pm
| Agreed,it is pretty bad!! I wonder why the 21SW150 was updated so quickly? Were there reliability issues does anyone know? |
Posted By: nickyburnell
Date Posted: 29 March 2009 at 11:55pm
Barry on here (BP) has a load of 21's and a load of 2 x 18's. No comparison, the 21's just sit and growl/rumble. The 2x18's do it all. Both cabs are refex, Cray 21, Opus 2 x18. 21's are PD, 18's Beyma G40.
2 x 18 all the way. 21's as an added extra to 18's or 15's maybe... ------------- It's everything, not everythink! |
Posted By: djstefanos
Date Posted: 30 March 2009 at 1:15am
| interesting topic |
Posted By: APMAUDIO
Date Posted: 30 March 2009 at 6:10pm
| This is what I would have thought but apparently the B&C 21's are much punchier than the old PD's.. |
Posted By: mstep77
Date Posted: 02 April 2009 at 6:22pm
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If you go for 21" then you've got the added bonus of the "look at the size of that badboy" factor! Everybody has thought about it, but I think the fact is that
2x18" will play very low anyway, a lot higher and be more punchey, I don't think theres much comparison.
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Posted By: levyte357
Date Posted: 02 April 2009 at 8:52pm
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I would imagine in an install, 4x 1x21" reflex cabs, would be slight upgrade on 4x 1x18 cabs reflex. Would be very interesting hearing 2x 4ohm 21s per side of a VZ5, in 2ohm stereo. ------------- "Who am I? I'm the guy who does his job.. You must be the other guy". |
Posted By: sKs01
Date Posted: 03 April 2009 at 3:13am
its not allways about how bug it is but how you use it, f121 anyone? bit off topic from a ported perspective but wth neo magnets geting stronger a 21" doesnt necisarily have to be slow and earth rumbling if implimented right. with the right 21" tuned right you aught to be able to design a cab with the same f3 with lower group delay if the rest of the T/s are up to it or am i missing something vital? ------------- You're a big man, but you're in bad shape. With me it's a full time job. Now behave yourself. |
Posted By: APMAUDIO
Date Posted: 04 April 2009 at 10:56am
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That's what I would have thought.Modern 21's with neo motors and lighter cones are much better than the early ones and with a monster modern amp they should be able to punch as well as 18's.By the looks of things,all you loose out on is SPL compared to 2x18's
Not getting into the F121 discussion as that's been done to death but there's no shortage of speed (or spl)from that box!
Have been looking into this as i'm about to build some new subs.As far as cost goes,a 1x21 is roughly the same as a 2x18. Still undecided tho
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