Want to build this sub and need info

ross johnson

New member
Mar 21, 2021
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I'm looking at building a 2-18" compact sub pretty much exactly like a now defunct Carvin trx2218b. I heard this sub and it is unbelievable how much low end it puts out compared to a proline JBL for example. I can see pics and cabinet dimensions for the cabinet but no info on how deep the ports are. kinda need that to be right. I can still buy those same speakers but I hesitate to buy something like that now knowing who the real manufacturer is in case I need replacements in the future. I'm leaning to go with Eminence speakers just to future proof the cabinet. any ideas on how I should proceed?
 

David Morison

Freshman
Aug 21, 2012
164
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Aberdeen, Scotland
The total performance of a loudspeaker system is the sum of its parts, so just copying the cabinet is not guaranteed to give you that performance you heard before. The driver matters too, as does any upstream processing/EQ being done as part of the integration of the sub with the rest of the system.
Unless you can replicate all of that, I wouldn't be too bothered about trying to copy one exact design. The "best" cabinet in the world can still sound rubbish with a mis-matched driver, or poor processing.
If you really want the exact sound you heard before, buying that product is the best way of getting it.
At least Carvin seem to publish TS parameters for their drivers so you can get a rough idea of what to look for in any potential replacement candidate. https://carvinaudio.com/collections/speaker-parts/products/ts18b-8-800w-18-inch-woofer
As for the port length, do you know anyone who still has these boxes? Asking them to take a grille off and measure for you would be the easiest option, if so.
Failing that, see if you can get a used one for cheap on EBay/Craigslist etc, measure what you want yourself, then sell it on again if you still prefer to manufacture new boxes yourself.
HTH,
David
 

Caleb Dueck

Junior
Jan 11, 2011
527
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Montana
If you're going to go through the hassle of designing and building your own subwoofer - please for the love of everything good - don't limit yourself right off the bat to old technology! If you want that exact subwoofer - just find some used and buy them. If you want a great sub - ask around here, get some great drivers (neodymium, high XMAX, from B&C, Faital, Eminence NSW, etc), model them in whichever software you are most comfortable with, ask questions here, then build them. You'll end up with better performing subs for similar cost.
 

Don Williams

Freshman
Jan 2, 2016
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Also keep in mind that unless you were actually hearing both sets of subs with the same source material at the same time and place, the comparison may not be valid. The room (if indoors) and how systems are processed (eq's, filters, limiters) all affect the sound of the sub greatly. A great sub processed incorrectly or without required processing will never perform at its best, and some source material (recorded music) really makes some subs "come alive" while other subs may sound better with different source material. What works great for EDM may not sound good at all with classical music. That's an extreem contrast, but what you will being using the sub for may make a difference in what works best for you.
 
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ross johnson

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Mar 21, 2021
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at this point I'm ready to build something. I've been reading a ton of threads and I'm looking hard at building keystone 1-18" subs.

any suggestions other than the keystone for best bang for the buck?
 

ross johnson

New member
Mar 21, 2021
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I got some wood and was ready to build the keystones but the cost per driver is $525! Some people build it with a lesser B&C speaker costing $350 each. I'm looking at the lower cost options. Being an eminence dealer I was trying to use them since I get a better price from them than paying retail for anything else but it seems that not many of the eminence speakers are in stock, and not many of them can reproduce sound very low frequency wise at a high sensitivity compared to B&C for example. Looks like I'm gonna build using B&C drivers. Just need to narrow down the best box.
 

Stef Smits

Freshman
Apr 4, 2017
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Think you're talking about the 18TBW100. Its a proven driver in de keystone, and will work fine.
18SW115 will have a nudge over the TBW100, but not that noticable probably.
 

Art Welter

Senior
Jan 11, 2011
836
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Florida
I got some wood and was ready to build the keystones but the cost per driver is $525! Some people build it with a lesser B&C speaker costing $350 each. I'm looking at the lower cost options. Being an eminence dealer I was trying to use them since I get a better price from them than paying retail for anything else but it seems that not many of the eminence speakers are in stock, and not many of them can reproduce sound very low frequency wise at a high sensitivity compared to B&C for example. Looks like I'm gonna build using B&C drivers. Just need to narrow down the best box.
Ross,

Having designed and extensively tested the Keystone sub over 10 years ago (where did that decade go!), have also tried to keep up with other commercial and DIY designs made before and after. In terms of output per size and efficiency with 35Hz extension, ease of build and transport, it still rates quite well. If the form factor works for you, go for it.
The Keystone sensitivity is actually greater loaded with a pair of Eminence LAB12 than the BC18SW115-4, but the greater excursion and heat dissipation of the 18SW115 allows for more output with less thermal compression.

Art