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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Subwoofer Forum => Topic started by: Chad Cain on November 18, 2011, 12:56:37 pm

Title: Dual 21 inch subs
Post by: Chad Cain on November 18, 2011, 12:56:37 pm
Hi guys, I'm new here. Looking to build my own dual 21 inch subwoofer cabinets. I plan to start a sound company in the near future and i'm going big from the start. The ones I've seen on the market are way too much for my pocket and I've seen sound systems owners who have built there own dual 21 inch subs and they perform like any Danley th-221 or eaw sb2001. I  cant seem to find any plans online. I plan to use B&C 21 inch drivers. Some help in finding a good plan with proper speaker placement and cabinet tuning would be appreciated.
Title: Re: Dual 21 inch subs
Post by: Douglas R. Allen on November 20, 2011, 06:58:45 pm
Hi guys, I'm new here. Looking to build my own dual 21 inch subwoofer cabinets. I plan to start a sound company in the near future and i'm going big from the start. The ones I've seen on the market are way too much for my pocket and I've seen sound systems owners who have built there own dual 21 inch subs and they perform like any Danley th-221 or eaw sb2001. I  cant seem to find any plans online. I plan to use B&C 21 inch drivers. Some help in finding a good plan with proper speaker placement and cabinet tuning would be appreciated.

Single 21s may be easier to lug. Something like these?

http://www.freespeakerplans.com/cubo-sub.html

I hate to say it but if your just starting out I'd go with the popular and easy to find used 18s out there. Building a box for a 21" and not get it quite right will make it all for nothing.

Douglas R. Allen
Title: Re: Dual 21 inch subs-So many questions-as usual
Post by: Ivan Beaver on November 20, 2011, 07:17:40 pm
Hi guys, I'm new here. Looking to build my own dual 21 inch subwoofer cabinets. I plan to start a sound company in the near future and i'm going big from the start. The ones I've seen on the market are way too much for my pocket and I've seen sound systems owners who have built there own dual 21 inch subs and they perform like any Danley th-221 or eaw sb2001. I  cant seem to find any plans online. I plan to use B&C 21 inch drivers. Some help in finding a good plan with proper speaker placement and cabinet tuning would be appreciated.
If you don't have a design already-how do you know that B&C 21" drivers are the right ones for whatever design  you want?

Why do you think 21" drivers will give you the performance you are looking for?

have you defined that performance?  ie how low do you need to go?  How high do you need togo (ie what are your full range cabinets and how low do they go?)-what type of music-how loud do you need to go?  what size cabinets can you easily transport?  Are you going to fly or ground stack them?

There are a lot of question that need answers, other than a design for a 21" driver.

Start by defining the needs-and that will lead you towards a proper design (using whatever size drivers) that will work best for you.
Title: Re: Dual 21 inch subs
Post by: Jeff Bankston on November 20, 2011, 11:42:58 pm
check out the 18" FaitalPro 18XL1600
Title: Re: Dual 21 inch subs-So many questions-as usual
Post by: Chad Cain on November 21, 2011, 10:12:58 am
If you don't have a design already-how do you know that B&C 21" drivers are the right ones for whatever design  you want?

Why do you think 21" drivers will give you the performance you are looking for?

have you defined that performance?  ie how low do you need to go?  How high do you need togo (ie what are your full range cabinets and how low do they go?)-what type of music-how loud do you need to go?  what size cabinets can you easily transport?  Are you going to fly or ground stack them?

There are a lot of question that need answers, other than a design for a 21" driver.

Start by defining the needs-and that will lead you towards a proper design (using whatever size drivers) that will work best for you.

Thanks for your reply...I'm really new to this and appreciate the help and advice. I live in Jamaica, so I would be doing mostly reggae and dancehall music and gospel events where I'd need extreme low end. I want to be competitive in the market from the get go as the large sound companies out here have dual 21 inch subs. I went to a show a few days back with about 6000 people and the PA company had 4 dual 21 inch subs per side for FOH with 8 jbl vertec vt4888 per side. The subs were custom built with B&C 21 inch drivers in them. They weren't too big. Didn't ask how much they weighed though. They low end was AMAZING!!!! You could feel the kick drums from anywhere on at venue. They used lab gruppen amplification with lake processing.

I'm not sure what type mid/hi boxes i'll use as yet but they need to be able to go loud and real loud and I need. I don't intend to buy everything at once but I really love music and wanted a live sound reinforcement from ever since I could say the words, so I'll buy little by little as the money comes. As it regards flying/ground stacking, subs will never be flown. Only line array speakers will be flown if i acquire any.
Title: Re: Dual 21 inch subs
Post by: Bill Hornibrook on November 21, 2011, 12:26:34 pm
I put together a couple of boxes using the design suggestions off the B&C website. I would not have done this project except that I got the drivers (B&C 21SW152s) for little more than half what they cost today, and I have the ability to put the cabs together myself here at my shop so they didn't cost too much.

These drivers are inefficient in a simple bass reflex box and really require a much more sophisticated and complex design to reach full potential. Nonetheless I'm happy with them whenever I'm doing DJ work playing contemporary tracks in smallish rooms. There are times when it feels like the floor is literally dropping out of the place.

Unless you are providing sound for EDM with substantial amounts of sub-40hz it would make more sense to go with 18s unless you literally have money to burn. The event you went to had - what - 16 21" B&C drivers? You're talking about a lot of money there.
Title: Re: Dual 21 inch subs
Post by: Iain.Macdonald on November 21, 2011, 12:45:32 pm
Hi guys, I'm new here. Looking to build my own dual 21 inch subwoofer cabinets. I plan to start a sound company in the near future and i'm going big from the start. The ones I've seen on the market are way too much for my pocket and I've seen sound systems owners who have built there own dual 21 inch subs and they perform like any Danley th-221 or eaw sb2001. I  cant seem to find any plans online. I plan to use B&C 21 inch drivers. Some help in finding a good plan with proper speaker placement and cabinet tuning would be appreciated.

How about something like the picture below, which uses Lab Subs.

Iain.
Title: Re: Dual 21 inch subs
Post by: Chad Cain on November 21, 2011, 07:17:06 pm
I put together a couple of boxes using the design suggestions off the B&C website. I would not have done this project except that I got the drivers (B&C 21SW152s) for little more than half what they cost today, and I have the ability to put the cabs together myself here at my shop so they didn't cost too much.

These drivers are inefficient in a simple bass reflex box and really require a much more sophisticated and complex design to reach full potential. Nonetheless I'm happy with them whenever I'm doing DJ work playing contemporary tracks in smallish rooms. There are times when it feels like the floor is literally dropping out of the place.

Unless you are providing sound for EDM with substantial amounts of sub-40hz it would make more sense to go with 18s unless you literally have money to burn. The event you went to had - what - 16 21" B&C drivers? You're talking about a lot of money there.

Thanks for your reply. Yes they had 16 21 inch B&C drivers. That was what they chose to take out for the show. They can go up to 8 subs per side which equates to 16 drivers per side. They are a large company so they can afford it. As I said before, I wouldn't buy everything at once. I'm just starting so I'd start small. However for the type of shows I want to do, I require alot of low end and I understand that going with 18's would be cheaper and the weight advantages would be better but I would need too many cabs to get the low end I require. I went to show recently and they have 16 eaw sb1000 subs per side powered by macrotech amplifiers and in my opinion, although they sounded good, the low end output from them came nowhere close to the 4 dual 21 inch subs per side at the other show I went to. So I had just made up my mind to go dual 21 inch from the start.
Title: Re: Dual 21 inch subs
Post by: Ivan Beaver on November 23, 2011, 06:46:25 pm
Thanks for your reply. Yes they had 16 21 inch B&C drivers. That was what they chose to take out for the show. They can go up to 8 subs per side which equates to 16 drivers per side. They are a large company so they can afford it. As I said before, I wouldn't buy everything at once. I'm just starting so I'd start small. However for the type of shows I want to do, I require alot of low end and I understand that going with 18's would be cheaper and the weight advantages would be better but I would need too many cabs to get the low end I require. I went to show recently and they have 16 eaw sb1000 subs per side powered by macrotech amplifiers and in my opinion, although they sounded good, the low end output from them came nowhere close to the 4 dual 21 inch subs per side at the other show I went to. So I had just made up my mind to go dual 21 inch from the start.
Just because you went to a show and whey used XYZ and you liked it and went to another show and they used ABC and  you didn't like it really doesn't say much about either system.

Unless you know how well the system was powered, setup/aligned, how good the mix guy was (specifically on how he handled the low end) and so forth, it is hard to say that one system worked better than another.

It could be that the EAW system you said you didn't like may have been operated that way for some reason.  I have done shows that the FOH guy would actually get rid of the deep lows because they didn't like it.

You really have to compared under more controlled situations with like sources to really start to understand the differences.

I am not defending one system or the other, but you really can't compare like you are trying to do-usually.

You say that you have heard systems that compare to the Danley TH221.  How many systems have you heard that use the TH221?  How do you know how well they compare?  Have the other sound companies done side by side testing? and were you there?

Just wondering how you can make such a comparisom.
Title: Re: Dual 21 inch subs
Post by: g'bye, Dick Rees on November 23, 2011, 06:48:06 pm


You say that you have heard systems that compare to the Danley TH221.  How many systems have you heard that use the TH221?  How do you know how well they compare?  Have the other sound companies done side by side testing? and were you there?

Just wondering how you can make such a comparisom.

Anything is possible in your dreams......
Title: Re: Dual 21 inch subs
Post by: Ivan Beaver on November 24, 2011, 09:04:32 am
Anything is possible in your dreams......
I often have dreams where I can take a hop and simply glide above the ground.  It is really cool and very real.  Until I wake up and have to walk to the shower.
Title: Re: Dual 21 inch subs
Post by: duane massey on November 24, 2011, 11:08:45 am


It could be that the EAW system you said you didn't like may have been operated that way for some reason.  I have done shows that the FOH guy would actually get rid of the deep lows because they didn't like it.



Yep, great point, Ivan. I did an install a few years back including a pair of massive 4x18 exponential bass horns, and the performance was truly impressive (considering the non-existent budget). Went back 2 months later to hear a show there (semi-national act) and there was very little bottom end at all. Asked the house guy "What the hell?" and he told me the band's engineer didn't believe in using anything below 75hz.
Title: Re: Dual 21 inch subs
Post by: Ivan Beaver on November 24, 2011, 12:32:56 pm
Yep, great point, Ivan. I did an install a few years back including a pair of massive 4x18 exponential bass horns, and the performance was truly impressive (considering the non-existent budget). Went back 2 months later to hear a show there (semi-national act) and there was very little bottom end at all. Asked the house guy "What the hell?" and he told me the band's engineer didn't believe in using anything below 75hz.
And if somebody was in the audience judging the quality of the bass-they might post on a forum that those cabinets had no bass.

Or in a different light, at on e of our stadium installs the subs went solid down into the 30's.  But they are highpassed somewhere around 50-60Hz.

The reason?  VIP seats.  While a lot more was spent on the rigging than the actual loudspeakers.  The loudspeakers are on the roof with the enclosed VIP sections are below them.  A LOT of attention was paid to keeping the bass out of those suites.

Every sub and full range cabinet was mounted with spring/rubber isolators in a "bunker".  Then that bunker was mounted on huge rubber isolators and the base went straight down to the main structure steel.

It works very well at keeping the bass from  around 60hz up out of those suites.  But  below that, the bass still gets into them and "annoys" them.  So rather than allowing the cabinets to be used down to their potential, they are highpassed.

And the causual person who would go to a game there and know what cabinets were being used would come back and say  "I heard the TH118's and they really didin't go that low".  Yes in THAT PARTICULAR situation they were not allowed to.  But you would still form an impression.

Unless you really know what all is going on, it can be hard to judge some aspects of performance during a performance-especially when other people are in control of the system setup and mix.
Title: Re: Dual 21 inch subs
Post by: Jeff Bankston on November 24, 2011, 05:34:18 pm
Al at u.s.speaker says the Ciare 18" woofs have the lowest freq response, i think he said they were flat to 30cps. 877-732-5374 http://www.usspeaker.com  .... all those guys are right about how the system is set up. the room/building/colusiem/etc makes a big difference on how a system sounds. the only way to judge is to do a side by side comparison.
Title: Re: Dual 21 inch subs
Post by: Tim Padrick on November 26, 2011, 06:35:57 am
I often have dreams where I can take a hop and simply glide above the ground.  It is really cool and very real.  Until I wake up and have to walk to the shower.

In mine, I don't have to hop - I just levitate and go - pretty quickly too.  And it is indeed cool as hell.
Title: Re: Dual 21 inch subs
Post by: Randy Frierson on December 07, 2011, 10:35:42 pm
Anything is possible in your dreams......

Buying componets is the easy part...building a sub cabinet takes alot of knowledge that you cannot get from any plans...
Title: Re: Dual 21 inch subs
Post by: Jeff Bankston on December 08, 2011, 02:13:24 am
Buying componets is the easy part...building a sub cabinet takes alot of knowledge that you cannot get from any plans...
you said it ! i learned that on my first cabnet build back in the 70's. waiting for the new FaitalPro 18xl1600 to arrive at u.s. speaker. then the task to build a cabnet and get it right begins. i got lots of plywood to experiment with.
Title: Re: Dual 21 inch subs
Post by: Art Welter on December 08, 2011, 05:56:22 pm
Thanks for your reply. Yes they had 16 21 inch B&C drivers. That was what they chose to take out for the show. They can go up to 8 subs per side which equates to 16 drivers per side. They are a large company so they can afford it. As I said before, I wouldn't buy everything at once. I'm just starting so I'd start small. However for the type of shows I want to do, I require alot of low end and I understand that going with 18's would be cheaper and the weight advantages would be better but I would need too many cabs to get the low end I require. I went to show recently and they have 16 eaw sb1000 subs per side powered by macrotech amplifiers and in my opinion, although they sounded good, the low end output from them came nowhere close to the 4 dual 21 inch subs per side at the other show I went to. So I had just made up my mind to go dual 21 inch from the start.
The Neo BC drivers are in a different league than the drivers used in EAW SB1000s, whether 18" or 21", but they do require lots of power to achieve the difference.

This is a good BR design for a BC21SW152:
http://www.data-bass.com/data?page=system&id=1&mset=32

If you tune higher (shorten the port) than the present 25 Hz Fb, sensitivity would go up quite a bit.
For most heavy bass musical genre an Fb of 30 Hz would be plenty low, and would kick up the LF response quite a bit.

Title: Re: Dual 21 inch subs
Post by: Bill Hornibrook on December 10, 2011, 03:05:42 pm
The 21" sub cabs I built for those drivers (based on B&C's design off their website) are smaller but tuned higher - at 33hz.
Title: Re: Dual 21 inch subs
Post by: Charlie Zureki on December 14, 2011, 10:08:34 am
 1.)  My advice to this young man is that he buy used, brand name sound gear.
 2.)  That wanting to build, and having the ability to build his own cabinets are two separate issues. Especially, if he wants some degree of performance from his build.
 3.)  That he get started with some type of system to generate money with which he'll reinvest to buy better gear....while, at the same time, learning about professional audio, building a reputation and a client list.
 4.) That this young man research the cost of a basic system that would provide audio coverage for three hundred people, outdoors, and with all the little things...like Mics, Stands, clamps, Wireless Mics, Mic cables, Electrical leads, Speaker cables, System Processing, Effects gear, Snakes, Foldback cabinets, Amplifiers (unless spkrs are self powered) cases, racks & trunks, some way to transport it all,  etc.... and realize that 1 sub cabinet is like a grain of sand on the beach compared to all of the other gear he'd need to provide audio for any show.
 
 Not trying to discourage him (you), but it's very hard to build a system...especially starting with a single subwoofer...and one piece at a time.  You need deep pockets.

  Good Luck,
  Hammer
 ps..the system you described sounds like Franz Ferdinands...?

 
Title: Re: Dual 21 inch subs
Post by: Jay Barracato on December 14, 2011, 11:34:52 am
I seem to remember a song along those lines:

"I got it one piece at a time, and it didn't cost me a dime..."
Title: Re: Dual 21 inch subs
Post by: Ivan Beaver on December 14, 2011, 12:57:52 pm
I seem to remember a song along those lines:

"I got it one piece at a time, and it didn't cost me a dime..."
Wasn't that a Johnny Cash song-about when he worked at a auto manufactuer and smuggled out all the parts in his lunch box.

And when He went ot register the car the model was a '56-57-58-59-60-61-62 etc.

ANd he assembled it with help of an "adapto Kit".

At least that is what I remember.
Title: Re: Dual 21 inch subs
Post by: g'bye, Dick Rees on December 14, 2011, 01:14:38 pm
I seem to remember a song along those lines:

"I got it one piece at a time, and it didn't cost me a dime..."


http://www.youtube.com/watch?v=rWHniL8MyMM
Title: Re: Dual 21 inch subs
Post by: Jay Barracato on December 14, 2011, 01:26:58 pm
Wasn't that a Johnny Cash song-about when he worked at a auto manufactuer and smuggled out all the parts in his lunch box.

And when He went ot register the car the model was a '56-57-58-59-60-61-62 etc.

ANd he assembled it with help of an "adapto Kit".

At least that is what I remember.

Yep you pegged it.
Title: Re: Dual 21 inch subs
Post by: g'bye, Dick Rees on December 14, 2011, 01:38:27 pm
Yep you pegged it.

The recitation of consecutive model years at the end of the song is a take-off on the "Auctioneer Song"..........with a nod to "I've Been Everywhere" as well.