Dimensions for single 12" bass cab?

Steve G · July 13th, 2008, 04:34 PM

I have a 12" bass speaker which I built a terrible cabinet for last year. Really sounded bad.

So I have some wood flying around, anyone got any suggestions on what size to make a cabinet, need it to be compact as possible.

Cheers
Steve

Tim Armstrong · July 13th, 2008, 09:50 PM

Avatar makes one, here's their page for it, there are dimensions in the text:

http://www.avatarspeakers.com/sB112.htm

Cheers, Tim

Steve G · July 14th, 2008, 05:27 AM

Thanks Tim, that one looks good. I wonder if reducing its size on the long edge would lose a lot of tone? Basically, the smaller the better as Im pushed for space at home. Maybe Im trying to have my cake and eat it..

martini · July 14th, 2008, 07:28 AM

I'm using a GK MBS3 for my smaller gigs, the whole combo is barely big enough to contain the single 12 inch speaker...it sound amazing.
It shows that if the design is right, theres no need to worry.

http://www.gallien-krueger.com/produ..._co_150s.html#

hockey_head · July 14th, 2008, 11:27 AM

see if you can find some prints at electro-voice. they used to publish nice thiele box designs and basic pointers about box / porting characteristics especially relating to their force series instrument speaks.
I think that's actually a section of the P.A. Bible which was a free publication they started in the late seventies.

Vince a · July 14th, 2008, 11:34 AM

It's not as simple as building a box around a speaker . . . each speaker has certain information . . . Q's, free air space, etc., etc., etc. . . . that must be used to execute the building of the box that will hold it.

Your first attempt may have not sounded well because of the size of the box - not how well you did or did not build it!

martini · July 14th, 2008, 02:01 PM

Quote:

Originally Posted by Vince a

It's not as simple as building a box around a speaker . . . each speaker has certain information . . . Q's, free air space, etc., etc., etc. . . . that must be used to execute the building of the box that will hold it.

Very true, I attempted to upgrade my Ampeg 410 cab with much higher powered speakers.....they couldn't handle the cab. Squeaked and complained on every note below Low A.
Spoke to one the Ampeg tech guys and he told me that each of the Ampeg cabs and speaker configurations were made and tuned to each other, hence a 100 watt speaker totally outperforming a 400 watt speaker. (Made by the same company BTW.)

Steve G · July 14th, 2008, 02:15 PM

Quote:

Originally Posted by Vince a

It's not as simple as building a box around a speaker . . . each speaker has certain information . . . Q's, free air space, etc., etc., etc. . . . that must be used to execute the building of the box that will hold it.

Your first attempt may have not sounded well because of the size of the box - not how well you did or did not build it!

This is exactly what I feared!

4mal · July 14th, 2008, 09:42 PM

so Steve, do you have any idea of make and model of the speaker ? If not it's a shot in the dark ...

Vince a · July 14th, 2008, 10:10 PM

Check this out:

Cursor down to where it starts with "Driver Properties," then look at the next three boxes to get an idea of the info that you'll need to make that box . . .

http://www.ht-audio.com/pages/BassBoxPro.html

. . . then further down it actually gets into making the right size box.

-V

PS. These are speaker boxes for cars . . .

aunchaki · July 14th, 2008, 11:01 PM

WinISD is a Windows program that help calculate optimal bass cab dimensions based on cab type, driver size, number, freq range, etc... It's cool.

Steve G · July 16th, 2008, 05:50 AM

Quote:

Originally Posted by 4mal

so Steve, do you have any idea of make and model of the speaker ? If not it's a shot in the dark ...

Nothing special, think its an eminence beta 12. 250w.

Steve G · July 16th, 2008, 05:51 AM

Quote:

Originally Posted by Vince a

Check this out:

Cursor down to where it starts with "Driver Properties," then look at the next three boxes to get an idea of the info that you'll need to make that box . . .

http://www.ht-audio.com/pages/BassBoxPro.html

thanks,
Ill take a look..

4mal · July 16th, 2008, 02:09 PM

Eminence Beta 12A Cab designs

The link above is what Eminence recommends for a standard Beta 12. There are a coupl of fidderent Beta 12 models so you might wantto email Eminence aboutthe specific model #, that is usually on a while paper lable, stuck to the side of the magnet.

Hope that helps.

Steve G · July 16th, 2008, 02:54 PM

Thanks 4mal, thats great. Ive got some sums to do I think!

4mal · July 17th, 2008, 12:12 PM

Unless you are building hi performance sub's, tolerances of about 10% are about as good as you really need. In the land of hi performance sub's the tolerance is more like 1 % as the energy levels involved can rip drivers to shreds ...

2. See if you can find a set of the EV TL606 plans for their 3.2 cu ft bass box. Dimensionally it's all wrong for you but - it's a really good guide for how to construct a slot port bass box.

3. the area of a circle is pi*r^2 so that 3" round port translates to something like 7.07 square inches, time 2 ports is 14.1 sq in or 45.5 sq cm ... you should probably migrate from the 2 3" round ports to a shelf port design like the TL box.

4. when construcing - the shelf of the port becomes an internal brace. Make the shelf itself in 2 pieces. The front portion you make 'shallow' and fixed in place. The last piece you make removable so you can 'tune' the cab by ear at the end of the process. The bottom of the cab is also 'removable during the tuning process - glue it and screw it down after tuning. Every other joint is glued and screwed during construction.

Back to the shelf .. given that Eminence is calling for 4.154 inches in depth, or 10.55 cm, then make the front portion say 8 cm and the back portion is the remained. Make is say 6 cm. Assemble, test at low volume, disassemble, pull the back portion of the shelf, make it narrower, reassemble, rtest, listen repoeat until you get the cab tuned *right*. You can always go back to the original 6 cm depth with a new piece if that's what sounded best.

These TL parameters - the spec's from Eminence have pretty large real world fluctuations from what I'm told. The age of the driver (hours in use), the attention to detail during manufacturing that day, the humidity present during testing as opposed to when you're playing all contribute to that +/- 10% tolerance I mentioned earlier. Bottom line is that you treat these as a good place to start. Real good ideas in fact, but do not slave to that sheet in a sense af attempting to achieve 100% accuracy. There's wiggle room there ...

I'm a novice at this stuff by the way. I have built several boxes over the last coule of years but I have something of a tutor. A fellow bassist who lives nearby and has a pro sound pedigree. The construction ideas above are pretty much straight from his advice to me and now on to you... He builds some really cool stuff ...

(note: math adjusted for formula error)

hockey_head · July 23rd, 2008, 07:47 PM

the area of a circle is pi R squared.

pi x d = circumfrance

4mal · July 24th, 2008, 11:48 AM

Thanks for the heads up. You would think that by 3PM I'd be awake enough ... but no....

July 13th, 2008, 04:34 PM	#1 (permalink)
Steve G Tele-Afflicted Join Date: Nov 2005 Location: LeeK (England) Posts: 1,757 60 Photos	Dimensions for single 12" bass cab? I have a 12" bass speaker which I built a terrible cabinet for last year. Really sounded bad. So I have some wood flying around, anyone got any suggestions on what size to make a cabinet, need it to be compact as possible. Cheers Steve __________________ "He was a drinkin' man with a guitar problem..." http://www.myspace.com/stevegiddings http://www.myspace.com/hiandlonesome

July 13th, 2008, 09:50 PM	#2 (permalink)
Tim Armstrong Moderator Poster Extraordinaire Join Date: Mar 2003 Location: Berlin, Maryland, USA Age: 49 Posts: 9,717	Avatar makes one, here's their page for it, there are dimensions in the text: http://www.avatarspeakers.com/sB112.htm Cheers, Tim __________________ http://www.moodswingers.org

July 14th, 2008, 05:27 AM	#3 (permalink)
Steve G Tele-Afflicted Join Date: Nov 2005 Location: LeeK (England) Posts: 1,757 60 Photos	Thanks Tim, that one looks good. I wonder if reducing its size on the long edge would lose a lot of tone? Basically, the smaller the better as Im pushed for space at home. Maybe Im trying to have my cake and eat it.. __________________ "He was a drinkin' man with a guitar problem..." http://www.myspace.com/stevegiddings http://www.myspace.com/hiandlonesome

July 14th, 2008, 07:28 AM	#4 (permalink)
martini Tele-Meister Join Date: Mar 2003 Posts: 366	I'm using a GK MBS3 for my smaller gigs, the whole combo is barely big enough to contain the single 12 inch speaker...it sound amazing. It shows that if the design is right, theres no need to worry. http://www.gallien-krueger.com/produ..._co_150s.html# __________________ Your attitude will always affect your altitude.

July 14th, 2008, 11:34 AM	#6 (permalink)
Vince a Tele-Holic Join Date: Feb 2004 Location: Modesto, CA Age: 62 Posts: 771	It's not as simple as building a box around a speaker . . . each speaker has certain information . . . Q's, free air space, etc., etc., etc. . . . that must be used to execute the building of the box that will hold it. Your first attempt may have not sounded well because of the size of the box - not how well you did or did not build it! __________________ Epiphone Elitist Les Paul Fender Am/Se Stratocaster Fender Am/Se Telecaster Fender '76 Doublebound Custom Telecaster Fender Am/Se Jazz Bass and P-Bass Special Simon and Patrick Rosewood C/W Acoustic/Electric

July 14th, 2008, 11:27 AM	#5 (permalink)
hockey_head Tele-Meister Join Date: Mar 2008 Location: shortsville, ny Age: 51 Posts: 379	see if you can find some prints at electro-voice. they used to publish nice thiele box designs and basic pointers about box / porting characteristics especially relating to their force series instrument speaks. I think that's actually a section of the P.A. Bible which was a free publication they started in the late seventies.

July 14th, 2008, 09:42 PM	#9 (permalink)
4mal Friend of Leo's Join Date: Mar 2003 Location: The Gorge Posts: 2,153	so Steve, do you have any idea of make and model of the speaker ? If not it's a shot in the dark ...

July 14th, 2008, 10:10 PM	#10 (permalink)
Vince a Tele-Holic Join Date: Feb 2004 Location: Modesto, CA Age: 62 Posts: 771	Check this out: Cursor down to where it starts with "Driver Properties," then look at the next three boxes to get an idea of the info that you'll need to make that box . . . http://www.ht-audio.com/pages/BassBoxPro.html . . . then further down it actually gets into making the right size box. -V PS. These are speaker boxes for cars . . . __________________ Epiphone Elitist Les Paul Fender Am/Se Stratocaster Fender Am/Se Telecaster Fender '76 Doublebound Custom Telecaster Fender Am/Se Jazz Bass and P-Bass Special Simon and Patrick Rosewood C/W Acoustic/Electric

July 14th, 2008, 11:01 PM	#11 (permalink)
aunchaki Tele-Afflicted Join Date: Mar 2006 Location: Western New York Posts: 1,251 16 Photos	WinISD is a Windows program that help calculate optimal bass cab dimensions based on cab type, driver size, number, freq range, etc... It's cool. __________________ Two Teles, One Strat, Two Acoustics (6 & 12 strings), One Solidbody Acoustic, Two Mandolins (4 & 8 strings), One Bass (5 strings)

July 16th, 2008, 02:09 PM	#14 (permalink)
4mal Friend of Leo's Join Date: Mar 2003 Location: The Gorge Posts: 2,153	Eminence Beta 12A Cab designs The link above is what Eminence recommends for a standard Beta 12. There are a coupl of fidderent Beta 12 models so you might wantto email Eminence aboutthe specific model #, that is usually on a while paper lable, stuck to the side of the magnet. Hope that helps.

July 16th, 2008, 02:54 PM	#15 (permalink)
Steve G Tele-Afflicted Join Date: Nov 2005 Location: LeeK (England) Posts: 1,757 60 Photos	Thanks 4mal, thats great. Ive got some sums to do I think! __________________ "He was a drinkin' man with a guitar problem..." http://www.myspace.com/stevegiddings http://www.myspace.com/hiandlonesome

July 17th, 2008, 12:12 PM	#16 (permalink)
4mal Friend of Leo's Join Date: Mar 2003 Location: The Gorge Posts: 2,153	Unless you are building hi performance sub's, tolerances of about 10% are about as good as you really need. In the land of hi performance sub's the tolerance is more like 1 % as the energy levels involved can rip drivers to shreds ... 2. See if you can find a set of the EV TL606 plans for their 3.2 cu ft bass box. Dimensionally it's all wrong for you but - it's a really good guide for how to construct a slot port bass box. 3. the area of a circle is pir^2 so that 3" round port translates to something like 7.07 square inches, time 2 ports is 14.1 sq in or 45.5 sq cm ... you should probably migrate from the 2 3" round ports to a shelf port design like the TL box. 4. when construcing - the shelf of the port becomes an internal brace. Make the shelf itself in 2 pieces. The front portion you make 'shallow' and fixed in place. The last piece you make removable so you can 'tune' the cab by ear at the end of the process. The bottom of the cab is also 'removable during the tuning process - glue it and screw it down after tuning. Every other joint is glued and screwed during construction. Back to the shelf .. given that Eminence is calling for 4.154 inches in depth, or 10.55 cm, then make the front portion say 8 cm and the back portion is the remained. Make is say 6 cm. Assemble, test at low volume, disassemble, pull the back portion of the shelf, make it narrower, reassemble, rtest, listen repoeat until you get the cab tuned right. You can always go back to the original 6 cm depth with a new piece if that's what sounded best. These TL parameters - the spec's from Eminence have pretty large real world fluctuations from what I'm told. The age of the driver (hours in use), the attention to detail during manufacturing that day, the humidity present during testing as opposed to when you're playing all contribute to that +/- 10% tolerance I mentioned earlier. Bottom line is that you treat these as a good place to start. Real good ideas in fact, but do not slave to that sheet in a sense af attempting to achieve 100% accuracy. There's wiggle room there ... I'm a novice at this stuff by the way. I have built several boxes over the last coule of years but I have something of a tutor. A fellow bassist who lives nearby and has a pro sound pedigree. The construction ideas above are pretty much straight from his advice to me and now on to you... He builds some really cool stuff ... (note: math adjusted for formula error) Last edited by 4mal; July 24th, 2008 at 11:46 AM.*

July 23rd, 2008, 07:47 PM	#17 (permalink)
hockey_head Tele-Meister Join Date: Mar 2008 Location: shortsville, ny Age: 51 Posts: 379	the area of a circle is pi R squared. pi x d = circumfrance

July 24th, 2008, 11:48 AM	#18 (permalink)
4mal Friend of Leo's Join Date: Mar 2003 Location: The Gorge Posts: 2,153	Thanks for the heads up. You would think that by 3PM I'd be awake enough ... but no....