DIY Sub for around $2k? - Page 5 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #121 of 158 Old 07-16-2013, 03:19 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,912
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 83 Post(s)
Liked: 272

For a ported enclosure you should line the walls. Sealed enclosure should be stuffed depending on the QTC of the enclosure. If the enclosure has a high QTC then you want to do a moderate to heavy stuff.

Mrkazador is online now  
Sponsored Links
Advertisement
 
post #122 of 158 Old 07-16-2013, 05:04 PM - Thread Starter
Advanced Member
 
simp1yamazn's Avatar
 
Join Date: Mar 2007
Posts: 657
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Liked: 67
Help a noob out. What is QTC? Also, if I fill the enclosure won't that reduce the effective volume?
simp1yamazn is offline  
post #123 of 158 Old 07-16-2013, 05:19 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,912
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 83 Post(s)
Liked: 272

 

Notice where it says QTC, its recommended to be at .7 but you can go higher or lower.

 

Here is some more info

http://www.nousaine.com/pdfs/Box%20Stuffing.pdf

http://www.data-bass.com/data?page=content&id=79

Mrkazador is online now  
post #124 of 158 Old 07-17-2013, 09:52 AM - Thread Starter
Advanced Member
 
simp1yamazn's Avatar
 
Join Date: Mar 2007
Posts: 657
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Liked: 67
Quote:
Originally Posted by Jay1 View Post

I dont know, 3 ft3 13hz box, using a amp that cant filter below 20hz? How is he going to port it without the port being something like 6' long, and what if he needs to set a HPF below the tuning point?

I think a miniDSP is mandatory for this

http://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4

You can pair that with the regular NU6000, so it will basically cost the same, or any other amp.

With that much power, and an EQ that nice, you could basically shape the response however you want. Just for a crazy idea, you could put 4 of these drivers in a single 4 ft3 box sealed box, one driver on each side, wired series/parallel for a 4 ohm load. A 22 x 22 x 18.5" box will get you the volume.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-469

Apply the below filters with the mini DSP (note the middle is - )


That would be the max output from the boosted response from a single channel of the NU6000, the system would still be capable of 120+ db above 30 hz. You could still build two of these quad woofer subs powered and EQ'd by the NU6000/miniDSP combo for $2k.

thoughts on the newer ultimax 15" vs the reference from dayton?
simp1yamazn is offline  
post #125 of 158 Old 07-17-2013, 10:13 AM
AVS Special Member
 
Jay1's Avatar
 
Join Date: Aug 2002
Location: AZ
Posts: 3,986
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 102
Quote:
Originally Posted by simp1yamazn View Post

thoughts on the newer ultimax 15" vs the reference from dayton?

The ultimax requires such a large box that having 4 in 4 ft3 would put the Q through the roof. Sure you could still EQ it, but I'm not sure if there's any benefit, considering you likely wont even be able to tax the HO's unless you can get more then 3k watts on them.



(had to use two 6 db cuts for the UM)
Jay1 is offline  
post #126 of 158 Old 07-18-2013, 06:37 AM
AVS Addicted Member
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 24,305
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 199 Post(s)
Liked: 1036
OP ,

What about 12" LMS tuned low ?

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
Mfusick is offline  
post #127 of 158 Old 07-18-2013, 12:13 PM - Thread Starter
Advanced Member
 
simp1yamazn's Avatar
 
Join Date: Mar 2007
Posts: 657
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Liked: 67
Quote:
Originally Posted by Mfusick View Post

OP ,

What about 12" LMS tuned low ?

ack, too many smart people with too many viable options biggrin.gif I assume tuned low being a ported design? I don't have any hard evidence, but anecdotally i tend to like sealed subs more. no proof, just preferences of subs that i've listened to tend towards sealed designs.

one thing i've been toying with is long-term planning with re-using drivers. there is a good chance I will be able to move into a space where I have more freedom with placement of multiple subs in the next 2-3 years. At that point, do I plan my current project and pick drivers based on what will work best later down the road? The only money I can really spend on my audio hobby/obsession is money that is gained from selling of other stuff. in terms of cost, quad 15" daytons is about $1350, quad 18" daytons $1620, dual uxl-18's $1750, single lms 5400 $1650. All seem doable for me right now. However, I think the LMS it out for two reasons, 1) to change configuration would mean building a whole new sub so long-term would essentially double the total cost and 2) i'm a little turned off because of QC with PE receiving an entire shipment of defect drivers that had somehow gotten demagnetized eek.gif

so my two options are the two quad daytons and the dual uxl-18. the two quad options would give me two dual-opposed for later down the road, and the dual uxl-18 would obviously give me a pair of uxl-18's. I dont' even know if quad 18's would work well in such a small enclosure but the quads would open the opportunity for quad subs!!! ahhhh!!!!!!!!!!! :brain exploded:

one thing i realized earlier today is any of the above designs are going to be seriously heavy. like pushing 200 pounds including amp eek.gifeek.gif

One more question on the enclosure itself. Do you think extra bracing would be needed if I used double MDF so it would be 1.5" thick all the way around? Or would it actually be better to use single 3/4" mdf with internal bracing?
simp1yamazn is offline  
post #128 of 158 Old 07-18-2013, 02:17 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
In terms of enclosure, you'll be MUCH better off using a single layer of 3/4" MDF with internal bracing than to double up. Even doubling up will require bracing. Doubling up more than doubles your weight while adding minimal benefits as compared to proper bracing. For example, my 1.25ft^3 sealed box would increase by ~25lbs if I doubled up the thickness. Adding a lattice style brace in the center of the box only added ~1lb or so. That's for a smallish 15" cube. I can't imagine what you'll be adding for 18" driver enclosures.
duc135 is offline  
post #129 of 158 Old 07-18-2013, 02:29 PM - Thread Starter
Advanced Member
 
simp1yamazn's Avatar
 
Join Date: Mar 2007
Posts: 657
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Liked: 67
Quote:
Originally Posted by duc135 View Post

In terms of enclosure, you'll be MUCH better off using a single layer of 3/4" MDF with internal bracing than to double up. Even doubling up will require bracing. Doubling up more than doubles your weight while adding minimal benefits as compared to proper bracing. For example, my 1.25ft^3 sealed box would increase by ~25lbs if I doubled up the thickness. Adding a lattice style brace in the center of the box only added ~1lb or so. That's for a smallish 15" cube. I can't imagine what you'll be adding for 18" driver enclosures.

my only concern, which could be completely unfounded, is strength of the sides that have the drivers themselves. each uxl-18 is 65 pounds and with constant vibration from the cone moving is there any reason to be concerned? I've seen quite a few builds that use double MDF for drivers.
simp1yamazn is offline  
post #130 of 158 Old 07-18-2013, 03:27 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Quote:
Originally Posted by simp1yamazn View Post

my only concern, which could be completely unfounded, is strength of the sides that have the drivers themselves. each uxl-18 is 65 pounds and with constant vibration from the cone moving is there any reason to be concerned? I've seen quite a few builds that use double MDF for drivers.

Sorry for the confusion. Yes, double or triple for the driver side (called the baffle btw). My build in progress is actually 4 layers thick with one of the center layers being 15/16" plywood for a smallish 15" Alpine driver. Total thickness is ~3.25" only because I want to recess the driver and the top plate of the Alpine with the rubber top plate cover is 1.5" tall which will leave me with an ample 1.75" of baffle to screw the driver to. I also used plywood in the center to reduce the chance of stripping the screws. MDF is not the greatest material in the world to hold screws. The rest of you box can be single thickness 3/4" MDF and well braced. What I do is use scrap MDF and cut them into 3/4" square sticks. I'll glue them together to form a grid with the squares being no more than 6" to a side. Think of a three dimensional tic-tac-toe box. In my opinion, you don't want anything more than an 8" square section to be without bracing. Even if its a double thickness wall.
duc135 is offline  
post #131 of 158 Old 07-19-2013, 07:21 AM - Thread Starter
Advanced Member
 
simp1yamazn's Avatar
 
Join Date: Mar 2007
Posts: 657
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Liked: 67
Got it. Seems like a quad driver design would add a decent amount of extra weight from having 4 baffles and would make strong internal bracing harder to accomplish
simp1yamazn is offline  
post #132 of 158 Old 07-19-2013, 10:13 AM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Well, with quads in a single enclosure the weight addition would be minimal by doubling or tripling of the baffles since most of the MDF would be removed to accommodate the driver cutout. I'm not sure how large your enclosure will be so it's hard to say. Depending on the dimensions you may only need to brace two sides. The top and bottom.
duc135 is offline  
post #133 of 158 Old 07-19-2013, 10:16 AM
AVS Addicted Member
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 24,305
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 199 Post(s)
Liked: 1036
Aren't you much better to just build 2 subs? In two locations. It sounds way better.

Audio theory:

Technically the best bass would be 4 subs, in four corners of the room. Two on the floor. Two on the ceiling.

You might not be able to do that, but placing a second sub in a second location would not only improve your sound quality- it also boosts your SPL too. Two subs in one box never play as loud as the same two subs in two boxes.

What's up with your continued fascination for multiple drivers? I am not understanding it.

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
Mfusick is offline  
post #134 of 158 Old 07-19-2013, 11:33 AM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Quote:
Originally Posted by Mfusick View Post

Aren't you much better to just build 2 subs? In two locations. It sounds way better.

Audio theory:

Technically the best bass would be 4 subs, in four corners of the room. Two on the floor. Two on the ceiling.

You might not be able to do that, but placing a second sub in a second location would not only improve your sound quality- it also boosts your SPL too. Two subs in one box never play as loud as the same two subs in two boxes.

What's up with your continued fascination for multiple drivers? I am not understanding it.

Actually, subs that are separated do not add SPL. If anything, separated subs have the potential to cancel each other out at certain frequencies depending on the location and distances from each other. Two subs co-located will add SPL. Subs that are separated will help to smooth FR, not add SPL (well, not appreciably). Two drivers in a single 3ft^3 enclosure will play the same as two drivers each in it's own 1.5ft^3 enclosure assuming they are wired the same in each scenario.

The benefits of sharing the enclosure is less material required and when dual/quad opposed, you will gain the benefits of cancellation of driver forces on the enclosure. Ever see or hear about a sub moving across a floor when playing loud? That's because the force of the driver moving in and out causes the enclosure to rock back and forth if there is not enough mass or bracing (not internal, but external as in straps) to prevent it from doing so. Dual/Quad opposed do not exhibit this behavior since the drivers move in opposite directions and the forces cancel each other out.

Maybe he wants to build four of these behemoths eventually, but is starting with one for now. That would be awesome if he does.
duc135 is offline  
post #135 of 158 Old 07-19-2013, 11:47 AM
AVS Special Member
 
Jay1's Avatar
 
Join Date: Aug 2002
Location: AZ
Posts: 3,986
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 102
Quote:
Originally Posted by simp1yamazn View Post

Got it. Seems like a quad driver design would add a decent amount of extra weight from having 4 baffles and would make strong internal bracing harder to accomplish

Quote:
Originally Posted by duc135 View Post

Well, with quads in a single enclosure the weight addition would be minimal by doubling or tripling of the baffles since most of the MDF would be removed to accommodate the driver cutout. I'm not sure how large your enclosure will be so it's hard to say. Depending on the dimensions you may only need to brace two sides. The top and bottom.

In addition to what duc135 said, the quad drivers are cancelling each other out, so all of the force they're exerting is pushing on the top/bottom panels. Add some solid bracing there and the sub should be pretty dead.
Jay1 is offline  
post #136 of 158 Old 07-19-2013, 11:58 AM
AVS Special Member
 
coolrda's Avatar
 
Join Date: Nov 2002
Location: Bakersfield, CA
Posts: 1,054
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Liked: 15
Quote:
Originally Posted by duc135 View Post

Actually, subs that are separated do not add SPL. If anything, separated subs have the potential to cancel each other out at certain frequencies depending on the location and distances from each other. Two subs co-located will add SPL. Subs that are separated will help to smooth FR, not add SPL (well, not appreciably). Two drivers in a single 3ft^3 enclosure will play the same as two drivers each in it's own 1.5ft^3 enclosure assuming they are wired the same in each scenario.

The benefits of sharing the enclosure is less material required and when dual/quad opposed, you will gain the benefits of cancellation of driver forces on the enclosure. Ever see or hear about a sub moving across a floor when playing loud? That's because the force of the driver moving in and out causes the enclosure to rock back and forth if there is not enough mass or bracing (not internal, but external as in straps) to prevent it from doing so. Dual/Quad opposed do not exhibit this behavior since the drivers move in opposite directions and the forces cancel each other out.

Maybe he wants to build four of these behemoths eventually, but is starting with one for now. That would be awesome if he does.

While its true that subs can cancel at certain frequencies, which as you mentioned can be an advantage to smoothing the FR, adding subs in different location does most definitely raises SPL. Otherwise we wouldn't see 8,12,16+ driver systems here. I've personally had my subs in front 12ft apart, to the sides 18ft apart and split in the back behind and have always measured a 6db db gain or close to it.
coolrda is offline  
post #137 of 158 Old 07-19-2013, 12:14 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,238
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1690
Quote:
Originally Posted by coolrda View Post

While its true that subs can cancel at certain frequencies, which as you mentioned can be an advantage to smoothing the FR, adding subs in different location does most definitely raises SPL.
+1. Cancellation will only occur where waves and their reflections off boundaries meet at and very close to 180 degrees out of phase. At all other frequencies SPL will go up, by as much as 6dB per doubling of sub count.
Quote:
Two subs co-located will add SPL.
The correct technical term for this is mutually coupled. Fully constructive mutual coupling occurs when subs are placed less than 1/4 wavelength apart, which makes it impossible for their waves to meet at or close to 180 degrees out of phase. When placed further apart coupling still occurs, but it's not fully constructive across the full band width.
Quote:
The benefits of sharing the enclosure is less material required and when dual/quad opposed, you will gain the benefits of cancellation of driver forces on the enclosure.
That should be qualified in that it reduces, or even eliminates, vector forces that otherwise might cause the sub to move. Some have taken this to mean that internal pressures on the enclosure panels are reduced or eliminated, and that's not the case.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #138 of 158 Old 07-19-2013, 12:29 PM
AVS Addicted Member
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 24,305
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 199 Post(s)
Liked: 1036
So in summation, a two sub set up should sound better and play a little louder than a single sub with two drivers ?

If I had a choice I'd build two subs instead of one. The only factor that might ever change that is your WAF OP.

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
Mfusick is offline  
post #139 of 158 Old 07-19-2013, 12:35 PM - Thread Starter
Advanced Member
 
simp1yamazn's Avatar
 
Join Date: Mar 2007
Posts: 657
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Liked: 67
Quote:
Originally Posted by Mfusick View Post

So in summation, a two sub set up should sound better and play a little louder than a single sub with two drivers ?

If I had a choice I'd build two subs instead of one. The only factor that might ever change that is your WAF OP.

Yup. Definitively vetoed on the duals a few days ago.
simp1yamazn is offline  
post #140 of 158 Old 07-19-2013, 01:21 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Quote:
Originally Posted by coolrda View Post

While its true that subs can cancel at certain frequencies, which as you mentioned can be an advantage to smoothing the FR, adding subs in different location does most definitely raises SPL. Otherwise we wouldn't see 8,12,16+ driver systems here. I've personally had my subs in front 12ft apart, to the sides 18ft apart and split in the back behind and have always measured a 6db db gain or close to it.
Quote:
Originally Posted by Bill Fitzmaurice View Post

+1. Cancellation will only occur where waves and their reflections off boundaries meet at and very close to 180 degrees out of phase. At all other frequencies SPL will go up, by as much as 6dB per doubling of sub count.
The correct technical term for this is mutually coupled. Fully constructive mutual coupling occurs when subs are placed less than 1/4 wavelength apart, which makes it impossible for their waves to meet at or close to 180 degrees out of phase. When placed further apart coupling still occurs, but it's not fully constructive across the full band width.

Thank you both for the correction. I was under the obviously incorrect impression that subs, must be co-located in order to increase SPL (doubling drivers = +3dB, doubling power = +3dB).

I use co-located here instead of the technically correct term "mutually coupled" here because I feel they can have different meanings. I'm assuming the definition of co-located means that they are next to each other while mutually coupled can mean they are merely within the area that the sound waves can be coupled together to increase SPL. In the case of LF waves this can be in the tens of feet. Correct me if I'm wrong in the definition of the two.
Quote:
Originally Posted by Bill Fitzmaurice View Post

That should be qualified in that it reduces, or even eliminates, vector forces that otherwise might cause the sub to move. Some have taken this to mean that internal pressures on the enclosure panels are reduced or eliminated, and that's not the case.

Yes, thank you for the clarification. It's been quite a few years since I've taken physics so I rarely think in technical terms anymore now that my profession does not require much thinking in those terms. That's why I gave the example of the sub moving across the floor due to the enclosure rocking back and forth due to the driver forces on the enclosure as the cone moves in and out.
duc135 is offline  
post #141 of 158 Old 07-19-2013, 01:25 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Quote:
Originally Posted by Mfusick View Post

So in summation, a two sub set up should sound better and play a little louder than a single sub with two drivers ?

Again, I don't think this to be the case. All other things being the same, two drivers in a 3ft^3 enclosure will play at the same SPL as two of the same drivers each in it's own 1.5ft^3 enclosure.
duc135 is offline  
post #142 of 158 Old 07-19-2013, 01:37 PM
AVS Special Member
 
Jay1's Avatar
 
Join Date: Aug 2002
Location: AZ
Posts: 3,986
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 102
Quote:
Originally Posted by Bill Fitzmaurice View Post


That should be qualified in that it reduces, or even eliminates, vector forces that otherwise might cause the sub to move. Some have taken this to mean that internal pressures on the enclosure panels are reduced or eliminated, and that's not the case.

With a for example 22" x 22" x 22" box with double thick 1.5" walls and a 14" cutout, there will be between 2" and 6.5" from the driver opening to the corners. Is it not effectively braced by the strongest portion of the box?
Jay1 is offline  
post #143 of 158 Old 07-19-2013, 01:44 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Quote:
Originally Posted by Jay1 View Post

With a for example 22" x 22" x 22" box with double thick 1.5" walls and a 14" cutout, there will be between 2" and 6.5" from the driver opening to the corners. Is it not effectively braced by the strongest portion of the box?

Only if there were drivers on all six sides. Sides without drivers would still need to be properly braced. In the case of the OP who planned for four drivers in a single enclosure, that leaves two sides that still require bracing even though they are 1.5" thick.
duc135 is offline  
post #144 of 158 Old 07-19-2013, 01:48 PM
AVS Special Member
 
Jay1's Avatar
 
Join Date: Aug 2002
Location: AZ
Posts: 3,986
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Liked: 102
Quote:
Originally Posted by duc135 View Post

Only if there were drivers on all six sides. Sides without drivers would still need to be properly braced. In the case of the OP who planned for four drivers in a single enclosure, that leaves two sides that still require bracing even though it is 1.5" thick.

Exactly. We are talking about a 4 driver box with only the top/bottom braced. I think Bill is saying that is not effective, I am curious why given the proximity to the corners.
Jay1 is offline  
post #145 of 158 Old 07-19-2013, 01:52 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
I believe he was referring to my comment that an enclosure with opposed drivers reduce the affects of the driver forces on the enclosure. He was just clarifying that the forces that are reduced are the forces that try to move the enclosure across the floor and does nothing to reduce the forces within the enclosure itself. The forces that only proper panel wall bracing would counteract.
duc135 is offline  
post #146 of 158 Old 07-19-2013, 02:29 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,238
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1690
Quote:
Originally Posted by duc135 View Post

I'm assuming the definition of co-located means that they are next to each
Co-located is a term that I've only seen in this forum, and only fairly recently. It's probably a term that someone unaware of the term 'mutually coupled' concocted.
Quote:
Only if there were drivers on all six sides. Sides without drivers would still need to be properly braced. In the case of the OP who planned for four drivers in a single enclosure, that leaves two sides that still require bracing even though they are 1.5" thick.
I'm not sure what you're getting at there. Opposing drivers cancel out the reaction force that would otherwise cause a cab to move in the opposite direction of the cone movement, since two (or more) cones are also moving in opposite directions. That has no effect on the need to cross brace the cabinet panels, including the baffles.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #147 of 158 Old 07-19-2013, 03:31 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Quote:
Originally Posted by Bill Fitzmaurice View Post

Co-located is a term that I've only seen in this forum, and only fairly recently. It's probably a term that someone unaware of the term 'mutually coupled' concocted.
.

Co-located is a term I've heard and used outside of this forum and not in reference to audio. I work in IT and we use it to refer to two entities using the same site to house their equipment. I have seen it here in these forums to refer to placement of two or more speakers adjacent each other.
Quote:
Originally Posted by Bill Fitzmaurice View Post

I'm not sure what you're getting at there. Opposing drivers cancel out the reaction force that would otherwise cause a cab to move in the opposite direction of the cone movement, since two (or more) cones are also moving in opposite directions. That has no effect on the need to cross brace the cabinet panels, including the baffles.

I was answering Jay1 who had questioned your statement when you were quoting me regarding my explanation of the benefits of opposed drivers to cancel the forces created by the moving cone masses which try to move the enclosure across the floor. He assumed we were talking about the forces on the panel walls created by the increase/decrease in internal air pressures while we were talking about the the forces of the moving cone mass that causes the enclosure to move across the floor. And yes, I do understand how the cancellation of these forces work.
duc135 is offline  
post #148 of 158 Old 07-19-2013, 03:53 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,238
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1690
Quote:
Originally Posted by duc135 View Post

Co-located is a term I've heard and used outside of this forum and not in reference to audio. I work in IT and we use it to refer to two entities using the same site to house their equipment. I have seen it here in these forums to refer to placement of two or more speakers adjacent each other.
That tells me some IT guy applied it, incorrectly, to speakers, and it caught on. Co-located to me would mean two subs occupying the same space.
Quote:
I was answering Jay1 who had questioned your statement when you were quoting me regarding my explanation of the benefits of opposed drivers to cancel the forces created by the moving cone masses which try to move the enclosure across the floor. He assumed we were talking about the forces on the panel walls created by the increase/decrease in internal air pressures while we were talking about the the forces of the moving cone mass that causes the enclosure to move across the floor. And yes, I do understand how the cancellation of these forces work.
+1. That's where the confusion comes in. I've seen it stated that opposing drivers reduces the flexing force applied to the cab panels, which of course it doesn't. It could only do so if the drivers were out of polarity, which would not only result in the cancellation of audio output, but it would double the force trying to move the cab. eek.gif

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #149 of 158 Old 07-19-2013, 04:12 PM
AVS Special Member
 
duc135's Avatar
 
Join Date: Apr 2009
Posts: 1,756
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Liked: 163
Quote:
Originally Posted by Bill Fitzmaurice View Post

That tells me some IT guy applied it, incorrectly, to speakers, and it caught on. Co-located to me would mean two subs occupying the same space.

Wait, I'm confused. So wouldn't that statement in bold mean the term IS being used correctly? The subs when placed next to each other are co-located, no? What I'm saying is that co-located speakers/subs are by default mutually coupled, but mutually coupled speakers/subs are not necessarily co-located.
duc135 is offline  
post #150 of 158 Old 07-19-2013, 05:33 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,238
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1690
Quote:
Originally Posted by duc135 View Post

Wait, I'm confused. So wouldn't that statement in bold mean the term IS being used correctly? The subs when placed next to each other are co-located, no? What I'm saying is that co-located speakers/subs are by default mutually coupled, but mutually coupled speakers/subs are not necessarily co-located.
To me co-located means occupying the same space. Einstein had problems with that concept, unless one brings other dimensions into play. All I'm saying is that there is no such word as co-located in the lexicon of audio engineering. When placed next to each other the usual term used is clustered.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off