Building a subwoofer

[bmwking]

I recently purchased a blown CT sounds meso 12 from one of the "just pay shipping" sales Coleman was having on FB.

 

I want to turn it into a badass 8 or 10, preferably an 8 but if the smallest I can go is a ten that's what I'll do.

 

So, I've never done this before, looked through a lot of threads, contacted Jorge at lordofbass, and still am coming up dry.

 

I'm having a bear of a time finding a compatible voice coil.  Does the new coil have to match the dimensions exactly?  Or is there a little play in the numbers?  

The dimensions I took are as follows (I can get whatever other ones that would be helpful):

 

6x127mm bolt pattern

The vent pole OD is 75.2mm/2.96”

the top plate ID is 81mm/3.19”

making the gap width 5.8mm

I measured the gap depth too, not knowing if it’s pertinent or not, at 72.5mm/2.85”.

the old coil that came out of it was a 3” OD coil, 2.15”/54.6mm tall

the winding on the old coil is ID -2.98"/75.7mm, OD - 3.135"/79.6mm

Winding height - 2.13"/54.2mm

 

 

If there's any other info you need, let me know.  I appreciate all the help any of you can offer!  Thanks!

[DLHgn]

Tuned in. 

[audiofanaticz]

The inside diameter of the voice coil needs the be larger than the inside gap, the outside diameter of the voicecoil needs to be smaller than the outside gap. Usually there are just MMs worth of differences in the coil sizes compared to the gap size.

Many times you will see the words 3 inch coil being used on subs, but its anything from the truth.. Ive seen coils that are 2.8 inches or even 3.3 inches, so the term is used loosely at best! So NEVER use the 3 inch coil size as a for sure thing because it varies from brand to brand so much.

Ideally the best sized coil for that sub will fit those specs of the old coil. That being said trying to find a higher quality coil maybe tough to do.
Though the more you can close up the gap around the coil the more BL you will gain, but it comes to the point that if its to tight you might have a great sub for going BURRRRRRRRRRP but could rub when playing music.

If you find one with the same ID and OD it but a longer winding height it wont matter much, however you must shim that coil up the difference of the additional winding height or else risk bottoming out.

Granted the additional winding height is essential going to be useless, but it may make it easier in finding a suitable replacement  trying to match only 2 dimensions instead of 3 for a sub your just learning on.

So if current coil is 54mm wind height and new coil is 60mm wind height, then the new coil will have to sit 6mm higher up in the gap compared to the old coil.
If the wind height is shorter you will most likely have less xmax.

Also as you already did, converting everything to the metric system makes things a lot easier when using mm instead of inches.

There is MWA Speaker, but a distributor only, they dont deal with the 1 coil here and there type customers, so I doubt they can help you unless you wanted to order a 100 of one thing but it maybe worth a try. I think I still have a old PDF of their products yet.  https://www.mwaspeakerparts.com/
Another company to check for parts is and they deal more with the public. https://www.springfieldspeakerrepair.com/

[audiofanaticz]

I just PMed you with a parts PDF from mwa

[DeeZer]

Keeping an eye out for updates

[bmwking]

11 hours ago, audiofanaticz said:

The inside diameter of the voice coil needs the be larger than the inside gap, the outside diameter of the voicecoil needs to be smaller than the outside gap. Usually there are just MMs worth of differences in the coil sizes compared to the gap size.

Many times you will see the words 3 inch coil being used on subs, but its anything from the truth.. Ive seen coils that are 2.8 inches or even 3.3 inches, so the term is used loosely at best! So NEVER use the 3 inch coil size as a for sure thing because it varies from brand to brand so much.

Ideally the best sized coil for that sub will fit those specs of the old coil. That being said trying to find a higher quality coil maybe tough to do.
Though the more you can close up the gap around the coil the more BL you will gain, but it comes to the point that if its to tight you might have a great sub for going BURRRRRRRRRRP but could rub when playing music.

If you find one with the same ID and OD it but a longer winding height it wont matter much, however you must shim that coil up the difference of the additional winding height or else risk bottoming out.

Granted the additional winding height is essential going to be useless, but it may make it easier in finding a suitable replacement  trying to match only 2 dimensions instead of 3 for a sub your just learning on.

So if current coil is 54mm wind height and new coil is 60mm wind height, then the new coil will have to sit 6mm higher up in the gap compared to the old coil.
If the wind height is shorter you will most likely have less xmax.

Also as you already did, converting everything to the metric system makes things a lot easier when using mm instead of inches.

There is MWA Speaker, but a distributor only, they dont deal with the 1 coil here and there type customers, so I doubt they can help you unless you wanted to order a 100 of one thing but it maybe worth a try. I think I still have a old PDF of their products yet.  https://www.mwaspeakerparts.com/
Another company to check for parts is and they deal more with the public. https://www.springfieldspeakerrepair.com/

So say, for instance, I went with this coil: https://fixmyspeaker.com/product/2-977-x-3-170-x-2-3-dual-1-8-alum-fw-615/

would the tolerances be too tight and therefore only good for a burp sub?  I set the ballpark to look for at 76mm X 80mm with a 54mm winding height, would those be musical/realistic dimensions to shoot for?

 

Thanks for all your help!

[bmwking]

11 hours ago, audiofanaticz said:

I just PMed you with a parts PDF from mwa

Thanks for that!  Laughable at the prices for sure, will have to look at it when I'm not on mobile so I don't go cross-eyed lol

[audiofanaticz]

The coil may work, hard to say. Im not familiar with the CT gaps much, but having a highe bl is always a bad thing.
There where some really tight gap subs out there like old Shockers, some DDs and some Mmatts (which use to be oem'ed by DD iirc) that had crazy tight gap to coil tolerances and just the slightest offset from back pressure in the box would cause the coil to rub.
I would say that coil would probably work, but since Im not the one taking the measurements of the gap or the coil myself Im not going to give a definite answer just because I know how easily you can hold a caliper just a tad off and get slightly different numbers.

[bmwking]

19 minutes ago, audiofanaticz said:

The coil may work, hard to say. Im not familiar with the CT gaps much, but having a highe bl is always a bad thing.
There where some really tight gap subs out there like old Shockers, some DDs and some Mmatts (which use to be oem'ed by DD iirc) that had crazy tight gap to coil tolerances and just the slightest offset from back pressure in the box would cause the coil to rub.
I would say that coil would probably work, but since Im not the one taking the measurements of the gap or the coil myself Im not going to give a definite answer just because I know how easily you can hold a caliper just a tad off and get slightly different numbers.

Completely understandable, I'll have a chance this Friday to double check my measurements.  I'll also have to get the former height since I realized I haven't yet.  That should help narrow it down some I think.  Again thanks for your help!  

 

Also, say I find a coil that will work with my motor, and a basket too, will choosing a spider, leads, all the accoutrements that follow be relatively self explanatory?  I imagine, based on my experience so far, that find the right coil is the tough part.  The rest is shimming, soldering, and glueing.  Would I assemble all of the parts after the spider and coil away from the motor or should I try to build from the bottom up so as to insure that nothing moves out of whack?

[bmwking]

Also, how do you go about determining where to set the coil in the gap, relative to height?  After reading the how to reconnect a sub threads I think I get how to shim it on the sides, but setting the depth... Nope, blank lol