EV fitting/polyfill lining in a Thiele

[lento]

Just got my mahogany Thiele cab today and have a couple of ?'s

The frame to fasten the speaker to is 3/4" thick - would I be better using screws or nuts and bolts, and what sizes ?

I'm going to fill the inside with polyfill approx 1" thick, is that enough ?
Is it best to line the whole of the inside but leave the port area bare ?
Tips appreciated.

thanks
Lyn

 

[edward]

Wait a minute. I don't think Thiele cabs came with any fill. IIRC, my Thiele has bare interior walls.

Edward

 

[edward]

sorry, duplicate

 

[lento]

Must point out that it's not a Mesa Thiele - this was custom made to the Thiele specs.
Regarding the polyfill, I have read previous posts about using it and extolling the benefits.

Lyn

 

[ramalam]

Delete

 

[ramalam]

Electro Voice's plans for the 12" Thiele cabs say, "Line top, both sides, and back with 3" fiberglass insulation. Insulation must not block the port opening on inside of cabinet". It also states, "Parts listed and dimensioned in chart below must conform to dimensions on drawing for proper cabinet tuning".

The insulation makes the cabinet act like an infinite baffle. They are not my favorite kind of cab but they do have more loudness and bass than anything I know of without going to larger cabs. All cabs are compromises though.

 

[jski59]

Hey lento,

I built my own widebody Thiele following the plans of someone else on this board. If you do a search, there might be some details in there.

But I just screwed the speaker to the baffle...nothing fancy.

And I also added the polyfill. I couldn't tell you how thick, but it was just one layer to all sides except the baffle. I just used a staple gun to install it.

I think the polyfill definitely improved the sound. It's seems tighter and got rid of a "ring" to the cabinet I didn't like.

I also have a stock Mesa Thiele with a C-90. When comparing them, I think my homemade version sounds a lot better. It has an Eminenece Delta 12 pro and the polyfill.

Jason

 

[Boogafunk]

for the speaker i would reccomend hurricane nuts. they are the best thing since sliced bread. parts express carries them and they're not to expensive. they really hold well and i've never had one "spin out" like tee nuts sometimes do. when dealing with a 20 pound speaker you have to consider inertia. every time the cab is set down where is the stress? screws will work, and they may last for a very long time, but considering how little it costs to use the right stuff, it just aint worth it to scimp out. (of course if you have to do the cab now just screw the speaker in and retrofit it later, that's easy, no sweat)

as far as damping material 2" thick stuff works well. go to a fabric store. do not use fiberglass insulation. ev put those plans out in the late 70's. they didn't have the stuff we have now. you should cover 4 sides (every side except the baffle and the port side)

 

[t0aj15]

I've got two Boogie Thiele cabs both loaded with EVM-12L's and the speakers are screwed in, using all eight holes in the speaker frame. And yes the insul will help, but as long as i've been dealing with/building speaker cabs (over 40 years) the method for insulating has always been opposite sides of the cab only. In other words the back and either the top or the bottom, and either one side or the other, so that three interior sides get insul and three don't. Just make sure that one side with insul faces one side without insul, this will prevent standing waves which can cause frequency cancelations.

 

[ramalam]

I've got two Boogie Thiele cabs both loaded with EVM-12L's and the speakers are screwed in, using all eight holes in the speaker frame. And yes the insul will help, but as long as i've been dealing with/building speaker cabs (over 40 years) the method for insulating has always been opposite sides of the cab only. In other words the back and either the top or the bottom, and either one side or the other, so that three interior sides get insul and three don't. Just make sure that one side with insul faces one side without insul, this will prevent standing waves which can cause frequency cancelations.

The opposite side method sounds like a good way to go though you would get less of the infinite baffle effect this way.

 

[t0aj15]

The opposite side method sounds like a good way to go though you would get less of the infinite baffle effect this way.

Just the opposite is true. The idea behind an infinite baffle is that you have a baffle so large that the sound travels away from the back of the speaker and no waves are reflected back to cause cancelations or standing waves. However it's obviously impossible to have a true infinite baffle so a cab is the next best solution. By having three sides bare and three sides insulated all sound waves can only be reflected a maximum of one time before they are absorbed and therefore the problem of to many reflections is avoided (or at least greatly reduced).

 

[lento]

Thanks to all who replied with their suggestions.
I eventually settled for screws as it'll mostly be used in a recording situation.

Regarding the polyfill, I've lined one side, top and bottom and the back, leaving the port bare.
Interesting comments on alternate methods though, I'll try them also.
I'm certain that whichever method one uses it's better than none at all.

Can confirm it definitely tightens up the sound and smoothes any peaks or troughs from waves. After all, monitors are treated as such.

Lyn

 

[Jeff R]

I insulated my 1x12 EV-loaded Thiele this weekend. It originally had a C90 in it. Did the back, bottom and non-port side and I'm pleased with the result - definitely tighter thump than non-insulated.

FYI, I went low budget for insulating material - I cut up cheap home central AC unit filters. I folded 'em over to double the thickness (probably 1.5 inches after folding) and attached via staple gun.