# Enclosure Stuffing



## TOOSTUBBORN2FAIL (Jan 31, 2011)

*Enclosure Stuffing, Black Hole Tile, Polyfil, Acoustuff*

So, I've been wanting to do this for a while, and had the chance to do it tonight. I didn't test everything I want to, but everything I had access to. 

Empty enclosure, title says it all.

Black Hole Tiles, 4 of them directly behind the speaker for a 8"x8" patch behind the speaker.

Polyfil, about half a pound.

Acoustuff, about half a pound.

I tested using the Omnimic mic, and REW. Mic was positioned 3" away from the speaker. Speaker is a HAT Imagine I6. Tweeter was disconnected. I ran it from 80hz on up, no low pass. High pass was 24db/octave. It is in a box in the house, with internal dimensions of 8"x8"x15". I ran 20hz-20,000hz sweeps, and it automatically averaged 8 of them. I have frequency response, waterfall plots, distortion, etc, but honestly, for now all I'm going to post is frequency response as I have work in the morning. 

Smoothed to 1/24. 


Green is the empty box. Tan is the Black Hole Tiles. Green/blue is the Polyfil. Purple is the Acoustuff.

Any input or other tests you would like to see, let me know.


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## rton20s (Feb 14, 2011)

Wait... there are multiple plots overlaid here?


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

Yup. I'm gonna retest at a higher level, but I'm not expecting much difference.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

Ill be without a home internet connection for about a week, but I retested at a much higher level, about 3db higher average volume, at 3 meters instead of 3", and my findings mirrored the low volume tests. As soon as I get a connection back, ill post up all the results from both tests. Again, if anyone can think of anything I'm missing, please chime in. So far I'm finding no significant benefits for stuffing a midbass or midrange enclosure.


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## REGULARCAB (Sep 26, 2013)

Oooh I have been looking forward to this. I like graphs


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## rton20s (Feb 14, 2011)

Are you posting your results in any of the home audio forums? If so, do you have a link ?


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## james2266 (Sep 24, 2009)

I have been looking forward to this too. I am absolutely shocked at the lack of difference in frequency response in all the different materials to nothing. I am curious if the other readings show anything significant or if stuffing an enclosure is pretty pointless outside of a sub box possibly.

Also, on a side note, what is up with the response from that i6 anyways? Seems very humpy considering it was not mounted in a vehicle for these tests. haha, oops didn't realize smoothed to 1/24


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## SPLEclipse (Aug 17, 2012)

You'd see a more dramatic change if you used ****tier enclosure, lol. 

Thanks for everything you do man, and enjoy your vacation from the internets.


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## zjprospe (Oct 11, 2013)

Was thinking about buying some polyfill for my enclosure... Now it just seems like it would be a waste.


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## SPLEclipse (Aug 17, 2012)

james2266 said:


> Also, on a side note, what is up with the response from that i6 anyways? Seems very humpy considering it was not mounted in a vehicle for these tests. haha, oops didn't realize smoothed to 1/24


Probably near a wall. That's a combing pattern.



zjprospe said:


> Was thinking about buying some polyfill for my enclosure... Now it just seems like it would be a waste.


If it's for a midrange driver and your enclosure is appropriately stiff and non resonant you won't hear (or see) a difference, but if any part of it incorporates part of the body of the car or something else sub-optimal it might make more of a difference. If your enclosure is for a sub, it will almost certainly make a difference. Look at the 10dB swing at 30hz in the picture. That's not to say you'd get anything like that as a result in your application, but it will almost certainly do_ something_ unless you're using a huge enclosure.


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## REGULARCAB (Sep 26, 2013)

I would never make a request of someone who already does so much, but a test of the same materials on a sub enclosure would be cool to see as well. I know with the gto804 and a tiny box it made a huge change.

It is cool to see that it didnt make a damn bit of difference for a mid.


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## zjprospe (Oct 11, 2013)

Might give it a try anyway I guess then as the enclosure is only .52 cubes after driver displacement.


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

Good eyes SPLEclipse, yep, I didn't move them for the testing. They are both about 12" from the rear wall. I'll get pics when my internets back up, maybe the 28th. They were meant as cheap quick boxes for the garage, and they migrated indoors as they sound better than the Bose 301's my dad left at the house. 

Keep the ideas coming guys, at some point after I finish the cld testing, ill try it outdoors, away from in house boundaries. I can also do a sub box at that time, as ill have my scan 26w's.


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## schmiddr2 (Aug 10, 2009)

Mic10is said:


> polyfill will have little effect in a sub enclosure. "Fill" in general works based on thermodynamics. Speaker is basically a piston. When it moves, it creates heat. Adding fill helps to dissipate the heat as the small fibers wiggles and move through the air movement.
> Thus the theory is that if enough heat is being dissipated by the fill, the speaker is "tricked" into behaving as if it were in a larger enclosure bc more heat can be produced.
> 
> The issue with polyfill in general is that it is not dense enough to have any real effect, from a thermodynamic or an absorption stand point.
> ...


These are some things I think would make for a good test.

And is the effect of these products going to vary greatly from speaker to speaker and in different size enclosures?


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

Man, I completely missed your post. 

I do plan on revisiting this when I have more time. I'm not sure when I'll have time to do it, I've been working 10-12's every day right now, but I do plan to do it. Next time I'll post distortion plots as well.


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## subwoofery (Nov 9, 2008)

Would be interesting to see the impedance curve of each test too. 

Kelvin


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

^agreed, I didn't have the tools at the time, ill have a woofer tester the next time.


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## Hanatsu (Nov 9, 2010)

Interesting test. Missed this one. Do a waterfall/CSD and a HD plot as well if you plan to re-test this sometime 

Wonder if stuffing affect midrange leakage though front-vented home speakers...


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## TOOSTUBBORN2FAIL (Jan 31, 2011)

I wasn't able to notice any kind of difference in the waterfall plot, I just forgot to save the image before closing it. I dont remember anything from the hd plots either, ill check my laptop to see if I still have the measurements on there. 

I dont see anything bad about stuffing, I just didn't see anything good about it either. It would definitely be interesting to see a ported enclosure test.


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## Hanatsu (Nov 9, 2010)

I do know it has an effect on Qtc in a sealed box, it does affect tuning of a vented box too. If there's box resonances in the lower midrange (from unbraced MDF for example) it should be able to dampen out some of it. Should be visible in a simple impedance plot with some power applied.


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