Will Speaker Damping Material Still Work if it's in a Plastic Bag? Let's try it and find out.

Bag it! If you are concerned that the plastic will crinkle and make a sound in the box, use cloth instead. Hey, you have a sewing machine, right? No? A stapler, then! Glue gun!
Seriously, there's little chance the bag will make a sound, since the inside of a speaker isn't a wind tunnel, and you'll want to keep it away from the port anyway. The port is windy, not the box. Got it?
The point is that SOUND GOES THROUGH thin stuff! RIGHT THROUGH! That includes thin plastic! RIGHT THROUGH! Sound isn't air. Sound isn't wind. Sound is energy and it goes RIGHT THROUGH thin stuff!!!
Seriously, again, thin plastic is perfect since it will completely contain the fibers you are losing sleep worrying about. And the sound passes RIGHT THROUGH IT! Like MAGIC!
So you can use it for those intimidating acoustic panels you want to build, but are terrified of the life-ending cancer-causing fibers that will devour your existence from the inside out! Just bag it, bro!

The big reveal on the recorded music is that the shallow box was B and the deep box is A. But I may have skewed the results of the guesses for each by leaving the label on each track. Also, guesses like this have a cascade effect, where guys will peruse the comments already left to see what the majority is going with, and may use that as a deciding factor if they are not quite sure.
If there's a difference between the two, it's a very small one and in my opinion not something to be concerned with. I know for a lot of guys any difference is a BIG difference, but my conclusion is that I wouldn't hesitate making a shallow speaker box if I need it to be shallow.
I'm thinking very specifically about how the driver is mounted in a transmission line speaker, usually partway down the length of the pipe and not having much space behind it.

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[IBuildIt]

Bag it! If you are concerned that the plastic will crinkle and make a sound in the box, use cloth instead. Hey, you have a sewing machine, right? No? A stapler, then! Glue gun!
Seriously, there's little chance the bag will make a sound, since the inside of a speaker isn't a wind tunnel, and you'll want to keep it away from the port anyway. The port is windy, not the box. Got it?
The point is that SOUND GOES THROUGH thin stuff! RIGHT THROUGH! That includes thin plastic! RIGHT THROUGH! Sound isn't air. Sound isn't wind. Sound is energy and it goes RIGHT THROUGH thin stuff!!!
Seriously, again, thin plastic is perfect since it will completely contain the fibers you are losing sleep worrying about. And the sound passes RIGHT THROUGH IT! Like MAGIC!
So you can use it for those intimidating acoustic panels you want to build, but are terrified of the life-ending cancer-causing fibers that will devour your existence from the inside out! Just bag it, bro!

The big reveal on the recorded music is that the shallow box was B and the deep box is A. But I may have skewed the results of the guesses for each by leaving the label on each track. Also, guesses like this have a cascade effect, where guys will peruse the comments already left to see what the majority is going with, and may use that as a deciding factor if they are not quite sure.
If there's a difference between the two, it's a very small one and in my opinion not something to be concerned with. I know for a lot of guys any difference is a BIG difference, but my conclusion is that I wouldn't hesitate making a shallow speaker box if I need it to be shallow.
I'm thinking very specifically about how the driver is mounted in a transmission line speaker, usually partway down the length of the pipe and not having much space behind it.

[rompdude]

If you think about the physics of how the materials reduce sound reflection and absorption. The material needs to be around the thickness of the sound wavelength.
Putting the material in a bag doesn't alter that property, but it does add a very thin reflection surface, which has very little mass behind it, which you would likely never notice in the auditable range.

[davebullard]

Thanks John, you finally goosed me enough to embark on my own speaker building project. Seeing some errors in my assumptions about "why things sound good" was and is really useful.

[jimmyjames]

Good stuff! I have been playing guitar for 30 years and just figured this out lol. It makes a huge difference to my ears when dampening my cab.. 👍👍

[jpz]

I like these kind of tests. I want to get a sort of a roadmap follow. Start with what makes the most difference to the sound and go down the list until you can't hear the difference any more and stop. For example... Box size - vent tuning - box shape - bracing - damping - diffraction - - - - - - - cables!

[adkywun]

tall box got a softer tone and more reflection, deep box sound brighter and deeper more direct, but the different is very very little. thank you for your time.🥰

[dedikSKB]

I just built speakers where I lined the inside of the enclosure in rock wool wrapped in fabric instead. I think you may be interested in trying it that way as well.

[skyblinked]

Wow. Perfect timing as i was looking into this to accoustically treat my ceiling with rockwool. Thanks

[BT-]

I recently bought an old pair of sansui tower speakers that have a side bass in its own ported compartment, two midrange ( i think) and a tweeter. I pulled all of the drivers out and found them to be in an as new condition, the build quality was reasonably good as were the crossovers but not a great deal of dampening. Builders wall sound proofing material which is in blanket form and easy to cut did a great job with no scary fibres 😊

[gizmobowen]

I heard a difference in the bass in the previous video, but I wasn't sure if I was listening in that range based on the measurements or I would have noticed otherwise. I did like the higher bass level, so maybe perfectly flat sound isn't alway as nice, especially when dealing with a small mid-bass that isn't really going to have that much extension? Glad I didn't "cheat" and try to read the screen. I liked taking the test and am glad you made that video, as well as this one. Thanks.

[paulhirst]

Next video stuff box with bare Rockwool and run sweep. Then put a bag in front and run sweep. You need to stir the pot more. Thank you for this series John. I really need to finish up my audio projects and get back to listening.

[isaeagle]

On my headphones, I could not discern a difference and doubt I would even on my reference system. I will say that there can be a difference in the midrange more as the wave is reflected back into the cone causing a bit of imd. This is why we stuff and use a non parallel rear wall in a midrange enclosure. This is even more important imo for a coaxial driver as the cone motion effects the waveguide property of the cone relative to the tweeter.

[_Rick_S]

I used to have a pillow that was made of little chopped up pieces of memory foam, this makes me wonder how well using one in each speaker would work. You could remove pieces to get it to the size and shape you wanted and just use the zip up pillowcase as the "bag". I've really been enjoying the listening room videos!

[GuteisFinger]

To my ears, which reached their conclusions prior to watching this video, A had more well defined high frequency sounds, more separation between them. B was more bass heavy with less well defined highs. Definitely a hearable difference even with a cheap set of headphones.

[thlchmst]

So was the opposite of what I thinking it was. B is the shallow box with more dense bass, Good to know for my second attempt on speaker build. (first attempt I made two deep boxes almost cubic with speaker in the exact center hoping for more bass, only now I found that speakers should not have symmetrical distances from the 4 edges and that shallow boxes have more bass)

[SharkRangler]

Hey John, how about comparing to poly fill. The idea behind stuffing is to slow down the rear waves and trick the speaker into thinking it’s in a larger box. Try 1 lb per cubic foot. Love these vids man.

[snailjob]

Hey John, in regards to the a/b comparo in your previous vid, you let the cat out of the bag even before the demo by posting the response curve and you can clearly see a bump in the lower frequencies. Regardless I definitely heard more extension with the deeper box..maybe a 1or 2 db bump. I believe the standing waves in the lower frequencies take more time to bounce off the back wall and come forward and thus is a better fit for that particular driver and therefore you don't see a difference in the upper freq's curve. Deeper enclosures always have a better bass output and that is why a lot of hi end bookshelf speaker manufacturers are engineering their bookshelves that way, in order to sound more full range. Anywho...great job as always John...no fluff, just honest perception.

Plz don't take offense to this but maybe you didn't notice a difference because you're getting up there in seasons...luv ya anyway

[wadimek]

I made bass traps putting wool inside cardboard boxes and it made huge measurable difference in room. Im thinking about makingnthem open from 2 sides but I probably gonna leave them as they are.

[whtube]

Hmmm! I’ve been thinking of sound waves as vibrating air particles, so I thought this wouldn’t work! I need to rethink my understanding of sound! 😆 Thank you 👍

[act..]

I did not zoom in to see the labels. I could not discern a difference between the two, but I am old and suffer tinnitus.