Can Polyfill "fix" a small box: Bass in a Small Space

I've always torn up shirts and used them, seems to work way better than stuffing

bro got the scale they use for whales lmao he looks like he smokes a lil

Hi I'm Don from Philadelphia Pa and I have a nice little surround sound system in my living room.ok my question is that I have 4 polk audio tsi 500s tower speakers and the bass ports are raceing down to the floor and I do have wall to wall carpet since I had them I been trying to achieve better quality I'm looking for that sweet spot on movies and music I have all 4 of my towers I have a plank of MDF under them and it improved the quality of sound but I noticed that I can hear an echo coming from the box I been thinking about lining the inside walls of the speaker cabinets with peal and stick rubberized mat I noticed that when I tap on the side of the box it has a bong sound to them if I coat all the wood that is exposed in side of the cabinet will this through out the tune of the box or will it help with the sound quality of the speaker.

...and its dangerous to put so much Polyfill because it can create a fire if the Polyfill touches the crossover inside the speaker cabinet witch can be hot

Why don't show us the actual sounds

So howmuch polyfill do you need?
Audioguy: Yes

this is so dumb, complete nonsense, recording engineers make .5db level changes constantly, and they are utterly and totally easy to hear. I'll further add that the box you are using is not properly sized for the 10" woofer, using poly fill or any other test is completely vapid in execution considering the reality, it's like trying to figure out how fast a car is with flat tires, gimme a break dude

Thank you so much. Your videos have humbled me in my knowledge. I've learned more, from 2 hours of your videos & and tutorials, than I acquired in my 26 years in car audio. Makes me feel for the people that came to me for advice and help 😮 thank you very, very much for your time and effort it must take to keep us entertained. Keep up the helpfull and super knowledgeable videos

Thanks!

Does anyone know the displacement for a Nvx vcx10 v3 inch sub?😢

Nice video, lots of good info, I do prefer the lower tones over the +70 hz range. Another measurement process is to do slower sweeps to get more data at frequencies at a slower rate. Another thought I've always wondered about using the "egg crate foam" that have peaks and valleys to break up the standing waves, similar to movie theater setups. Can you test that to see if it makes a difference?

Thank you sir.

If kicker use it means it does work..

I wish I knew half the sh!t you’ve forgot…😂😅

How about using metric measurements and then we will know what you are talking about?
Ounce, mile, foot... What are they? we abandoned them in 1966

There is a mat that you glue to the inside of the enclosure. Think insulation in your house. I have found that that has some changes in frequency response. Stuffing the box😜🤣for some reason does seamingly increase volume. I don’t know why because it technically decreases the volume/air space. I just use a raw box for better resonance but to each his own. Do your math!

We’re all of these enclosures built to spec for each woofer?

I always follow the advice a friend gave me years ago: Do what makes you happy when it comes to car audio. People's ears are different. As are people's tastes. I've had filling and no filling in my sub boxes. I didn't care either way. Do what makes you happy.

Do a comparison of a shallow mount sub vs a normal sub and show us the difference

jl audio all ways has polly fill in there boxes

Where did you have that bag of poly fill during the tests? If it was in the testing room it could impact results

perhaps the effect of cutting the higher frequencies a bit makes the subwoofer sound as though it is producing more of the lower frequencies?

I jammed a small cloth bag of thermal foam in a really cheap ported subwoofer cab to stop it from distorting on very low notes. Not only did it eliminate the distortion, but I think it extended the low end a bit via slowing the air down to the port. The bass also sounds less boomy without significant output loss. Better all around for $15.

The polyfill is for damping internal reflections and standing waves, especially in a cubic box

Small box I cannot change. With basket and back of sub taking all that space inside the box, thinking if I went with a shallow mount sub, maybe I can reach proper inclosure. Or since I have the sub with all that basket, just stick with it.

GET TO THE POINT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

There's no replacement for displacement, I would not expect miracles from polyfil.

can you review the BBOX E12D subwoofer box? it has an inch thick faceplate it seems interesting 😂

My truck doesn't have space for a .4 cu box that I need for my 10 inch sub, but I can make one with .3 cu, should I use polyfill?

What's your opinion on putting some inside a 6x9 box?

Polyfill sucks sideways

What about on ported enclosures, any differences there ? Curious if it would help a ported box thats to small for recommended driver....

The best enclosure is no enclosure. Infinite baffle!

To be honest what I thought would happen is that the higher bass would be attenuated and the lower bass also attenuated but more so, so it would sound "deeper" but you'd have to bump up the amp gain slightly to compensate. So I'm surprised at some gained efficiency on the lower bass notes, seeing as polyfill is taking up room in the box and making it smaller. The only thing I can think of is the polyfill simulating a longer coiled up tube in the box (as if you mounted the speaker in a funnel that went into an "intestine" with rigid walls with the other end closed off, or you made a long and skinny sealed box with a half wavelength at a low bass frequency), would it have some half wave resonance that boosted the output, even with the same total airspace?

I put poly fill in a Pearl Master BRX birch bass drum... night and day difference, as in BIG improvement!

I use it in my pa company, remember magnet cooling problems with vented pole, make box bigger and use damping around outside of box, not this pillow stuffing, it's helps with quality of sound and standing waves, the cone won't be interrupted as much with damper,, use it in vented boxes also,,

I guess nobody here learned about thermodynamics. The glass fibers on fiberglass fill pull heat away from the voice coil. This is like using plastic heatsinks in an amplifier. Polyfil is a total amateur move. No wonder drivers die faster.

I've been using Polyfill religiously for 30+ years which I was audibly sold on in the early 90's for sealed boxes. I've never noticed a tune difference on an RTA but I've been mesmerized my whole life on the audible differences in SQ. With that being said, I know it's sometimes hard to measure the psychoacoustics of what we hear especially with static frequency responses. Transient frequency testing is I believe where the differences could be measured. The "theory" is the Poly threads need to be able to absorb rear in-box sound waves, convert to kinetic energy and then dampen vibration as these fibers want to return to rest thus causing heat. Just know they can't absorb effectively if they are packed too tight, they need wiggle room per se. Probably why Kicker states "loosely half full". If this can be done most effectively in the sweet spot of compliance, we are essentially decreasing the pressure gradients (SPL) inside the box on a time scale. Testing should measure SPL inside a box over X amount of time. I think this is the effect of the psychoacoustic response we are hearing. If people want to call it bass in a small space, maybe that's the consensual audible perception? Audibly, I've felt the same way whether it can be measured effectively or not. Thanks for the video!!

Can you do a video on polyfill vs acoustic foam for subwoofer enclosures?

I love research and development!! I am currently going through a similar project in which I am trying to have an SPL/SQ system in my small truck. I've been doing this for 30 years, and I have done plenty. I think much deeper than most. Sound is truly a language, weapon, tool and art. Somewhere along the line, we lost that knowledge. Thanks for the RnD!

Thanks for linking me to this from your other video, and for taking the time to do all these tests.
I work in pro audio - the big stuff. I've seen pro manufacturers like Meyer, L'Acoustics, EAW, etc. use batting in their boxes for decades, so I have to think it must serve a purpose. Otherwise they would get rid of it and save the money in manufacturing.

One difference, is I've never seen polyfill. It's always fiberglass batting sheets. This leads me to wonder if the density of it would give you different results than poly.
Sadly, I don't have the test equipment to do my own experiments.

I have no test devices. But could tell audibly a difference. I built my own wedge shaped box to hold 3 DB Drive 10s for my regular cab S10. I built it only deep enough to give the sub maybe 4mm clearance from the back of the box. When I finished it, I wasn’t happy with the height. So I cut it down 6 inches, and added polyfill. The same higher bass note from a song played on the box when it was larger was now not as loud when played On the smaller box. I lost higher end but got the resonant frequency farther down in the lower end. Although, this modification did seem to narrow the loudest playable frequency range. I’d say the polyfill was worth the effort. And I didn’t use much of it either.

The comments seem to confirm that you are only proving some people use polyfill for the wrong reason. Besides resonance issues, polyfill is a requirement for some drivers in sealed cabinets to keep the driver cone from misbehaving. I have a pair of bookshelf speakers in my garage that sound great. When I was building them, I tested without polyfill and the driver cones slapped and buzzed. Adding medium fill corrected the issue and the low end from those small drivers is impressive. So, besides for resonance issues, polyfill is useful for changing the air pressure in sealed cabinets. But not so much for getting more bass.

What about the quality of the bass?

I’m not sure if this has been asked, but I wonder if lining the insides of the box with Dynamat type sound dampening material vs. not would have an impact on these tests. I don’t know whether to assume your boxes had dampening material in them or not because I can certainly understand a case for either way making sense. I tried to look into the box when you were removing the speakers and adding the fill and to me it “looked” like the boxes were unlined, but I admit I could be completely wrong, so I’ll just ask:

Did the test include using poly fill on unlined boxes only or using boxes lined with a sound dampening material like Dynamat? Additionally, do you think the answer would matter to your results?

Great video! It would be more interesting to test it with pink noise. Just make a try! With certain speakers (speaker and cabinets) the difference can be interesting... Polyfill always used for reason. Resonancy control / shaping / tuning, in-box echo reduction, harmonic distortion reduction caused by box resonancy, etc... The difference can be more noticeable in ported boxes. For example, if I would remove the polyfil from my studio sub, it would make a plunky, "flat" knocking bass. With the originally installed polyfill it gives smooth, soft but deep and accurate bass. During the past so many years I found that the amount of fill really depends on the speaker, cabinet qualities. How they behave together. And, if something sounds good in an isolated environment might not sounding the same in another room. It is not as easy as 1 x 1.

What About Ported Boxes ?

As far as the hearing of frequency. I can hear frequencies most can’t. I don’t know how that is! But I can and I’ve had expert I’ve proven wrong and they changed the tuning of their speaker box designs