Poly Fill? Anyone ever used thiss?

[imhungnurnot 9]

Ok, so I have a 3.3 total cuft box as a center console and i cannot reach over to the other side of the truck to roll down the window/unlock the door. (no power windows/locks sucks) I hear if you add poly fill to an enclosure, the enclosure behaves as if it is larger.. So I was thinking build a smaller box, but add polyfill to make it seem larger. So in the end, I will not have sacrifice output with a smaller box. If this is possible, about how much air space could polyfill potentially account for?

[sefugi 166]

I have not used this myself but found this site Ultimate Polyfill Subwoofer Enclosure Resource [audiojunkies] give it a read. Sounds convincing, but havn't tried yet. Hope this give a little insite.

[imhungnurnot 9]

I have not used this myself but found this site Ultimate Polyfill Subwoofer Enclosure Resource [audiojunkies] give it a read. Sounds convincing, but havn't tried yet. Hope this give a little insite.

Good read!! Thanks!!!

[Randal Johnson 544]

I use it. (kick pannels & sub enclosures) Works great when used correctly.

You could cut your back wall for a blow thru.

Edited June 30, 2010 by Cablguy184

[imhungnurnot 9]

I use it. (kick pannels & sub enclosures) Works great when used correctly.

You could cut your back wall for a blow thru.

Lol, I always thought about doing a blow through.. I use my bed though, and I know i'd start spending a lot of money on subs and amps with all that room to play with.. lol

[KU40 173]

It only gains about 10% of box volume, so you'd only be able to cut your box down to 3 cubes. Not sure how much of a difference that will make.

[imhungnurnot 9]

It only gains about 10% of box volume, so you'd only be able to cut your box down to 3 cubes. Not sure how much of a difference that will make.

That sucks.. lol I was hoping to get more like %20 percent since the net volume is only 2.6.. (i hear this method is most effective in smaller enclosures)

Edited July 1, 2010 by Im Hung N ur Not

[sandt38 448]

I use fill in all my sealed cabinets. Several years ago I did some side by side comparisons, all subjective listening, nothing objective or measured about this. I noticed improvement in depth in and FR on maybe 75% of the woofers, and my testing was done on about a dozen woofers. Of note, these woofers were all in .7 Q cabinet designs, they weren't in smaller cabinets then "ideal". IMO, there was enough improvement in the sound of those it did affect, so that I use them in all my cabinets.

The general rule of thumb is 1 lb per ft^3. It is also generally accepted that, as KU40 stated, you can expect to notice a 10% gain in perceived enclosure volume.

[imhungnurnot 9]

I use fill in all my sealed cabinets. Several years ago I did some side by side comparisons, all subjective listening, nothing objective or measured about this. I noticed improvement in depth in and FR on maybe 75% of the woofers, and my testing was done on about a dozen woofers. Of note, these woofers were all in .7 Q cabinet designs, they weren't in smaller cabinets then "ideal". IMO, there was enough improvement in the sound of those it did affect, so that I use them in all my cabinets.

The general rule of thumb is 1 lb per ft^3. It is also generally accepted that, as KU40 stated, you can expect to notice a 10% gain in perceived enclosure volume.

Does it matter where you place the fill? i.e. along/around the walls? bunched up in one corner?

[KU40 173]

You want it spread evenly along the walls, or just loosely placed in there. You don't want to bunch it up. If you bunch it, you'll start actually reversing its effects and it will act like something taking up room in the box, effectively making it smaller.

[sandt38 448]

I use fill in all my sealed cabinets. Several years ago I did some side by side comparisons, all subjective listening, nothing objective or measured about this. I noticed improvement in depth in and FR on maybe 75% of the woofers, and my testing was done on about a dozen woofers. Of note, these woofers were all in .7 Q cabinet designs, they weren't in smaller cabinets then "ideal". IMO, there was enough improvement in the sound of those it did affect, so that I use them in all my cabinets.

The general rule of thumb is 1 lb per ft^3. It is also generally accepted that, as KU40 stated, you can expect to notice a 10% gain in perceived enclosure volume.

Does it matter where you place the fill? i.e. along/around the walls? bunched up in one corner?

I have not really heard tale of an ideal stuffing, but I would suggest placing it as evenly as possible around the entire enclosure. Personally, I usually just toss it in the box and let it do it's own thing, just making sure that it will not hinder the cone's travel, and a pound of fill will take up a whole cubic foot. The theory is the fill slows down the sound wave, so logic would dictate it would be best to hinder the sound wave equally throughout the box. Remember, that any type of disturbance will travel via the easiest path of resistance... everything in nature does. So with that in mind, I have just made it a habit to fill the whole box rather then packing it tight in one location and not another. Some people prefer to use screen, mesh, chicken wire, or whatever to keep it tighter to the walls and I assume they have similar success with it, so I guess it is really not a science... more of just a do what seems right to you kind of thing.

One thing to keep in mind, if you get the fill in a port, it will also slow down the wave, effectively lengthening the port. Outside of transmission line cabinets where port lengths are absolutely enormous, it is not really recommended to get fill in a port.

Also, Bass Box Pro has an option to get the Q or the enclosure design based on using polyfil. But to be honest, I don't like the calculations that BBP uses in determining the optimal enclosure for the driver in question. I have found that even with a light fill or even no fill selected, the ideal cabinet size is way off when compared to a classic calculation like that of WinISD. So if you opt to use the BBP methodology, I would be safe and select the light fill option, and pack it fairly heavily. But keep in mind, that the response plots shown may differ wildly from the actual response in an anechoic chamber.

If I were in your shoes, I might try packing the cabinet you have in there already, and see how the system behaves in your vehicle, before going to the trouble of building a new cabinet, only to be dissatisfied with the results. At least you will get a baseline of the behavior you can expect in your vehicle, with the driver in question. It may save you a lot of time and hassle.

[imhungnurnot 9]

I have not really heard tale of an ideal stuffing, but I would suggest placing it as evenly as possible around the entire enclosure. Personally, I usually just toss it in the box and let it do it's own thing, just making sure that it will not hinder the cone's travel, and a pound of fill will take up a whole cubic foot. The theory is the fill slows down the sound wave, so logic would dictate it would be best to hinder the sound wave equally throughout the box. Remember, that any type of disturbance will travel via the easiest path of resistance... everything in nature does. So with that in mind, I have just made it a habit to fill the whole box rather then packing it tight in one location and not another. Some people prefer to use screen, mesh, chicken wire, or whatever to keep it tighter to the walls and I assume they have similar success with it, so I guess it is really not a science... more of just a do what seems right to you kind of thing.

One thing to keep in mind, if you get the fill in a port, it will also slow down the wave, effectively lengthening the port. Outside of transmission line cabinets where port lengths are absolutely enormous, it is not really recommended to get fill in a port.

Also, Bass Box Pro has an option to get the Q or the enclosure design based on using polyfil. But to be honest, I don't like the calculations that BBP uses in determining the optimal enclosure for the driver in question. I have found that even with a light fill or even no fill selected, the ideal cabinet size is way off when compared to a classic calculation like that of WinISD. So if you opt to use the BBP methodology, I would be safe and select the light fill option, and pack it fairly heavily. But keep in mind that the response plots shown may differ wildly from the actual response in an anechoic chamber.

If I were in your shoes, I might try packing the cabinet you have in there already, and see how the system behaves in your vehicle, before going to the trouble of building a new cabinet, only to be dissatisfied with the results. At least you will get a baseline of the behavior you can expect in your vehicle, with the driver in question. It may save you a lot of time and hassle.

So when designing an enclosure, you rather WinISD over BBP as far as enclosure size and tuning is concerned (disregard the polyfil calculation BBP is capable of)?

But yes, I already thought about doing that to my current box. Only issue is how to keep the fill from getting in the port? mesh?

Also, I've seen mass produced enclosures with mesh covering the outside of the port. Is this to make the port "effectively" longer? How does this not decrease port area? Does it work? If it works well, it seems like a good idea because I could make the box even smaller by using mesh and making the port shorter and compensate with mesh over the opening.

[sandt38 448]

Yes, I prefer WinISD, and yes I have all 3 programs (BBP, ISD Beta and ISD Pro). ISD uses classic calculations that are closer to what should be expected for real world anechoic results. BBP seems to manipulate results. In most cases they are closer to manufacturer recommendations. Why? I am not really sure. Maybe they take into account an average vehicle cabin or something and therefore it assumes an in car response. No matter, really, as the QTS of the system should really only account for the cabinet and the subwoofer, as those are the only "certain" and fixed variables. Assuming a cabin gain, or room size, or room shape into the total system Q is assuming too much IMO.

Please keep in mind, whichever program you use, that the enclosure and it's response curves, SPL, impedance curves, transfer function curves, etc are based off of either an in room response (BBP) or an anechoic chamber (ISD). When you place the system in your vehicle, the curves will change in relation to your vehicle. These programs are simply baselines for you to work upon, they are not response curves set in stone.

As far as worrying about the fill in the port, with the air moving in and out of the port, and how much the fill bonds to itself, I wouldn't worry about it. When you get your hands on the fill, you will see what I am saying. It isn't just going to fall apart and come out of the port.

Can you put the mesh there, if you are really worried about it? Sure, I don't see why not. Am I certain it will not affect the tuning at all? No, I am not certain. But if it does affect port tuning, I would think it would be so nominal that it would not be audible, maybe 1 or 2Hz.

As far as the mesh on the outside... I can't say for sure. But like I said, I don't think it will effectively alter port tuning to an audible level. If someone were to come in here and argue and say I am wrong, I would respectfully bow out and not argue, but logically it would seem to me that it wouldn't affect it much more then a couple Hz. Does it decrease port area? I don't see how, as it shouldn't affect the length or width of the opening. It is more likely added to reduce turbulence, port noise, or "chuffing", similar to aero ports