Polyfill for SPL

[shizzzon 461]

Ok, let's say you need a larger enclosure for SPL competition and you have ran out of port options...

You need a larger enclosure... would polyfill help or would it actually drop pressure potential...

My ports are starting to tune past my peak and i can't enlarge my port area too much more...

Was wondering if i start dropping polyfill in the enclosure if it will not only start to lower the tuning back some but keep me gaining as well...

Is it worth a try?

[Jay-C76 333]

IMO it will reduce the actual volume (because it takes up space)

thus changing the tuning slightly.

How much depends on how much polyfill you put in.

It's really not a good idea to use this in a vented enclosure,

unless you like fibers all over in you car.

[shizzzon 461]

well, i can keep it in the box, that's no problem.

I NEED it to change tuning. Polyfill virtually increases internal volume... so by keeping the same port area and length, the more polyfill added, the lower tuning will go.

From what i read about polyfill, polyfill will only start to consume internal volume if packed instead of loosely spread and secured.

[jcarter1885 995]

your best bet is to try it considering it can be either temporary or permenant solution since it is removable, go for the gusto and tell us how it came out. just my .02

I always thought that adding polyfill would decrease internal volume regardless if it was packed or loosely placed in their since it is taking up space but I guess you learn something new everyday.

Edited August 3, 2009 by jay-cee

[Jay-C76 333]

From what i read about polyfill, polyfill will only start to consume internal volume if packed instead of loosely spread and secured.

Right about the don't pack it in thing.

But physics have taught us that polyfill is matter....

No two objects of matter can occupy

the same exact space at the same time.

So it has to account for something...

It'll change the tuning alright,

just not sure if it'll be to your desire.

EX. If you have a 5 gallon bucket full of water

put the polyfill into another empty bucket.

Pour the full bucket of water into the empty bucket

containing polyfill.

I bet you can't fill it without overflowing the bucket with polyfill!

Edited August 3, 2009 by Jay-C76

[shizzzon 461]

well, of course polyfill physically takes up space but it doesnt appear to it installed loosely, but actually gains volume.

Dont we wish some things in life just worked backwards, lol

[Jay-C76 333]

LMAO...yeah!

I believe how polyfill actually works is that it disperses the sound waves kinda like a filter.

Since the sound waves aren't traveling through wide open space,

they seem to appear to sound lower.

[shizzzon 461]

i know lots of people use it to enhance their low end but it also does lower tuning which means that a sub actually performs like being in a larger enclosure.

Well, it's time to quit speculating...

I'm gonna try shrinking port area to reduce tuning to see if i can ever get louder by doing that then when that fails, i'll go get some polyfill.

[Jay-C76 333]

Which way are you trying to go with the tuning, up or down?

[shizzzon 461]

down.

When keeping the same port area and length, increasing internal volume will lower tuning... so the more i cut off the port from here... the more polyfill that would be needed to maintain the same note peak.

[Jay-C76 333]

sh....my bad...

Try shrinking the opening a little, which in turn the port will have to lengthen a little..(maybe a lot?)

[shizzzon 461]

that's what i'm gonna do... Although in spl testing, shrinking port area is a nono so it's a toss up to see what will happen.

what effects spl more, wrong tuning or smaller port area... ill find out soon.

[Jay-C76 333]

Honestly it's going to be a crap shoot from here....

You already have a set enclosure and design.

The variables would've been easier to get close during

the initial design phase on the computer.

[shizzzon 461]

not really, i've got the largest enclosure with the largest port area i can fit... everything else is downhill.

[sadistic 13]

down.

When keeping the same port area and length, increasing internal volume will lower tuning... so the more i cut off the port from here... the more polyfill that would be needed to maintain the same note peak.

ya i hear you on needing more air space. is the suv already striped? like seats taken out? this will account for air space. also there right on the poly fill i have noticed it acts the same way in my boxes. like takes up space.

[Duran 387]

LMAO...yeah!

I believe how polyfill actually works is that it disperses the sound waves kinda like a filter.

Since the sound waves aren't traveling through wide open space,

they seem to appear to sound lower.

Polyfill works when sound waves pass by it and the fibers vibrate, this heats the air and amplifies the sound waves.

The general rule of thumb is one pound of polyfill per cubic foot of airspace.

[Jay-C76 333]

LMAO...yeah!

I believe how polyfill actually works is that it disperses the sound waves kinda like a filter.

Since the sound waves aren't traveling through wide open space,

they seem to appear to sound lower.

Polyfill works when sound waves pass by it and the fibers vibrate, this heats the air and amplifies the sound waves.

The general rule of thumb is one pound of polyfill per cubic foot of airspace.

There it is!!!

I couldn't find the right words to say what you said..LOL

[shizzzon 461]

so when u say amplify... there is no "except for..." scenario? it just amplifies pure and simple?

If it's as easy as just sayin it... wouldnt just putting a pound of it in the port help SPL output considering i've got over a cube of airspace in the port alone.

[shizzzon 461]

also just got back from testing reducing port area to drop tuning...

I tested dropping port area by sliding a single sheet of mdf in the port area one at a time...

At low volume, all 3 sheets helped... at max volume, only 1 sheet was beneficial and not by much.

I need to go back and test what is the port tuned to every time i shrunk it's area down again but i only gained 0.05dbs by shrinking area using a single sheet....

I gained WAY more than that with just an extra 2" on the port length, i believe it was 0.2dbs doin that before i cut it off.

[Jay-C76 333]

You're like a mad audio scientist .....LOL

It's cool you're doing hands on experiments

and sharing the results!

I'd say that isn't a car anymore it's a bass lab!

[///M5 2,833]

IMO it will reduce the actual volume (because it takes up space)

thus changing the tuning slightly.

How much depends on how much polyfill you put in.

It's really not a good idea to use this in a vented enclosure,

unless you like fibers all over in you car.

Your opinion is uneducated and stupid and shouldn't be shared on an audio forum. Stop talking out your ass on something you know nothing about. Polyfill will make the woofer think it is in a larger enclosure no ifs ands or buts about it.

*your post ranks as one of the dumbest set of advice I have read on this site and you are getting warned for it :(

[Jay-C76 333]

That's you opinion and you're entitled to it..........

As for the slam on me....

Way to show your ass man!

You are a Mod who is supposed to make people feel welcome to this site...

I have no clue why you always pick me to bash on..

Warn me...?

Dude you're acting like a little punk..

Judge my level of education on something???

Get off your high horse man....

If you were so God like, you'd hold all the records and have all the answers huh....

Pick a fight elsewhere man,

I grew up a long time ago,

I think you should too!

[Adrian_D 520]

LMAO...yeah!

I believe how polyfill actually works is that it disperses the sound waves kinda like a filter.

Since the sound waves aren't traveling through wide open space,

they seem to appear to sound lower.

this heats the air and amplifies the sound waves.

Ummm, NO. It does not 'amplify' the sound waves.

Do you guys ever take the time to read the Technical Info section ?

[Adrian_D 520]

You are a Mod who is supposed to make people feel welcome to this site...

Take the time to read the topic I linked in my previous post and argue after that it the infromation you posted is right or not.

[rushnrun 14]

IMO: Poly-fill and SPL applications won't play well together..

(this may not be 100% dead on but you'll get the idea of my opinion on polyfill)

IMO the polyfill will reduce the airflow by adding restriction--causing the port to seem longer or the enclosure to seem larger--lowering the apparent tuning..

however, I think that the restriction caused by using the poly fill will also have the same result as shrinking the port (actually I think you'll see an even bigger drop in spl.. It'll be very hard to tun with the polyfill---I don't know of anyway to calculate for adding polyfill).. Polyfill is know for making boxes/woofers sound lower, it's not know for gaining SPL...

IMO it's not a good choice for SPL...

Just for reference--my only experience with polyfill and a ported box... I added polyfill to a 2cube box with one 4" areo tuned 35hz to see if it'd play a little lower/sound a little better.. It did sound better at low volumes but it fell on it's face at higher output levels (had tons of port noise compared to the non-filled box), at the time I didn't have an SPL meter so I can't tell you what it lost or if it did...

Trying adding an internal flare to the end of your port... I'm sure it won't be easy but I've had more gains from flaring the port than anything else (given that I'm already pushing the limits of port area and length)

We sat with my buddies full size blazer one day and gained almost 2db by just adding flares to the port and box face