Polyfill for SPL

[rushnrun 14]

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

good quick read... it show's that some of my ideas on polyfill were way off... so read it

Edited August 4, 2009 by rushnrun

[shizzzon 461]

if you actually read the reason for this thread, you'd see the whole point i am talking about polyfill for SPL is so I CAN lower tuning so i can get the port to peak at my car's frequency!

My application is well worth a shot of using this technique.

My port area is at it's largest right now. At 20" long, i metered the loudest possible. Cutting any more off will raise tuning. I am not done tuning my port yet, i want to cut more off but to get tuning to drop, i must add polyfill...

I've read that using a short port, approximately 4-5" long at the most will yield the best SPL output IF it is peaking properly...

I am trying to reach this length but tuning must drop as i get there.

Also, I've been told this too-

HOW DO YOU FLARE WOODEN PORTS?

[Jay-C76 333]

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.

WoW from 2007!

That was before I joined here.

Nice write up BTW Neil.

Science made simple.

I never wished to argue anything except that M5 is an ass and shouldn't

put people down like that just to make himself appear to be cool.

Adrian D,

Thank you for being respectful and correcting me on this.

It was a nice lesson on polyfill.

M5,

Hope for the day bro!

Keep slamming people like that and one day you'll do it to the wrong person!

[Jay-C76 333]

Also, I've been told this too-

HOW DO YOU FLARE WOODEN PORTS?

I can show you how in person if you'd like.....

Sorry for the drama on your thread man....(out of my control)

[rushnrun 14]

if you actually read the reason for this thread, you'd see the whole point i am talking about polyfill for SPL is so I CAN lower tuning so i can get the port to peak at my car's frequency!

My application is well worth a shot of using this technique.

My port area is at it's largest right now. At 20" long, i metered the loudest possible. Cutting any more off will raise tuning. I am not done tuning my port yet, i want to cut more off but to get tuning to drop, i must add polyfill...

I've read that using a short port, approximately 4-5" long at the most will yield the best SPL output IF it is peaking properly...

I am trying to reach this length but tuning must drop as i get there.

Also, I've been told this too-

HOW DO YOU FLARE WOODEN PORTS?

By all means try the poly fill... I'd like to see the results... I'd try it for you but my box is already tuned lower than necessary (if it's tuned any lower my peak will be sub 30hz...).

To "flare" my ports I use PVC cut in quarters or sonotube...

***port length may matter but it'd be a hard thing to test... with less port you need more volume... more volume changes things along with the new port length...

You're getting REAL in depth with this

keep up the testing...!

[Aaron Clinton 2,372]

Can we please relax and focus on learning more about this?

[Jay-C76 333]

Sorry,

I was trying to learn and participate but........

I really want to know the outcome of shizzzon's theory.

Video of the different attempts would be cool.

[shizzzon 461]

well, it's gonna be a week or so since i gotta order it.

I'm gonna get the $$$ Acoustastuff that partsexpress sells because people are sayin it's the best in it's genre so might as well try it rather than some bare minimum type.

This is what i know so far-

Using a certain port area which isn't large enough for the best in spl output-

this port area + a given length = best metered output.

shrink port length to change tuning but burp at same note = loss of spl.

shrink port area to lower the tuning back to the above comparison, it's not the same spl level.

Having the WRONG tuning but the proper port area will yield higher numbers vs having the right tuning but not enough port area.

[shizzzon 461]

Ok, just ordered the "stuff".

It will be shipping out tomorrow, factory only 3 hrs from my house so hopin i get it friday... crossin my fingers...

If i get it by then, i'll have some test results by monday or earlier...

If it comes monday, don't expect any results until middle to end of next week.

I am gonna due another test tomorrow i think, if i got time, comparing the difference between using 1 port area vs another smaller port area and showing the difference of output of the two.

I will be doing this off of low power output so possible port turbulence will not be an issue on the smaller port which would likely cause a problem with the test comparison if i were to blast it.

This will show u guys the necessity of port area. This will also be posted in the SPL tricks section soon too.

[tech2332 3]

Ok, just ordered the "stuff".

It will be shipping out tomorrow, factory only 3 hrs from my house so hopin i get it friday... crossin my fingers...

If i get it by then, i'll have some test results by monday or earlier...

If it comes monday, don't expect any results until middle to end of next week.

I am gonna due another test tomorrow i think, if i got time, comparing the difference between using 1 port area vs another smaller port area and showing the difference of output of the two.

I will be doing this off of low power output so possible port turbulence will not be an issue on the smaller port which would likely cause a problem with the test comparison if i were to blast it.

This will show u guys the necessity of port area. This will also be posted in the SPL tricks section soon too.

You should get it soon. Parts-express ships fast! I ordered a port the 4th and it's coming tomorrow (6th)

[shizzzon 461]

and u in texas.... why havent I got my stuff yet!!! i just ordered it 22 minutes ago Damnit! I'm gonna call them at midnight and see where my package is!

[///M5 2,833]

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

I never pick on you, just on what you type. Stop giving advice on what you know nothing about and it won't get called out. You were really distracting the purpose of the thread with false info.

My answer was extra exuberant since all the misinformation is really frustrating to me and it happened on a night where there was a ton of it. It wasn't meant to be personal other than hopefully strong enough so you learn to not "help" when you shouldn't. Polyfill will make the driver "think"it is in a larger enclosure.

[KU40 173]

HOW DO YOU FLARE WOODEN PORTS?

Run a router over the edges of the port.

[rushnrun 14]

HOW DO YOU FLARE WOODEN PORTS?

Run a router over the edges of the port.

helps a little, but I'm talkin a much bigger flare... atleast 1.5" radius or larger (perferably 3-" radius flare)

[KU40 173]

Oh, so you want to do like a kerf flare. Search for it on here, I'm pretty sure somebody has done a write-up of how to do it.

Basically you make vertical cuts along the back side of the port that don't go all the way through the wood. This allows you to bend the wood backwards in a curve.

[Adrian_D 520]

Oh, so you want to do like a kerf flare. Search for it on here, I'm pretty sure somebody has done a write-up of how to do it.

Basically you make vertical cuts along the back side of the port that don't go all the way through the wood. This allows you to bend the wood backwards in a curve.

I believe it was fritosaregood who built a massive squre flared port ? Sorry if I messed up the name.

I've only built a flare out of fiberglass, for a round port

[Jay-C76 333]

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

I never pick on you, just on what you type. Stop giving advice on what you know nothing about and it won't get called out. You were really distracting the purpose of the thread with false info.

My answer was extra exuberant since all the misinformation is really frustrating to me and it happened on a night where there was a ton of it. It wasn't meant to be personal other than hopefully strong enough so you learn to not "help" when you shouldn't. Polyfill will make the driver "think"it is in a larger enclosure.

Ok....

1) I actually have messed with polyfill in the past....

2) Produced poor results in a vented enclosure, for me anyways.....

3) I was not distracting from anything having to do with this thread..

4) I've personally watched you bash on a ton of people on this forum, myself included......

5) I took your comment personally, how else was I supposed to? (read what the hell you typed!)

6) I am far more intelligent about mobile audio than you make me out to be....

7) Stop trying to "call people out" with your wording you make yourself sound like a conceited jackass!

Correcting a person is one thing, calling them names and questioning intelligence is belittling...

8) You've really pissed me off with your comments to me as well as other fellow forum members.

9) Mellow out man! We are all here to learn and have a good time sharing ideas!

10) This will be my last time I address this issue unless you keep pushing it....

I'm done, end of discussion......

Shizzzon: Keep up the great work on your system, I've enjoyed every minute of it!

As for flared porting,

Run the cuts about 5/8"-11/16" deep on the panels.

On most of the radius I've done I've used anywhere from 10-16 spaced cuts.

Keep the cuts about 3/8" apart from each other.

It's very important to keep the saw straight to prevent a wide spot in one of the kerfs,

if the spacing isn't dang near perfect when you form the radius the piece may split.

It also helps to run a small 3"-4" strip with the kerf cuts to use as a gauge when plotting out

the measurements for the location of the kerf.

This will also help to decide how many cuts are needed to for the actual radius.(unless you like doing the math)

Before the actual cuts are made it helps to drill 1/4" holes 1/2" deep on the plotted lines.

Stagger the holes on the line so they don't touch. (I usually space them about 3"-5" all the way down each line)

This will aid in the poly resin (F/G) seeping all the way down into the cuts after the radius is formed.

The holes allow any air bubbles that may be trapped, to rise to the surface. (I credit Thumpper for this trick)

Like everything practice makes perfect...

Hope you guys found this helpfull!

[shizzzon 461]

ok, i have a question.

Let's say i have a port that is oh... 20" long.

Whatever port i make, it will protrude out of the box by 5" but the total port length for this example is 20"

If i cut back 5" from the front of the port making only the port on the outside of the box flare, will the port length still be 20" long acoustically as if i never flared it or would it be 15" long + end correction?

Basically, should i just start over with a whole new lengthy port and flare the outside and make the port as long as possible and then start cutting length off again and retest everything?

[tech2332 3]

ok, i have a question.

Let's say i have a port that is oh... 20" long.

Whatever port i make, it will protrude out of the box by 5" but the total port length for this example is 20"

If i cut back 5" from the front of the port making only the port on the outside of the box flare, will the port length still be 20" long acoustically as if i never flared it or would it be 15" long + end correction?

Basically, should i just start over with a whole new lengthy port and flare the outside and make the port as long as possible and then start cutting length off again and retest everything?

That's what I would do. Just make it a few inches longer than it should and cut what you dont need. I always ask but everybody says " Try it on sketchup".

[rushnrun 14]

roughly 2/3 of the flare's length counts as port length (1/4 circumference-- not radius length) (I read this somewhere and have been using it ever since--with good results)

hope that makes sense... it may take a little tweaking but that'll get you close (calculating it doesn't do much good on smaller radii--you'll see at the end of the example)..

example....

if you use a 3" radius

pi(3.14) x d(6) = cir (18.84)

since it's a quarter of a circle divide by 4 = 4.71

and using my 2/3 rule = 3.11 length counts toward total port length.. so roughly an eighth inch longer than the radius... so not really even a notable difference...

[shizzzon 461]

Acousta-stuf will be here tomorrow so testing will be this weekend.

[Tirefryr 1,742]

Shizzon, if I were you, I'd try adding to the vent on the exterior of the enclosure. Quick, simple, and doesn't take up any internal volume.

[Tirefryr 1,742]

All the stuffing is going to do is flatten the response, just as enlarging the enclosure would do. Not something you want for SPL.

[shizzzon 461]

my application is different, i'm curious.

I cant add anymore to the port on the outside, i will be put into Radical class against the crazy-asses of competition and i am not destroying my car to compete with these people in that division.

I need something to lower my tuning while i am cutting more port off....

I'm hoping this works...