To poly fill or not to poly fill, that is the question....

[Alexander]

 I was thinking of replacing the factory foam pieces with poly fill in a set of klf-30s. The question is how much and where to place it. Anyone already done this and if so what do you think of the out come?

 

[CECAA850]

14 minutes ago, Alexander said:

 I was thinking of replacing the factory foam pieces with poly fill in a set of klf-30s. The question is how much and where to place it. Anyone already done this and if so what do you think of the out come?

 

Foam is normally used to stop standing waves or reflections.  Polyfill is used to make the box "seem" bigger to the driver.

[Alexander]

1 hour ago, CECAA850 said:

Foam is normally used to stop standing waves or reflections.  Polyfill is used to make the box "seem" bigger to the driver.

OK, so we keep the factory foam is no problem. What about adding polyfill?

 

 

[CECAA850]

24 minutes ago, Alexander said:

What about adding polyfill?

What are you trying to fix?

[Alexander]

29 minutes ago, CECAA850 said:

What are you trying to fix?

 

Not really trying to fix anything, just was thinking of experimenting.

 

Have read how some members have used it and was asking if anyone had done this to klf30s (or 20s). If so they might give pointers that they had already tried.

 

And if I did not like what it does one could easily reverse the possess.

[CECAA850]

36 minutes ago, Alexander said:

just was thinking of experimenting.

Stuff some in there and see if you notice a difference.

 

 

  I've heard that bracing the cabinets seems to help tighten the bottom end up.  You might try that if you're in there playing around.

[rebuy]

Inspecting my New to me speakers,

when I looked in the ports, they contained

Zero Foam or anything in the bottom of the cabinets.

But they sound really good, so I wouldn't

do anything to mine to mess up the sound.

If it ain't broke, can you fix it?

 

[rebuy]

I did have a Large Pair of Polks, S60 Signature that was Boomy

and contained 3--6&1/2 inch drivers.

The top driver was the transition drivers to the Tweeter

but Polk left the cabinet completely open to the top.

I filled the cabinet just behind the top driver (midrange) 

with Poly and it Stopped the Boominess and really

cleared up the Mids. 

I never could get those Speakers to sound right

so I sold them and got new Klipsch.

They sound Sooo Much Better.

[Alexander]

 

The klf-30s already had two braces side to side, I had added two more braces from the motor board to the back pail in the same location.

 

Maybe some loose polfill put behind the upper woofer, the lower cross brace will keep it from falling down into the bottom blocking the ports. The space between the two cross braces would occupy about one cubic foot factoring in the space the woofer takes up. And then there is the rest of the upper cabinet to consider, it would be a bit over another cubic foot. This is where we are looking for some feedback from fellow members that might be able to help us.

 

 

[Frzninvt]

You aren't going to gain anything.  If the engineers thought the speaker would benefit from polyfil they would have added it.  Anyway standard home insulation works far better than polyfil if your goal is to try and slow the bass wave down (fooling the woofer into thinking it's in a bigger box).  In a blind listening test you will not hear an audible difference.

[wuzzzer]

I thought polyfill helped with sealed cabinets, not ported?

[Edgar]

https://stason.org/TULARC/entertainment/audio/general/12-24-What-is-the-best-stuff-to-fill-a-speaker-cabinet-wit.html

 

"... the goals and physics of stuffing a vented box are different than those of a sealed box."

[pzannucci]

On 7/17/2020 at 4:37 PM, Alexander said:

 

The klf-30s already had two braces side to side, I had added two more braces from the motor board to the back pail in the same location.

 

Maybe some loose polfill put behind the upper woofer, the lower cross brace will keep it from falling down into the bottom blocking the ports. The space between the two cross braces would occupy about one cubic foot factoring in the space the woofer takes up. And then there is the rest of the upper cabinet to consider, it would be a bit over another cubic foot. This is where we are looking for some feedback from fellow members that might be able to help us.

 

 

Bracing if used judiciously (not eating up hardly any volume) is good.  Adding much polyfill behind the woofers, not so good.  May have gained a drop of extension with the counter effect of punch disappeared.  The best thing for the woofers if you want punch and a little more extension is a bigger cabinet.  No replacement for displacement as the old saying goes.

[Alexander]

4 hours ago, pzannucci said:

Bracing if used judiciously (not eating up hardly any volume) is good.  Adding much polyfill behind the woofers, not so good.  May have gained a drop of extension with the counter effect of punch disappeared.  The best thing for the woofers if you want punch and a little more extension is a bigger cabinet.  No replacement for displacement as the old saying goes.

 

Below is a pic of what a fellow member did with his klf-30s, the (two) side to side braces are OEM and the front to back are added. I copied this mod into my klf-30s using 1x2s.

 

Adding any form of fill in an OEM ported box:

After some thought the idea occurred that with a given enclosure volume there is a tuned port to match . So to change the “effective” enclosure volume would require a re tuning of the port(s). I realize this is all in theory but how much would this really apply in real life I do not know.

 

It should be easy enough to test though - testing the impedance of the speaker with & with out the filler with something like DATS. Would this not show where/if the double hump moves?

 

 

[pzannucci]

The impedance won't tell the whole story.  Listening does.

[Alexander]

8 minutes ago, Alexander said:

 

Below is a pic of what a fellow member did with his klf-30s, the (two) side to side braces are OEM and the front to back are added. I copied this mod into my klf-30s using 1x2s.

 

Adding any form of fill in an OEM ported box:

After some thought the idea occurred that with a given enclosure volume there is a tuned port to match . So to change the “effective” enclosure volume would require a re tuning of the port(s). I realize this is all in theory but how much would this really apply in real life I do not know.

 

It should be easy enough to test though - testing the impedance of the speaker with & with out the filler with something like DATS. Would this not show where/if the double hump moves?

 

 

 

Note:

I understand that this would be nothing more than an excise in theory and would not mean the speaker would would sound any better than it's current configuration.

 

 

 

 

[Alexander]

You beat me to it pzannucci

 

[Edgar]

39 minutes ago, Alexander said:

It should be easy enough to test though - testing the impedance of the speaker with & with out the filler with something like DATS. Would this not show where/if the double hump moves?

 

I know from personal experience that blocking flow through or to the ports turns a vented box into a sealed box, verified by measurements with DATS. (The double impedance hump becomes a single hump.) In fact I did it intentionally with the R-51M pair that I have in the office. Using polyfill to block the ports turned them into sealed boxes with Qtc equal to 0.75 and Fc about 90 Hz -- perfect, because it completely removed a lot of boominess evident in my small room. I handle the bass below 90 Hz with a subwoofer.

[pzannucci]

One good thing about the KLF-30s, if positioned correctly, unless you have to have bass under 25 hz, you probably don't need a sub. The key is the room and positioning.  A little bigger box and it would be flatter down there though.