Polyfill Yes or No if box is big ??? - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 11Likes
  • 1 Post By corradizo
  • 1 Post By Gdaddy66
  • 1 Post By Mike Butny
  • 1 Post By corradizo
  • 4 Post By rhodesj
  • 2 Post By corradizo
  • 1 Post By datranz
 
Thread Tools
post #1 of 21 Old 01-12-2018, 04:38 PM - Thread Starter
Senior Member
 
Phonzo07's Avatar
 
Join Date: Nov 2011
Location: DC,MD,VA
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 75
Polyfill Yes or No if box is big ???

Good evening Gents,

I recently acquired 2 HS24mkii subwoofers and overbuilt my sealed boxes. I honestly was aiming for about 10-12 cuft per but ended up I was way off with cutting and putting it together. (If my calculations are correct) I have with 14-15 cuft. I really messed up with the cut measurements and ended up with a bigger box. Thank God I have the space.

According to the Rule of thumb, I would need about 15 cuft of polyfill for each enclosure. As I don't have equipment to measure "Q" or something, I have no idea as to whether I need the polyfill or not. I already have it, but read conflicting information in a bunch of forums on whether I may need it.

One one hand I've read if the boxes are built to spec (which mine are not because the HS24MKII is specd for about a 10cuft box), I may have needed polyfill because the box would be smaller. I've built the box bigger and don't know if I need any. I've read that fill is used to "trick" the box into thinking it was in a bigger box. Do I still need it??

Since there's conflicting information and the box is built with MDF.. I cannot keep drilling and/or re-drilling the baffle as MDF isn't built for that. I cannot keep removing fill and adding fill etc. Also these things are HEAVY .

Please , Please let me know your opinions and wisdom and experiences.



Thanks in advance...

If you KRANK it.. They will Listen..
Phonzo07 is offline  
Sponsored Links
Advertisement
 
post #2 of 21 Old 01-12-2018, 06:27 PM
AVS Forum Special Member
 
corradizo's Avatar
 
Join Date: Aug 2009
Location: near Chicago
Posts: 3,401
Mentioned: 80 Post(s)
Tagged: 0 Thread(s)
Quoted: 1520 Post(s)
Liked: 1570
I would fill it lightly to the top, don't pack it in, use some netting to hold it back.
Shreds likes this.
corradizo is online now  
post #3 of 21 Old 01-12-2018, 06:46 PM
Member
 
Join Date: Apr 2017
Location: Mason, Ohio (a little north of Cincinnati)
Posts: 15
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 4
Your problem sounds exactly like mine! Apparently, I didn't calculate correctly when building my subwoofer boxes and they are a little on the big side. Is it possible to to use cheap polyfill pillows from walmart? If they can be used, would you bust open the pillows and just use the fill or place the pillows intact inside the enclosure. If using intact pillows, would you fill the entire cabinet or just line the cabinet walls?

Sorry for asking more questions in your thread.

thanks,

tom
4anaudionut is offline  
Sponsored Links
Advertisement
 
post #4 of 21 Old 01-12-2018, 08:31 PM
 
carlthess40's Avatar
 
Join Date: Jun 2017
Posts: 190
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 63 Post(s)
Liked: 19
Polyfill Yes or No if box is big ???

I thought add polyfill made the driver act like it is in a bigger box
If the box is to small , add polyfill
What if you changed it to a ported box? Ported boxes are larger then what a Sealed box needs to be. Can the driver work in a ported box?
carlthess40 is offline  
post #5 of 21 Old 01-13-2018, 08:35 AM - Thread Starter
Senior Member
 
Phonzo07's Avatar
 
Join Date: Nov 2011
Location: DC,MD,VA
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 75
Quote:
Originally Posted by corradizo View Post
I would fill it lightly to the top, don't pack it in, use some netting to hold it back.
Ok.. I'll use some netting, but is it needed?? we're talking about 50 bucks or more worth of polyfill .. Will it mess with the response??

If you KRANK it.. They will Listen..
Phonzo07 is offline  
post #6 of 21 Old 01-13-2018, 08:38 AM - Thread Starter
Senior Member
 
Phonzo07's Avatar
 
Join Date: Nov 2011
Location: DC,MD,VA
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 75
Quote:
Originally Posted by carlthess40 View Post
I thought add polyfill made the driver act like it is in a bigger box
If the box is to small , add polyfill
What if you changed it to a ported box? Ported boxes are larger then what a Sealed box needs to be. Can the driver work in a ported box?
I cannot change it to ported. I will have to rebuild another box. The box would be about 20 or so Cuft. It'll be big, but it'll be sweet also.. lol I'm trying out sealed for now. Maybe later I would try ported. lol ..

Since it is recommended for smaller boxes, I probably don't need any for this size box. I'm still unsure.

If you KRANK it.. They will Listen..
Phonzo07 is offline  
post #7 of 21 Old 01-13-2018, 08:50 AM
Member
 
Gdaddy66's Avatar
 
Join Date: Nov 2016
Posts: 112
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 58 Post(s)
Liked: 48
You could create a divider inside the box to achieve the proper volume. Fill or no fill it will never be right.

Even the use of expanding foam will reduce volume.
Phonzo07 likes this.
Gdaddy66 is offline  
post #8 of 21 Old 01-13-2018, 08:50 AM
AVS Forum Special Member
 
Mike Butny's Avatar
 
Join Date: Oct 2004
Location: Orland Park, Il
Posts: 2,005
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1001 Post(s)
Liked: 2161
Quote:
Originally Posted by Phonzo07 View Post
Ok.. I'll use some netting, but is it needed?? we're talking about 50 bucks or more worth of polyfill .. Will it mess with the response??
The rule I read says 1 lb of poly-fil per cuft so you need 14lb. I bought it from Walmart and it was $3 dollars for a 3.2lb bag. Just buy as much as you need, should be less than $20. I used gorilla spray glue on the inside of the box and also sprayed the poly-fil as I add so it would stick to each other. I didn't use a net but I may add 1.
Phonzo07 likes this.

Equipment List: Benq W6000, Darbee DVP-5000S Video Processor, JKP Affinity 100 inch 16x9 .9 gain reference screen, Marantz SR7013 Receiver, 3-Marantz Ma700 and 2-Ma6100 monoblocks, 7.4.2 Atmos, B&W Nautilus 805 front speakers, B&W Nautilus HTM2 center speaker, Volt 6 Atmos Speakers, Mirage HDT-R side speakers, Jamo THX surround one rear speakers, 2 PSA S3600I'S, and 2 UM18-22/iNUKE6000DSP DIY subs.
Mike Butny is online now  
post #9 of 21 Old 01-13-2018, 08:53 AM
AVS Forum Special Member
 
Mike Butny's Avatar
 
Join Date: Oct 2004
Location: Orland Park, Il
Posts: 2,005
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1001 Post(s)
Liked: 2161
Quote:
Originally Posted by corradizo View Post
I would fill it lightly to the top, don't pack it in, use some netting to hold it back.
What kind of netting and how did you attach it to the inside of the box?

Equipment List: Benq W6000, Darbee DVP-5000S Video Processor, JKP Affinity 100 inch 16x9 .9 gain reference screen, Marantz SR7013 Receiver, 3-Marantz Ma700 and 2-Ma6100 monoblocks, 7.4.2 Atmos, B&W Nautilus 805 front speakers, B&W Nautilus HTM2 center speaker, Volt 6 Atmos Speakers, Mirage HDT-R side speakers, Jamo THX surround one rear speakers, 2 PSA S3600I'S, and 2 UM18-22/iNUKE6000DSP DIY subs.
Mike Butny is online now  
post #10 of 21 Old 01-13-2018, 09:09 AM
AVS Forum Special Member
 
corradizo's Avatar
 
Join Date: Aug 2009
Location: near Chicago
Posts: 3,401
Mentioned: 80 Post(s)
Tagged: 0 Thread(s)
Quoted: 1520 Post(s)
Liked: 1570
Quote:
Originally Posted by Mike Butny View Post
What kind of netting and how did you attach it to the inside of the box?
I used r13 pink fluffy fiberglass, peeled the paper off and stacked it in the box. Never had an issue because it doesn't fall apart.

Anything else that is loose and I'd grab some netting, like screen door material and I'd staple it to the box to hold back whatever stuffing you have to keep it away from the driver.

The only way to know if you need any stuffing or not is to take an impedance measurement with something like DATS or REW. Generally you do need some which is why I recommended to lightly fill.

Pete
Mike Butny likes this.
corradizo is online now  
post #11 of 21 Old 01-13-2018, 09:52 AM
AVS Forum Special Member
 
rhodesj's Avatar
 
Join Date: Apr 2005
Posts: 2,158
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 600
Quote:
Originally Posted by carlthess40 View Post
I thought add polyfill made the driver act like it is in a bigger box
If the box is to small , add polyfill
Stuffing lowers the Qtc of the subwoofer. Making the box larger also lowers Qtc. This changes the response graph of the subwoofer in the same way.
However, making the box larger makes the subwoofer more efficient; it takes less power to reach xmax. Adding stuffing does not do that!

Quote:
Originally Posted by Phonzo07 View Post
Good evening Gents,

I recently acquired 2 HS24mkii subwoofers and overbuilt my sealed boxes. I honestly was aiming for about 10-12 cuft per but ended up I was way off with cutting and putting it together. (If my calculations are correct) I have with 14-15 cuft. I really messed up with the cut measurements and ended up with a bigger box. Thank God I have the space.

According to the Rule of thumb, I would need about 15 cuft of polyfill for each enclosure. As I don't have equipment to measure "Q" or something, I have no idea as to whether I need the polyfill or not. I already have it, but read conflicting information in a bunch of forums on whether I may need it.

One one hand I've read if the boxes are built to spec (which mine are not because the HS24MKII is specd for about a 10cuft box), I may have needed polyfill because the box would be smaller. I've built the box bigger and don't know if I need any. I've read that fill is used to "trick" the box into thinking it was in a bigger box. Do I still need it??
Bigger is always better for sub enclosures. You'll need less power to reach xmax. This is a good thing! If you already have the polyfill, just use it. Large coil drivers don't model accurately and have weaker motors, and thus higher Q response, than basic T/S parameters indicate.

So just fill it up and don't worry about any of it.
rhodesj is offline  
post #12 of 21 Old 01-13-2018, 09:59 AM
 
carlthess40's Avatar
 
Join Date: Jun 2017
Posts: 190
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 63 Post(s)
Liked: 19
Quote:
Originally Posted by rhodesj View Post
Stuffing lowers the Qtc of the subwoofer. Making the box larger also lowers Qtc. This changes the response graph of the subwoofer in the same way.

However, making the box larger makes the subwoofer more efficient; it takes less power to reach xmax. Adding stuffing does not do that!





Bigger is always better for sub enclosures. You'll need less power to reach xmax. This is a good thing! If you already have the polyfill, just use it. Large coil drivers don't model accurately and have weaker motors, and thus higher Q response, than basic T/S parameters indicate.



So just fill it up and don't worry about any of it.


I was not to sure as to how that worked,
carlthess40 is offline  
post #13 of 21 Old 01-13-2018, 10:04 AM
Senior Member
 
Purenv's Avatar
 
Join Date: Oct 2016
Location: In the land of Oz
Posts: 340
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked: 102
If you have WinISD you could model the new enclosure and see what the new Q is.


Sent from my iPhone using Tapatalk
Purenv is offline  
post #14 of 21 Old 01-13-2018, 11:35 AM
AVS Forum Special Member
 
corradizo's Avatar
 
Join Date: Aug 2009
Location: near Chicago
Posts: 3,401
Mentioned: 80 Post(s)
Tagged: 0 Thread(s)
Quoted: 1520 Post(s)
Liked: 1570
Quote:
Originally Posted by Purenv View Post
If you have WinISD you could model the new enclosure and see what the new Q is.


Sent from my iPhone using Tapatalk
And if you lower Qa from 100 to lightly filled 10-15 (jury is out on this but a heavily stuffed box is a 5) you can estimate the effect. Also any standing waves or artifacts above the passband will also get squashed. It's just insurance on a good sounding box imo.
Purenv and Phonzo07 like this.
corradizo is online now  
post #15 of 21 Old 01-13-2018, 12:57 PM
Senior Member
 
Purenv's Avatar
 
Join Date: Oct 2016
Location: In the land of Oz
Posts: 340
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked: 102
it looks like at 14cuft internal the QTC is showing .646, at which i would only line the walls with a 1-2" layer of batting to reduce standing waves. no extra fill would be needed. Your bass may not sound as "tight" compared to the 10cuft enclousure but it would be nearly impossible to hear the difference unless you had both size boxes right next to each other. You actual have the more optimized option for home theater low frequency extension from what i can see in WinISD.
Purenv is offline  
post #16 of 21 Old 01-13-2018, 11:18 PM
AVS Forum Special Member
 
datranz's Avatar
 
Join Date: Feb 2008
Location: fontana, california
Posts: 1,084
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 63 Post(s)
Liked: 48
i still would stuff it all around the walls with pillows to help with standing waves. like rhodesj said, since its sealed, the larger box will be more efficient at to low end. A good thing imo because at the end of the day, all seal boxes need some eq to lift up the bottom end.
SpinMonster likes this.
datranz is offline  
post #17 of 21 Old 01-13-2018, 11:59 PM
Advanced Member
 
SpinMonster's Avatar
 
Join Date: Apr 2014
Location: Colorado Springs, CO
Posts: 941
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 486 Post(s)
Liked: 295
Quote:
Originally Posted by datranz View Post
i still would stuff it all around the walls with pillows to help with standing waves.
This is true especially if your box has one exaggerated dimension such as being much taller than the depth/width.
SpinMonster is online now  
post #18 of 21 Old 01-14-2018, 10:52 AM - Thread Starter
Senior Member
 
Phonzo07's Avatar
 
Join Date: Nov 2011
Location: DC,MD,VA
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 75
Quote:
Originally Posted by Purenv View Post
it looks like at 14cuft internal the QTC is showing .646, at which i would only line the walls with a 1-2" layer of batting to reduce standing waves. no extra fill would be needed. Your bass may not sound as "tight" compared to the 10cuft enclousure but it would be nearly impossible to hear the difference unless you had both size boxes right next to each other. You actual have the more optimized option for home theater low frequency extension from what i can see in WinISD.
Since I will be using EQ. Does it matter to fill or not?? Like will the tightness still be there without polyfill and this size.??? I would rather have efficiency more than anything if it doesnt affect the sound quality as much especially for home theater. My usage is almost 90-100% movies. So is it really noticable even if I have EQ?? I wish I could have winisd, and try the program, but for some reason it won;t work well on Windows 10 for me.

If you KRANK it.. They will Listen..
Phonzo07 is offline  
post #19 of 21 Old 01-14-2018, 10:59 AM - Thread Starter
Senior Member
 
Phonzo07's Avatar
 
Join Date: Nov 2011
Location: DC,MD,VA
Posts: 251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
Liked: 75
Quote:
Originally Posted by rhodesj View Post
Stuffing lowers the Qtc of the subwoofer. Making the box larger also lowers Qtc. This changes the response graph of the subwoofer in the same way.
However, making the box larger makes the subwoofer more efficient; it takes less power to reach xmax. Adding stuffing does not do that!


Bigger is always better for sub enclosures. You'll need less power to reach xmax. This is a good thing! If you already have the polyfill, just use it. Large coil drivers don't model accurately and have weaker motors, and thus higher Q response, than basic T/S parameters indicate.

So just fill it up and don't worry about any of it.
Got it.. I will try it with the fill and hope it does great. I just followed the "Rule of Thumb" without questioning it. What made me think of no polyfill is the owner of DeepSeaSounds said he doesnt use polyfill in his 10 cuft box, and I'm sure it sounds great also.

There have been such great debates on this matter.

If you KRANK it.. They will Listen..
Phonzo07 is offline  
post #20 of 21 Old 01-14-2018, 11:16 AM
Advanced Member
 
Shreds's Avatar
 
Join Date: May 2014
Location: NC
Posts: 875
Mentioned: 66 Post(s)
Tagged: 0 Thread(s)
Quoted: 571 Post(s)
Liked: 631
I'm for polyfill but a pound per cube packs it too tight IMO.
Shreds is offline  
post #21 of 21 Old 01-14-2018, 03:25 PM
Senior Member
 
Purenv's Avatar
 
Join Date: Oct 2016
Location: In the land of Oz
Posts: 340
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked: 102
Quote:
Originally Posted by Phonzo07 View Post
Since I will be using EQ. Does it matter to fill or not?? Like will the tightness still be there without polyfill and this size.??? I would rather have efficiency more than anything if it doesnt affect the sound quality as much especially for home theater. My usage is almost 90-100% movies. So is it really noticable even if I have EQ?? I wish I could have winisd, and try the program, but for some reason it won;t work well on Windows 10 for me.


Read this from Ricci on data-bass which is from someone who we all respect for his efforts in un-biased documentation of subwoofers and sub systems. Then make up your own mind.

http://data-bass.com/data?page=content&id=79

My 2cents would be to NOT use polyfill to fill the enclosure. I would only line the walls with 2” thick rockwool denim insulation like this:
https://www.homedepot.com/p/UltraTou...6482/202710055




Sent from my iPhone using Tapatalk
Purenv is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off