What should i use for stuffing in dual opposed sealed boxes? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 16 Old 07-10-2012, 06:46 AM - Thread Starter
Advanced Member
 
omegaslast's Avatar
 
Join Date: Sep 2007
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
I have some sonic acoustic barrier foam stuff, but i dont think it will make much of a difference

Using MFW-15 drivers in a box that has about 5cu ft after bracing:
xcGcn.jpg

Do i even need to use anything?
omegaslast is offline  
Sponsored Links
Advertisement
 
post #2 of 16 Old 07-10-2012, 07:30 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,209
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1684
Quote:
Originally Posted by omegaslast View Post

Do i even need to use anything?
What's system Q? If higher than 0.8 add pillow stuffing to lower it. If not just line the cab to damp harmonics.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #3 of 16 Old 07-10-2012, 01:42 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,892
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 73 Post(s)
Liked: 267
Mrkazador is offline  
post #4 of 16 Old 07-10-2012, 04:08 PM - Thread Starter
Advanced Member
 
omegaslast's Avatar
 
Join Date: Sep 2007
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Are there T/S for the MFW-15 drivers? Is it the same as dayton DVC15?

I assume the Q will be closer to .7 then .8

>MrKazador is there something less irritating to throat/ears than fiberglass i could use? I have a pound or two of polyfill..
omegaslast is offline  
post #5 of 16 Old 07-10-2012, 04:21 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,209
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1684
Quote:
Originally Posted by omegaslast View Post

Are there T/S for the MFW-15 drivers? Is it the same as dayton DVC15?
I assume the Q will be closer to .7 then .8
>MrKazador is there something less irritating to throat/ears than fiberglass i could use? I have a pound or two of polyfill..
Your box modeling program should tell you the final system Q.As for home insulation fiberglass, avoid it. Polyfill is the right stuff.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #6 of 16 Old 07-10-2012, 04:53 PM - Thread Starter
Advanced Member
 
omegaslast's Avatar
 
Join Date: Sep 2007
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Doh

Re 3.04 Ohms
Le 2.07 mH
QM 6.62
QE 0.34
QT 0.32
Xmax 13.02 mm
Pe 225 Watts
Bl 14.08 Tm
fs 15.0 Hz
Mms 235.2 grams
Mmd 221.6 grams
Cms 0.476 mm/N
Rms 3.356 N sec/m
Vas 458.9 litres
SD 823.7 cm^2
VD 1072.3 cm^3
EBP 44.1
SPL 88.5
Z 4 ohms


using these^ I got .88 Q in winisd... so i guess i need quite a bit of polyfill to get that under .8

Should i buy those pillows from walmart? (whatever theyre called)
omegaslast is offline  
post #7 of 16 Old 07-10-2012, 05:18 PM
Bass Enabler
 
Scott Simonian's Avatar
 
Join Date: Oct 2001
Location: Clovis, CA
Posts: 14,309
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 859 Post(s)
Liked: 1030
Nah. You're cool. I have Unibox set for walls lined (stuffing) and I get a .82 Qtc and that's right at the sweet spot for excursion control. 300w safe per driver.

Are they hooked in series, parallel or powered separately?

My Dual 18" LLT subs 120dB down to 10hz

 

Plan9Reloaded Co-host

Listen to the Plan9Reloaded Gaming and Technology Podcast (may contain NSFW language)

https://soundcloud.com/plan9reloaded/sets/podcast - direct pod link

http://plan9reloaded.com/site/ - main website

Scott Simonian is offline  
post #8 of 16 Old 07-10-2012, 05:42 PM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,209
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1684
Quote:
Originally Posted by omegaslast View Post

I got .88 Q in winisd... so i guess i need quite a bit of polyfill to get that under .8
Not that much, fully stuffed would probably take the Q down to well below 7.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #9 of 16 Old 07-10-2012, 08:22 PM - Thread Starter
Advanced Member
 
omegaslast's Avatar
 
Join Date: Sep 2007
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
Quote:
Originally Posted by Scott Simonian View Post

Nah. You're cool. I have Unibox set for walls lined (stuffing) and I get a .82 Qtc and that's right at the sweet spot for excursion control. 300w safe per driver.
Are they hooked in series, parallel or powered separately?

Depends on how the ashly KLR-3200 likes driving them
omegaslast is offline  
post #10 of 16 Old 07-10-2012, 10:17 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,892
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 73 Post(s)
Liked: 267
Quote:
Originally Posted by Bill Fitzmaurice View Post

Your box modeling program should tell you the final system Q.As for home insulation fiberglass, avoid it. Polyfill is the right stuff.

Why avoid insulation?

Mrkazador is offline  
post #11 of 16 Old 07-10-2012, 11:37 PM - Thread Starter
Advanced Member
 
omegaslast's Avatar
 
Join Date: Sep 2007
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
I have to fill 3 more of these and i dont feel like spending a ton on polyfill.. how much are the pillows from walmart again?

http://www.walmart.com/ip/Poly-Fil-Fiberfil-10-Pound-Carton/20713592

$25 for this.. guess im going to just pick it up
omegaslast is offline  
post #12 of 16 Old 07-11-2012, 06:17 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,209
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1684
Quote:
Originally Posted by Mrkazador View Post

Why avoid insulation?
It falls apart, and the resulting pieces can get all tangled up in the driver. The only fiberglass that should be used is rigid Type 700.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #13 of 16 Old 07-11-2012, 07:15 AM
AVS Special Member
 
caper_1's Avatar
 
Join Date: Jun 2009
Location: Cape Breton, Canada
Posts: 1,474
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 24
where can i find more info on polyfill: why use it and how?

HT: Yamaha RX-V565 | 3 X Energy Take FPS, 2 X VS Surround, 2 X Take LCR | DIY Subs: SDX12 APR15 & TRIO12 Dual APR 12's | 47" LCD

Music: Yamaha RX-V863 | 2 X Energy RC-70 | MA RXw12 Sub

Bathroom: 2 X Energy Take LCR

Car: Sony Xplod HU, Xplod 6X9s, Kenwood 4"s, Alpine 12" Type-S, Rockford Amp,...

caper_1 is offline  
post #14 of 16 Old 07-11-2012, 08:52 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,209
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1684
Quote:
Originally Posted by caper_1 View Post

where can i find more info on polyfill: why use it and how?
In a sealed cab with a Q of higher than 0.8 adding polyfill will lower the Q, when tightly packed by as much as 0.2. This shows what that does to response, blue trace before, red after:
700

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
post #15 of 16 Old 07-12-2012, 12:24 AM - Thread Starter
Advanced Member
 
omegaslast's Avatar
 
Join Date: Sep 2007
Posts: 885
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 18
How many pounds of polyfill do you guys think i should use per enclosure? I just ordered 10lbs.. i had about 2lbs, so it will be 3lbs per enclosure.
omegaslast is offline  
post #16 of 16 Old 07-12-2012, 05:55 AM
AVS Addicted Member
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 10,209
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 1684
I can't say what it will take in terms of weight but with the fairly low starting Q you have I'd fill the cab completely, compressing it only slightly. The only way to know if more than that is beneficial is to measure the results; if a response hump remains try adding more and see what happens. You also can measure the finished cab Q with a WT3 or the equivalent, adding more stuffing until it gets to 7 to 7.5.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
Bill Fitzmaurice is offline  
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