6th order bp port area, help! - Car Audio Classifieds!
Car Audio Classifieds!  

Go Back   Car Audio Classifieds! > Enclosures, Fabrication & Sound Deadening > Enclosure Discussion & Design Construction Help

Enclosure Discussion & Design Construction Help Have questions about enclosure design neeed some help thoughout your build, ask here.


Notices

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-09-2012, 03:34 PM
New CACO Member
 
Activity Longevity
0/20 14/20
Today Posts
0/11 ssssssss7
Location: maryland
Thanks: 0
Thanked 0 Times in 0 Posts
iTrader: (0)
Feedback Score: 0 reviews
Default 6th order bp port area, help!

ok so i have been searching around and have found that for the rear chamber you should use about 6 - 8in2 of port per cube. and for the front chamber about 18 - 22in2 of port per cube. is this correct?

i am using 2 10's and i have been using winlsd and everything is looking good so fa. i have the rear chamber all figured out but the front chamber is smaller than the rear. 3.5ft3 @ 32hz and 1.8ft3 @ 59hz is what models the best on winlsd, but because the front chamber is 1.8ft3 the port will be pretty small. were talking 36in2 of port and im thinking that will choke the 10's. any help? thanks
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 08-28-2012, 11:52 AM
CACO Member
 
Activity Longevity
1/20 17/20
Today Posts
0/11 ssssss211
Location: Texas
Thanks: 3
Thanked 25 Times in 20 Posts
iTrader: (2)
Feedback Score: 2 reviews
Default

Use the vent length that will maintain vent velocity under 10% mach, which is approx. 35m/s. If it is larger than this, then THAT is what will tell you if the woofer is being choked or not.

I don't do the whole "so many sq in per cube" thing ; I work with actual speaker requirements. The system needs to be modeled with the right amount of power. That tells you if you have enough port area or not--by looking at vent velocity.
Reply With Quote Quick reply to this message
  #3  
Old 08-28-2012, 11:57 AM
Micksh's Avatar
Elite Member
 
Activity Longevity
0/20 15/20
Today Posts
0/11 sssss2596
Location: Mansfield Ohio
Thanks: 24
Thanked 346 Times in 237 Posts
iTrader: (6)
Feedback Score: 6 reviews
Default

Quote:
Originally Posted by guitar maestro View Post
Use the vent length that will maintain vent velocity under 10% mach, which is approx. 35m/s. If it is larger than this, then THAT is what will tell you if the woofer is being choked or not.

I don't do the whole "so many sq in per cube" thing ; I work with actual speaker requirements. The system needs to be modeled with the right amount of power. That tells you if you have enough port area or not--by looking at vent velocity.
^^^Someone who gets it here...
__________________
Old school installer, 1995 USAC Pro 251-500 Legal SPL World Record Holder
My Youtube page
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Astro build log link
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
 
  #4  
Old 08-28-2012, 01:16 PM
CACO Member
 
Activity Longevity
1/20 17/20
Today Posts
0/11 ssssss211
Location: Texas
Thanks: 3
Thanked 25 Times in 20 Posts
iTrader: (2)
Feedback Score: 2 reviews
Default

Quote:
Originally Posted by Micksh View Post
^^^Someone who gets it here...
Thanks. I had left car audio for a long time to focus on other things. Not that I was a competitor or anything like that, but I started building boxes when I was 13-14 yrs old and started with two books, Ray Alden's Speaker Systems, and Vance Dickason's Cookbook, with a basic 4 function calculator, volt/ohm meter, resistors, and a signal generator. That was all I needed to accurately determine (within about 5%) all the necessary T/S parameters, and even VERIFY actual enclosure tuning. I would even call my local weather center to ask about current temperature/humidity/baro. pressure in order to be able to calculate air density to accurately determine the speed of sound for the Vas calculation. I even had to discover on my own how to raise a number to a decimal exponent WITHOUT having a convenient "x" button, or a square root button on my calculator. Ya'll should try doing that without help from google.

Now a days, life is much easier with computers and hardware like the WT3/DATS. No offense to whoever likes "sq in per cube", but it just doesn't jive. It's not like you can arbitrarily CHOOSE to make a box 1 ft and ONLY use 14 in for a massive 15" subwoofer that can move 1"+ each way. Same thing goes the other way--you can't just make a 80 ft box for a 12" woofer and accurately reason you need, say, 12in for EACH cubic foot, especially when the woofer can only do 3/4" peak-to-peak excursion--you'd end up with a ginormous 960 in of port area--equivalent to twelve 12" woofers! Ridiculous! More excursion for a given woofer diameter simply requires more port area to keep vent velocity low to avoid port compression losses, plain and simple. It's been in the books for decades and nothing has changed about the rules of physics.

Last edited by guitar maestro; 08-28-2012 at 01:30 PM.
Reply With Quote Quick reply to this message
The Following 2 Users Say Thank You to guitar maestro For This Useful Post:
ridintwo6s (08-28-2012), SPLEclipse (08-28-2012)
  #5  
Old 08-28-2012, 01:28 PM
Micksh's Avatar
Elite Member
 
Activity Longevity
0/20 15/20
Today Posts
0/11 sssss2596
Location: Mansfield Ohio
Thanks: 24
Thanked 346 Times in 237 Posts
iTrader: (6)
Feedback Score: 6 reviews
Default

I think for the average kid with a ground pounder box in the trunk or an SUV, the sq in per cube thing will get them at least somewhat close....but it obviously doesn't take full advantage of the woofer's capability...it just won't get the full potential in something like an SPL system.
__________________
Old school installer, 1995 USAC Pro 251-500 Legal SPL World Record Holder
My Youtube page
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

Astro build log link
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Car Audio Classifieds! forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Location
Where you live
Level of Car Audio Knowledge
What's your level of car audio?

Log-in



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Quasi 6th Order Bandpass port orientation... quagmire Enclosure Discussion & Design Construction Help 10 06-07-2012 11:23 PM
port area 4th order constantprojects Enclosure Discussion & Design Construction Help 28 05-15-2012 12:39 AM
how much port area per cube for a 4th order laextreme5 General Car Audio Discussion & Questions 20 01-20-2012 12:14 AM
12w7 in a 4th order or 6th order box for trunk kanoftuna Enclosure Discussion & Design Construction Help 10 09-01-2011 08:12 PM
4th order port through rear deck need design help, and build help in MN or IA area maddog2099 Enclosure Discussion & Design Construction Help 6 05-21-2011 10:19 PM

» Amps
A/d/s/
Advent
Alphasonik
Alpine
American Bass
ARC Audio
Atomic
Audio Art
Audio Gods
Audiobahn
Audiocontrol
Audiopipe
Audison
Aura
Autotek
Avionixx
Bazooka
Beyma
Blaupunkt
Boss
Boston Acoustics
Bravox
Cadence
Cascade (CAE)
CDT Audio
Cerwin Vega
Clarion
Clif Designs
Concept
Coustic
Critical Mass
Crossfire
Crunch
DB Drive
DC Audio
DC Power
DEI
Denon
Diabolo
Diamond
Digital Designs
Directed
DLS
Dual
DYnamat
Dynaudio
Earthquake
Eclipse
Elemental Designs
ESX
Eton
Farenheit
Fi Car Audio
Fix My Speaker
Focal
Fusion
Genesis
Ground Zero
Hafler
Helix
Hertz
Hifonics
Hushmat
Image Dynamics
Infinity
Interfire
JBL
Jensen
JL Audio
JVC
Kenwood
Kicker
Knu Konceptz
Kole Audio
Kove Audio
Lanzar
Lightning Audio
Linear Power
MA Audio
Magnat
Marantz
Massive Audio
MB Quart
McIntosh
Memphis
Metra
MMATS
Mobile Authority
Morel
MTX
Nakamichi
Niche Audio
O2 Audio
Ohio Generator
Optima
Orion
Oxygen Audio
OZ Audio
PG Audio
Phase Linear
Phoenix Gold
Pioneer
Polk
Power Acoustik
Powerbass
Powermaster
Precision Power
Profile
Pyle
Pyramid
RadioShack
Rainbow
Rampage
RE AUdio
Rockford Fosgate
Scanspeak
Scosche
Seas
Sony
soundstream
Sparkomatic
SPL Dynamics
Stinger
Sundown Audio
Swiss Audio
Targa
TC Sounds
TREO Engineering
TRU
Tsunami
Ultimate
US Acoustics
US Amps
Velodyne
Vifa
Viper
Visonik
Xtant
Zapco
Zed Audio
Powered by vBadvanced CMPS v3.2.3
Links
Amp Guts
amplifier, amp guts, ampguts, car audio classifieds, speakers and subs for sale with listings of 12 volt sound systems. Security systems for sale for aftermarket car audio equipment with amplifier and amps for sale
Car Audio Forum
car audio forum, moble audio, car stereo, wholesale car audio, 12 volt, with, amplifier, amp, subwoofer, sound quality, buy car audio, and sell automotive stereo systems for cars
Car Audio Sound Quality Forum
Sound QUality science based car audio forum, amplifier, subs and speaker design, fabrication help, sound systems forum, aftermarket car audio website for sound quality.
Car Stereo Forum
DIYMA car audio stereo forum for 12 volt car audio subwoofer and amplifier systems that have sound quality with wholesale car audio products.


All times are GMT -5. The time now is 12:00 AM.


Powered by vBulletin
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
SEO by vBSEO 3.6.0
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.