Box tuning technical discussion - 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 08-15-2015, 07:26 PM
Lock up your daughters!
 
Activity Longevity
0/20 11/20
Today Posts
0/11 sssss1342
Location: Ames, Iowa
Thanks: 130
Thanked 110 Times in 93 Posts
iTrader: (7)
Feedback Score: 7 reviews
Default Box tuning technical discussion

Ok, lets discuss the tuning of different boxes. Iíd like to learn more about the technical side of things.

If I am wrong about anything, please do correct me

Starting off, sealed. Smaller sealed boxes are ďtunedĒ higher and donít have good low-end response. To my understanding, itís better to have a larger box up to a certain point. I forget when, but a large sealed box acts similar to IB after a certain number of times larger than the subís VAS.

Two peaks in the response curve are the subís resonant frequency and the enclosureís resonant frequency.

Next is ported, which gets a lot more complicated.

Port length and area the same, making a box larger lowers tuning. Making a box smaller raises tuning. I donít remember if larger or smaller boxes are more peaky.

Box volume and port area the same, increasing port length lowers tuning. Decreasing port length raises tuning.

Box volume and port length the same, increasing port area raises tuning. Reducing port area lowers tuning. Increasing port area increases efficiency and makes response more peaky at the tuning frequency. Reducing port area makes response ďflatterĒ and less efficient. However, you canít reduce port area too much, or you will get port noise. There is debate on what amount of port area is necessary per cube. Aeroports are generally accepted as being more efficient than slotted ports, and flared aeroports are the most efficient, therefore requiring less square inches per cube.

Three peaks in a ported boxís response curve iirc. First is subís resonant frequency, then the boxís resonant frequency, and the portís resonant frequency.

Ok, 4th order bandpasses. Here, Iím not knowledgeable. I know there are general ratios of sealed to ported volumes that people follow for different design goals. Iíve never paid attention to or researched 4th orders, because Iíve never had room for them. Now i do, and would like to be informed about them.

How does changing each chamberís volume affect tuning? Which chamber do you want tuned higher and why?

I see lots of big builds running 4th orders. Would a 4th order be better than a ported wall if Iím looking to play as loud and flat as possible from 25hz to 50hz?

Quasi Sixth orders. I would really like to build one of these. The inside ported box is usually smaller than the outer chamber. How does changing the volume, port area, and port length of each chamber affect tuning and overall response?

Buck is designing me a quasi sixth order. I would just like to learn a lot more about them, so i can fine tune things after building the box and testing.

Going to look like a much larger version of this:



Here is a link to my other thread asking for help with a 6th order:

DD Z 6th order help!

With roughly 30 cubes of space and two 18ís, what box type would be best for me? I would really like to do a quasi sixth. I am willing to learn all I need to know, and spend lots of time building/tuning/adjusting. Would consider a 4th if there are some serious advantage to it over a ported wall.

Thanks!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 08-15-2015, 08:55 PM
jt_buck's Avatar
don't shoot
 
Activity Longevity
0/20 16/20
Today Posts
0/11 sssss4423
Location: Nashville
Thanks: 142
Thanked 154 Times in 133 Posts
iTrader: (2)
Feedback Score: 2 reviews
Default

When I designed that series it was my first and inaccurate tuning. The rear was tuned lower than I realized. It took me a TON of research to figure that out. But that's why it was my first.

As you increase in orders, the more variables you have (talking mainly about 6ths here). You have air traveling/pressurizing in all sort of places and in different ways. When you get to bandpasses it's literally boxception, like a box within a box.

And then you have the woofer. You know, small boxes play "flatter", only if your sub likes small boxes. So you have to know what your woofer can handle while manipulating 2 ports and 2 air chambers to make the kind of sound that you like.

Port area, especially in rear ported chambers, can vary SOOOOO greatly. And then the front port doesn't have to be there in these big walls in most cases. The airspace you're compressing with the box is smaller than the airspace of the box in say like b-pillar walls. When you have that much pressure floating around, there is no loading problem. You're front port can be 5 or 10 times bigger than the rear port, or just twice as big.

Some of what I say is really general but it totally comes down to the specifics with bandpasses, and the mind state. What do you want out of your bandpass. I could just go on because there's infinite possibilities.
__________________
Alpine - C&D Tech - CT Sounds - Batcap - EA - eD- Rainbow
Reply With Quote Quick reply to this message
The Following User Says Thank You to jt_buck For This Useful Post:
adulbrich (08-15-2015)
  #3  
Old 08-15-2015, 08:57 PM
jt_buck's Avatar
don't shoot
 
Activity Longevity
0/20 16/20
Today Posts
0/11 sssss4423
Location: Nashville
Thanks: 142
Thanked 154 Times in 133 Posts
iTrader: (2)
Feedback Score: 2 reviews
Default

And I apologize if that's a jumble I'm tired. May not be the best representation.
__________________
Alpine - C&D Tech - CT Sounds - Batcap - EA - eD- Rainbow
Reply With Quote Quick reply to this message
The Following User Says Thank You to jt_buck For This Useful Post:
adulbrich (08-15-2015)
 
  #4  
Old 08-15-2015, 09:17 PM
Lock up your daughters!
 
Activity Longevity
0/20 11/20
Today Posts
0/11 sssss1342
Location: Ames, Iowa
Thanks: 130
Thanked 110 Times in 93 Posts
iTrader: (7)
Feedback Score: 7 reviews
Default

Thank you! That was very helpful
Reply With Quote Quick reply to this message
  #5  
Old 08-15-2015, 09:56 PM
Elite Member
 
Activity Longevity
0/20 20/20
Today Posts
0/11 sssss4405
Location: N. Alabama
Thanks: 296
Thanked 674 Times in 524 Posts
iTrader: (9)
Feedback Score: 9 reviews
Default

My responses in red


Ok, lets discuss the tuning of different boxes. Iíd like to learn more about the technical side of things.

If I am wrong about anything, please do correct me

Starting off, sealed. Smaller sealed boxes are ďtunedĒ higher and donít have good low-end response. To my understanding, itís better to have a larger box up to a certain point. I forget when, but a large sealed box acts similar to IB after a certain number of times larger than the subís VAS.

Response and gain will be determined by both the enclosure volume and the driver's TSPs (fs, qts, and vas). When a sub is put in a sealed enclosure its natural resonance (fs) is raised. The smaller the enclosure the more the resonance is raised, so you loose low-end. Total "Q" is also raised more as the enclosure becomes smaller. Higher Q means you have a bigger bump in gain around resonance with a sharper roll-off down low. There's a lot more to the Q figures then that but that's the basic effect. A speaker with a small vas can be put into a smaller enclosure without raising the fs or qts as much as a speaker with a larger vas. IB can typically be defined as an enclosure about 10x as large as a driver's vas.

Two peaks in the response curve are the subís resonant frequency and the enclosureís resonant frequency.

You only have a single peak in impedance with a sealed enclosure (or IB, or free air). This represents the resonant frequency of the speaker (if free air) or the effect of the enclosure which raises the fs (if in an enclosure).

Next is ported, which gets a lot more complicated.

Port length and area the same, making a box larger lowers tuning. Making a box smaller raises tuning. I donít remember if larger or smaller boxes are more peaky.


Either can be peaky depending on how they are designed. Once you get about an octave above the port tuning with a vented enclosure, the box acts as if it is sealed, so the same rules as sealed enclosures apply. At tuning, the port becomes more efficient as the enclosure volume increases. A small enclosure with a large port can be peaky (typically higher in frequency) and a very large ported enclosure can be more peaky around tuning.

Box volume and port area the same, increasing port length lowers tuning. Decreasing port length raises tuning.

Box volume and port length the same, increasing port area raises tuning. Reducing port area lowers tuning. Increasing port area increases efficiency and makes response more peaky at the tuning frequency. Reducing port area makes response ďflatterĒ and less efficient. However, you canít reduce port area too much, or you will get port noise. There is debate on what amount of port area is necessary per cube. Aeroports are generally accepted as being more efficient than slotted ports, and flared aeroports are the most efficient, therefore requiring less square inches per cube.

Port area will not effect frequency response directly. An undersized port that is restrictive might lead to acoustic compression if driven at high amplitude, and that will make it less efficient, but it depends on the speaker and power you are using. There is no rule for port area. A large speaker with a ton of stroke being fed a lot of power will require more port area than a small speaker with little throw on less power.

Three peaks in a ported boxís response curve iirc. First is subís resonant frequency, then the boxís resonant frequency, and the portís resonant frequency.

There are only two impedance peaks with a vented enclosure. The dip between them is your tuning frequency. There are two resonances on either side of the tuning frequency, but it would be incorrect to think of them as belonging to either the enclosure or the speaker.

Not going to get into higher order enclosures just yet as I've got a 17 month old tugging at my shirt to come play, lol.
Reply With Quote Quick reply to this message
  #6  
Old 08-15-2015, 10:12 PM
Lock up your daughters!
 
Activity Longevity
0/20 11/20
Today Posts
0/11 sssss1342
Location: Ames, Iowa
Thanks: 130
Thanked 110 Times in 93 Posts
iTrader: (7)
Feedback Score: 7 reviews
Default

Alright, thanks for the response and the correction about the number of peaks!
Reply With Quote Quick reply to this message
  #7  
Old 08-15-2015, 10:31 PM
jt_buck's Avatar
don't shoot
 
Activity Longevity
0/20 16/20
Today Posts
0/11 sssss4423
Location: Nashville
Thanks: 142
Thanked 154 Times in 133 Posts
iTrader: (2)
Feedback Score: 2 reviews
Default

Ya that was way more technical than what I said. When you get in a program you'll see the graphs and what not where those peaks are.

I will have to throw this in here: with the massive amount of Bl some of these woofers have, it changes the dynamics of how a woofer typically acts, in my opinion. You're getting woofers the will have like 30-40 Bl and a 30 mm @ 70% with 4000w. The range and simple abuse these woofers can take also comes into play. You're generating so much pressure, there's going to be a lot of loading in the box and the vehicle. All this is going to help control your woofer through a wide range.

Even with about 15 cubes, my two Fi BL 18's on 1200 watts a piece played within 2 db from 60 hz to about 27 hz. And the it'd still play well below 20 hz.
__________________
Alpine - C&D Tech - CT Sounds - Batcap - EA - eD- Rainbow
Reply With Quote Quick reply to this message
  #8  
Old 08-18-2015, 12:20 AM
New CACO Member
 
Activity Longevity
0/20 8/20
Today Posts
0/11 sssssss85
Location: ABQ
Thanks: 3
Thanked 1 Time in 1 Post
iTrader: (0)
Feedback Score: 0 reviews
Default

Wow, some good info in here!
Reply With Quote Quick reply to this message
  #9  
Old 08-22-2015, 10:17 PM
CACO Member
 
Activity Longevity
1/20 17/20
Today Posts
0/11 ssssss208
Location: Texas
Thanks: 3
Thanked 24 Times in 19 Posts
iTrader: (2)
Feedback Score: 2 reviews
Default

perhaps there needs to be some clarification. The OP is specifying peaks in the response curve, and SPLeclipse is referring to the impedance curve, perhaps thinking that is what the OP was referring to. Or perhaps the OP thought the impedance curve was similar to a response curve, which it is not.

One major correction that was not addressed:
  • Once a speaker is installed in a properly constructed, preferably very rigid and non leaky, sealed or standard vented enclosure there is only ONE resonance. not two, not three, etc. The speaker and enclosure become one resonant system. Same for a vented enclosure---the driver with the enclosure with the port is ONE resonant system. Yes the overall behavior is different for each, but it is still a single resonant system.
  • This is irregardless of how many impedance peaks there are---there is still only ONE resonance for standard 2nd order sealed and 4th order vented enclosures (yes standard vented enclosures are 4th order, not talking about 4th Order bandpass boxes)
  • Peaks in the actual frequency response are consequences of any one particular alignment (combination of specific speaker and enclosure specs), and not necessarily correlated with impedance peaks or other artifacts of the impedance graph.

To learn the real deal, look up "damped harmonic oscillator", and "damped double-mass double-spring harmonic oscillator". It's all rooted in physics.

Last edited by guitar maestro; 08-22-2015 at 10:21 PM.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Tags
bandpass, box, enclosure, sixth, tuning

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
box tuning BallzFast General Car Audio Discussion & Questions 9 11-16-2011 06:47 AM
lvl5 18 box discussion 4th/6th order Highs On Bass (DC) 25 04-19-2011 10:45 AM
Box Tuning cotyballs Tutorials & Quick References 15 03-30-2011 12:59 AM
Box design for a 98 Altima. *Discussion* Drunken.Swagger Enclosure Discussion & Design Construction Help 1 01-19-2009 02:55 PM
Post reviews here only, take discussion to General Discussion forum. nismos14 Car Audio Product Reviews 0 11-20-2008 08:02 AM

» 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 11:35 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.