Ported or enclosed sub box??

[Ferio_vti]

What's the difference between ported and enclosed??
Also what does insulating a box do to the sound??

[Moonracer]

For starters you must have insulation in a box, either type, to stop the sound waves from bouncing around too much inside the box causing major resonance peaks. There will always be resonance's but you must minimize them. A sealed box will give a more boomy and tighter bass response but will lack a little on the low end frequencies. Good for rock and roll!
A ported box will give you a nice low resonance frequency allowing a good low end response and can still be tight when controlled with a good amp. Good for music requiring a very low response such as, classical or hip hop. Ported is most commonly used these days cause it's the best all round design.
I'd go for ported for in car or home :thumbsup: Hope that helps.

[JGerke]

Both boxes are great, just depends on what kind of music is coming out of it, and what you like!!

[mx3gtx]

it also depends on the sub some work better in a ported box ond some better in a sealed box most sealed boxes are insulated i never have had a ported box insulated

[Zero102]

Ported boxes result in the higest SPL (short of bandpass, but those are usually used for specialized drivers), but with a cheaper amp, you will get a boomy sound, which is good for hip hop and stuff like that, but for anything else, it will sound too 'loose'.

Sealed boxes give a very even frequency response, but will never play as loud as a ported box, but you can get away with cheaper equipment in a sealed box, providing your box is sized appropriately.
Here is where insulating comes into consideration.
When you stuff a box, that is to add fiberglass or polyfil, you fool the driver into thinking it is inside a larger box, because the pressure waves inside the box propagate differently. The general rule on stuffing, is you do not want to exceed 50% fill on a box, if you need to stuff over 50% to make the volume you want, your box is too small. Some people will stuff a box completely full, and they will get a very muffled dull sound.

Now that I have mentioned the effects of stuffing, it is worth noting that you do not want to stuff a ported box. If you stuff it, it will reduce the sound output of the ports (although it will have a significantly reduced effect of fooling the driver), and obviously, this is not desirable. From my experience, I have found that the best thing to do is to rubber-coat the inside walls of a ported box. I have used rubber under-coating in the past with good results, and I am planning to try using brown bread or dynamat on my next box.

However, most drivers are suited better for one box type over another. i.e. some have a stiffer suspension, and a softer cone, allowing for better ported response, while others will have a loose suspension and a harder cone, allowing them to stand up to the pressure of a sealed box.

For this reason, you will want to make your box type decision based on the driver you have selected. So, keep in mind the type of box you would like to build when shopping for your sub(s).


Hopefully that was of some help =)

[tt398]

When I build a ported box, I line the inside walls with approx. 1" thick fiberglass wool - stapled TIGHTLY to the walls. I find this treatment makes the bass response smoother and less "boxy sounding".

I agree with the other posts - DONT stuff a ported enclosure with sound dampening material.

:rolleyes:

[Zero102]

TT398 that is not a bad idea. It will reduce the SPL slightly, but it will sound cleaner than the undercoat does. Both are a compromise, because it is impossible to eliminate echoes and not drop the SPL.

As long as you staple it tightly (like you said) it should not dampen the sound too much.

[illeagle]

I like Ported boxes, sounds more deeper

[Moonracer]

Originally posted by tt398
When I build a ported box, I line the inside walls with approx. 1" thick fiberglass wool - stapled TIGHTLY to the walls. I find tthis treatment makes the bass response smoother and less "boxy sounding".

I agree with the other posts - DONT stuff a ported enclosure with sound dampening material.

:rolleyes:

Yeah you never want to stuff a box completely full of insulation, but any ported or sealed box should have at least some. It's common for a ported design with just half the box insulated and the other half near the port not insulated.

[tt398]

The whole thread is drilling down to Theil-Small parameters of a particular woofer - and how to design a particular enclosure to attain certain design goals.

Here are a few links - (Geek Links with lots of math)

http://homepage.mac.com/gcameron/.cv/gcameron/Public/Theile-Small.pdf-link.pdf

http://sdf1.cc/~neowall/vas/phy.htm

http://pub14.ezboard.com/fcaraudiotalkfrm27.showMessage?topicID=26.topic - this is a good link that shows what the abbreviations mean

http://www.linearteam.dk - has a good beginners' speaker design program called WinISD - which uses Theil-Small parameters

Hope this helps out!

:burnout: :burnout:

[npham]

Originally posted by Moonracer


Yeah you never want to stuff a box completely full of insulation, but any ported or sealed box should have at least some. It's common for a ported design with just half the box insulated and the other half near the port not insulated.

Wow, why don't you CA noobs get a real fucking clue and learn something about boxes. Man you are dumb. Lets think about this one.....

I make a ported box. I tuned it to 32hz. about 60% port area. Now I add some fill to "make the box seem bigger." Since the waves are now travelling through the dense fill and not using the solid walls of a box to create the tuning freq. Don't you think that is going to mess with the overall tuning of the box?????

Please understand what you are talking about before you shoot your mouth off. I know a few record holders, and they would shoot themselves if they read this.

BTW sealed boxes do not sound boomy, they are tight, crisp hitting enclosures. Ported boxes are louder, on average 3 dbs, but lack sql.

[Moonracer]

Originally posted by npham


Wow, why don't you CA noobs get a real fucking clue and learn something about boxes. Man you are dumb. Lets think about this one.....

I make a ported box. I tuned it to 32hz. about 60% port area. Now I add some fill to "make the box seem bigger." Since the waves are now travelling through the dense fill and not using the solid walls of a box to create the tuning freq. Don't you think that is going to mess with the overall tuning of the box?????

Please understand what you are talking about before you shoot your mouth off. I know a few record holders, and they would shoot themselves if they read this.

BTW sealed boxes do not sound boomy, they are tight, crisp hitting enclosures. Ported boxes are louder, on average 3 dbs, but lack sql.

Take your head out of your ass and realize who the "fuck" you are talking to before you shoot your mouth off. Do you know me? You are the one that is dumb and add ignorant to that as well.
Yeah just take it easy fella, it's pretty hard to explain everythhing in great detail on a forum like this. Just trying to give some general info man! :nut:

[npham]

whoa, seems someone is getting angry. well if you are going to post wrong info, why post it as "general info" I'm sure this is not the first time you got flammed and nor will it be the last. I am not going to continue to bicker and crap with you. To each his own.

[Moonracer]

:rofl: :rofl: :rofl:
Now you're learning! :thumbsup:

[Zero102]

Wow, I'll be taking bets on this event... lol

For the most part, do NOT add loose fill to a ported box. It will definately affect the tuning, plus it will decrease the SPL. A little insulation attached to the walls of the box will be enough to keep the echoes down, while minimally affecting the tuning of the box.

[tt398]

The only box I suggest STUFFING is a 1/4 wave transmission line enclosure. This size of these beasts makes them mostly unusable in automobile audio applications. (except for the :eek: lunatic fringe :eek: )

Even a sealed enclosure with an acoustic suspension driver is best served with approximately 1" thick dampening material TIGHTLY stapled to the inside walls of the enclosure. This treatment is intended to reduce internal reflections and their resultant intermodulation distortion levels by (hopefully) 3 - 6 dB. Some folks like fiberglass wool, some like polyester, some folks say the only treatement to use is long hair wool!!

It is public point of debate (in audio engineering circles) that the dampening material gives a HUGE enhancement to extended bass response - some say YES - others say NO. You'll need to experiment with this issue and form your own conclusions. (this is delving into the realm of psycho-acoustsics - unfortunately this is an area where I have no professional expertise)

Stuffing any enclosure with dampening material will negatively affect the overall "Q" factor of the enclosure - serverly restricting entended bass response, efficiency and dB SPL.

This all boils down to the proper use of Theil-Small parameters for a particular low frequecy driver AND your ultimate design goals. The crux of this matter is that the prospective designer and builder should perform some extensive research if they expect to produce an enclosure that delivers better than mediocre results. This isn't rocket science - but it is also not brainlessly simple.

A good place to start are the following publications:

Audio Amateur
Speaker Builder

A good site to visit is

http://www.decware.com - great forums on audio AND speakerbuilding

If you need some help, send me a PM.

;) :burnout: :rolleyes:

[npham]

what am I learning? I am the one giving out the lessons here....muahahahahahha :drama:

[Moonracer]

Shit guys, we all know something. I'm a certified audio engineer but :whocares:
I'm more into home audio hi fi which is a little different but alot of the principals are similar. Check any high end speaker cabinets and you will find insulation in them. Yes the insulation can rob you of cubic inches inside the cabinet, so you adjust your calculations for it. The guy who started this thread didn't say he was looking for info on competition subs. There are hundreds of different parameters to consider but I'm sure all he wanted is some basic info. :dunno: :banghead: :D
And to npham: sorry for the harsh response but you deserved it...lol lot's have coffee and make up! :tongue:

[npham]

coffee? what about a kiss? lol :bigpimp:

[Moonracer]

Oh man you better not be foolin' :rofl:

[tt398]

Originally posted by Moonracer
Shit guys, we all know something. I'm a certified audio engineer but :whocares:
I'm more into home audio hi fi which is a little different but alot of the principals are similar. Check any high end speaker cabinets and you will find insulation in them. Yes the insulation can rob you of cubic inches inside the cabinet, so you adjust your calculations for it. The guy who started this thread didn't say he was looking for info on competition subs. There are hundreds of different parameters to consider but I'm sure all he wanted is some basic info. :dunno: :banghead: :D
And to npham: sorry for the harsh response but you deserved it...lol lot's have coffee and make up! :tongue:

Moonracer has a point about cabinet insulation - you need to do the calculations to design and build a proper cabinet - irrespective of what type of cabinet alignment to plan to use.

[Phat_Tercel_YO!]

Originally posted by tt398
The only box I suggest STUFFING is a 1/4 wave transmission line enclosure. This size of these beasts makes them mostly unusable in automobile audio applications. (except for the :eek: lunatic fringe :eek: )

I like this dude.

(Sorry, I usually don't post whore, but I think he's about the least illogical person here from what I've seen).

Good info guys.

[tt398]

Originally posted by Phat_Tercel_YO!


I like this dude.

(Sorry, I usually don't post whore, but I think he's about the least illogical person here from what I've seen).

Good info guys.

Thanx Phat.
Even though we don't agree on every design concept, at least we can maintain a civil dialog.

Audio systems are much like religions - part logic, and part faith. New levels of knowledge can be attained if we dialog in a civil fashion, and refrain from trying to "draw blood"..

My side of audio is horn loaded systems (compression drivers etc) and active filter circuit design. I love the sound of a triamped system using MOSFET power amps biased Class "A". My dream system (which I completed two years ago) uses my own knock-off of Electro-Voice HR6040 bi-radial horns with JBL titanium diaphragm compression drivers. The high ends are handled by JBL "cheek" bi-radial tweeters. The woofers are 10 cu foot corner cabinets with JBL 2235H woofers in an aperiodic alignment. The two subs have 2 JBL 2245H (18") woofers in a Extended Bass shelf ported arrangement. All the electronic crossivers are my own design - using Linkwitz-Riley topology - 24 dB / octave slopes.

As you can see form the above I have my own audio prejudices - I don't go for the dB drag racing stuff - and don't much care for most car audio systems because of their distortion levels. I want low distorion, superb transient response, extended bass, and high efficiency. You can only get that combination with very large enclosures. There are some exceptions - like the servo-electric subwoofers - that use motors to drive the diaphragms. Example the ContraBass by ServoDrive

http://www.servodrive.com/contrabass.html

Everyone has their own preferences and ultimate design goals. What works for one person may or may not work for the other.
I would be happy to help anyone on this board with any questions about enclosure design math / physics or activce fileter (crossover) design and construction.

Sorry for the crappy typing - I 've misplaced my glasses and I'm a very bad touch typist.

t.t.


;) ;)

[Phat_Tercel_YO!]

And I would definately have to thank you for keeping things very civil (although I most likely deserved a flame for butting into the thread regarding my opinion on sacrifice for one or the other goals in a sound system).

I used to be in the very same boat as you. I strived ever so long for the perfect sound (to me, of course) without much avail, and attemtping some of the crazier designs in an automobile (such as ribbons in the floor, aperiodic enclosures in doors, folded horns, tranny's, etc). SQ was of the utmost priority.

That was then.

Now I've seemed to have taken to the bug of SPL, purely for the scientific nature of it, as it is very challenging to excel in some areas, and attempting to narrow down the focus of your sound is exactly the cat in the bag for me. I still love SQ and would never forfeit my front stage for anything in the world, heck, I don't even listen to it very loudly (poor SPLer!).

Very interesting to hear of someone who enjoys active crossover circuitry, class A amplification, and horn loaded devices. I myself prefer passive series crossovers (yes, I am the school of lunatics who believe different caps sound better), Tubes over FETs, and I think the only thing we can actually agree on is the aperiodic alignment that produces that ever so smooth and flowing bass lines.

Interestingly enough I feel I am maturing (or degrading) my own personal tastes, as my own crossover designs and equipment selection is actually biased towards what I had originally deemed to be acoustically unacceptable under any circumstances.

I think perhaps one day we could collaberate on a few interesting designs and see where our faiths may take us.

[tt398]

Audio has changed signficantly since the advent of digital sound sssources such as CD, SACD, dVd, and dVd Audio. During the analog days, the dynamic range capabilities of speakers were a "nice to have" - but were not considered paramount by most audiophiles. During that era low distortion was the number one priority.

Nowadays, digital sources can easily produce dynamic ranges of 110 dB. This has placed a new emphasis on high efficiency and low distortion speaker systems. This has caused a major "turnabout" in the thinking of most hard core audiophiles. As you have probably surmised from my posts, I am an "old fart" - having grown up during the tube / horn era. I still have some Macintosh tube gear and Altec / Lansing horn systems that I inherited from my father! (This stuff is over 50 years old).

My tastes have swumg away from the esoteric designs of speakers, such as electrostatics and ribbons - just because of the digital revolution. Although these designs are silky smooth, with super low distorion, they can't effectively handle the wide dynamic ranges offered by digital signal sources. Serious damage can ensue when these speakers get hit with the "louder than loud" passages on some dVd soundtracks.

What we have here is a great circle - the new digital signal sources are causing hard core audiophiles to revisit the high efficiency "huge box" designs from the 1950's and 1960's. The mid-range horn's signature "blat sound" has now been fixed by some really elegant constant directivity designs.

In a home system you can have all three of the design goals (low distortion, extended bass, and dB SPL) if you can tolerate really large enclosures. My big system actually fools people into thinking that they are in a large movie theater. Not surprising because it uses the same gear that I have designed and installed in a few large theaters and public halls.

Now the quest is to get the same performance levels in car audio
:eek: :eek: :eek:


t.t.

P.S. - actually polypropylene and polystyrene capacitors in the signal path are MANDATORY for superb sound. I have shown this with my Bruel and Kjaer distortion test set! In a power amp, the BIGGER the PSU capacitors used the more current dirve the amp can offer to the speaker load. SO we can actually agree on things!!:D :D

No problem on the collaboration - I have all the design software needed, a well equipped elctronics test bench, and a cabinet -making shop. I am right in the middle of the design / build cycle on some clone Jensen Imperial corner horns. These versions are upsized from the originals - they use Hartley 24" woofers - and the cabinets are 8 feet tall. The customer is an INSANE bass freak! YIKES!