Sound Quality: The Sealed/Ported misconception

[bigred78797 10+ year member]

Yawn... will this ever end. They design the speaker for a sealed enclosure... which is pretty easy to do with programs like reverse Spead where basically it tells you what materials to use. Anybody who has read up on Transmission line speakerboxes have read that theoretically the Trasmission line can be the PERFECT sound system... theoretically. But because those boxes are larger corperations sunk their money into developing speakers that fit into smaller enclosures. But before the Transmission line could become perfect it would need the perfect matching subs designed specifically for that size and type enclosure taking into effect all the different aspects of the total system.

Sealed + Right speaker = Accurate

Ported + Right speaker = Accurate

Bandpass + rightspeaker = bah i never read up much on those i always skipped that chapter.

PR + Right speaker = Haven't the slightest clue, same as bandpass

God i love to keep things going //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Oh if anything here is incorrect jlaine or g - guy correct me //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[geolemon 10+ year member]

TL's... theoretically yes, but that's 1/2 wave theory... and honestly even still couldn't be as phase-correct as sealed. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

You can build them under 1/4 wave theory also, and I haven't read as much... but they theoretically would seem to face the same phase issues as a ported box then.. with a really big port... only coming within 90 degrees of phase difference.

Bandpass boxes have their own inherent delay since ALL the sound is coming from a port (or two)...

But you have to match the subs to the enclosures the same way:

Sub with a low EBP or high Qts = 4th order (rear sealed chamber bandpass)

Sub with a high EBP or low Qts = 6th order (both chambers vented) bandpass.

PR's are like ports, essentially. But the mass of the port dictates the resonant frequency of the PR, rather than the size/length of the port (really the mass of the air and the friction from the pressure mass acting against it) for a vent.

So, ported box subs apply here also. //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

 

[bigred78797 10+ year member]

Thanks goele.. and yes was talking about the quarter-wave theory //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif. I think im gonna learn how to do bandpass and passive radiator boxes now //content.invisioncic.com/y282845/emoticons/idea.gif.5acb6a39a9b92425414c316dda202bad.gif You have inspired me.

 

[geolemon 10+ year member]

Here's a fun one to start with:

http://www.betteraudio.com/geolemon/isobp/isobp.htm

(not that I'm biased or anything) //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[sumone 10+ year member]

The question at hand is based upon fact and not opinion right? From what I've read, it seems Geolmon stated the facts, so what else is there? What books are good to read about this topic?

I feel like such a newbie; when my ultimate career goal is to design and program electronic circuits dealing with the music/sound reproduction industry...

ahh...I've said nothing important. I'll let you veterans work this thread...

 

[nweibley 10+ year member]

Back on the first page: I'm having this problem today!

I installed a JL Audio 12" W6 in a ported box buildt to JL's exact specs... exactly...

He got a new amp, and I set all the gain up with a multi-meter and 0db test tones, got everything tweaked out, made sure the X-Over was good, everything sounded great.

I played a freq-sweep from 250hz-20hz to make sure his woofer -> subwoofer transition was smooth. It was, and when it got to the sub, it was suprisingly loud. Darn loud.

Then he popped in some Static-X ... and was like "The kick drum, it doesn't sound as boomy as it used to! Why dont I feel it vibrating my seats?!" I just can't figure out why these people can't accept that there is more than just boomy bass. A kick drum should sound like a kick drum, not an 808 kick from an outkast song! Jeez, to me it sounded downright good... to him, not enough boom...

Why are people so ignorant?! //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Just another rant about how people's opinions differ on what 'sounds good'... I guess.

-----Nate

 

[bigred78797 10+ year member]

One last question, do you have any websites with the math behind them. I like to learn the math behind boxes before i build them( building them is the fun part //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif ). I want all the information on all the boxes.. arent i greedy.

 

[DBfan187 5,000+ posts]

Here's a fun one to start with:http://www.betteraudio.com/geolemon/isobp/isobp.htm

(not that I'm biased or anything) //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Did you build that box? That box was !SICK! It looked like a granite countertop! How much $money$ did you sell it for!

 

[DBfan187 5,000+ posts]

Can anyone tell me how to build a snail shell enclosure or my sub? (dimensions really:evil

RF HE2 4ohmDVC 500watts RMS 1000watts max.

geolemon is GOD!

 

[sumone 10+ year member]

Also, can it be said that a sealed box can be given some eq and sound like a ported? (Dont know where the phase stuff and all would fit in though)

But I think it would be harder to make a ported sound like a sealed?

Like if someone doesn't feel the boomy presence they once did on their ported box with their sealed, it's not a matter of that the boom can't be recreated right? The ported just acted as a kind of passive equalizer, while the sealed would provide the flat un-attenuated response?

 

[Below 30 10+ year member]

I liked bigred78797's response about sealed and ported = acc. That right there sumed up my entire point from first post. Sealed is not SQ and no other type of box is. SQ box, is a box that sounds good to a person.

The boom from ported is not an eq effect, its the woofer vibrating more freely through the motions. I noticed the hi-tech post too, but you all now are going to believe ported causes more stress on a woofer. That is truly sad, so if anyone has an idea and uses big words and makes an essay post, its automatically law.

Fact is, most of you skimmed the first post and saw somebody shedding light on the fact that sealed is nothing special and you all come in with your lack of facts or actual comparisons like i did. Remember, once somebody decides not to follow the leader, its hard for the others to stand on their own, for fear of abamdonment. I don't fear it.

 

[helotaxi 5,000+ posts]

I liked bigred78797's response about sealed and ported = acc. That right there sumed up my entire point from first post. Sealed is not SQ and no other type of box is. SQ box, is a box that sounds good to a person.

Pleasing sound is what sounds good to a person, Sound Quality is accurate reproduction of the signal presented.

The boom from ported is not an eq effect, its the woofer vibrating more freely through the motions. I noticed the hi-tech post too, but you all now are going to believe ported causes more stress on a woofer. That is truly sad, so if anyone has an idea and uses big words and makes an essay post, its automatically law.

The more you type the more you show how little you really do know. The pressure inside a ported box IS higher than inside a sealed box whether you choose to believe the PHYSICS behind it or not. Just because you think the law of gravity isn't correct, doesn't mean you won't fall if you jump off a building. The cone on a sub in a vented enclosure moves LESS at resonance than it does above resonance whether you choose to believe it or not. Displacement limited power handling for a sub in a vented enclosure is MUCH higher at or above resonance than for the same driver in a sealed enclosure. Why? Because the air moving in and out of the port works to dampen the movement of the cone and keep the sub from reaching its mechanical limits. Result, the stress on the woofer in higher. Below resonance the air moves through the port and the pressure equalizes during the stroke and the inertia of the air moving in and out of the enclosure actually pushes/pulls the woofer farther than it wants to move. Result, overexcursion and likely a trashed woofer. But, hey its just physics, not like there's any science behind it or anything. Feel free to disagree.

Fact is, most of you skimmed the first post and saw somebody shedding light on the fact that sealed is nothing special and you all come in with your lack of facts or actual comparisons like i did. Remember, once somebody decides not to follow the leader, its hard for the others to stand on their own, for fear of abamdonment. I don't fear it.

Fact is you haven't actually understood anything that anyone who knows anything about the topic has said. Since their SCIENCE does not agree with your OPINION, they obviously must be wrong and you are clearly correct. Pardon me for disagreeing with you, your Highness. The Earth really IS flat.

 

[jlaine 10+ year member]

The boom from ported is not an eq effect, its the woofer vibrating more freely through the motions. I noticed the hi-tech post too, but you all now are going to believe ported causes more stress on a woofer. That is truly sad, so if anyone has an idea and uses big words and makes an essay post, its automatically law.

Fact is, most of you skimmed the first post and saw somebody shedding light on the fact that sealed is nothing special and you all come in with your lack of facts or actual comparisons like i did. Remember, once somebody decides not to follow the leader, its hard for the others to stand on their own, for fear of abamdonment. I don't fear it.

You should fear abandonment based on the fact you can't comprehend basic physics as it's being explained to you. This research has been done in the late 60's, it's been public knowledge for that long.

Here's my lack of facts as presented:

"Compared to closed-box systems, vented enclosures posess several unique characteristics:

A. Lower cone excursion near the box resonance frequency, resulting in relatively higher power-handling and lower modulation distortion.

...

C. ... driver design requiements of lower required cone mass and less required voice coil overhang...

"

Source: LDC 6th edition, Author Vance Dickason

I'll even help you out further:

ISBN 1-88250-33-8 order one and learn something, you are starting to grow irritating in your blind wanderings.

 

[Below 30 10+ year member]

So basically you people believe that sealed enlosures are the best, because one man used a dictionary to write a post. Non of you will explain why a sealed struggles to play wave bass, yet carry on like sealed is end-all.

Foolish talk about this silly sealed = SQ. Thats elementry train of thought. Some highly respected member of audio decades ago, was probably at a cocktail party and just said "You know, sealed is the best SQ, because I say so". Then everyone just said "Ya he's right, sure sealed doesn't play the low end the way music producers intend, but he must be right". Notice in music studios, producers use ported/vented speakers (But I guess you guys know more than music producers).

It's funny to see you guys talk yang, just admit that your hurt that vented does more justice for low-end and stop your dictionary foolishness. It's a good thing you guys don't have anything to do with PA and home and car SPL. Audio would be dull and dead if that was the case. Sealed is a just a woofer -deadening- enclosure for people who can't handle 808 bass.

 

[bigred78797 10+ year member]

You really should buy the book... read it... then argue your point. Start out by reading Chapter 2...the first paragraph.