Sound Quality: The Sealed/Ported misconception

[Below 30 10+ year member]

I've been seeing how sealed enclosures is refered to as a SQ enclosure and know that it is very misleading. SQ should be a term to mean how well the sound is reproduced. If you think about it, sealed has many limitations that would not justify it as SQ.

 

A sealed box is a permanent suspension counter on a woofer, which basically strongly restricts cone movement. With the highly restricted cone movement, the woofer losses the ability to fully reproduce all the low frequencies well. Example; a humans sound system (our voice) is a ported system. The port is our nose. Start to hum, then plug your nose and hum. You hear and feel the difference. Its much harder to make the sound and its not as loud.

 

First off I can respect the fact that some people don't like boom, wave, extended bass (what-ever else its called). Another fact is, its supposed to sound like that. I'm going of hip-hop for this. Example; Warren G's track, "This DJ". It's is a boom-bass heavy track. If you play that in a sealed box, you hear the faint struggling boom and heavy kick drum. Play it, in a vented box and the boom comes out in full force.

 

The woofer in a vented box is less restriced by air pressure and the cone can more accuratly, to vibrate the -boom- sound, that your supposed to hear as Warren G produced. I believe in opinions of ones self to be valid, thats why I dis-agree with SQ refering to sealed universaly. If anything, vented is the true SQ enclosure.

 

So SQ should not be used to describe enclosure types, only woofer brands themselves.

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[sumone 10+ year member]

Good claim - I'm pondering if I want a ported instead of a sealed box now...

But how do you feel about jazz in a ported box compared to live jazz?

 

[DiB 10+ year member]

It's all subjective. And your last statement is too. You can take an all out spl woofer and make it sound quite nice with the right enclosure or make it do 62hz louder then no other and sound like ass for anything else. If anything, it's all math. If you want true SQ you need to determine the type of box needed to most accurately reproduce your desired range of frequencies IE 20-80hz. Bu that is still subjective!

In my book it boils down to semantics. We needs simple words to describe what we without getting too technical. So we(we as a generalized whole but not all since there are always exceptions) came up with SQ sounding smooth across the entire spectrum. Then SPL was for an all out boom usually set for a desired frequencies. SQL was deemed to be a mix of the two.

I'm sure you know all this but as you might or might not know a sealed box often times is easier to make then say a box tuned to a lower hz 20-35 and a sealed box does meet the requirements for the major consensus on the definition of an SQ setup. It might not be as loud but it doesn't just produce those frequencies softer, it does a lot more.

Ok, that is my morning rant, tear me down or build me up, whatever just my opinion.

 

[Below 30 10+ year member]

Here is the thing, the woofer is going to reproduce the signals the amp sends it. So if the track is a tight bass produced song, thats how it will sound in a ported enclosure (assuming a properly built box a capable sub).

 

I have never actually listened to jazz on a true system, I like listening to smooth jazz on the radio with headphones when I'm doing something (Wave 94.7 in Canada). But it will sound the way its supposed to sound in the ported box. I'm just amazed how people think that a tight bass produced track will sound -boomy- in a vented. How can there be boom when the amp isn't telling the woofer to boom.

 

Maybe people used flea-market speakers in vented boxes and then just blacklisted ported as boom boxes. I think that people who think vented is boom, actually never heard the particular track in full frequncey before and didn't know the track has boom in it. Do you realize alot of 80's arcade games had serious bass in their tracks, like Double Dragon. Non of us could, because the arcade speakers were basically midranges, so we lost the low frequency effect. Now if someone where to here its track in a vented, they'd think, oh its a boomy vented box. No, its the way the music is supposed to sound, just that you never knew.

 

 

[Below 30 10+ year member]

From your opinion, I see you are on a similar track as mine. The idea of subjective I fully agree with. So if somebody ask what is difference between sealed and ported, one shouldn't say, sealed is Sq and vented is boomy. One should explain that sealed puts more strain on woofer cone to cancel out 808 boom-bass produced in hip-hop and vented reduces strain and improves DB output. But if built wrong, can cause speaker failure, due to frequency tuning error and power management.

 

[DiB 10+ year member]

My 4 15's are are tuned to 31 hz so anything and everything I listen to sounds great even jazz(Diana Krall) imo. I totally agree that a sealed box "can" muffle songs but I had a sealed box for 2 12's that was a bit on the large side and sounded fantastic. My personal preference is a low tuned box because everything sounds smooth and when hip hop comes on it goes boom boom like it was intended. This board is pretty good about asking people what type of tunes they listen to and what type of sound they are going for before suggesting things. Hopefully threads like these can continue to educate new minds.

 

[helotaxi 5,000+ posts]

What about group delay? That is the reason that most vented systems sound muddy. If you want the ultimate in accuracy: infinite baffle. It's just the amp and the speaker. No interference from the enclosure at all.

 

[Below 30 10+ year member]

Problem is, so few subs support IB. Plus any delays are something only true audiophiles would ever notice anyway.

 

[DBfan187 5,000+ posts]

I agree with everything you say! But in reality, SQ is biased or opinionated. I say sealed because I like "tight" bass, but for wider ranges of bass I would say ported because you can get the best of both worlds. It's about a 50 - 50 of everyones opinion. From everything you said, ported may be the best overall enclosure to get the optimum performance from your subwoofer. But, Why is it that sealed boxed subs tend to sound louder outside of the vehicle?

 

[Below 30 10+ year member]

Check it out, it's ported for life, for me. My idea tho, is like what most of you are mentioning, Objective. It's just that many people who don't seem to remember about objectivity, universally call sealed SQ. Thats why I came up with points to prove that they should not be called that by default.

 

I would be contradicting the entire thread if I said one type is the best. Non of them is the best and non of them should be referred to as SQ. I have no idea about the physics of the vehicle, but I imagine since sealed excels in -kick- drum bass, which can be heavy, it's easier to hear outside than, lighter wave/boom, that may need more power to push outside the ride.

 

[helotaxi 5,000+ posts]

Problem is, so few subs support IB. Plus any delays are something only true audiophiles would ever notice anyway.

Most will work IB you just can't power the crap out of them. Only the Qtc of the driver itself is keeping the excursion in check.

Most any configuration can be made to give accurate bass. Ported designs, by virtue of the port, will not provide truely linear response. There is a reinforcment of the frequencies right around the Fb. That is not accurate. The sub itself plays a huge role in the overall accuracy of the bass. Matching the sub to the enclosure is the rest of the equation.

It is also said that ported plays lower. To a point this is true. In an anechoic environment, the F3 of an optimal ported box is lower than its sealed counterpart. The difference is in the rolloff. A sealed box rolls off at 6 dB per octave while ported rolls off at 12. So you just tune lower on the ported box right. Not so easy. The system Q changes when you mess with enclosure size and tuning and accuracy suffers as a result. Also, the car is anything but an anechoic environment. Cabin gain works at about 6 dB per octave, coincidentally the same rate that a sealed box rolls off. This actually works to flatten the in-car response of a sealed box system. In a ported system the cabin gain tends to over accentuate the low frequencies and make the bass sound exaggerated. Again, not accurate.

Last point, the basis of your whole argument to begin with is that a sealed box overdampens the cone of the sub. Well as a ported enclosure nears resonance, the motion of the cone is much more restriced than in a sealed system.

Take the subjectivity out of the equation. Overlay a RTA readout of the signal with the RTA readout of in-car frequency response for both a sealed and ported system. All we are interested in is the sub-bass region say 70 Hz and below. Run a few delay plots as well. Tell me what you find.

It doesn't take an audiophile to hear group delay, BTW.

 

[Below 30 10+ year member]

Actually, in a ported box, appearantly below tuning, the woofer has even less restriction, not more. That is why they can be damaged, because of over-excursion, they act like they are in free-air below tuning, appearantly.

Trust me, people coming here everyday asking, what sub should I get for $100, are not going to notice this group delay and they are the mass majority.

 

[helotaxi 5,000+ posts]

But, we, you and I, are not talking about the mass majority, now are we. We are talking about accuracy. Most anyone who would know group delay would not be asking about a $100 woofer, you are correct, but you started this post with a bunch of big words and said you wanted to discuss accurate bass and the merits of different enclosure types. That pretty much goes beyond the level of the $100 dollar woofer guys, so why bring them into this.

In a ported enclosure, there is basically massive cancellation below the tuning freq. The driver is completely unloaded as well. Result: no output and a destroyed woofer to show for it.

Now if all you listen to is rock and hip hop, then a ported enclosure might work well for you. The impact from the drums and the drum machines will be accentuated. It can sound pretty tight. It might give you the sound you want, but it will not necessarily be accurate.

If you listen to classical or any kind of synth music that has really low frequencies (think subsonic here) then a vented sub will just flutter and will sound terrible and likely get damaged in the process. A 16Hz fundamental on a pipe organ will eat a ported sub primarily set up for rock/hip hop for lunch. A truly accurate system will reproduce it with correct tonal balance and with authority. The ported system will reproduce the 32Hz harmonic and you will think that the fundamental is there. It isn't. Psychoacoustics at work.

There is a reason that most SQ competitors go with a sealed or IB setup. You want to talk SQ then talk SQ. SQ is tonal accuracy, dynamics, detail and linearity. You cannot honestly argue that a vented enclosure beats a sealed enclosure in all, or even most of those areas. Yes, there are sealed sub systems that sound like crap. There are far more vented systems that sound even worse.

 

[Zee33man 10+ year member]

Is it feasible to have both sealed and ported enclosures switchable by some type of remote valve?

Specifically, I have a 350z that I am building a sealed fiberglass enclosure for my 10" Audiobahn aw1006t. Currently there is a ported enclosure behind the driver's seat and under the floor that I built for my 8" kicker comp vr (this enclosure now ports into the trunk space).

My idea is to link the fiberglass enclosure with the 10" sub to the hidden enclosure with the 8" sub. They would be linked by some type of remotely switchable valve so that when the valve is open, the unpowered 8" sub will act a passive radiator.

It won't be truely ported even when the valve is open, it will just increase air space and utilize a passive radiator to help boost lower frequencies.

Am I correct in my thinking? And does anyone know of a valve that I could use in this project? Any thoughts/ideas are appreciated! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Zee33man 10+ year member]

Does anyone have an idea on this? Surely I'm not the first to think of having a switchable sealed/ported box...am I???