Sound Quality: The Sealed/Ported misconception

[helotaxi 5,000+ posts]

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

Trying to use an unpowered sub as a passive radiator will at best sound bad. That being said, the original Speaker Warehouse Blazer that won the IASCA 0-100W category at the finals 4 times in a row had an enclosure for 4 iso-pairs of JL 10W5's that had a moveable baffle in it to change its internal volume. It was a custom flapper type valve that was gasketed and moved by a linear actuator, so it can be done, sort of.

I think you will be better off directing your energy elsewhere to get better sound, i.e. getting a basic enclosure to the proper size to optimize the 10 rather than trying to complicate the problem.

 

[Zee33man 10+ year member]

The only problem is that I'm pretty much having to guestimate the air space because the enclosure is going to be WAY too curvy to use trig to figure out volume. It arches in the center up to the sub, and only touches the trunk floor at the far left and right.

Why would the unpowered sub sound bad as a passive radiator? Aren't most passive radiators unpowered? I'm not trying to be a smart a$$, I'm just asking cause I don't know.

Thanks

 

[Diplexers 10+ year member]

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.

If I ever need a taxi, you're my guy! //content.invisioncic.com/y282845/emoticons/smokin.gif.f1dc8d2acb1809e863ebd6a47eaa0d45.gif

 

[DBfan187 5,000+ posts]

Most PR's don't have a magnet or at least the ones I've seen.

Maybe these will help you:

http://www.humanspeakers.com/whatis/PR.htm

http://www.danmarx.org/audioinnovation/flatpassives.html

http://www.diysubwoofers.org/prd/ = I hope they help you in some way?

 

[Zee33man 10+ year member]

Good links dbfan! I'm going to do some more research before I make my decision about this.

 

[Below 30 10+ year member]

I would like to see where I said that either type of enclosure is better than the other. I would like to see where I said this whole topic was about SQ.

 

[XDrkmanX 10+ year member]

//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[helotaxi 5,000+ posts]

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.

 

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.

 

I would like to see where I said that either type of enclosure is better than the other.

Ringin' any bells yet???

I would like to see where I said this whole topic was about SQ.

Maybe the SUBJECT line and the whole first post you made???

 

[helotaxi 5,000+ posts]

The only problem is that I'm pretty much having to guestimate the air space because the enclosure is going to be WAY too curvy to use trig to figure out volume. It arches in the center up to the sub, and only touches the trunk floor at the far left and right.

Build it, fill it with water, measure the amount of water it holds. If it is too big, expanding foam can be your friend, as can clay, body filler, blocks of wood glassed in place, use your imagination. Anything that you can put in place to displace air can be use to make the enclosure smaller. Now if its too small, well, I hope you are patient.

 

[sumone 10+ year member]

Most of us just want the simple answer:

If you want SQ go with a ______ enclosure, and if you want SPL, go with a ________ enclosure.

Should the answers be ported,ported?

 

[helotaxi 5,000+ posts]

Most of us just want the simple answer:
If you want SQ go with a ______ enclosure, and if you want SPL, go with a ________ enclosure.

Should the answers be ported,ported?

The answers should be: it depends, ported.

From the standpoint of accuracy, the proper sealed enclosure will be more linear and faithful to what is in the recording. Some people think that this sounds muffled and want the extra output of a ported enclosure. This is their idea of "quality." To each his own. It's not really linear, but it sounds good to them and that is what is really important I guess.

For real SPL, ported is the only way to go. Of course the sub will sound like utter trash and you could damage it trying to play music through it, but if you want to win at dB Drag...Again, to each his own.

 

[Redford 10+ year member]

err didnt read 2nd page.. nevermind

 

[OGButch 10+ year member]

The answers should be: it depends, ported.
From the standpoint of accuracy, the proper sealed enclosure will be more linear and faithful to what is in the recording. Some people think that this sounds muffled and want the extra output of a ported enclosure. This is their idea of "quality." To each his own. It's not really linear, but it sounds good to them and that is what is really important I guess.

For real SPL, ported is the only way to go. Of course the sub will sound like utter trash and you could damage it trying to play music through it, but if you want to win at dB Drag...Again, to each his own.

So what I seem to be taking away from what you are saying is that no matter what type of music you listen to, sealed is the way to go. This is because of the accuracy and reflective true intended sound of the music.

If you listen to all types of music would you sugjest a sealed enclosure?

 

[Diplexers 10+ year member]

So what I seem to be taking away from what you are saying is that no matter what type of music you listen to, sealed is the way to go. This is because of the accuracy and reflective true intended sound of the music. If you listen to all types of music would you sugjest a sealed enclosure?

Yes!........

 

[Berry47 10+ year member]

I had a proted box with my old eclipse sub and it was loud, but as soon as I switched to sealed it sounded much better. it was tighter and cleaner.

Isn't it true that some woofer just perform better in sealed then proted and some exist better in a ported enclosure. It should be sub specific. (THis is not entirly true)