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Sealed active subwoofers?

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I almost never come across sealed active subwoofers.

Why is this?
Since they offer nicer sound (at the expense of outright volume) I would expect a variety of these to be available?
I know the vented subs use that to cool the amp, but sure the amp can be mounted externally to avoid these issues?

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Sealed go lower and gradual roll-off. Ported boomier but not as low. I use stereo sealed 12" subbies which go beyond 31hz.

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Maybe they're just hiding :). 75% of the subs I sell are active and sealed (e.g. JL Audio, Wilson Benesch, Omega etc).

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I have a pair of Power Sound Audio XS30's dual 15" sealed subs, they're awesome. :)

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I have a sealed Seaton Submersive F2 HPi ...2800 watts in solo setup, up to 6000 watts with a slave added ... All that power equates to an an unbelievably low, smooth and detailed sound.

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Hi,

 

 

My 2 Velodyne HGS 15's are sealed and the 1250W amps never even get lukewarm.

 

The top line Velo's have always been sealed..........love the clean, tight and low punch 

Edited by JohnL

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Interesting thread.

Some misconceptions to start and a buttload of humble brags to follow :P

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Interesting thread.

Some misconceptions to start and a buttload of humble brags to follow :P

.... Spoken like a Logitech owner LOL!

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As a matter of interest.......

 

Would I be right in assuming that the plate amps in MOST active subwoofers (sealed or ported) don't get very hot due to being Class "D"??

 

As opposed to "A" or "A/B"  like higher end stereo power amps?? 

Edited by JohnL

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I almost never come across sealed active subwoofers.

Why is this?

Since they offer nicer sound (at the expense of outright volume) I would expect a variety of these to be available?

I know the vented subs use that to cool the amp, but sure the amp can be mounted externally to avoid these issues?

 

You must be looking in the wrong places. The cheapies are often ported as they want to get the most noise out of subs with wimpy amps and drivers, built to a price. Once the budget moves into decent sub territory, it's more like 50/50 in terms of sealed and ported designs.

 

To put it simply, when using the same amp and driver, a ported sub that is twice the volume and tuned around say 20 Hz will equal two half sized sealed equivalents in the bottom octave (max SPL) and above 40 Hz they will be about equal. The sealed sub will often sound tighter when plonked into a room, especially if it has not been EQ'd to the same response - in other words, the tightness will often be related to a different frequency response. If you take those two subs and EQ them to the same target curve, a large portion of the difference will disappear. Ported subs maintain low distortion down to their tuning point where sealed subs experience a rise. Where a good sub might maintain say 3% THD at a given level, with the sealed sub it may reach 30% or greater at 20 Hz.

 

The main problem with ported subs is that they have some practical design difficulties. They usually don't live up to their full potential because with modern high excursion drivers, even those that are not pushing the excursion envelope, getting a low tuned port that is aerodynamically adequate is quite difficult.

 

Interesting thread.

Some misconceptions to start and a buttload of humble brags to follow :P

 

Amateur attempts at the humblebrag! This is how you do it:

 

I know horn subs are cool 'n all but seriously, I'm just over fixing the house every time I watch a movie!

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.... Spoken like a Logitech owner LOL!

 

My mains have 8" woffers I din't even need a subwoffer! :hiccup

 

?

 

 

 

...

I know the vented subs use that to cool the amp, but sure the amp can be mounted externally to avoid these issues?

 

 

 

misconception?

 

Amateur attempts at the humblebrag! This is how you do it:

 

I know horn subs are cool 'n all but seriously, I'm just over fixing the house every time I watch a movie!

 

That's the slightly more formiddable "crumble brag" @@Paul Spencer :lol:

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That's the slightly more formiddable "crumble brag" @@Paul Spencer :lol:

 

Clearly a connoisseur of the brag!

 

 

Although when it comes to bragging about subwoofers, I prefer the Paul Hogan approach ie "you call that a subwoofa? That's not a subwoofa, THIS is a subwoofa!"

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@ Paul Spencer ... am i reading what you have said correctly that sealed subs have much more THD?  I always thought it was the opposite.

 

Why would you buy a sealed sub then as they cost a LOT more to power.

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@ Paul Spencer ... am i reading what you have said correctly that sealed subs have much more THD?  I always thought it was the opposite.

 

Why would you buy a sealed sub then as they cost a LOT more to power.

 

with subs, the higher the excursion the higher the distortion, so just above their tuning, ported subs have much lower excursion than sealed subs hence much lower distortion.

 

Well above tuning, a sealed sub and a ported sub will have comparable distortion.

below tuning a ported sub is in dangerous, driver destroying excursion and extreme distortion

 

horses for courses:

  • sealed subs have slower rolloff than ported (2nd order vs 4th order), which means less group delay.
  • Sealed is easier to EQ - a simple Linkwitz Transform can be used
  • sealed can be easier to integrate into a room, as you don't have the port complicating matters (port is 90 degrees out of phase with the driver)

 

Mike

Edited by almikel

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@ Paul Spencer ... am i reading what you have said correctly that sealed subs have much more THD?  I always thought it was the opposite.

 

Why would you buy a sealed sub then as they cost a LOT more to power.

 

You bought one, so you could ask yourself that question!

 

Above 40 Hz the distortion will be similar in sealed and ported designs. In the bottom octave sealed box subs have a marked rise in distortion that is related to the much higher excursion. A ported design is tuned such that the excursion is very low at tuning. The result is much lower distortion. Below tuning the distortion and excursion shoots up but this is below the intended use and a rumble filter should be used here to filter it out.

 

It takes an extremely good driver to avoid the rise in distortion in a sealed box. TC Sounds LMS5400 is one example but it's extremely expensive.

 

Both ported and sealed subs have their place. Ported subs usually fail to live up to their full potential due to port compression. It's all about port aerodynamics and the vast majority of ports can't handle the required displacement of modern high excursion drivers without serious compression and audible chuffing. Ported subs have pragmatic challenges.

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As a matter of interest.......

 

Would I be right in assuming that the plate amps in MOST active subwoofers (sealed or ported) don't get very hot due to being Class "D"??

 

As opposed to "A" or "A/B"  like higher end stereo power amps?? 

 

My sub is sealed

My sub plate amp is A/B

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@ Paul Spencer ... am i reading what you have said correctly that sealed subs have much more THD?  I always thought it was the opposite.

 

Why would you buy a sealed sub then as they cost a LOT more to power.

 

depends…velodyne with their DD series and later DD plus for instance have always particularly targeted  for low distortion, using servo feed back and control and very very good drivers reducing distortion from 10-20% typically to under 0.5% at typical listening :)

 

interview from bruce hall president of velodyne going way back that talks through their designs and technology to get around the sealed subwoofer challenge to do low distortion designs, 

http://www.hometheaterhifi.com/videos/secrets-studios/bruce-hall-velodyne-2-8-05/bruce-hall-velodyne-2-8-05-index.html

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I've spent quite a bit of time on vented boxes.

 

Like Paul said... if looking for very high quality outcomes, then I think ports are a lot harder to design than people give credit for.... and then even once designed well, they can present issues in integration and EQ.

 

 

Perhaps I am just not smart enough, but I don't like the idea of increasing the order of the mechanical system.    To me, a second order system  (just a bare driver, or a driver in a sealed box), presents enough of a mystery.....  adding more opportunities for energy storage and time constants, makes my head hurt.

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under 0.5% at typical listening

 

This is very low for subwoofer frequencies  (eg. <40hz)  .....  no matter how typical listening is defined.

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You bought one, so you could ask yourself that question!

 

Not surprisingly, I bought it because it would fit and it was the best sub-woofer I had heard that would LOL!

 

Audyssey eq's it down to 5hz and (not that I have anything to compare it to) I would not have described its output as distorted at all.

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depends…velodyne with their DD series and later DD plus for instance have always particularly targeted  for low distortion, using servo feed back and control and very very good drivers reducing distortion from 10-20% typically to under 0.5% at typical listening :)

 

Despite a relatively excellent result, distortion was measured much higher than 0.5% here and that's for the 18inch version (which should be the lowest).

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IME I reckon the end user should just get the sub (or subs) that best suits their tastes, partnering equipment and room.

 

My only caveat would be.......whether ported or sealed...........spend AS MUCH as you can afford!!!!

 

I see SO MANY systems where the owner has skimped on the Sub and it just brings everything down!!!

 

Even though I am a sealed fan I would steer someone needing maximum output/extension for minimum dollars towards ported.

 

I think sealed subs seem to mostly reside in the higher $$ range.

 

The cheapest, decent, sealed sub I have heard so far is the $1K Whatmough Tornado.

 

What I love about sealed is the speed and tightness which also aids in musicality.

 

Years ago I remember going from 2 Whatmough Typhoons to a single Velodyne HGS 15.........stunning!!! 

Edited by JohnL

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Hi Gee Emm,

 

 

That IS interesting!!

 

What brand is the Sub and/or the plate amp??

 

 

Cheers

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