Monitors : Ported -versus- Acoustic Suspension

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CoolCat

CoolCat

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WHY ARE WE USING PORTED SPEAKERS FOR STUDIO MONITORS???

In 1954, Acoustic Research released the acoustic suspension or sealed system that exhibits a very smooth frequency response and is often favoured over other methods by many studio pros and home audio experts alike.
-The air inside the box acts as shock absorber that keeps the natural inertia of the driver under control for a tighter bass response with less distortion and overhang.


The most common enclosure type, patented by Albert L Thuras in 1932, is the ported or bass reflex design.
-The trouble is that bass reflex systems can run into problems with excessive ringing or peaks in the bass around the port-tuning frequency, particularly if the enclosure and port dimensions have not been designed properly.
-Also, without the airtight suspension of the sealed design to dampen the excursion of the driver, the woofer can lose its linearity or accuracy when tracking the audio waveform at louder volumes, or at frequencies below the resonant tuning of the enclosure.
-Plus, there's nothing more disturbing than copping a blast of air or audible chuffing from the speaker's front port on every bass note.
-Lastly, if the port is mounted on the rear of the box, the speaker's proximity to the immediate wall or corner behind it becomes a larger factor in the level of bass output.

Question: Any inputs as to why nearly all retailers only sell ported cabinets?
Seems for Studio Monitors we want "Accuracy" = Acoustic Suspension??? The only explanation i've heard from a friend is "it costs more to Manufacture a sealed air-tight cabinet."
 
The AR suspension, while interesting, has some flaws. Yes, with a very low resonance speaker and a sealed cabinet to supply the complience, it can get down very low.

Unfortunately, the air suspension design needed a heavy, stiff cone to prevent cone flexing and breakup, and the efficiency is very low, needing lots of power.

The 60 gram AR cone was slow to start and stop, making it okay for pipe organ recordings and terrible for kick drum reproduction.

You can use higher efficiency speakers that will respond better to transients, and add a port to increase bass response below the higher resonant point of a higher efficiency speaker.

As in microphones, it's all about compromise and trade-offs when it comes to designing this stuff.
 
thanks H.

i'd been reading on this and the articles are out there, but the sealed cab speakers are rare.

never heard any sealed-cabs as nearfields.
never see them at Musicians friend or GC either etc..?
appears everyone gave up on the sealed cabinet designs due
to all these issues.

but using the air to "tighten up" the bass makes sense to me.
spring effect. never thought about the cone stress.

not being a big fan of front ports on nearfields at 1 meter,
i was looking for other possibilities than ports...
and the sealed cabinet is an interesting concept.

"slow to start/stop" that makes sense with the air-resistance.


Anyone know about the coaxial design?
what made them fall from grace?
I was reading an old Mix magazine and it listed them as the best monitor?
perfect axis and dispersion.
 
Hello -

All of our monitors to date have featured sealed box designs (both for the SUB and SATs). You can read more about why we chose this type of design on our website. www.abluesky.com/ports

Cheers!
 
Blue Skys Sealed Spectacular Sub sounds speakers sets??

Thanks for the Blue SKy input...

if nothing else its great to see Blue Sky improving-modernizing the sealed cab designs. A Sealed Sub cabinet too!! thats interesting.

at least Blue Skys trying to tighen up the flabby bass port sound.
the port concept is like "blowing into a bottle"...
and thats the kind of sound i hear from the port when up close.
hear it once and it's like a fake bass... like holding a tube up to your ear.

a powered efficient sealed cabinet..with tighter bass. thats progress.
 
Slowly surrendering to the Sealed Subwoofer Speaker Sets

thats alot of reading. very good unbiased articles.

the first article was abit above me technically.
the SOS, setting up a sub, without an oscilliscope, was a good HR read.
the last article very unbiased for ports & sealed...all the different flavors.

so it seems all Low Hz roads... lead to subwoofers these days.
Your design group is syaing "surrender to the sub"...thats the best available until we can figure out Whale communciation methods?

Question 2:
If using a sub, either type.. ported or sealed, would work the same?

In other words,depending on what your Port is "tuned" to...
If your small Nearfield has a "tuned port" at 70hz center/target, for example.. and you set the sub crossover at 80 hz...
there wouldn't be any port sound from the satellites...just background noise..like a hole in your cabinet?

good reads, very tempting to try a set of sealed, sats/subs...matched too.

i can't blame my mixing skills on the speakers,
but i can use any help i can get! :eek:
 
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