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sealed vs. port cabs

Keld

Keld

Jul 9, 2009
30
0
PDX
#1
Ok, don't shoot me if this has already been haggled about to death, but I haven't really seen enough info on it.

I'm looking for a good cab to compliment my Mesa 400+ and I'm having a h*ll of a time with it.

- Bought a used Aguilar db212 and one of the drivers is blown :mad:
- tried to buy a Mesa cab off of Craigslist only to have the guy sell it out from under me :mad:
- drove up to Seattle and while I was there wanted to check out the Berg NV cabs from a reputable dealer, only to find that they don't actually have any in stock. So much for up to date web sites...:mad:

ah, ok, rant over. Now onto the real question of this post:

So,... can you describe the tonal difference, if any, between a ported cab and a sealed cab? I need something to cut through at least one loud (another might be added) Marshall 4x12, and I'm thinking a 610 or 810 might be the ticket. Seems Ampeg or Bergantino are the two most prominent choices of the sealed cabs and I'm thinking a Mesa (powerhouse 610/810 or maybe a 1200) or maybe a different Aggie in the ported vein.

Any help would be *greatly* appreciated. I can probably get a Mesa or Ampeg locally, but the Berg and Aggie stuff takes a bit more work.

Cheers.
 
#2
The quick and easy on these is ported cabs usually go lower and are more efficient. Sealed cabs are tighter(better low frequency speaker control) that tube amps just seem to work better with IME IMHO. But they are also usually not as efficient as the ported cabs. This is just a generalization.
 
#4
Sealed are tighter, ported have better low response.
But you must remember - if you have back ported cab, you shouldn't put it near the wall - you'll lost huge amount of power by doing that.
The sound and efficiency of the back ported cab depends where you put it. You should leave least a 1,5 meter between back of the cab and the wall.
You can put sealed and front ported cab anywhere you want without any problems.
You'll lost a little of low response when you lift ported cab from the ground, but that's not a problem usually.
 
#5
bassforce said:
But you must remember - if you have back ported cab, you shouldn't put it near the wall - you'll lost huge amount of power by doing that.
The sound and efficiency of the back ported cab depends where you put it. You should leave least a 1,5 meter between back of the cab and the wall.
Click to expand...

With a rear-ported cab, you should position in it no closer than a port width from the rear wall - i.e. less than 3" or 75mm for most cabs.

The sound and efficiency of ALL cabs, whether ported or sealed, depends on where you put them. The only difference with rear ported cabs is your need about a hand's width of clearance at the back minimum. Nothing like 1.5m!!!

Alex
 
#6
I meant that you can put sealed and front ported cab just by the wall and the sound will be there.
1,5m might be a big exaggeration, I just wrote what I hear while playing.
I had few back ported cabs, and the 3'' or 75mm did not work with them.
I always tried to put them as far from the wall as I could and it always worked.
It never worked when I had to put them near the wall. Maybe it should, but never did.
 
#7
bassforce said:
I had few back ported cabs, and the 3'' or 75mm did not work with them.
I always tried to put them as far from the wall as I could and it always worked.
It never worked when I had to put them near the wall. Maybe it should, but never did.
Click to expand...

They'd have had the same problem if they were front-ported, obviously just an unfortunate cab alignment that resulted in too much boom with a rear-wall providing boundary reinforcement. Nothing to do with where the ports were located though. There is a tendancy for rear-ported cabs to be smaller than front-ported cabs, and it is this size issue that causes boom, not where the ports are. If you look at Acme cabs (which are extremely well designed) the B1 has a side port, the B2 two rear ports and the B4 one front port and two rear ports. Yet they all sound identical!

Alex
 
#9
bassforce said:
Now I see. So the problem was that they were lame not back ported.
Click to expand...
The usual reason for rear porting is that there's not enough room for them on the front. When there's not enough room for them on the front it often indicates a cab that's too small, and a cab that's too small will boom.

The reason why a well engineered cab would be sealed is that the drivers used in them require a sealed cab for best results, or that they won't work any better in a vented cab, so there's no point in making the cab more complicated. The response of sealed tends to be thinner in the low end, but that's not because it's a sealed cab per se, it's because that's what the driver is capable of. Ported cabs can have fatter low end, but not necessarily, depending on the drivers used and the cabinet tuning- see above. A good engineer can make a ported cab with exactly the same response as a sealed cab, and most drivers are designed to work best in ported cabs, so the main reason for the continued existence of sealed is consumer demand based upon preconceived notions of inherent tonal differences between sealed cabs versus ported.
 
#10
I picked up an Ampeg 810 classic about 2 months ago,I gotta say I liked it better than any cab I've ever played through. I could hear everything my amp put out, I could boost the mids without being nasaly,the top end was just right(no tweeters!). So I'm getting a custom 610 made voiced just like,or close to,the ampeg 810. Got nothing against ported cabs,you just gotta see what works best with your gear,and what your ears prefer.
 
#13
billfitzmaurice said:
...When there's not enough room for them on the front it often indicates a cab that's too small...
Click to expand...

Hi Bill,

Are you including Bag End cabs in this generalization? I realize that you qualified it with "often". I thought the BEs were supposed to be engineered well, and I see a trend toward rear porting with some Ashdown cabs and the Aguilar DB810 for instance. Is that just marketing in your opinion or in some cases does it work?

The original Goliaths were rear ported too, why do you think they switched to front porting?

-FF
 
#15
maxbass said:
I've been there too, and ended buying a Bergantino NV610.
The Perfect Cab
Click to expand...

Oh, I thought that was settled. Hands down the NV610, I ran this for a couple of years and it was the balls.

IMG_2666.gif
 
#16
My svt has always worked best through sealed cabs. I have tried numerous cabs with that head and it always seems too loose in the low end through a ported cab. My guess is that older design tube heads dont have as good dampening factors of modern heads and sealed cabs always make them sound tighter. I love my avatar 410 neo through just about any head except my ampeg, it really sucks with that combination, the speakers seemed to start jumping around to easily and i was afraid i was going to blow them and sounded muddy in the low end. On the other hand the avatar sounded just great with a solid state 800 watt power amp and pre amp and would go very loud. I'll stick to my sealed 810 for the ampeg.
 
#17
Ported cabinets are more efficient but give up low end response. Most ported enclosures are tuned at around 55Hz and roll off drastically below that frequency. Rear ports on all speakers are out of phase with the front of the cabinet and need to sit near a wall so the energy can bounce off of it and reflect in phase. Front ports are in phase because the negative energy of the speaker hits the back of the cabinet and reflects the energy through the front ports. Front ports offer a more controlled response and the cabinet tends to sound characteristically the same regardless of where you use it. Rear ports are harder to control and the placement variables make it harder to eq. You generally have to reset every time you use it in a different venue.

Sealed or Infinite Baffle enclosures have controlled, extended low end response. The air in the sealed enclosure acts like a buffer for the cone and controls the excursion range of the voice coil. They usually use long excursion speakers with a rubber surround on the cone to achieve the solid, fundamental low end frequency. Sealed enclosures are less efficient and need 2x's the power to push them to achieve the equal db level of a similar ported enclosure.

The GK Micro Series amps like the 150MB and the 200MB before that, and the Ampeg 810 are the most popular examples of sealed box amplifiers / enclosures

On the surface, the Mesa Scout enclosure looks like a sealed enclosure that uses a passive radiator to convert the negative energy of the speaker into usable audio. This is a hybrid because you get the low end of a sealed box but the efficiency of a ported enclosure. This concept has been used in home audio for years, good to see it finally trickle down to bass amps.
 
#18
To save me some typing, all the following quoted is wrong:

laklandplayer said:
Ported cabinets... ...give up low end response. Rear ports on all speakers are out of phase with the front of the cabinet and need to sit near a wall so the energy can bounce off of it and reflect in phase. Rear ports are harder to control and the placement variables make it harder to eq.

Sealed or Infinite Baffle enclosures... ....usually use long excursion speakers with a rubber surround on the cone to achieve the solid, fundamental low end frequency. Sealed enclosures are less efficient and need 2x's the power to push them to achieve the equal db level of a similar ported enclosure.

...the Mesa Scout enclosure... ...is a hybrid because you get the low end of a sealed box but the efficiency of a ported enclosure.
Click to expand...

Alex
 
#19
Thanks for the great feedback.

Sounds like design is a significant dictator of the low end response (well duh... :-) ). To some extent I was aware of concerns with walls and corners, but didn't realize how un-directional the ports were.

Wish I could play a few more of these cabs first, but looks like the NV610 is the general fav for the 400+.
 

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