When purchasing a bass cabinet, there are many factors to consider, such as speaker configuration, size, weight, power handling, portability, and of course, how it sounds. However, a somewhat overlooked component of a speaker enclosure’s overall sound is whether it is sealed or ported. Both cabinet formats have their own benefits and drawbacks, and this article will cover the basic differences and help you determine which one will be the optimal choice for your bass amp setup.
Sealed Bass Cabinets
Sealed bass cabinets are exactly what their name implies- the enclosure is sealed, making it so that no air can escape. This means that all the sound comes from the front of the speakers themselves. The trapped air inside the cabinet acts as a spring controlling the movement of the speaker resulting in a tighter, punchier, and more responsive and articulate sound. The low end of the speaker is rolled off slower, so it may sound a little more rolled off on the low end than a ported cabinet. Note this is determined by the box size and the speaker used, so sealed does not always mean less low end. Another over looked feature of this type of cabinet is that the internal air holds the speaker from over movement at very low frequencies like an internal limiter. If the cabinet is ported, very low frequencies below the port tuning will release the internal air’s hold on the speaker and it could damage the speaker at much lower wattage than the speaker’s handling wattage.
These cabinets are convenient in that they can be more compact and possibly lighter weight than ported cabinets. However, they may be less efficient at low frequencies, therefore they may require a more powerful amplifier, but because they are sealed they usually can take the extra power at lower frequencies. Another advantage is they usually always sound the same wherever they are placed in the room, unlike a rear ported cabinet that changes with its distance from the wall behind it.
This Carvin Audio BR210 is a sealed cabinet.
Ported Bass Cabinets
Ported cabinets, also known as bass reflex cabinets, have ports either in the front or rear. These are used to tune the enclosure to a certain low frequency based on the speaker being used.
More technically, a this type of cabinet design tunes the cabinet to a resonant frequency that works with the speaker to create more output at low frequencies up to the roll off point. This is done by sharpening the low end roll off which peaks up the low frequencies to this roll off point. The port puts out these lower frequencies like another speaker resonating in the cabinet. This lets more air movement and thus the speaker moves more at these low frequencies making the cabinet provide an extended bass response that the same sealed cabinet would not be able to produce at the same power level. As such, these cabinets can sound louder at low bass frequencies.
While big, rumbly bass may be awesome, the transient response of this low bass in this type of cabinet may not be as good as its sealed counterpart. Going back to the spring analogy, the spring in a sealed cabinet is always connected with a fast recoil due to the trapped internal air. In a ported cabinet the spring will release the speaker if the frequency goes below the port tuning due to the air escaping, because the speaker can’t pull it back. A poorly designed port with a “tubby” low end may provide an overwhelming amount of bass that is difficult to tame in certain rooms. In addition, ported enclosures may be larger than sealed enclosures due to the extra cabinet area needed to accommodate the port.
Note as stated a few times, if you go below the ported cabinet’s designed low frequency, the port will unload the speaker, meaning it will not control or hold the speaker any more, which can result in the speaker moving beyond its capability. This can result not only in no sound for a moment, but in damage to the speaker. In some instances of this you can actually hear the voice coil of the speaker hit the back of the magnet plate. This is certain to cause permanent damage.
The Carvin Audio BR115, a ported cabinet.
Choosing the Right Cabinet
The debate of sealed vs. ported is very common in the bass guitar world. The selected speaker enclosure type can have an effect on the type of bass response the speaker will have, but a well designed cabinet that is either sealed or ported for a specific purpose should not be as much of a difference as some may think. And with bass cabinets, a huge part of the overall tone comes from the interaction between the speaker cabinet and your surroundings. If you are making the decision between these two types, keep in mind these basic differences but also remember that no two ported or sealed cabinets will sound the same, and there may be enclosures that sound uncharacteristic- for example, you may find a ported cabinet that sounds punchier than a sealed cabinet! Also note that changing the speakers used may drastically change the sound capability of either type cabinet tuned to the original speakers. Be sure to try as many cabinets as you can while using your amplifier head.
Which cab type are you currently using in your setup? Let us know in the comments!
22 Responses
Al
Almost forgot! I’m running a 15", rear ported, 8ohm Bag End cab under my Carvin MB12.
For big stages I have a nice Trace Elliot 2×10H on an 1818(got a deal on them). They show 8ohms each to my Carvin B1200, so I’m not using anywhere close to the available power of the amp. Both cabs are tuned nicely(IMHO), and the B1200 really kicks for upright and electric Basses!
Al
Great column! I always knew you could screw up your woofers with a wrongly tuned cab, but didn’t know sealed or infinite baffle designs were not affecting drivers in the same way! I’m gonna buy a 21" woofer and mount it in a sealed enclosure to hear what it does! Also, does it matter if cabs are tuned on the SIDES? I know rear porting is effective, so why not the sides? Especially with a sprayed on coating instead of cloth or carpet. Seams like you could tune for an18", or 21" that way, and keep the cab size down while lightening the load!
Jim Colbert
Awesome info thanks…Love my MB215
Greg
I have an old Red Line RL210T. When it was used with an RL115 the system sounded great. By itself it farted if pushed. I changed out the 10" speakers to Delta Lite neo’s, with a higher X factor, it fixed the problem, the cabinet sounds good at any volume.
John R. Cook
BR210-4
br115-4
mike aschenbrenner saint francis, wisconsin
right now I am using a B2000 bass amp with one BRX10.4. I’m also using a Sans amp bass driver with a passive Dean bass guitar. I actually cannot believe the sound that’s coming out of that one cabinet. I’m amazed I still have a hard time believing it. But I hear it. being the B2000 goes down to 2 ohms , and the cab is 4 ohms I’m ordering another BRX10.4 cab. Never ever thought I would be writing a review but I have to because it’s that good.
Jim Elshaw
One of my rigs is a Carvin BX700 head with an Avatar B210 cabinet with two 10" neo speakers. It’s great for smaller venues – light weight, great sound, plenty of volume, lot of flexibility.
randy
my brx410 with the 1200 head gets complements all the time for the deep end sound!
Jeffrey Todd Esaias
I use the Carvin B2000 head on a Carvin BR410 sealed cab. My band says leave it that way and use no other set up. Sounds amazing!
Jeff from Iowa
Rich Owen
I’ve been using the BR210 cabinet for the last 10 years or so and it is, by far, the best sounding cabinet I’ve ever had (my first cabinet was the Ampeg V4B double folded horn bass reflex cabinet – I called it the refrigerator and bought it new in 1972). My only regret is that, when I bought it (BR210), it only came in 4 ohms so I can only use one with my amp. If I was buying it now I would get it in 8 ohms and have the option of using 2. I absolutely love it. The tone is fantastic from very low volumes to very high – AND, it’s compact and light (very important as you get older).
Bill Greene
I have been playing a Pro-Bass 500 thru your 2×10 (no horn) and a 1×15 I bought new from Carvin in 1992. I get lots of compliments on my overall sound.
Darryl
Still using my 1981 Carvin Bass Master amp. One, 15-Inch JBL cabinet, with a 125-Watt head.
It, and my 1981 Carvin LB50 Koa bass have never parted company.
James Schulz
I found this information interesting and useful. I’n not a bass play (yet) but I can see how this translates to other guitar/vocal scenarios. I do a solo act and I"m alwaus looking for a better way to optimize the sound when it’s just a guy with a guitar. It seems that a sealed cabinet for low end, paired with a good mid-range/horn/tweeter tower would give a richer, more complete sound. Can’t wait to try it.
Paul
All my cabinets are ported. Carvin 4×10, Epifani 2×12, Schroeder 1210PL Custom and a Gauss 15" driver in a custom cabinet. All sound different and have their own applications depending on the room, band, amp and bass.
Mario Sangermano
I’ve been using Carvin bass amps since 1992, and to this day use only Carvin bass amps. I’ve played through just about every brand of bass amp over the years, not as an owner but trying them out at music stores, having to use them when that was the only backline available. Carvin by far blows them away in uncolored tone, construction, abundance of EQ, and overall great bass reproduction. I currently use the BX1600 amp ( live and for sessions), what a great amp, don’t ever get rid of It!! and the BRX 4/10 ported cabinet, and the MB15 Micro bass amp. Another keeper. What a great sounding and powerful combo amp!!
Bob Comarow
I generally use a combination.
If I am playing a larger room, I have a 15" JBL in a custom made ported cabinet, basically an upgrade of the sub bass for a Peavy PA without the horn.
Then I run a sealed 2 10" cabinet with that.
The combination is better than the parts. It sounds incredible.
Otherwise, I use a SWR Working Man’s 12, which has a ported 12" speaker and a sealed twitter. It sounds great. I use this for both electric bass and upright bass, and have played probably a thousand gigs using it.
When I need a big sound, playing rock, country rock, this is my baby.
On rare occasions I have used my Working Man’s 12 with my
JBL 15" with it’s home made ported enclosure. I can play bigger auditoriums with bigger crowds.
I also use the SWR 12 as a stage amp, and then I go into the PA.
Mostly I play big band jazz.
Gilberto Molina
Excellent Information ! I do have both kinds ! Thanks Carvin !
Mike
I have a sealed 4×10 acoustic 400 watt 8 ohm cab and a ported 4×10 Mark Bass 800watt 4 ohm cab. I use the acoustic for practice and the Mark Bass at gigs.
I use my Little Mark 800 watt amp for both cabs.
Jack Adams
Currently I use 2 of your Neo BRX 210 cabs with the B1000. But if like to try the BR410..hmm..I play both 4 and 5 string basses.
Don Howell
It should be noted that for ported cabinets: Rear ports cause multiple problems at gigs. The bass out of the rear port(s) bounce off the wall behind you causing a low frequency bass rumble that irritates the band and sometimes the audience. Sometimes bands play backed up to a glass bar storefront, which is even worse. If you are going to buy a ported cabinet, go with front ported.
Also not mentioned is that there is quite a difference in sound with a round port(s) versus a shelf style port. And the most awesome port for a bass cabinet is a folded horn style, which now-a-days is considered too large if a cabinet…but it can produce the best response compared to other cabinet designs.
Guido
I’ve only had front ported cabs but the two times I’ve played through Ampeg 8×10s or their sealed 4×10s they sounded great.
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