Preference For Sealed Cabs? Why?

[DukeLeJeune]

I've found I can make lots of different cabs sound good at low levels and with less low end. It's when you're trying to get up over the drums and guitars where things can get nutty, not to mention so many crappy sounding rooms one might be faced with playing live. Try to add more lows in your amp, and the midrange can go to pot real quick. It's not a home installation where everything gets tuned to that particular space, then stays there. The goal, in my mind, is an attempt to lessen the variables one encounters playing different rooms every night with a tone that the player finds pleasing to them.

I don't pretend to know the answer, but I know bass guitar and upright for that matter, ask a lot from our cabs from the low end up.

I can't say for sure whether a ported box is better or worse than a sealed box in the midrange at high SPL. I can think of advantages both ways and don't know which would win out.

An open-back guitar cab, like the one you see in post number 158 a couple pages back, is a high-tuned ported box (tuning frequency perhaps in the 110-130 Hz ballpark) with the port on the back. Both open-back and sealed guitar cabs have a following, and of course there are tradeoffs between the two. My personal opinion is that, as long as the stage volume doesn't get too loud, open-back generally sounds better... but no doubt many guitarists would disagree (probably starting with my underlying assumption that there is ever such a thing as "too loud").

 

[Sundogue]

Light, loud and low. The holy grail of bass cabdom for many. Note that it does not say light and low only. Many bass players are wanting their cabs to handle the low end cleanly and still be able to carry it without throwing out one's back. But the biggest issue is that it also needs to handle high volume as well.

I've found I can make almost any cab (even some cheap, speaker-in-a-box POS) sound great with enough EQing and tone controls if played at low volume. But hey, once you get into rock band, high volume territory, all bets are off. That's where the proof in the design and build comes through. Ported or sealed, both can produce the goods...as well as the bad.

 

[morebass!]

"Preference For Sealed Cabs? Why?" I agree sealed cabs sound tight/,fast, have good dynamics - all that has been said. I really enjoy their tone and feel. However, its tough to get enough low end out of a sealed cab of reasonable size and weight to hang with a loud band. For example, I love the sound of Ampeg's sealed 410he but it's ~85 lbs and isn't loud enough on its own to play rock/blues without PA support. I found that I was better off in that situation with a ported 2x15, slightly bigger, slightly heavier but much more low end. Recently I've tried using Fdeck's HPFIII to duplicate the sealed tone/feel with my ported 1x10 and1x15 cabs and it gets maybe halfway there. Its still a nice compromise. If I find myself in a situation where I need more low end I can reduce the roll-off frequency of the HPFIII. I'd still prefer a nice sealed neo 2x12....if only someone made one. Not a lot of sealed cabs on the market these days so I'd guess that the sealed cab lovers are in the minority.

 

[dukeorock]

"Preference For Sealed Cabs? Why?" I agree sealed cabs sound tight/,fast, have good dynamics - all that has been said. I really enjoy their tone and feel. However, its tough to get enough low end out of a sealed cab of reasonable size and weight to hang with a loud band. For example, I love the sound of Ampeg's sealed 410he but it's ~85 lbs and isn't loud enough on its own to play rock/blues without PA support. I found that I was better off in that situation with a ported 2x15, slightly bigger, slightly heavier but much more low end. Recently I've tried using Fdeck's HPFIII to duplicate the sealed tone/feel with my ported 1x10 and1x15 cabs and it gets maybe halfway there. Its still a nice compromise. If I find myself in a situation where I need more low end I can reduce the roll-off frequency of the HPFIII. I'd still prefer a nice sealed neo 2x12....if only someone made one. Not a lot of sealed cabs on the market these days so I'd guess that the sealed cab lovers are in the minority.

I don't think there's any doubt that sealed cab lovers are in the minority. I think most people's point of reference is what they get to try at GC, or whatever. I don't imagine a lot of bass players think about it at all and that's fine too, if they're happy with their tone

 

[agedhorse]

A couple of thoughts here...

1. How might a ported cabinet affect the midrange? I can think I of a couple, the first being the low freq. excursion modulating the midrange (Doppler distortion) and the second being that the choice of driver optimized for LF ported cabinet use might not have the ideal properties for midrange reproduction. Darn tradeoffs. Of course, a proper high pass filter can eliminate the root cause of Doppler distortion which is why I have designed them into every product I have designed in the past 20 years.

2. Comments about the port leaking midrange have some validity but there is more leakage from the reflections off of the inside of the box and out through the paper cone. This is more of a problem with the lighter weight, thinner pulped cones.

3. There are some creative dsp (and analog) solutions that can be developed with both ported and sealed speakers to minimize respective problems and improve respective benefits.

 

[dukeorock]

A couple of thoughts here...

1. How might a ported cabinet affect the midrange? I can think I of a couple, the first being the low freq. excursion modulating the midrange (Doppler distortion) and the second being that the choice of driver optimized for LF ported cabinet use might not have the ideal properties for midrange reproduction. Darn tradeoffs. Of course, a proper high pass filter can eliminate the root cause of Doppler distortion which is why I have designed them into every product I have designed in the past 20 years.

2. Comments about the port leaking midrange have some validity but there is more leakage from the reflections off of the inside of the box and out through the paper cone. This is more of a problem with the lighter weight, thinner pulped cones.

3. There are some creative dsp (and analog) solutions that can be developed with both ported and sealed speakers to minimize respective problems and improve respective benefits.

Great post! Thanks!

 

[Arjank]

Something that hasn't been mentioned yet is impedance curves.

Ported cabs have 2 impedance spikes in the lower region where sealed has one.

Depending on that second spike, some ported cabs don't "get along well" with some tube amps.

That can easily be fixed with an LCR on the 2nd spike.
But, most cab designers don't know about these kind of trix...

 

[Arjank]

How might a ported cabinet affect the midrange?

In several ways.
One of them is a standing wave along the lenght of the port.
Some designs have ports that are long and take up quiet a portion of the total volume of the cab, these are the types of designs that are prone to standing waves inside the port. It even gets worse if you have a tall cab, a long port and when the port is placed on one end of the cab....

 

[Arjank]

Ported boxes can affect the mids in two ways. First, ports can act as open ended pipe resonators. These are excited by sound at or close to the resonant frequency from the main driver. The Q of these can be quite high. An impedance sweep will show a blip at the ports pipe resonant frequency. I designed and built a cab with a bad case of this. This can be prevented by crossing the woofer well below the pipe resonance. You can also use shorter ports, pushing their resonant frequency above the woofers passband..

+1

 

[Arjank]

I too like the low tuned, EBS-like alignments. Early on, after the initial 'wow, listen to that bass! ' reaction to near flat alignments (with the bass response rolloff knee only a few db below reference), I found that there was actually too much bass in-room, and that the quality of the bass was not as good as I had hoped. Using an low-tuned alignment that drops the knee 4-6 db below reference solves this and results in excellent bass quality. You do have to watch for a power handling 'sag' between Fb and the upper peak. There can be a lot of energy there and the driver behaves as though it were in a sealed box, above its resonant frequency. I prefer an alignment that loads the driver down to the lowest expected frequency (like low B, E, etc). The lowest expected frequency should fall within the impedance trough.

+1

 

[MJ_Sotti]

Ive had both. I'm a sealed guy...It sounds tighter

 

[smeet]

Fascinating discussion. I've never played through a sealed cabinet (that I know of, maybe some of my old cabs were). But some of the reasons I feel drawn to flat wound strings sounds kind of like what I'm hearing people say about sealed cabinets. I like the hard fast attack in the lows, and the fact that the lows don't seem to extend as low or last as long. And the notes don't have as much of a harmonic "halo" around them, so they sound more focused. But I miss the high end sometimes. I wonder if a sealed type cabinet might give me the sound I'm going for...

I'm finding that flats don't "boom" as much as rounds, even though they have a "bassy" sound. Is any of what I'm saying making sense???

 

[will33]

Fascinating discussion. I've never played through a sealed cabinet (that I know of, maybe some of my old cabs were). But some of the reasons I feel drawn to flat wound strings sounds kind of like what I'm hearing people say about sealed cabinets. I like the hard fast attack in the lows, and the fact that the lows don't seem to extend as low or last as long. And the notes don't have as much of a harmonic "halo" around them, so they sound more focused. But I miss the high end sometimes. I wonder if a sealed type cabinet might give me the sound I'm going for...

I'm finding that flats don't "boom" as much as rounds, even though they have a "bassy" sound. Is any of what I'm saying making sense???

Makes sense to me. Your flats are throwing a completely different relationship of harmonics before anything is even getting affected by any amps or speakers. Could use various different speakers to enhance that....or not.


I think it would be cool to have an 8-string bass, tuned like a regular 4-string with an octave double of each string, a bit like a 12-string guitar, the put flats on the low strings and roundwounds on the octave strings.

 

[Coolhandjjl]

That can easily be fixed with an LCR on the 2nd spike.
But, most cab designers don't know about these kind of trix...

Parallel notch filters, P-Traps, whatever you want to call them, are quite common in the Hi-Fi arena. Even more of a dark art than crossover design. But they are not a cure-all, they can cause a speaker to sound lifeless or veiled.

Oftentimes, it is the defects that make things sound real. In the Visual Arts, the effect is referred to as "The Uncanny Valley". The more real or prefect a thing is made to be, the more we respond to it uncomfortably. A cartoon is accepted and we feel comfortable watching it as we know it is not real, no attempt is made to make it look real. Not a real person. When CGI started to be used to make these 3D animated movies like Shrek, it looked a bit creepy because they tried to make it look real. But since we knew it was fake, it created a conundrum in our minds. Avatar was creepier yet because the "actors" looked even more real. But they weren't. Cadavers and zombies are at the nadir of the valley. Real? You bet. Creepy? Most certainly. The valley has not been crossed yet.

 

[FFTT]

A vintage SVT AlNico 8X10 with a great amp is really tough to beat.

I have played the SVT, Sunn 200s, Fender B-300 and Peavy Mark III and my current Reeves 225 through it.
So I know this cab.

The AMP makes all the difference in the world.

I ran a Univox UB-250 cab loaded with a 15" Altec Lansing White Frame bass driver as my lazy gig
-rehearsal cab. It got the job done.

The amp you use can dramatically change the results you get through any chosen cab.

 

[Sundogue]

I would add that almost anything in your signal chain is introducing variables into the equation to almost make this "sealed vs. ported" thing almost moot. From string choice, to the bass, to amps, effects, etc. that by the time it's coming out of the speakers, the cab they are loaded in may or may not be what sounds right for any given player.

Me? I'm really digging my ported cab, but honestly I have SO much going on before it even gets to the cab, that while it reminds me of a "tube amp into a sealed cab" tone, it most definitely is not either.

 

[Coolhandjjl]

Agreed, it really is an entire system from strings, to pups, to guitar, player, head, cab, and the room.

 

[FFTT]

I only have my ported OS 2X12 to go by, but it sounds way bigger and can totally hold its own against most any Marshall 4X12 with greenbacks.

But, I'm also running an EVM12L & Fane Medusa 150-C which are both high efficiency tight, cast frame drivers.
$500.00 worth of speakers.

 

[Fuzzbass]

the ingress of unwanted livestock into an unguarded port....

Stolen from Reiner Amplification's G+ page:

 

[FFTT]

Bottom ported behind the grill solves the critter issue.

I have to take apart my studio near field monitors and check them for stink bugs.
They hide in every place they can find.