# Vented boxes are not for SQ? Myth!



## Hanatsu

I have seen this too many times here now. Lets remove the myth that vented enclosures are worse than sealed and IB for SQ applications. 

I know this has been covered before, but I'd like to debunk all myths and discuss the pros and cons in detail in this thread.

Here are some common statements;

"Vented sound sloppy compared to..."

"Vented sounds boomy compared to..."

"Transient response is MUCH worse with vented..."

In this thread I want to break it down to the basics. Let's discuss WHY these issues are so common, what is required, what matters and what doesn't.

This gonna be an ongoing discussion, I'll post the first set of data later. I will begin with presenting the thesis that vented can subjectively sound extremely similar to sealed.


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## audison1

It very much is dependent on the driver. I have heard some that sound extremely sloppy and some that are tight .


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## Bayboy

Pure myth.


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## Hanatsu

All right.

Let's discuss vented enclosures.

Why is it common that people believe that vented boxes are "sloppier" or less "tight" than sealed enclosures in general?

-The main reason is simple, it's the frequency response. With a vented box you gain more output than with a sealed box. Together with the natural cabin gain you can get a FR that displays massive peaks. Since the transient response is tied to the frequency response, simply correcting the response will make a vented box sound very similar to the sealed counterpart. 

Group delay of a vented vs a sealed. With and without EQ to mimic the sealed enclosures FR;



Notice the vast improvement some EQ performed? The difference in group delay at such low frequencies can be ignored. It's not audible.

-The vented enclosure will inhibit much lower non-linear distortion due to less excursion. The simulation below is the excursion of a vented box vs a sealed;



At Fb (tuning frequency) the subwoofer moves about 1,5mm, the sealed however, requires 14mm for the exact same output. That's a great deal!

-Efficiency! With the same amount of power input, a vented enclosure will outperform a sealed enclosure with huge margins. 



At 30Hz the vented enclosure will require a little over 40W to produce a SPL of 105dB in this example (anechoic level). The same SPL can be reached by feeding the sealed enclosure about 260W at the same frequency. You need more than a 4 times as powerful amp to drive the sub at the same level in this example.


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## Bayboy

Application of EQ on a vented enclosure should be fundamental so I would say that point is a bit moot unless it is in the hands of someone unknowing. Even in that case they're far behind in being the least bit knowledgeable about car audio acoustics. I think for others, the argument of group delay becomes more of an over analytical issue. At some point you have to trust your ears rather than poring over specs/graphs too much.


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## Hanatsu

The audibility of group delay is a pretty well researched subject, I've read a tons of papers regarding this and come to the conclusion that for all intents and purposes can be almost completely ignored within the boundaries of car audio.

http://www.davidgriesinger.com/asa05.pdf

The simplest way to describe it is that the audibility of GD is dependent on how reverberant the room is. In the modal range a room can be described as VERY reverberant. The ratio of delay in a subwoofer will NEVER go beyond the lingering of constructive modal frequencies and are therefore masked. 

Here's another source debunking the audibility the phase distortion in real life scenarios;

Human Hearing - Phase Distortion Audibility Part 2 | Audioholics

Another thing I've researched is the phase ratio of the fundamental and harmonics and the audibility threshold of this. The lower lowpass you use, the less problem this will be as indicated from the group delay simulation in the former post. A steeper slope will also reduce the issue to a minimum. Overall, I've not found this to be audible with a variety of configurations in the car either.


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## Hanatsu

Bayboy said:


> Application of EQ on a vented enclosure should be fundamental so I would say that point is a bit moot unless it is in the hands of someone unknowing. Even in that case they're far behind in being the least bit knowledgeable about car audio acoustics.  I think for others, the argument of group delay becomes more of an over analytical issue. At some point you have to trust your ears rather than poring over specs/graphs too much.


To be able to analyze why something sound different you can't simply use your ears and just make an educated guess. You'd be surprised how many who have no clue that EQ is mandatory when using a vented enclosure in a SQ oriented setup, because the sealed box sounded good with the same settings...

I believe other than sheer enclosure size that vented enclosures are superior sealed in almost every aspect. I simply wanted to highlight this topic to those who share these common misconceptions regarding vented boxes.


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## Bayboy

Trusting your ears in what sounds good to you over what a group delay plot may read is a bit different than the reason why in which you speak. The simple truth you have already stated... it simply isn't that big of a deal in that manner. Anyone that makes an issue of such is simply being anal about specs without actually hearing if there is any audible difference which there are many within that category.


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## sqnut

I spent six months trying to get a ported box to sound like my sealed one and no amt of tuning , box size, port dimensions/types could get the kind of integration with the mid bass that I could get with the trusted 1.3 cube sealed. 

If you listen to some jazz or R&B, there is a lot happening in the 40-300 range. A lot of stand up bass, foot drums, bass lines etc. One way to get a seamless blend between the sub and the mids is to ensure that the transition between this range doesn't mess with the visuals of that instrument. A bass line from a foot drum or stand up bass should sound,feel and visualize like one instrument, even when it's playing frequencies that go back and forth in this range. That cohesion is what I couldn't achieve with music that is revealing. In a busier mix, or while driving one didn't notice it as much. 

I think it's much easier to integrate a sealed box with a 6.5" mid due to the sealed boxes smoother roll off. As long as you have mids that can pick up ~ 70hz (read most mids) integrating the sub with the mid comes down to using some eq on the mid, getting the timing right and choosing how steep a slope you want on the sub.

In a vented enclosure eq the peak needs some serious PEQ, it's tougher to do with a 1/3 oct GEQ. The roll off characteristics will be different making integration slightly tougher.


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## cajunner

I think the problem with vented boxes is that you can hear the back wave, through the port which colors the sound.

I know that chuffing noises are adding to the distortion at high levels, but I'm talking about the fact that there's a hole in a box with sound in it, so some will come through. Not even talking about port "resonant" noise, like pipe organ harmonics either...


even if it's attenuated 40 db it still will color the sound, and THD of the driver, all those harmonics that aren't part of the signal, will also come through the hole.

so you might try and pin the sound a vented box makes as "sloppy" or "less-defined" or "boomy" but what you are hearing isn't necessarily the group delay or the phase shift, but more the leakage of higher harmonics through the port along with the back wave's fundamentals.

It's not magic, you can't put a port in the box and only low bass comes out.


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## Hanatsu

Sqnut; Vented boxes are more advanced than sealed in several ways. Right out of the box a sealed box will always sound better due to the cabin gain boost, which often brings up the low end enough to measure quite flat. You talking about the 40-300 range, the sub would be -45dB (or so) down at 300Hz if you using a 4th order, 80Hz LP. As you already know, the most important aspect in integrating sub/mids is equal magnitude at the crossover point and also making sure that phase matches up pretty well as it has a direct effect on how well the mids/sub(s) sum around the crossover. Phase aligning vented boxes generally require about 2-10ms delay of the mids (and the rest of the system as well) more than a sealed. This due to higher group delay, the GD does have an effect on T/A - noticed this several times when viewing minimum phase plots of full system measurements. As you said, taming the response often require PEQ and some creative work with the crossovers. In every setup I've built, the vented boxes yielded better results in the end. It's a bit tricky to compare sealed vs vented as well as a sub made for sealed/IB won't be optimal in a vented box and vice versa. Subs that require enclosures larger than the VAS rarely sound good in vented boxes. QB3 alignments with Fb around 30-33Hz tend to sound best imo. With vented boxes you also want to avoid putting the crossover right at the upper impedance peak.

Cajunner; Non-linear distortion leaking through the vent is plausible. However, a sealed box will induce much higher amounts of distortion than a vented and would by this logic color the sound even more. Midrange leakage has been a hot topic among audiophiles for years and many manufacturers has even placed vents on the rear to reduce this issue. I've designed quite a few home audio speakers now and found that midrange leakage is a very minor issue. In most nearfield measurements I've done, it doesn't affect the FR more than 1dB or so (the deviation being high Q). The audibility of this should be quite low. It can be further reduced with adequate internal stuffing, absorbing some of the higher unwanted frequencies. Air turbulence can easily be cured with large vents. Vent air velocity shouldn't exceed 5% of the sound speed in an optimal configuration.


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## Alrojoca

Subscribed. :lurk:


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## cajunner

thought experiment:

a madman audiophile kidnaps 100 people.

and you and me.


he says, "I want to put an end to the vented vs. sealed argument." 

so he gives you complete access, total super control, maximum software on superfast computer, so you can develop a vented box with tweaked group delay, minimal phase shift, every trick in the book like bowtie vents or parabolic flare with the nifty golf ball dimple surface, whatever your little heart desires.

you see, you have to build a box that your life depends on.


because if I build a sealed box, and after 100 people go through the car and say my sealed box sounds more accurate, tighter, more palpable, whatever, I don't take the hemlock, you do.


but if your super developed highly linear vented box takes the prize, it's bye bye for me.


now, are you ready? Do you believe in vented being superior such that you can bet your life on it?

I'll have basic tools at my disposal, as will you. Nothing special, maybe a linkwitz transform circuit, maybe a little phase shift controller, but two things are fixed:

crossover is at 100 hz, 48 db/octave.

SPL during the test not to exceed 10 db over the 1W sensitivity, and the same sub is used on both boxes, a .36 Qts, 10" with standard 2" coil and 46 oz ferrite magnet and a sensitivity spec of 89 db @ 100 hz with 2.83V applied.

sounds like fun, russian roulette, audio style..


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## sqnut

cajunner said:


> crossover is at 100 hz, 48 db/octave.


I wouldn't like to hear either car. The better tuner wins.


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## cajunner

sqnut said:


> I wouldn't like to hear either car. The better tuner wins.


this is not about you.



and the better tuner doesn't necessarily have the ability to change the fundamental sound signature of a vented box vs. a sealed box, based on my stipulation that the only extra circuits allowed to manipulate the response would be a linkwitz transform, a 10 band parametric equalizer and a phase shift control.

all the wizardry in the software and the super fast computer, is just to design the box, and not to manipulate the signal afterward.


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## Hanatsu

Here's a measurement i did for a project. This is sealed enclosure FR.



Same sub outside of the car:



Here's one of a vented inside the car with applied EQ (close-up):



Doesn't look so bad right?

So let's skip the FR (includes phase), vent leakage/noise and harmonics for a second. Is there anything else that you guys think is different? Or "worse"?


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## sqnut

Hanatsu said:


> So let's skip the FR (includes phase), vent leakage/noise and harmonics for a second. Is there anything else that you guys think is different? Or "worse"?


Ok so let's start at the top, you have heard both. Does a vented box sound different to you vs a sealed box? Assume this is after you have matched the output in the pass band and tuned to integrate the sub with the rest of the sound. Do you hear a difference?


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## Hanatsu

sqnut said:


> Ok so let's start at the top, you have heard both. Does a vented box sound different to you vs a sealed box? Assume this is after you have matched the output in the pass band and tuned to integrate the sub with the rest of the sound. Do you hear a difference?


Yes I do


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## cajunner

yes, yes!

let's skip the stuff we think is responsible for the sound difference between vented and sealed and just go directly to the question, can you say that a vented box system is always undetectable compared to a sealed, and if not, then why? And if so, then which is the better sounding box?

Maybe if someone admitted that there can be a difference that no consumer-grade electronic whiz-bang circuitry can provide for the null, or make that difference no longer there, then we can move on to which box actually sounds better...


and when we realize that nobody is going to bet on their vented box to save their life, there must be something holding them back...




and whatever "that" is, it's why there is a myth.


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## sqnut

cajunner said:


> and the better tuner doesn't necessarily have the ability to change the fundamental sound signature of a vented box vs. a sealed box, based on my stipulation that the only extra circuits allowed to manipulate the response would be a linkwitz transform, a 10 band parametric equalizer and a phase shift control.
> 
> all the wizardry in the software and the super fast computer, is just to design the box, and not to manipulate the signal afterward.


Nah, more likely you're over thinking things as usual . The better tuner will win because everything else will be so much better that you may not notice the difference between the boxes. You can tell the 100 folks the competition is about how the subs sound, but in reality if one car is tuned much better, more people will choose that one.


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## cajunner

sqnut said:


> Nah, more likely you're over thinking things as usual . The better tuner will win because everything else will be so much better that you may not notice the difference between the boxes. You can tell the 100 folks the competition is about how the subs sound, but in reality if one car is tuned much better, more people will choose that one.


the reason I limited electronic signal manipulation is to mimic the circuits/hardware the average guy has at his disposal when installing a sub box.

so the "tuner" won't be advantaged on either side, vented or sealed.

You have basic signal manipulation available, the linkwitz transform will help the sealed box and the parametric equalizer will help the vented box, and the phase shifter will give both boxes as close to linear phase as possible so the vented box actually gets a pass here.

I overthink nothing!

actually, I make this thought experiment with the hope of people participating, with their opinions of whether or not they would take the challenge of being able to build a superior vented box, when you know the average guy can pull off a good-sounding sealed box.

this is how I split the peas, the vented box requires some heavy numbers crunching and some serious manipulation of that vent, so that it may take several actual builds before hitting the one that doesn't get shown up by the sealed guy's half-hour assembly example.


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## Hanatsu

I think vented generally sounds better. This due to much less non-linear distortion. If you have heard a Velodyne servo sub you know that non-linear distortion is audible, especially IMD which I believe is responsable for the "mud" in the lower regions present with many high excursion small subs in sealed boxes. Play a 20-30Hz note at moderate volume - these frequencies should be felt more than heard, yet normally we do hear quite much bass. This is non-linear distortion creating overtones not present in the signal.


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## cajunner

Hanatsu said:


> I think vented generally sounds better. This due to much less non-linear distortion. If you have heard a Velodyne servo sub you know that non-linear distortion is audible, especially IMD which I believe is responsable for the "mud" in the lower regions present with many high excursion small subs in sealed boxes. Play a 20-30Hz note at moderate volume - these frequencies should be felt more than heard, yet normally we do hear quite much bass. This is non-linear distortion creating overtones not present in the signal.



again, I think cabin gain is being scapegoated for distortion increases when using those "high excursion small subs" as most people seem to like more bass when it's available in the car, due to tire rumble making most bass notes indistinct unless they are able to "cut" through, like a guitarist in a band has to do to get somewhere...


and I think if you believe those long throw subs have extra IMD then maybe it's because the amount of bass people want is quality limited by the mechanism, as the longer the throw the less capable the motor is to control the cone.

I'm of the sealed box is cleaner, but I like the output of vented.


if we're talking sound quality competition and we limit output to 100 db then the sealed box isn't in long throw mode and isn't throwing out crazy distortion from ringing modes on small box parameters and isn't running the coil out of the gap on low notes.

so the advantage the vented gives in excursion control is negated by the phase shift/group delay smudge of the vent being a second source.


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## Hanatsu

I have measurements over a few cars in the 20-100Hz region. If we look at the time domain (RT60) or by observing decay times from a waterfall, there will be large amounts of ringing approaching 1000-1500ms. The sheer output of a vented box will "light up" these modal points in a higher degree if we don't limit low end output with EQ. Again a simple tuning issue. A linkwitz transform will increase non-linear distortion even higher if we were to use such a circuit together with a sealed box.


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## cajunner

Hanatsu said:


> I have measurements over a few cars in the 20-100Hz region. If we look at the time domain (RT60) or by observing decay times from a waterfall, there will be large amounts of ringing approaching 1000-1500ms. The sheer output of a vented box will "light up" these modal points in a higher degree if we don't limit low end output with EQ. Again a simple tuning issue. A linkwitz transform will increase non-linear distortion even higher if we were to use such a circuit together with a sealed box.


I guess I don't know enough about the linkwitz transform circuit.

I thought it offered an electronic way to increase the amount of low bass in a sealed system without any sonic penalty, other than whatever issues the driver might have in extreme output modes.

But since we are limiting the output in my thought experiment to 100 db, the linkwitz transform would not be forcing the driver or require massive power inputs as it might if we were testing the output limit of the sealed system in the car.

So, if I have not understood this part correctly I apologize, as I'm concerned mainly with whether or not, as your title suggests, sealed is better for SQ.

I describe SQ as being of a quality and not quantity metric, however if a linkwitz transform circuit is going to cause my linear sealed system to approach some sort of limit that makes non-linear distortion increase to a point where it impacts the quality part of the measure, then I will remove it as an electronic circuit from our thought experiment.

now we only have parametric equalization and a fixed crossover point, to go with that nifty phase shifter that will help both designs to some degree.


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## sqnut

cajunner said:


> even if it's attenuated 40 db it still will color the sound, and THD of the driver, all those harmonics that aren't part of the signal, will also come through the hole.


When we talk of the typical sub box made with ~ 1" mdf or similar, the sealed box will only start to trap harmonics above ~ 3.5khz. Below that the harmonics will leak out of the sealed box (wavelength too long to be contained by 1" thickness). Worrying about a 30th order distortion of a 50 hz fundamental _is over thinking_ the issue.


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## sqnut

Hanatsu said:


> Play a 20-30Hz note at moderate volume - these frequencies should be felt more than heard, yet normally we do hear quite much bass. This is non-linear distortion creating overtones not present in the signal.


Imho, play the 20-30 hz signal with the sub out of the car and you'll feel more than you hear. In the car the 20-30 that you hear is the harmonics exciting the cars body.


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## cajunner

sqnut said:


> When we talk of the typical sub box made with ~ 1" mdf or similar, the sealed box will only start to trap harmonics above ~ 3.5khz. Below that the harmonics will leak out of the sealed box (wavelength too long to be contained by 1" thickness). Worrying about a 30th order distortion of a 50 hz fundamental _is over thinking_ the issue.


would you agree that the sealed system's "spring" is immediate, and the vented system's "spring" is delayed in time by the force of the air moving in the vent being dependent on the velocity, and that the cone of a sealed system is more tightly controlled in regards to standing waves inside the box moving the cone directly?

and that a vented system not only has pipe resonances to deal with but sound will naturally travel through a light cone with low Qts parameters, in comparison to a heavy cone with high Qts.


and that the motor control must be higher on vented systems necessitating a larger motor structure and a higher cost of entry for a "real" vented spec driver, so that you can get too high in motor strength in comparison to the Fs which means your vented driver won't dig low and the port has to do all the work?

2 things:

in a car space is limited and a vented driver's characteristics involve a strong expensive motor and a larger more bulky box.

the vented driver will naturally have a low Qts specification due to it's low Xmax which takes advantage of the port's involvement, limiting excursion acoustically and requiring the amp to play through the resonance, which adds distortion from phase shift electrically and also creates group delay acoustically, which can magnify standing wave interaction and natural peaks and nulls from the resonating bomb that a car's acoustic blueprint consists of...

but don't let that stop ya.


how about we make the statement that you believe you can make 100 people believe your vented box sounds better than my sealed box?


maybe then we can move on to answer questions that regard values of how and why this can be true, before we agree that it is true.


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## cajunner

sqnut said:


> Imho, play the 20-30 hz signal with the sub out of the car and you'll feel more than you hear. In the car the 20-30 that you hear is the harmonics exciting the cars body.



I believe that you will hear 20-30 hz the same, if they are reaching your ears at the same decibel level.

In a car, you will hear a combination of the original note and the cabin gain's free addition, and also non-related frequencies coming from excitation of panels and reverberation from the metal monocoque, or balloon quality that the metal enclosure of the car's body/cabin represents.

The harmonics of 20-30 hz that you didn't hear outside the car, is not coming from the sub because if it were you'd have heard it.

That 20-30 hz region is comprised of fundamental notes, and cannot be harmonics, but the 40-60 hz tones that come from the sub, from all subs, can be harmonics.


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## sqnut

I'm not saying 20-30hz is harmonics. In a car when you play the 20-30hz you get a tactile feedback and an auditory feedback. What you're hearing in a large part are resonances from harmonics that the sub is producing when it plays the 20-30hz track.


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## Hanatsu

But I'm basing my experience on home audio subs as well. The resonances of the car's chassis are only a part of the audible distortion. Non-linear distortion induced by the driver itself is real and very audible. Why do we even care about high quality subs otherwise? The difference between a bad and good sub will largely depend on the non-linear distortion performance.


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## sqnut

Ok let's trace our steps back. Can we agree that any difference we hear is either in the time or response domain? Those are the only two ways that we hear a difference. Based on the evidence presented thus far we have only looked at response. What about timing?


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## Hanatsu

Let's differentiate things here.

_Magnitude deviations, phase deviations from signal = Linear distortion._

_Any changes to the waveform = Non-linear distortion._

Vented boxes does have higher linear distortion than sealed even EQed the same (phase distortion). Sealed boxes have higher non-linear distortion than vented, this is more or less facts.

We are basically arguing which of these distortion forms are more audible. I'm saying that non-linear distortion is more important below 200Hz than common phase deviations related to vented alignments. 

We also need to differentiate absolute phase and relative phase. Absolute phase is NOT audible, which means that we do not hear any phase distortion if we do not put it in relation to a second source (which we are doing when we using multiple drivers in a system). Relative phase affect both staging and the magnitude response when two sources reproduce sound in the same space. This is what we do when we time aligning our systems, changing the relative phase. This is very much audible. 

I'm saying that integrating a vented box is a simple tuning matter. The relative delay at the crossover is not problem to match if you using mids in IB/Sealed configuration, even the relative phase of the harmonics should be close to zero since group delay decreases the farther away you get from the vent gain region. An octave or so above Fb the phase distortion would be approximately the same as a sealed. Again, the audibility of GD is highly questionable, the non-linear distortion however, is not above a certain level.

Phase, Time and Distortion in Loudspeakers

http://www.zaphaudio.com/nonlinear.html

Here's some audio samples I made showing how much non-linear distortion is audible. These are pure tones and there's no masking effect present as there would if you're reproducing music. Still, even if it's more audible with pure tones, IT WILL be audible playing music as well, just at higher levels.

https://www.dropbox.com/s/eub6rv1g9ijmi2d/non-linear%20distortion.zip?dl=0


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## Hanatsu

sqnut said:


> Ok let's trace our steps back. Can we agree that any difference we hear is either in the *time or response domain?* Those are the only two ways that we hear a difference. Based on the evidence presented thus far we have only looked at response. What about timing?


No. That's just the frequency response. I'm saying that it is the deviation to the waveform (induced new frequencies) that's audible. It will not necessarily show up in a frequency response measurement unless it's really high.


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## Alrojoca

Is vented the same as ported? Just want to be clear if this could be ported vs sealed, vented has more vents or ports than single ported making it very hard make, vented are not popular, ported boxes are more common.

Most if not all SQ competitors use sealed boxes, not sure if that says anything, maybe easier to tune, most expensive subs sound better in sealed boxes or are designed for sealed boxes. This is a different topic. Again maybe ported is not vented maybe ported falls in the same category, please clarify it for me.


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## Hanatsu

Alrojoca said:


> Is vented the same as ported? Just want to be clear if this could be ported vs sealed, vented has more vents or ports than single ported making it very hard make, vented are not popular, ported boxes are more common.
> 
> Most if not all SQ competitors use sealed boxes, not sure if that says anything, maybe easier to tune, most expensive subs sound better in sealed boxes or are designed for sealed boxes. This is a different topic. Again maybe ported is not vented maybe ported falls in the same category, please clarify it for me.


Yes. Vented = ported. 

Your second point is a very big reason why I made this thread in the first place. Sealed boxes are easier to build, more tolerant to T/S parameter deviations and can basically play flat to DC and still not "unload" like a vented box would. They can also be made smaller. A great number of "SQ subs" have T/S parameters that fits sealed/IB better. 

Still, why is it that some of the best home audio speakers in the world uses vented enclosures? My favorite speakers 'B&W Nautilus 800-series' uses vented designs for example. I can assure you that noone would complain about the bass performance in those.

In my home audio system, both subs and mids use vented boxes. I've pushed non-linear distortion below 1% at 90dB 20-20kHz. There's basically zero what I call "tonal smearing" - the ability to detect small changes in pitch. I'm fairly certain that non-linear distortion is responsible limiting this. 

I made a post regarding this a while back;

http://www.diymobileaudio.com/forum/1984403-post1.html


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## Hanatsu

Continuing my rant... Here's measurements of a Scan-Speak 30W in a vented enclosure:

20Hz:



25Hz:



40Hz:



The 40Hz measurement is with the sub playing right through resonance (Fsc).

Getting such distortion numbers below 30Hz is impossible with a sealed enclosure. At equal levels the sealed would have 5-15% distortion.


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## hot9dog

This thread is good reading material!! Ive had both sealed and vented setups. All have had their own sound signature and their own unique EQ setup. My last setup was a sealed 15 and it was by far the best all around setup. My new system im building will have a PG ELITE 12 and im on the fence for sealed or vented. Now this needs to be said about my goals for the new build- it will not be a purist SQ build. I want a fun loud lively sound but still realistic sounding, hence why im on the fence. Keep this thread going..... its helping me out with my decisions-


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## BuickGN

Hanatsu said:


> I have seen this too many times here now. Lets remove the myth that vented enclosures are worse than sealed and IB for SQ applications.
> 
> I know this has been covered before, but I'd like to debunk all myths and discuss the pros and cons in detail in this thread.
> 
> Here are some common statements;
> 
> "Vented sound sloppy compared to..."
> 
> "Vented sounds boomy compared to..."
> 
> "Transient response is MUCH worse with vented..."
> 
> In this thread I want to break it down to the basics. Let's discuss WHY these issues are so common, what is required, what matters and what doesn't.
> 
> This gonna be an ongoing discussion, I'll post the first set of data later. I will begin with presenting the thesis that vented can subjectively sound extremely similar to sealed.


My personal opinion is ported is better than sealed in almost all cases *assuming the owner has and knows how to use EQ and builds the enclosure correctly. If I had a box in the trunk it would be ported. I think the reasons why have already been stated and for me, sealed would be last on my list of choices.

About IB, I think it helps bridge the gap a bit when done a certain way. Two large subs with lots of linear excursion reduces excursion and distortion just as ported does. Efficiency on the low end is considerably better than a similar sealed setup with a single 12" (probably the most common sealed setup) but maybe not as efficient as some ported setups. 

I wonder sometimes what would be better in a wider bandwidth sub setup, say one that plays up to 100-120hz. Would a single 12" ported or a pair of 15s IB play with less distortion and higher efficiency? I've modeled different pairs of 15s IB against single 12s and 15s ported and generally it seems as if IB has the advantage a lot of times if you look at average SPL over the entire bandwidth, not just the peak near tuning.

Obviously you can always argue that a pair of ported 15s will significantly kill a similar IB setup which is true. I think for most of us a pair of 15s in a ported or even sealed box is not doable but it's very doable when IB and that's the only reason I compare such an "unfair" single 12" vs dual 15" setup. 

But yeah, I think ported is far superior to sealed in almost every possible way and on a level playing field with similar displacement it's superior to IB. I hate that user or tuning errors are blamed on the type of box. Instead of trying to fix the problem such as tuning to a lower frequency, using a larger box, or some EQ, the owner chalks it up to the ported stereotypes and progress stops. To be honest and risking getting killed on here, I think some of the most realistic sub setups I've heard were ported.


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## BuickGN

Hanatsu said:


> Continuing my rant... Here's measurements of a Scan-Speak 30W in a vented enclosure:
> 
> 20Hz:
> 
> 
> 
> 25Hz:
> 
> 
> 
> 40Hz:
> 
> 
> 
> The 40Hz measurement is with the sub playing right through resonance (Fsc).
> 
> Getting such distortion numbers below 30Hz is impossible with a sealed enclosure. At equal levels the sealed would have 5-15% distortion.


Is it possible the increasing distortion by 40hz would be lower in a large dual sub IB setup, assuming all else being equal?


----------



## Hanatsu

BuickGN said:


> About IB, I think it helps bridge the gap a bit when done a certain way. Two large subs with lots of linear excursion reduces excursion and distortion just as ported does.
> 
> I wonder sometimes what would be better in a wider bandwidth sub setup, say one that plays up to 100-120hz. Would a single 12" ported or a pair of 15s IB play with less distortion and higher efficiency? I've modeled different pairs of 15s IB against single 12s and 15s ported and generally it seems as if IB has the advantage a lot of times if you look at average SPL over the entire bandwidth, not just the peak near tuning.
> 
> Obviously you can always argue that a pair of ported 15s will significantly kill a similar IB setup which is true. I think for most of us a pair of 15s in a ported or even sealed box is not doable but it's very doable when IB and that's the only reason I compare such an "unfair" single 12" vs dual 15" setup.
> 
> But yeah, I think ported is far superior to sealed in almost every possible way and on a level playing field with similar displacement it's superior to IB. I hate that user or tuning errors are blamed on the type of box. Instead of trying to fix the problem such as tuning to a lower frequency, using a larger box, or some EQ, the owner chalks it up to the ported stereotypes and progress stops. To be honest and risking getting killed on here, I think some of the most realistic sub setups I've heard were ported.


IB is in many cases superior to sealed. It is most often a lower distortion configuration, large surface area to counteract high excursion will improve non-linear distortion for sure. Vented is however always more efficient than IB at and above Fb (except at Fsc perhaps). In the lower octave the efficiency gain can be as high as three to five times that of a sealed box. It does of course matter where the sub's -f3 lies. Many sealed enclosures got a -f3 of 50-60Hz and these might yield a flat response combined with the cabin gain. A vented box EQed to the same response can be lots more efficient, in my example below, 10.5dB more efficient around Fb. IB is generally the most inefficient configuration higher up around midbass frequencies, the reason is that Fsc (resonance) ends up lower in frequency than a sealed enclosure.


----------



## Hanatsu

BuickGN said:


> Is it possible the increasing distortion by 40hz would be lower in a large dual sub IB setup, assuming all else being equal?


Yes, dual subs would lower the distortion by 6dB approximately. Not only in IB. The 40Hz distortion peak would probably end up somewhere else in IB. It's related to the resonance (Fs) in IB.


----------



## BuickGN

Hanatsu said:


> IB is in many cases superior to sealed. It is most often a lower distortion configuration, large surface area to counteract high excursion will improve non-linear distortion for sure. Vented is however always more efficient than IB at and above Fb (except at Fsc perhaps). In the lower octave the efficiency gain can be as high as three to five times that of a sealed box. It does of course matter where the sub's -f3 lies. Many sealed enclosures got a -f3 of 50-60Hz and these might yield a flat response combined with the cabin gain. A vented box EQed to the same response can be lots more efficient, in my example below, 10.5dB more efficient around Fb. IB is generally the most inefficient configuration higher up around midbass frequencies, the reason is that Fsc (resonance) ends up lower in frequency than a sealed enclosure.


I don't mean to turn this into a vented vs IB thread so let me know if I'm going too off topic and I'll stop. I'm on my phone so multi quoting would take forever, or else I would do it for the sake of clarity. 

When you say vented will always be more efficient than IB, you're talking same size/type/number of subs (a level playing field) in each setup, not a pair of 15s vs a single 12, right?

I guess my main question or concern is what happens to the single vented 12" sub that has equal output at tuning to the pair of 15s IB as frequencies rise? With all else being equal wouldn't the pair of 15s begin to dominate in SPL and even distortion the farther you get from tuning?

I might have to go back and relearn everything but I've always thought at some point above tuning the efficiency of the vented setup is going to go down to that of a similar sealed/IB setup? Does the port still reinforce the output at say 80hz when it's tuned to 28hz?

I guess that's my main question that's kind of on topic. Vented gives you the edge in efficiency and distortion where it matters the most (well efficiency anyway) but the higher displacement setups will eventually overtake the vented setup in efficiency and distortion as frequency rises, right?

So can't a sealed and especially an IB setup that's more prone to have massive displacement compete with vented near tuning in output and distortion and have more average output over wider bandwidth? To clarify I'm talking about a single 12 vented vs a pair of 15s IB. Like I said, I would go vented over IB if I was willing to give up the trunk space. 

I apologize if this is all over the place, I contributed a few lines at s time spread out over several hours so I probably repeated myself a lot.


----------



## Hanatsu

I meant with the same driver size/amount of drivers. Two IB subs will most likely be more efficient than a single 12 vented (kinda generic answer but anyway)...


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## sqnut

Hanatsu said:


> Continuing my rant... Here's measurements of a Scan-Speak 30W in a vented enclosure:
> 
> 20Hz:
> 
> 
> 
> 25Hz:
> 
> 
> 
> 40Hz:
> 
> 
> 
> The 40Hz measurement is with the sub playing right through resonance (Fsc).
> 
> Getting such distortion numbers below 30Hz is impossible with a sealed enclosure. At equal levels the sealed would have 5-15% distortion.


Do you have plots like this for a sealed box? I'm thinking about something and just need to see if it verified by similar plots on a sealed box.


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## Hanatsu

Yes... I'll see if I can find them. I have like 3000 pics in my car audio folder lol.


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## sqnut

Hanatsu said:


> Yes... I'll see if I can find them. I have like 3000 pics in my car audio folder lol.


----------



## 14642

Vented can be SOOOOOOOOOOOOOOO much better than sealed. 

First, the excursion of the woofer over its entire operating range (above Fb) can be reduced and DRAMATICALLY reduced at Fb. Less excursion means less distortion. 

Second, If you have singe band of EQ, you can design the box to minimize the excursion over the widest range of frequencies possible and then use the EQ to shape the response. This often requires a low tuning frequency and a boost near Fb. Boosting near Fb is fine because excursion is at a minimum. Impedance is also at a minimum at Fb, so more power is available from the amp at that frequency than is available above and below that.

Finally, once you've developed the box and the response you want, putting it in the car will result in a MASSIVE peak. Removing that peak with EQ further eliminates excursion, reduces the power required and leaves plenty of additional room for reproducing transients. 

The benefit of a sealed box is that you can just throw one together and toss in in the trunk and it'll sound damn close to any other sealed box that you might put together for that woofer.


----------



## Hanatsu

sqnut said:


> Do you have plots like this for a sealed box? I'm thinking about something and just need to see if it verified by similar plots on a sealed box.


I messed up the measurements kind of... this one is somewhat correct though (don't mind the fundamental level difference, SPL inside REW wasn't calibrated):

25Hz with the vent plugged;



HD2 went up from 1,8% to 8.79%
HD3 from 0,48% to 5,62%

Taller HD products wasn't affected much apparently.


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## Hanatsu

Andy Wehmeyer said:


> Vented can be SOOOOOOOOOOOOOOO much better than sealed.
> 
> First, the excursion of the woofer over its entire operating range (above Fb) can be reduced and DRAMATICALLY reduced at Fb. Less excursion means less distortion.
> 
> Second, If you have singe band of EQ, you can design the box to minimize the excursion over the widest range of frequencies possible and then use the EQ to shape the response. This often requires a low tuning frequency and a boost near Fb. Boosting near Fb is fine because excursion is at a minimum. Impedance is also at a minimum at Fb, so more power is available from the amp at that frequency than is available above and below that.
> 
> Finally, once you've developed the box and the response you want, putting it in the car will result in a MASSIVE peak. Removing that peak with EQ further eliminates excursion, reduces the power required and leaves plenty of additional room for reproducing transients.
> 
> The benefit of a sealed box is that you can just throw one together and toss in in the trunk and it'll sound damn close to any other sealed box that you might put together for that woofer.


Nice post! Agree fully with this. A properly designed vented box will outperform a sealed in almost every way.


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## 82cj8

What type of "eq" are we talking here.dsp or basic radio bass adjustment which is what most people have?What would be a good entry level eq for controlling the peak of a vented enclosure?


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## Hanatsu

The parametric EQs many new Alpine HU's got (for example) would probably be adequate. A proper DSP is of course preferable. 

Sent from my Samsung Galaxy S5 using Tapatalk


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## subwoofery

Hanatsu said:


> Sqnut; Vented boxes are more advanced than sealed in several ways. Right out of the box a sealed box will always sound better due to the cabin gain boost, which often brings up the low end enough to measure quite flat. You talking about the 40-300 range, the sub would be -45dB (or so) down at 300Hz if you using a 4th order, 80Hz LP. As you already know, the most important aspect in integrating sub/mids is equal magnitude at the crossover point and also making sure that phase matches up pretty well as it has a direct effect on how well the mids/sub(s) sum around the crossover. Phase aligning vented boxes generally require about 2-10ms delay of the mids (and the rest of the system as well) more than a sealed. This due to higher group delay, the GD does have an effect on T/A - noticed this several times when viewing minimum phase plots of full system measurements. As you said, taming the response often require PEQ and some creative work with the crossovers. In every setup I've built, the vented boxes yielded better results in the end. It's a bit tricky to compare sealed vs vented as well as a sub made for sealed/IB won't be optimal in a vented box and vice versa. Subs that require enclosures larger than the VAS rarely sound good in vented boxes. QB3 alignments with Fb around 30-33Hz tend to sound best imo. *With vented boxes you also want to avoid putting the crossover right at the upper impedance peak.*
> 
> Cajunner; Non-linear distortion leaking through the vent is plausible. However, a sealed box will induce much higher amounts of distortion than a vented and would by this logic color the sound even more. Midrange leakage has been a hot topic among audiophiles for years and many manufacturers has even placed vents on the rear to reduce this issue. I've designed quite a few home audio speakers now and found that midrange leakage is a very minor issue. In most nearfield measurements I've done, it doesn't affect the FR more than 1dB or so (the deviation being high Q). The audibility of this should be quite low. It can be further reduced with adequate internal stuffing, absorbing some of the higher unwanted frequencies. Air turbulence can easily be cured with large vents. Vent air velocity shouldn't exceed 5% of the sound speed in an optimal configuration.


I'd like more info on what you said above. Why is that? 

Kelvin


----------



## sqnut

Hanatsu said:


> I messed up the measurements kind of... this one is somewhat correct though (don't mind the fundamental level difference, SPL inside REW wasn't calibrated):
> 
> 25Hz with the vent plugged;
> 
> 
> 
> HD2 went up from 1,8% to 8.79%
> HD3 from 0,48% to 5,62%
> 
> Taller HD products wasn't affected much apparently.


So what if we were to say that the higher distortion in lower orders makes the sound 'warmer'......... We actually prefer higher distortion in the lower frequencies. Distortion at taller orders (where we are beginning to get more sensitive to distortion) are actually lower on the sealed sub. Win win Although I'm not sure if we can hear a difference between 0.4% and 0.04% at 200hz....


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## Hanatsu

subwoofery said:


> I'd like more info on what you said above. Why is that?
> 
> Kelvin


I probably should rephrase that line, I should have said 'avoid crossovers above the 2nd peak'. It's something I've noticed several times when designing systems, especially when using less than optimal drivers with higher Qts. Seen significant distortion rise around the second resonance peak with lots of woofers. Crossing below that peak will keep distortion at a minimum. While designing an enclosure you need to take notice of the region where vent gain is prominent, like Andy said - you want a low Q boost from the vent, that will push the second impedance peak higher in frequency. Otherwise you might be limited to crossovers in the 40-50Hz region if you want to pursue this. Another minor reason would be that amplifier will be facing very reactive load impedances around the peak. A combination of low impedance loads with steep impedance phase angles can be hard on amplifiers in general.


----------



## Hanatsu

sqnut said:


> So what if we were to say that the higher distortion in lower orders makes the sound 'warmer'......... We actually prefer higher distortion in the lower frequencies. Distortion at taller orders (where we are beginning to get more sensitive to distortion) are actually lower on the sealed sub. Win win Although I'm not sure if we can hear a difference between 0.4% and 0.04% at 200hz....


Stop preferring distorted sound then 

The audibility of non-linear distortion in the lows is not at all low imo. If you think logically about it, it should be the most audible range (where distortion is induced). The fundamental tone lies in a area where our ears in insensitive, but the distortion overtones propagates higher in frequency where our ears are more sensitive, therefore the distortion is more audible in the bottom octave. It also screws up up front bass imaging slightly at higher levels as distortion will end up all the way into the lower midrange. 

Take a listen at a Velodyne servo sub. That's how lows are supposed to sound, we are just so used to high distortion in the lows. Tailed together with harmonic distortion comes IMD which can be even more audible as products might end up at "odd" frequencies where there's basically zero masking in songs for example (IMD ain't masked by natural harmonics present in the music).


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## Hanatsu

Here's an example how much crap that a speaker puts out when we take a look at a spectrum plot with a 2-tone input! These products are low in level but imagine 10% distortion (which isn't uncommon with subs). 10% is only -20dB from fundamental, I guarantee you all, it's very audible.

Edit: I find it very funny that people keep discussing sonic signatures in source units, amps, DACs and crap but don't care about/don't find it audible with several percent of distortion induced in the speakers/subs.


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## sqnut

Hanatsu said:


> Stop preferring distorted sound then


I'm a cranky, stubborn, old dude who prefers sealed boxes



Hanatsu said:


> The audibility of non-linear distortion in the lows is not at all low imo. If you think logically about it, it should be the most audible range (where distortion is induced). The fundamental tone lies in a area where our ears in insensitive, but the distortion overtones propagates higher in frequency where our ears are more sensitive, therefore the distortion is more audible in the bottom octave. It also screws up up front bass imaging slightly at higher levels as distortion will end up all the way into the lower midrange.


Which is why the lower distortion on taller orders from a sealed box will be preferred imo.



Hanatsu said:


> Take a listen at a Velodyne servo sub. That's how lows are supposed to sound, we are just so used to high distortion in the lows. Tailed together with harmonic distortion comes IMD which can be even more audible as products might end up at "odd" frequencies where there's basically zero masking in songs for example (IMD ain't masked by natural harmonics present in the music).


Depends on where the IMD occurs. In the lower octaves we are less sensitive to changes in both amplitude and pitch. I'm not sure we can tell the difference between linear and non linear distortion below ~ 200, open to correction.


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## sqnut

Hanatsu said:


> Edit: I find it very funny that people keep discussing sonic signatures in source units, amps, DACs and crap but don't care about/don't find it audible with several percent of distortion induced in the speakers/subs.


^^^this!!


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## Hanatsu

sqnut said:


> I'm a cranky, stubborn, old dude who prefers sealed boxes


Funny thing is that I am using sealed in main build myself at the moment lol ^.^



sqnut said:


> Which is why the lower distortion on taller orders from a sealed box will be preferred imo.


But it doesn't have lower tall order distortion. It's higher... generally.

My second measurement can be taken with a grain of salt if you referring to that one. It's only level matched towards the old measurements between ~20-27Hz.



sqnut said:


> Depends on where the IMD occurs. In the lower octaves we are less sensitive to changes in both amplitude and pitch. I'm not sure we can tell the difference between linear and non linear distortion below ~ 200, open to correction.


I will try to provide a test proving that it is 

Linear distortion can be magnitude and phase distortions. Severe frequency response deviations will be unmistakable for linear distortion. Non-linear distortion you don't notice (if not severe) until you suddenly remove it. The best way I can describe it is that a very clean speaker/sub sound "dryer", as in playing a speaker in a highly absorbent room or something in those lines.


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## sqnut

Hanatsu said:


> Funny thing is that I am using sealed in main build myself at the moment lol ^.^


Lol so you started this thread cause you felt guilty about secretly liking a sealed box




Hanatsu said:


> Linear distortion can be magnitude and phase distortions. Severe frequency response deviations will be unmistakable for linear distortion. Non-linear distortion you don't notice (if not severe) until you suddenly remove it. The best way I can describe it is that a very clean speaker/sub sound "dryer", as in playing a speaker in a highly absorbent room or something in those lines.


Two words I can relate to and understand. Drier and cleaner sound. Dry vs wet / lush sound is mostly due to low end yes, but cleaner is more mid range and HF....but I get what you're saying.


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## subwoofery

Hanatsu said:


> I probably should rephrase that line, I should have said 'avoid crossovers above the 2nd peak'. It's something I've noticed several times when designing systems, especially when using less than optimal drivers with higher Qts. Seen significant distortion rise around the second resonance peak with lots of woofers. Crossing below that peak will keep distortion at a minimum. While designing an enclosure you need to take notice of the region where vent gain is prominent, like Andy said - you want a low Q boost from the vent, that will push the second impedance peak higher in frequency. Otherwise you might be limited to crossovers in the 40-50Hz region if you want to pursue this. Another minor reason would be that amplifier will be facing very reactive load impedances around the peak. A combination of low impedance loads with steep impedance phase angles can be hard on amplifiers in general.


Wonder why that is? I know that using a too big of a port lowers the 1st port resonant frequency. Same thing happens when you install a sub in a vented enclosure too big for it. 

Kelvin


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## Rs roms

Hanatsu said:


> I probably should rephrase that line, I should have said 'avoid crossovers above the 2nd peak'. It's something I've noticed several times when designing systems, especially when using less than optimal drivers with higher Qts. Seen significant distortion rise around the second resonance peak with lots of woofers. Crossing below that peak will keep distortion at a minimum. *While designing an enclosure you need to take notice of the region where vent gain is prominent, like Andy said - you want a low Q boost from the vent, that will push the second impedance peak higher in frequency.* Otherwise you might be limited to crossovers in the 40-50Hz region if you want to pursue this. Another minor reason would be that amplifier will be facing very reactive load impedances around the peak. A combination of low impedance loads with steep impedance phase angles can be hard on amplifiers in general.


And what is the effective way of doing that, i mean use a low qts sub or what to change in design ?


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## Hanatsu

Low Qt driver combined with a small enclosure with Fb in the low 30's. QB3 alignments are usually a good starting point if the driver "allow" for it.

Sent from my Samsung Galaxy S5 using Tapatalk


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## Rs roms

Hanatsu said:


> Low Qt driver combined with a small enclosure with Fb in the low 30's. QB3 alignments are usually a good starting point if the driver "allow" for it.
> 
> Sent from my Samsung Galaxy S5 using Tapatalk


Sorry for being off topic, how would you do a vented P1224 with qts 0f 0.54 and 14mm of xmax. After modeling, i tuned it just below its fs to get the peak out of FR and some eq to flaten it up. i am sure it can do better because the problem i see is that its second impedance peak is around 42hz. And according to as you described earlier, crossover should be kept below that peak to keep the distortion out of equation. I might be way off here, but still i would love to know that how you will do it with this particular sub.


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## Hanatsu

Have to model it later but Qt of 0.5+ isn't optimal with vented. Sometimes you need to tune below Fs when enclosure volume is above VAS. I'm on my phone atm... I'll check later 

Sent from my Samsung Galaxy S5 using Tapatalk


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## Rs roms

Hanatsu said:


> Have to model it later but Qt of 0.5+ isn't optimal with vented. Sometimes you need to tune below Fs when enclosure volume is above VAS. I'm on my phone atm... I'll check later
> 
> Sent from my Samsung Galaxy S5 using Tapatalk


VAS was 1.93 cuft, i ended up with 2.3 cuft @26 hz, would love to see your take on this one.


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## Hanatsu

Rs roms said:


> VAS was 1.93 cuft, i ended up with 2.3 cuft @26 hz, would love to see your take on this one.


The best I could get it was 1,7cu ft / Fb 35Hz. Need to EQ it, bring down the peak by 10dB or so.

This driver is better suited for sealed or IB imo.


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## rimshot

I have been enjoying my first ported box in car EVER, but must say, does nobody care about the extreme low frequencies lost below tuning frequencies in a ported box? My box is tuned to 33hz, and after careful adjustments, and trial with the subsonic filter, its was set at 30hz. The frequency response is mostly flat until 28hz (besides the huge peak that has to be tamed at 40hz). I can notice the absolute low end is missing in much of my music, its like the timbre is different if you know what I mean.

Has anybody else experienced this? The output, on the other end, is insane, for a single 10 sub (in about 1.35 ft^3 with an aeroport).


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## Hoptologist

You could always tune lower 

Also depends on the subwoofer. I temporarily swapped my 2 12's sealed for 1 GZNW 12 ported tuned to 36hz, and with leaving all amp and DSP settings the same, it plays 20-30hz louder than my 2 sealed 12's did.


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## 14642

Interesting discussion. 

The impedance peak or peaks are indications of resonance. In a sealed box, there's one, which is essentially the same peak as the speaker by itself, modified by the stiffer suspension resulting from the combination of the speaker's suspension and the stiffness of the air in the box. The impedance peak is ACTUALLY, EMF created by the motor. That EMF causes current to flow in opposition to the flow of current from the amplifier. We don't display it as EMF, we display the effect of that current flow as impedance.

In a vented box at Fb, the speaker doesn't move and doesn't create EMF. Above and below Fb (where the port plays and the speaker doesn't) there are two peaks. These peaks are LOWER IN AMPLITUDE than the original peak if the box is sealed. Essentially, the big peak is split in two by the non-movement of the cone at Fb. Fb is the impedance minimum between the two peaks--obviously, since the coil isn't moving much--the Z is very close to the Revc of the coil.

If you were to measure the distortion of the output of the box a little differently, you'd see that the distortion in a vented box from the WOOFER is much lower, but it can be MUCH higher from the port. If you placed the port on the back of the box and the woofer on the front and placed the woofer in an infinite baffle (2-pi), you'd see lower distortion from the woofer. Then, if you turned the box around, you MIGHT measure lots of distortion from the port and it would be mostly EVEN order because the distortion at the outside mouth of the port is more audible than distortion from the mouth INSIDE the box. Symmetrical conditions contribute odd order distortion and the distortion inside the box as the air moves back and forth is somewhat contained INSIDE the box.

What's the fix for that? A MUCH bigger port or giant flares on the ends.


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## 14642

A sealed bandpass box can virtually eliminate distortion created in the woofer, since the port is a low pass filter. If you're going to design one of those (or a bandpass box where both sides include ports), it's important to design the PORTS for low distortion.


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## Hanatsu

Thanks for the input, Andy. Interesting indeed. I've not tested many bandpass enclosures yet. I'd like to experiment with 6th order (dual chamber vented BP), they tend to be hard to get right - tried to build a few in the past but without much success. I didn't have access to proper DSPs back then so it might have been a contributing factor.

Sent from my Samsung Galaxy S5 using Tapatalk


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## FG79

sqnut said:


> I spent six months trying to get a ported box to sound like my sealed one and no amt of tuning , box size, port dimensions/types could get the kind of integration with the mid bass that I could get with the trusted 1.3 cube sealed.
> 
> If you listen to some jazz or R&B, there is a lot happening in the 40-300 range. A lot of stand up bass, foot drums, bass lines etc. One way to get a seamless blend between the sub and the mids is to ensure that the transition between this range doesn't mess with the visuals of that instrument. A bass line from a foot drum or stand up bass should sound,feel and visualize like one instrument, even when it's playing frequencies that go back and forth in this range. That cohesion is what I couldn't achieve with music that is revealing. In a busier mix, or while driving one didn't notice it as much.
> 
> I think it's much easier to integrate a sealed box with a 6.5" mid due to the sealed boxes smoother roll off. As long as you have mids that can pick up ~ 70hz (read most mids) integrating the sub with the mid comes down to using some eq on the mid, getting the timing right and choosing how steep a slope you want on the sub.
> 
> In a vented enclosure eq the peak needs some serious PEQ, it's tougher to do with a 1/3 oct GEQ. The roll off characteristics will be different making integration slightly tougher.


I have yet to do a vented enclosure in a car, but I figure that the integration with the midbass is what the challenging part is all about here like sqnut mentions.

In a home system you rarely ever need to worry about too much subbass/midbass, so the vented alignment is welcome and preferred in many cases just to get the proper response. 

Car is quite different. Sealed is much more plug and play......volume versus volume plus tuning frequency is significant.

As far as the ported in a car, I've been told it can definitely work. But most people are going with an enclosure volume that is often too small to yield proper SQ. A proper enclosure is usually a bit larger than most people want to deal with -- forget what T/S specs say, it's not the end all be all, because if it was we wouldn't be having this discussion.

I like quoting JL Audio for I believe was their 10W2 woofer -- 2.5 - 3.0 cubic foot per driver, vented. That's about as big or bigger than most guys put 15s in (don't get started on what a properly sized ported 15 should be). A 10" shouldn't be ported at 1 -1.5 cubic foot....too small. 

It also begs the question of whether it even makes sense to go ported except for the coolness factor. It's easier and cheaper to go multiple drivers.

Unless of course you have to have some ridiculous bottom end extension. But by achieving that monstrous bottom end you take away from midbass. 

The audio geek in me wants to go ported, but the pragmatist says I shouldn't.


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## Bayboy

Those findings haven't been my experience and I listen to Jazz, R&B, and an assortment of other genres. In fact, while I have used both sealed & ported, I find ported to be cleaner & easier to integrate on the upper end since the cone isn't moving as much. It surely seems to react to slight EQ adjustments compared to sealed which helps to eliminate the Linkwitz transform that can occur in many sealed subs that roll-off too soon and the user winds up overcompensating for. 

The main advantage is the upper & lower output are more even. Just knock down the low end portion a bit and there you go. However, we can generalize about either, but the main discord is probably more based in the actual driver selection. There is no doubt that there are drivers that favor one design over others and that must be accounted for to make a fair comparison. 

As to enclosure size.... well, that isn't so easy to generalize either. A perfect example is the HO 10" fitting in a .7 cube, although it requires a long port to account for xmax. However, it's roll-off point is extremely low (around 25hz!). That's something that even some larger subs can not reach in recommended boxes. Build complexity is probably the biggest defeat. I plan on going back to ported for it's low end efficiency, but I'm too lazy to build again.


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## cubdenno

Personally I have been playing around with the same sub in different enclosures since 2008. I have tried to replace it with forum favorites and have not been able to in a manner that justifies the money. That said, sealed enclosures have not sounded "right" to me since going ported. They just don't reinforce the low end that a ported enclosure does even remotely as effortlessly. And as Andy mentioned for true "clean bass", a bandpass can't be beat when done correctly.

The amount of FM and AM distortion added by a sealed enclosure vs a bass relex design seem to be, in my opinion the main reasons I am on the ported bandwagon.

Which also begs a question I have been wanting to ask in regards to running midbass drivers so low and especially a 2 way set up where the woofer also does the midrange duties and passes off to a tweeter. Doesn't crossing over so low (below 80 hertz) cause audible FMD when you are asking for midbass output? I know it was something I noticed with my two way crossing over low. 

I realize any FM distortion added by the excessive cone movement in the lower registers reproduced by a subwoofer are probably not going to necessarily be noticeable or distinguishable, but for those who are on a non subjective crusade for SQ, I would think that anything that reduces cone movement would be preferable.


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## Hanatsu

I'm doing a ported vs sealed blindtest in a few weeks. Same woofers, EQed the same. Found 3 people that will participate so far. Gotta build the enclosures and setup the system so it will take some time. It will be done in my apartment. Signal will be fed through a pair of MiniDSPs. 

Thought it would be interesting.


----------



## Bayboy

It is preferable and certainly is audible at some point. I think many worry about transient response and prefer that over the added distortion. It can become quite subjective at that point for there are several successful examples on either side of the fence. Again, that points to driver selection though.

As to crossover point.. well, crossing a sealed sub high seems to add to the distortion to me. Ported not so much. But again, many like the sound of their front mids producing gobs of upper bass. Can sound good and lay a lot of fundamentals, but there seems to be some drawbacks to that as well. During a tuning session with the sub off, I begin to notice how much of the fundamentals were laid much higher up.... well into the tweeter range. Nothing new though. It was subtle, but audible. The sub was dialed back in, but because of it's slightly rough upper output, it seemed to muddy the overall response a bit even at lower levels. Of course I was being a bit picky. The only way I could get it to complement how I wanted was to reduce cone movement which would also lower output, yet the lower response wasn't there the way I needed it. Goosing the EQ down low without separate bands for each channel isn't good. Ported may have solved that issue.


----------



## Hanatsu

cubdenno said:


> Doesn't crossing over so low (below 80 hertz) cause audible FMD when you are asking for midbass output? I know it was something I noticed with my two way crossing over low.
> 
> I realize any FM distortion added by the excessive cone movement in the lower registers reproduced by a subwoofer are probably not going to necessarily be noticeable or distinguishable


What is FM distortion? Never heard that term before.


----------



## cubdenno

Hanatsu said:


> What is FM distortion? Never heard that term before.


frequency modulation distortion

Distortion caused by diaphragm motion at lower frequencies causing frequency shifts in higher frequencies due to Doppler effect.


It usually occured for me when I was listening at a higher volume with a lower crossover point on the midbass/midrange. Again subwoofer-wise, I couldn't necessarily pinpoint it except in the manner that sealed enclosures did not sound near as good as a ported enclosure when eq'd to get as close a FR match as possible.


----------



## Hanatsu

cubdenno said:


> frequency modulation distortion
> 
> Distortion caused by diaphragm motion at lower frequencies causing frequency shifts in higher frequencies due to Doppler effect.
> 
> 
> It usually occured for me when I was listening at a higher volume with a lower crossover point on the midbass/midrange. Again subwoofer-wise, I couldn't necessarily pinpoint it except in the manner that sealed enclosures did not sound near as good as a ported enclosure when eq'd to get as close a FR match as possible.


Ok. That's a type of non-linear distortion. Believe I've read about it on the Klippel site.


----------



## BuickGN

FG79 said:


> I have yet to do a vented enclosure in a car, but I figure that the integration with the midbass is what the challenging part is all about here like sqnut mentions.
> 
> In a home system you rarely ever need to worry about too much subbass/midbass, so the vented alignment is welcome and preferred in many cases just to get the proper response.
> 
> Car is quite different. Sealed is much more plug and play......volume versus volume plus tuning frequency is significant.
> 
> As far as the ported in a car, I've been told it can definitely work. But most people are going with an enclosure volume that is often too small to yield proper SQ. A proper enclosure is usually a bit larger than most people want to deal with -- forget what T/S specs say, it's not the end all be all, because if it was we wouldn't be having this discussion.
> 
> I like quoting JL Audio for I believe was their 10W2 woofer -- 2.5 - 3.0 cubic foot per driver, vented. That's about as big or bigger than most guys put 15s in (don't get started on what a properly sized ported 15 should be). A 10" shouldn't be ported at 1 -1.5 cubic foot....too small.
> 
> It also begs the question of whether it even makes sense to go ported except for the coolness factor. It's easier and cheaper to go multiple drivers.
> 
> Unless of course you have to have some ridiculous bottom end extension. But by achieving that monstrous bottom end you take away from midbass.
> 
> The audio geek in me wants to go ported, but the pragmatist says I shouldn't.


I fully agree that most car subs are put into enclosures that are entirely too small. 

The rest, ported is better in every way. That big hump down low just needs to be eq'd down and you end up with far less excursion and less power required for the same output. 

It's much cheaper to go ported for not much more money than sealed and get the same output as buying another sealed sub and amp. It's MUCH cheaper to go ported for a given output and it takes up less space than adding an extra sealed sub.


----------



## Bayboy

Too small of a box can be subjective due to the fact that cars can take advantage of higher roll-offs associated with sealed. The only issue is the usual knee response unless the use of a low Q driver with a strong enough suspension & motor is incorporated in that smallish box. With the latter, you can still attain an ideal Q with a F3 that dovetails with the car. On the other hand, for many that may not exhibit enough low end as most do like a little bloat. Still, it is hard to beat the low end efficiency of a properly built vented alignment and no longer are the days where giant boxes are required to attain it. Just more power.


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## BuickGN

Regardless of cabin gain I would prefer a larger sealed box and have to eq down the low end and drive efficiency up. 

You still get less cone cone control, more ringing (same thing), and less efficiency with the smaller enclosure. 

After going IB I realized how badly the low end is lacking on most systems. I didn't know any better and was happy, plus I bought into the whole little to no content from 35hz and below idea. That simply isn't true, "normal" music that you would never suspect of having content that low had it. Even the 40hz area sounded cleaner and more effortless. 

When I think of a bloated low end I think of too small of an enclosure. That gives the bloated, boomy sound. Larger tends to be flatter, easier to tune, less boomy, and just smooth, effortless, and tight and punchy. Why make the sub work harder than it needs to?

I think everyone needs to experience a good low tuned ported setup properly eq'd and even a sealed setup in "too large" of an enclosure because I think opinions would change very quickly as to what's better and what's too big. This is why I look at small sealed as a last resort and ported as the way to go with IB when using lots of cone area to be a valid alternative to ported if space is an issue. While knowing for the same cone area, ported will always have advantages but more cone area is usually available IB due to soace limitations. 

I went off topic again but efficiency and cone control and distortion are a few of the big reasons to not go small sealed and to go ported or even large sealed


----------



## Bayboy

There's a couple of things out of context with my reply. Bloated doesn't necessarily pertain to a specific frequency or range. That is why I stated "low end" as in a flatly tuned ported enclosure once placed into a vehicle. It can apply to a knee response as well. 

As far as small sealed.... again that could mean two different things. Too small as being on the higher end of Qtc for a sub that can readily attain a lower value, or it could pertain to subs designed for a small enclosure and made to dovetail with cabin gain for a more natural response without EQ assistance. I have built & auditioned numerous of each... not all can be lumped into the same pile so easily. Definitely can not overlook the constraints of real estate that makes some designs unreasonable. Pick the right driver for the job and issues will be little to none.


----------



## Rs roms

BuickGN said:


> Regardless of cabin gain I would prefer a larger sealed box and have to eq down the low end and drive efficiency up.
> 
> You still get less cone cone control, more ringing (same thing), and less efficiency with the smaller enclosure.
> 
> After going IB I realized how badly the low end is lacking on most systems. I didn't know any better and was happy, plus I bought into the whole little to no content from 35hz and below idea. That simply isn't true, "normal" music that you would never suspect of having content that low had it. Even the 40hz area sounded cleaner and more effortless.
> 
> When I think of a bloated low end I think of too small of an enclosure. That gives the bloated, boomy sound. Larger tends to be flatter, easier to tune, less boomy, and just smooth, effortless, and tight and punchy. Why make the sub work harder than it needs to?
> 
> I think everyone needs to experience a good low tuned ported setup properly eq'd and even a sealed setup in "too large" of an enclosure because I think opinions would change very quickly as to what's better and what's too big. This is why I look at small sealed as a last resort and ported as the way to go with IB when using lots of cone area to be a valid alternative to ported if space is an issue. While knowing for the same cone area, ported will always have advantages but more cone area is usually available IB due to soace limitations.
> 
> I went off topic again but efficiency and cone control and distortion are a few of the big reasons to not go small sealed and to go ported or even large sealed


When you say larger sealed box, than that means greater than VAS?

I used many subs in sealed alignments in the past and only thing which worked was a larger sealed box. The issue which i ran into when using small sealed enclosures was ringing and distorted bass at higher volumes. I wasn't able to evaluate if the distortion was BL related or else. But when i reverted to vented 26hz tuned enclosure as i mentioned on a earlier post, i couldn't be much happier. As you said, if you eq the low end right, the results are fantastic. The only worry i have at this moment of time is the 2nd impedance peak which falls around 42Hz.


----------



## Hanatsu

Rs roms said:


> When you say larger sealed box, than that means greater than VAS?
> 
> I used many subs in sealed alignments in the past and only thing which worked was a larger sealed box. The issue which i ran into when using small sealed enclosures was ringing and distorted bass at higher volumes. I wasn't able to evaluate if the distortion was BL related or else. But when i reverted to vented 26hz tuned enclosure as i mentioned on a earlier post, i couldn't be much happier. As you said, if you eq the low end right, the results are fantastic. The only worry i have at this moment of time is the 2nd impedance peak which falls around 42Hz.


IB would be considered somewhere around 4x VAS. A "large box" to me means a Qtc below 0,7. The 2nd impedance peak may or may not be an issue, depends on the performance of your driver, if it's a low distortion transducer you can be less worried about this.


----------



## Bayboy

Hanatsu said:


> A "large box" to me means a Qtc below 0,7.


I'm glad that you clarified this as many seem to mistake a lower Q having to be a very large box. Several subs can attain a low Q while still maintaining a small enclosure.... HO 10", Credence small box 8" (Solobaric), Peerless XXLS, etc....


----------



## Alrojoca

My technical contribution to this thread is 0, I appreciate the great tech info posted as a learning experience.

I have listened to expensive popular and probably the best subs in sealed boxes.

The sound is tight and maybe dry compared to my ported sub, but maybe mine needs tuning or a dedicated EQ for just for that channel.

It's hard to know but I tend to prefer the sound of an electric or acoustic bass having some natural resonance or extension if I can call it that rather than the short dry sound I hear. It is not a big deal, it is something I can get used to it and if I get a sealed box maybe when I play my ported one, I would probably say it was boomy or it would need tuning to make it sound like a sealed box.


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## Bayboy

I think the biggest mistake anyone can make is trying to make a vented sub sound like a sealed. That defeats the purpose. Play some hip hop tracks on a good designed sealed, then on a good designed vented.... you will want to throw the sealed in the closet! However, for other genres with deep electronic notes like Bass 305 the smoother roll-off of the sealed will shine a little better down low where eventually the vented will drop off at some point. With pop music from the 80's & 90's, a bit higher Q sealed will fare better as most of it's content is centered above 50hz. There really is no such thing as perfect except what suits best for your taste, and if you're like me where you listen to a vast array of genres, then you have to make a small amount of sacrifice somewhere. Not a bad one, but that's what EQ presets are good for.


----------



## 14642

cubdenno said:


> frequency modulation distortion
> 
> Distortion caused by diaphragm motion at lower frequencies causing frequency shifts in higher frequencies due to Doppler effect.
> 
> 
> It usually occured for me when I was listening at a higher volume with a lower crossover point on the midbass/midrange. Again subwoofer-wise, I couldn't necessarily pinpoint it except in the manner that sealed enclosures did not sound near as good as a ported enclosure when eq'd to get as close a FR match as possible.


Doppler distortion is mostly caused by the movement of the cone at low frequencies WHILE it reproduces high frequencies. Because the cone changes its distance from the listener according to the bass signal, the origin of high frequencies changes with the bass signal. You hear this as a warbling sound caused by the high frequencies being in and out of phase periodically at high excursion because of the bass signal.

This can be a problem in small speakers used with very low high pass filters and a frequency band that extends well into the high frequencies. If you're crossing your subs at 80Hz, (or anywhere below 1kHz) this is not a problem. In addition, besides being irrelevant if the speaker isn't playing midrange and high frequencies, it's a function of excursion. The lower the excusrion, the lower the doppler distortion. 

So, the fix for doppler distortion is to reduce excursion or reduce the bandwidth by eliminating high frequencies from the speaker that makes a lot of bass. 

This can be a real problem in coaxial drivers, because the woofer's cone is also the baffle for the output of the tweeter at frequencies where the dispersion is mostly spherical (below about 8k for a 1" tweeter). The frequency that's a problem in that example corresponds to the movement of the cone AND the distance from the cone to the tweeter.

From a practical standpoint, this basically means that a 6" in the door that has to reach a 1" tweeter crossed at 3-4k SHOULDN'T be crossed at a frequency that causes lots of excursion. 

MINIMIZING excursion minimizes all kinds of disortion. When i read posts written by people who complain that the "midbass isn't moving" and who are looking for a way to make them move more, I cringe. 

Vented boxes MINIMIZE excursion at low frequencies. So long as the port is big enough not to create a bunch of harmonic distortion, vented boxes can make far less distortion than sealed boxes. Couple that with the additional output, additional headroom they offer the amp at low frequencies once you've removed the big peak with EQ and they are the obvious choice.

The group delay thing is a non-starter. So long as you're tuning the box to something like 30Hz and not designing in a giant peak in the response, you're not going to suffer from excessive GD (or "slow bass").


----------



## FG79

Bayboy said:


> I think the biggest mistake anyone can make is trying to make a vented sub sound like a sealed. That defeats the purpose. Play some hip hop tracks on a good designed sealed, then on a good designed vented.... you will want to throw the sealed in the closet! However, for other genres with deep electronic notes like Bass 305 the smoother roll-off of the sealed will shine a little better down low where eventually the vented will drop off at some point. With pop music from the 80's & 90's, a bit higher Q sealed will fare better as most of it's content is centered above 50hz. There really is no such thing as perfect except what suits best for your taste, and if you're like me where you listen to a vast array of genres, then you have to make a small amount of sacrifice somewhere. Not a bad one, but that's what EQ presets are good for.


I never particularly liked high Q sealed enclosures. They do hit hard but didn't sound as good as midbasses hitting hard, and the low end smoothness and warmth were never quite there for my liking.

I've yet to hear every subwoofer size and enclosure combo out there, so it's hard for me to make definitive statements on this stuff (yet).

One thing I do know is that ported is absolutely the way to go in home systems because without it you get no low end in most cases. The woofers behave the same way in a car but because you have the big cabin gain you can still get deep bass from a sealed alignment.

I still think about the ideal enclosure situation -- a big SUV or station wagon. Throw $$ out of the picture because if you are serious, then it's not an issue. You have money and space, now what?

In that case I don't see what's wrong with let's say three 12" subs in a low Q (~0.5) sealed setup. Your low Q gives you the low end and smoothness/fast response. The three subs gives you the cone area for SPL (if you still need more, what about four then, etc). 

Are you telling me that a well designed single 12" ported is going to characteristically have a sound that multiple 12s (same model) would not have in a good sealed? 

Most of your musical bass is coming from your door woofers....the sub is just there to reinforce.


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## FG79

Bayboy said:


> *I think the biggest mistake anyone can make is trying to make a vented sub sound like a sealed. That defeats the purpose. * Play some hip hop tracks on a good designed sealed, then on a good designed vented.... you will want to throw the sealed in the closet! However, for other genres with deep electronic notes like Bass 305 the smoother roll-off of the sealed will shine a little better down low where eventually the vented will drop off at some point. With pop music from the 80's & 90's, a bit higher Q sealed will fare better as most of it's content is centered above 50hz. There really is no such thing as perfect except what suits best for your taste, and if you're like me where you listen to a vast array of genres, then you have to make a small amount of sacrifice somewhere. Not a bad one, but that's what EQ presets are good for.


To get to your specific point:

I think what people are trying to achieve is to get the best of a sealed alignment with a bit more SPL and low end. Enclosure size and tuning difficulty isn't the only compromise -- you lose some SPL as well, perhaps some critical punch if you like that sorta "violence". If all you ever listened to was rap music, then possibly a 35 hz box will always be better than a 28 hz box (generally speaking of course). 

However, assuming the enclosure isn't humongous I think I'd still would prefer these flatter sounding vented enclosures as I listen to a ton of different music. 

As my listening tastes evolved I do think I miss the basshead side of the experience from time to time, but overall I value the "never have a bad sounding note" aspect a lot more. 

This will always be a fascinating topic because it's so hard to build all of these enclosures and know anything really definitive on the topic. It's so easy to listen to speakers and amplifiers, but sub enclosures is a different ballgame altogether.


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## therapture

FG79 said:


> Most of your musical bass is coming from your door woofers....the sub is just there to reinforce.



Amen to that. If your midbass sucks, that "phat" blues bass guitar is going to sound like ass no matter what sub(s) you have.


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## Bayboy

FG79 said:


> I never particularly liked high Q sealed enclosures. They do hit hard but didn't sound as good as midbasses hitting hard, and the low end smoothness and warmth were never quite there for my liking.
> 
> I've yet to hear every subwoofer size and enclosure combo out there, so it's hard for me to make definitive statements on this stuff (yet).
> 
> One thing I do know is that ported is absolutely the way to go in home systems because without it you get no low end in most cases. The woofers behave the same way in a car but because you have the big cabin gain you can still get deep bass from a sealed alignment.
> 
> I still think about the ideal enclosure situation -- a big SUV or station wagon. Throw $$ out of the picture because if you are serious, then it's not an issue. You have money and space, now what?
> 
> In that case I don't see what's wrong with let's say three 12" subs in a low Q (~0.5) sealed setup. Your low Q gives you the low end and smoothness/fast response. The three subs gives you the cone area for SPL (if you still need more, what about four then, etc).
> 
> Are you telling me that a well designed single 12" ported is going to characteristically have a sound that multiple 12s (same model) would not have in a good sealed?
> 
> Most of your musical bass is coming from your door woofers....the sub is just there to reinforce.



Not sure you have grasped what I have said. What you're talking about is output and perhaps extension. However, there will still be a difference in the tonal characteristics even between one 12" ported & three 12" sealed unless you EQ the piss out of them (still not sure it will attain it), but that winds up eating extra power.

As to depending on the "midbass" drivers... of course they're important, but many try to play them down too far which causes problems in itself. Also, we can not ignore the fact that subs can & should play higher than many cross them over at. Many try to cross subs around 60hz or even less which I don't recommend. A lot of upper bass should still come from them while mids & even tweeters should only lay down the fundamentals. I've run subs as high as 120hz with good results once proper leveling is attained. Ported often is more helpful in that aspect.


----------



## Alrojoca

Kind of like the acoustic suspension vs bass reflex argument for home speakers, I also went from AS to BR at home, pretty much most home speakers had some port in the front or the back when I upgraded mine in the late 90's versus what I had in the mid 80's

In a car,
starting with a sealed box having one for a long time and loving it, try a few hrs with a ported box or listening to another system, and no way, something was off, I rather stick to my tight solid bass. But then for one reason or another we end up with a good ported sub in our system and I got used to it. Making it very hard to go back to a sealed box once we listen to one. Thinking about a good sub in a sealed box now, but maybe I'll need to do some more listening. 

Question, is it worth using a HP with a sealed box? Or just a LP is enough? Ported boxes always should be bandpassed to protect them from low freq excursion.


----------



## Hanatsu

Ported doesn't need a highpass if Fb lies around 30Hz (imo).

Sent from my Samsung Galaxy S5 using Tapatalk


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## Bayboy

Depends on the source material and power applied.


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## Rs roms

I don't use subsonic on my vented enclosure. Guess what, its not needed. 26hz tuned and 800 rms into it.
Hanatsu you are right as usual 

Sent from my SM-N9005 using Tapatalk


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## Hanatsu

Of course source material and power matters... Having said that, I have never used highpass on my enclosures, neither in any system I've setup. I usually tune around 30-33Hz. I have extremely little music with content below 30Hz (with over 3000 songs on my iPod, I can think of 3 or 4 songs with any real content down there). Most metal/electronic music have fundamentals around 45-60Hz. Also - cabin gain boost the crap out of anything below 30Hz. Most of my enclosues measure flat down to 20Hz even though Fb is at ~30Hz. 

It's not like the enclosure will unload 0.5Hz below Fb. If you tune at 30, you're probably ok down to 25-26Hz (depending on enclosure size). If you absolutely must use a highpass (I recommend that if you tune around 40Hz), place it about 10Hz below Fb. Basically it's not a big deal if you ain't placing Fb too high (again IMHO).

Sent from my Samsung Galaxy S5 using Tapatalk


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## Hanatsu

Alrojoca said:


> Kind of like the acoustic suspension vs bass reflex argument for home speakers, I also went from AS to BR at home, pretty much most home speakers had some port in the front or the back when I upgraded mine in the late 90's versus what I had in the mid 80's
> 
> In a car,
> starting with a sealed box having one for a long time and loving it, try a few hrs with a ported box or listening to another system, and no way, something was off, I rather stick to my tight solid bass. But then for one reason or another we end up with a good ported sub in our system and I got used to it. Making it very hard to go back to a sealed box once we listen to one. Thinking about a good sub in a sealed box now, but maybe I'll need to do some more listening.
> 
> Question, is it worth using a HP with a sealed box? Or just a LP is enough? Ported boxes always should be bandpassed to protect them from low freq excursion.


HPF with sealed is generally not needed. Absolutely meaningless actually unless you run very large enclosures or IB with drivers not designed for sealed/IB with low Xmax.

Sent from my Samsung Galaxy S5 using Tapatalk


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## Bayboy

Yeah... I thought the same too about content, but material does matter. Not sure how much I have in my library, but I still have a lot of electronic music that I like to listen to. It isn't very often, but when I do I rather not be limited in output due to unloading. However, one day I would like to utilize a ported HO 10" if I could find a way to keep the enclosure compact as possible.


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## Alrojoca

Manufacturers recommend bandpassing their ported boxes, maybe most 10's or 12's may not need it if they can handle the excursion, not sure it is worth the risk with a smaller 8" driver or even using a higher than a 12db slope as some recommend.


----------



## Hanatsu

Alrojoca said:


> Manufacturers recommend bandpassing their ported boxes, maybe most 10's or 12's may not need it if they can handle the excursion, not sure it is worth the risk with a smaller 8" driver or even using a higher than a 12db slope as some recommend.


Of course they do. Better safe than sorry for their part.

Smaller drivers are often tuned higher, hence the required highpass.


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## BuickGN

Hanatsu said:


> HPF with sealed is generally not needed. Absolutely meaningless actually unless you run very large enclosures or IB with drivers not designed for sealed/IB with low Xmax.
> 
> Sent from my Samsung Galaxy S5 using Tapatalk


I agree but it can reduce power input a little for whatever little it's worth.


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## cubdenno

Andy Wehmeyer said:


> Doppler distortion is mostly caused by the movement of the cone at low frequencies WHILE it reproduces high frequencies. Because the cone changes its distance from the listener according to the bass signal, the origin of high frequencies changes with the bass signal. You hear this as a warbling sound caused by the high frequencies being in and out of phase periodically at high excursion because of the bass signal.
> 
> This can be a problem in small speakers used with very low high pass filters and a frequency band that extends well into the high frequencies. If you're crossing your subs at 80Hz, (or anywhere below 1kHz) this is not a problem. In addition, besides being irrelevant if the speaker isn't playing midrange and high frequencies, it's a function of excursion. The lower the excusrion, the lower the doppler distortion.
> 
> So, the fix for doppler distortion is to reduce excursion or reduce the bandwidth by eliminating high frequencies from the speaker that makes a lot of bass.
> 
> This can be a real problem in coaxial drivers, because the woofer's cone is also the baffle for the output of the tweeter at frequencies where the dispersion is mostly spherical (below about 8k for a 1" tweeter). The frequency that's a problem in that example corresponds to the movement of the cone AND the distance from the cone to the tweeter.
> 
> From a practical standpoint, this basically means that a 6" in the door that has to reach a 1" tweeter crossed at 3-4k SHOULDN'T be crossed at a frequency that causes lots of excursion.
> 
> MINIMIZING excursion minimizes all kinds of disortion. When i read posts written by people who complain that the "midbass isn't moving" and who are looking for a way to make them move more, I cringe.
> 
> Vented boxes MINIMIZE excursion at low frequencies. So long as the port is big enough not to create a bunch of harmonic distortion, vented boxes can make far less distortion than sealed boxes. Couple that with the additional output, additional headroom they offer the amp at low frequencies once you've removed the big peak with EQ and they are the obvious choice.
> 
> The group delay thing is a non-starter. So long as you're tuning the box to something like 30Hz and not designing in a giant peak in the response, you're not going to suffer from excessive GD (or "slow bass").


In regards to the doppler effect, I am really interested in the SQ guys take for a two way set up. Running very low crossover points. I suppose as per anything, it's going to matter the most listening at volumes higher than car off levels when you want a little more midbass kick and a smaller ~6" driver (or less). Your little woof is going to really be moving trying to produce the output down low. What effect does that induce to the higher frequencies?


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## FG79

Bayboy said:


> Not sure you have grasped what I have said. What you're talking about is output and perhaps extension. *However, there will still be a difference in the tonal characteristics even between one 12" ported & three 12" sealed* unless you EQ the piss out of them (still not sure it will attain it), but that winds up eating extra power.
> 
> As to depending on the "midbass" drivers... of course they're important, but many try to play them down too far which causes problems in itself. Also, we can not ignore the fact that subs can & should play higher than many cross them over at. Many try to cross subs around 60hz or even less which I don't recommend. A lot of upper bass should still come from them while mids & even tweeters should only lay down the fundamentals. I've run subs as high as 120hz with good results once proper leveling is attained. Ported often is more helpful in that aspect.


Tell me more about the tonal differences between the two enclosures.....I think I have an idea but haven't heard a good ported in a car yet, and sealed vs. vented in home I'm not sure applies the same.


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## FG79

Hanatsu said:


> Of course source material and power matters... Having said that, I have never used highpass on my enclosures, neither in any system I've setup. I usually tune around 30-33Hz. I have extremely little music with content below 30Hz (with over 3000 songs on my iPod, I can think of 3 or 4 songs with any real content down there). Most metal/electronic music have fundamentals around 45-60Hz. Also - cabin gain boost the crap out of anything below 30Hz. Most of my enclosues measure flat down to 20Hz even though Fb is at ~30Hz.
> 
> It's not like the enclosure will unload 0.5Hz below Fb. If you tune at 30, you're probably ok down to 25-26Hz (depending on enclosure size). If you absolutely must use a highpass (I recommend that if you tune around 40Hz), place it about 10Hz below Fb. Basically it's not a big deal if you ain't placing Fb too high (again IMHO).
> 
> Sent from my Samsung Galaxy S5 using Tapatalk


The low tuning frequency like you said plus a nice size enclosure pretty much eliminates the need for an infrasonic filter.


----------



## Bayboy

FG79 said:


> Tell me more about the tonal differences between the two enclosures.....I think I have an idea but haven't heard a good ported in a car yet, and sealed vs. vented in home I'm not sure applies the same.


Not sure I can explain it correctly of if I could explain it at all. Basically, it's something that you would have to hear comparing the same sub. Perhaps it is because of the flatter response, but that would be down lower in frequency. Overall lower excursion maybe? It's just a different sound, but nothing bad. I've only used ported in open cabins like hatchbacks so..


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## BigRed

I had a 10 cube box ported with two dd9515 woofers in it. It received a perfect 20 score in the sub category during IASCA regionals in 2008. It can sound good


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## subwoofery

BigRed said:


> I had a 10 cube box ported with two dd9515 woofers in it. It received a perfect 20 score in the sub category during IASCA regionals in 2008. It can be made to sound good


Edited  

Kelvin


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## Bayboy

Damn that's a big box!


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## Rs roms

BigRed said:


> I had a 10 cube box ported with two dd9515 woofers in it. It received a perfect 20 score in the sub category during IASCA regionals in 2008. It can sound good


Do you mind sharing a picture of it? Wanna see how big 10 cubes are actually


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## CoLd_FuSiOn

Hanatsu said:


> The best I could get it was 1,7cu ft / Fb 35Hz. Need to EQ it, bring down the peak by 10dB or so.
> 
> This driver is better suited for sealed or IB imo.


Having heard the sub in a ported and sealed enclosure as well,I would also suggest that.


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## DDfusion

Ported can sound just as good but it's not free. You will give up some bandwidth and output. If you don't have a strong front stage it will not obviously. Most don't have a strong front stage. My 9512s had just as good of a response as any good sealed box after I pulled the minimal peak down. Same for my SW2508sc. You can only polish a turd so much but if you start with a good driver you can have good results.


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