big vs small driver subs

[Crashpc]

That's the thesis of the paper right there, and you agree with it. We could stop there

While it is true that if you use a resonant enclosure (ported box) and a driver with a qts of greater than about .5, there will be a time delay associated with stopping the cone. This is well known. And it's not an issue if you design properly.

You´re right. It is mostly due to the wrong design. No reason to discart it. More to it later.

Keep the tuning below 40 hz and the ringing associated with the resonance will be completely swamped by the ringing associated with the room rta.

Here:
1) we didn´t set a rule for certain room, right? We might talk half space situation as well.
2) No. If you have speaker "poor enaugh", which happens from time to time, no bassreflex tuning will save you. You will only decide how much bad you will add to it.

And since most of what we hear is frequency response, if you design or eq to have a flat in room frequency response it will not sound "slow" even if there is a couple ms of ringing associated with the resonance.

There is some truth in it, but I cannot completely agree. Once you have hugely resonating system and room to it, you eq it under actual "flat line" SPL to perceive it as flat. At least it absolutely works that way with my ears and listening sense.

And the lower you tune the less of a problem it is, as the cycles get longer in time and human hearing gets less sensitive.

No, it doesn´t solve your problem. Your room can add 10db peak (at least perceived) easily, so even without tuned bassreflex with flat system, you have huge problem right there. That´s why I would like to avoid offtopic room situation.

The analogy with cars is interesting, but we are talking about small changes in weight vs force.

Count twice. There are full numbers ratios between speakers. 1:3 in certain situations seems great enaugh. 1,5ton or 4,5ton car is great difference to me. Go get your 1.5t and give me 4.5t car and lets do crashtests against each other.... 🙂

not large changes that would cause tires spinning due to not being able to transfer the power to the ground.

I wrote it´s not good to make analogies. We would need to prove this one. You have this feeling when we talk about braking capabilties? Look at how trucks brake compared to fast cars...

I would agree if Mms was out of control, like a kg or more, but that isn't the case. The biggest drivers have high Mms (like 600 g or a bit more) but they also have huge motors that can throw that weight around forcefully enough.

We can go right there, and count that ratio to see. I know that it is similar to modern PA speakers. So it´s not easy to make a general statement. It is closer to imposible.

The problem is inductance, since those large coil speakers are synonymous with high inductance.

As long as Resistance doesn´t drop under 3-4Ohm, it is not really for bass speakers. Those 0,5Ohm car beasts or B&C PA IPAL Powersoft beasts, it can be different story.

If you want to know where to start in disproving the paper, you need some measurements to show that invalidate the measurements shown in the paper.

No. If the measurement is used in an unusable way for the case, I don´t need to disprove a measurement. Would you need to disprove for example dimensions measurement of the speaker when we talk about power handling? Absolutely not. The situation simply doesn´t talk the problem.

But since you specifically agreed with the thesis of the paper in the sentence I quoted here that's going to be hard for you to do. It seems like you have more of a problem with their bold use of math and physics (that may be slightly off the mark) but don't actually disagree with the thesis or the measurement.

I don´t have problem with their math. I have slight problem with using even more advanced math to talk the topic. Particulary calculating cone position after some time using different accelerations. Don´t have free space for this in my head, although it should be easy. It would take me some google learning, which I don´t want to spend (my time) at, because it would not disprove the measurement. The measurement is right. That way, I believe you miss where is the disagreement... I disprove the way they go. It is literally offtopic.

Anyway, it is always about poor design, and saying large speakers generally are slow is pointless. These are just more prone to the poor design, because there is more often not enaugh force given to these (see many models with the same motor, from 12" to 18") and because smaller speakers with the same cone excursion often are not able to deliver the amount of SPL at low frequencies, so the upper range is way stronger, so it is perceived as great kick and less boominess.

 

[just a guy]

Here:
1) we didn´t set a rules for certain room, right? We might talk half space situation as well.
2) No. If you have speaker "poor enaugh", which happens from time to time, no bassreflex tuning will save you. You will only decide how much bad you will add to it.

1. Rooms are dissimilar, so when talking about rooms you have to generalize.
1a. In the case of half space the resonant delay is a tradeoff the designer must choose, IMO it's completely worth it considering the massive gains to be had from resonant loading. The delay is minimal and if tuned below 40 hz, it's mostly inaudible, even in half space. If tuned at 20 hz or lower it's almost completely inaudible unless the delay time is huge (several cycles long, which at low frequencies is measured in seconds).
2. If the resonant damping delay is COMPLETELY swamped by the room rta the "bad added" is not significant.

There is some truth in it, but I cannot completely agree. Once you have hugely resonating system and room to it, you eq it under actual "flat line" SPL to perceive it as flat. At least it absolutely works that way with my ears and listening sense.


No, it doesn´t solve your problem. Your room can add 10db peak (at least perceived) easily, so even without tuned bassreflex with flat system, you have huge problem right there. That´s why I would like to avoid offtopic room situation.

Here you are getting into psychoacoustics and room modes. The first I am not going to even address as it has nothing at all to do with the paper titled "Woofer Speed", the second can either be tolerated or obliterated with any number of multiple woofer setups.

Count twice. There are full numbers ratios between speakers. 1:3 in certain situations seems great enaugh. 1,5ton or 4,5ton car is great difference to me. Go get your 1.5t and give me 4.5t car and lets do crashtests against each other.... 🙂

I wrote it´s not good to make analogies. We would need to prove this one. You have this feeling when we talk about braking capabilties? Look at how trucks brake compared to fast cars...

We can go right there, and count that ratio to see. I know that it is similar to modern PA speakers. So it´s not easy to make a general statement. It is closer to imposible.

All we have to do is look at the worst case scenario, very heavy cones with weak motors. We do have examples of 600+ g Mms with .5 or higher qts. Even for these woofers, the motor force is adequate to move them as fast as they need to go to achieve a decent impulse. But in most cases with woofers like that the inductance will limit their response speed. INDUCTANCE, not FORCE.

As long as Resistance doesn´t drop under 3-4Ohm, it is not really for bass speakers. Those 0,5Ohm car beasts or B&C PA IPAL Powersoft beasts, it can be different story.

Resistance alone means nothing. You need to look at normalized values, like normalized inductance = Le/Re.

No. If the measurement is used in an unusable way for the case, I don´t need to disprove a measurement. Would you need to disprove for example dimensions measurement of the speaker when we talk about power handling? Absolutely not. The situation simply doesn´t talk the problem.

What is unusable about the measurement presented?

They showed the impulse response of:
a. a driver
b. same driver with mass added
c. same driver with inductance added

And the measurement showed clearly that their thesis was correct, you even agreed the thesis is correct. Since the thesis is correct and the measurement supports the thesis, by definition it is not "unusable", it is very useful.

As far as dimensions and power handling, dimensions have EVERYTHING to do with power handling. Larger enclosures use up their usable excursion faster (using less power) than smaller enclosures, so there is less thermal issues (power compression). Smaller enclosures may be too small for the driver to reach it's excursion limits unless you dump enough power into them to cause massive power compression, thermal failure and all that implies (different frequency response, higher Re leading to less spl requiring more power in an endless cycle to maintain spl level until driver coil melts).

See this post I just wrote last night to see that dimensions have everything to do with power handling - http://www.avsforum.com/forum/155-d...e-larger-sealed-box-hst18-2.html#post44814801

I don´t have problem with their math. I have slight problem with using even more advanced math to talk the topic. Particulary calculating cone position after some time using different accelerations. Don´t have free space for this in my head, although it should be easy. It would take me some google learning, which I don´t want to spend (my time) at, because it would not disprove the measurement. The measurement is right. That way, I believe you miss where is the disagreement... I disprove the way they go. It is literally offtopic.

You can literally disregard the ENTIRE PAPER except for the zoomed in impulse graph, that graph contains the thesis of the paper and all you need to know about the subject in this paper called "Woofer Speed". The paper is not called "resonant enclosure damping speed", it's not called "added bad speed", it's not called "room rta speed", it's called "Woofer Speed" and you agreed with the thesis a long time ago, so I don't know what this continued discussion is about.

 

[Crashpc]

1. Rooms are dissimilar, so when talking about rooms you have to generalize.
2. If the resonant damping delay is COMPLETELY swamped by the room rta the "bad added" is not significant.

No. For this reasons in woofers topic, we need to avoid the room completely.

All we have to do is look at the worst case scenario, very heavy cones with weak motors. We do have examples of 600+ g Mms with .5 or higher qts. Even for these woofers, the motor force is adequate to move them as fast as they need to go to achieve a decent impulse.

This I believe, is very wrong. For bass speakers in tuned enclosure and slow boomy bass at 70Hz and lower, main focus should not be speaker response measured (free air, closed box?) doesn´t matter how. At port tuning frequency and around, the speaker cone is not even the primary source of the sound! It´s many decibels under. But the port is! (while driven by the speaker, at the same outputting only fraction of the accoustical power). Why would you measure that on the speaker cone then? See how absurd is that?

But in most cases with woofers like that the inductance will limit their response speed. INDUCTANCE, not FORCE.

1) No, as I posted earlier. Look at the Re and inductance around bassreflex enclosure tuning. There is no significant inductance to speak of.
2) If I would ever touch the inductance problem, it wouldn´t be really in time domain, but rather phase domain. This one alters SPL a lot, especially when using multiple sources (subwoofer and mids crossed together).

Resistance alone means nothing. You need to look at normalized values, like normalized inductance = Le/Re.

You mean impedance. I measured dozens of speakers, and they´re very close to Re at low frequencies except for resonance peak.

What is unusable about the measurement presented?

They showed the impulse response of:
a. a driver
b. same driver with mass added
c. same driver with inductance added

And the measurement showed clearly that their thesis was correct, you even agreed the thesis is correct. Since the thesis is correct and the measurement supports the thesis, by definition it is not "unusable", it is very useful

I agreed that the reaction speed is correct. This one doesn´t give you full behavior data in dynamic situation of making sound. Sorry. The same as weak car will start to move as fast as fast car, but it will not move fast after some period of time, compared to the fast car. There are so many things obvious and totally avoided, even when one brings explanation, that come to that speechless mood again. Sorry. It´s not you, but it is hard to fight this situation.

As far as dimensions and power handling, dimensions have EVERYTHING to do with power handling. Larger enclosures use up their usable excursion faster than smaller enclosures, so there is less thermal issues (power compression). Smaller enclosures may be too small for the driver to reach it's excursion limits unless you dump enough power into them to cause massive power compression, thermal failure and all that implies (different frequency response, higher Re leading to less spl requiring more power in an endless cycle to maintain spl level until driver coil melts).

You didn´t get it. I was talking about the actual transducer dimensions, not the box. What if we put 500W piece into 150l box and 2000W piece in the same box and feed it with 1200W? You know what. But based on the dimensions, which can and are (I can bring few examples) the same for some speakers, the outcome can be vastly different. The same as woofer speed reaction. Even the smallest woofer will react in the same time, but it won´t give the same CONE SPEED as a large woofer, when we set the same output SPL.

You can literally disregard the ENTIRE PAPER except for the zoomed in impulse graph, that graph contains the thesis of the paper and all you need to know about the subject in this paper called "Woofer Speed". The paper is not called "resonant enclosure damping speed", it's not called "added bad speed", it's not called "room rta speed", it's called "Woofer Speed" and you agreed with the thesis a long time ago, so I don't know what this continued discussion is about.

I see you don´t. It is about distinction between woofer reaction speed, and the actual speed, and the outcome of it. And about power, sensitivity, frequency response, GD, efficiency, resonant circuits. That´s what decides about perception of the woofer and how you feel the sound. Tight, FAST, or SLOW. The SPEEED 🙂

 

[just a guy]

So you want to leave the room out of the discussion but include resonant enclosure delay?

This makes no sense. The article is called "Woofer Speed", it talks ONLY about woofer speed. This type of high excursion driver Adire was making is almost exclusively used in small sealed boxes in domestic size living rooms. So it would make more sense to leave resonant enclosure damping delay out of the discussion and include room effects. The room effects add FAR more delay than resonant enclosure damping delay anyway.

But if you like we can leave both the room AND the resonant enclosure damping delay out of the equation. But it's either one or the other - discuss both or ignore both.

I bet you can't show any examples (or at least very few) of high(ish) normalized inductance drivers with high mass used in resonant style enclosures. They are almost exclusively used in small sealed boxes. And for the low mass, low normalized inductance drivers it makes no difference if the box is sealed or ported, as long as qts isn't absurdly high there is plenty of force to accelerate the mass fast enough to give a decent impulse response.

The "Woofer Speed" paper ABSOLUTELY was not intended to discuss the full behavior data in the dynamic situation of making sound. You are agreeing with the thesis of the paper but saying it doesn't matter because ported boxes are "boomy". This is absurd, the paper has only one thesis, which is woofer speed in relation to mass and inductance, and you agree with this thesis. What you are arguing is well outside the scope of the paper, and as I have mentioned, resonant enclosure damping delay doesn't matter as these types of drivers that have speed issues are used almost exclusively in small sealed boxes, and because resonant enclosure damping delay is trivial when compared to room rta AND it's inaudible if designed properly (to have flat in room frequency response and with a tuning low enough to be out of the sensitive range of human hearing).

The paper is NOT about power, sensitivity, frequency response, GD, efficiency or resonant circuits. That's the problem. You are taking the paper WAY out of context and arguing that things OTHER than woofer speed affect perception, which is in itself arguable, as I mentioned, because good design makes the delay inaudible.

 

[Crashpc]

So you want to leave the room out of the discussion but include resonant enclosure delay?

Yes.

This makes no sense.

To you, obviously...

The article is called "Woofer Speed", it talks ONLY about woofer speed.

Good. Now read the topic name and some posts from the begining. It generally talks about speaker enclosures and drivers in it.
So, isolated woofer speed (transducer) article will not make much sense in real world situation using an enclosure, right?

This type of high excursion driver Adire was making is almost exclusively used in small sealed boxes in domestic size living rooms. So it would make more sense to leave resonant enclosure damping delay out of the discussion and include room effects. The room effects add FAR more delay than resonant enclosure damping delay anyway.

That is the topic you picked. I didn´t. Maybe the merit of our disagreement comes from this not spoken decision. Of course room adds Far more delay. I excluded it from my side of discussion for that reason, and because the speaker CAN sound boomy and slow even outside. So while isolating the problem, we don´t leave it close to "non existent". With woofer alone, or even using sealed box and setting frequency response, the problem almost ceases to exist, which is not good choice for our thread topic.

But if you like we can leave both the room AND the resonant enclosure damping delay out of the equation. But it's either one or the other - discuss both or ignore both.

Not really. Leaving the room out of the equation still leaves us with things to discuss and solve. Without accoustical circuit only thing to solve in sealed enclosure really is frequency response, and it is generally done in that document. If we ignore both, you´ll find I´ll start to agree. The problematics is directly connected to the speaker-enclosure circuit. And this one is left out of the equation in that document, which is bad, because it will not help us in real world using tuned enclosures.

I bet you can't show any examples (or at least very few) of high(ish) normalized inductance drivers with high mass used in resonant style enclosures.

Not that I couldnt. Possessing measurement tools for both impedance and SPL, I could. But icompared to that document, it would take way more time and effort, because it needs to be measured in time domain with phase control to see the full outcome. Lot of work to prove for somebody just in one discussion.

They are almost exclusively used in small sealed boxes. And for the low mass, low normalized inductance drivers it makes no difference if the box is sealed or ported, as long as qts isn't absurdly high there is plenty of force to accelerate the mass fast enough to give a decent impulse response.

Impulse response doesn´t really solve many problems. Nobody tuning his audio system would be okay with just THAT one measurement.
I believe most hesitation comes from arguably low differences. I recommend you to take the time, and build only bassreflex (bandpass, with speakers inside the box) powered system from 30 to 1000Hz, to fully understand and feel what is the problem with tuned and resonant circuits. 🙂

The "Woofer Speed" paper ABSOLUTELY was not intended to discuss the full behavior data in the dynamic situation of making sound.

Cool cool cool cool! That´s what I was saying all the time? Maybe my bad english didn´t do well here. That is exactly what I´m pointing at. Good God, mission accomplished.

You are agreeing with the thesis of the paper but saying it doesn't matter because ported boxes are "boomy".

These are not boomy just like that. They can be built boomy even with fast, light, stiff suspension, low inductance driver. That is the point.

This is absurd, the paper has only one thesis, which is woofer speed in relation to mass and inductance, and you agree with this thesis.

Only REACTION SPEEED from starting point.

What you are arguing is well outside the scope of the paper

Yes. And the paper is way too isolated scope for our thread/topic.

and as I have mentioned, resonant enclosure damping delay doesn't matter as these types of drivers that have speed issues are used almost exclusively in small sealed boxes

Right. Then these don´t sound boomy and we have nothing to talk about. 🙂
I picked the situation where we have things to talk about.

The rest would be just repeating each other.

 

[cbdb]

Your wrong again. The driver dosnt move the mass of air its moving some mass but also using the force to compress the air, which is non linear, the force increases with driver excursion because the air pressure increases, where is that in the equations you don't understand?

 

[Crashpc]

Your wrong again. The driver dosnt move the mass of air its moving some mass but also using the force to compress the air,

Yes, compressing air by moving its mass. Where it comes wrong in the corelation to my post?

which is non linear,

As the motor strenght in excursion, suspension restoring force, our ears response to SPL and frequency. What does it have in common with the topic, making it wrong on my side, huh?

the force increases with driver excursion because the air pressure increases, where is that in the equations you don't understand?

Both motor force and air contra force increase with speaker excursion. Please make it obvios why you pick these facts as something technical against(negating) my posts. I don´t see it.

Equations I don´t understand to, hhhhhh. Which are these?

 

[cbdb]

My response was for just a guy. I question the equations used at the beginning of this thread. As I mention earlier the math doesn't add up and now I say either dose the physics when the contribution of air pressure seems to have been left out. So I question there results.

 

[just a guy]

I would greaty disagree to what they wrote in that document. Anybody to discuss each aspect in a civil way? 🙂

This was your original post in this thread.

Shortly after you said you actually agreed with the thesis of the paper, and you didn't have a problem with the math they used.

Then you went on to say that there are other factors NOT COVERED BY THE PAPER that can cause "slow" bass in your opinion and apparently THAT was why you disagreed with the paper, even though you found no fault in the paper itself.

Can you see how this causes confusion, as you almost immediately contradicted your first post by saying they got the thesis correct?

THAT PAPER IS NOT COVERING ANYTHING EXCEPT THE IMPULSE RESPONSE "WOOFER SPEED" AS RELATED TO MASS AND INDUCTANCE.

Ported box resonance damping delay has NOTHING to do with the paper or this thread called "big vs small driver subs". You've completely changed the topic to suit your own purposes and contradicted yourself while you were doing it.

Now if you want my opinion on resonant enclosure damping delay, here it is. It makes no difference if you design the box properly.

If you make a ported box that has the same frequency response as a sealed box (with the same driver) - and this is not hard to do - and make sure the port tuning is below 40 hz, ideally 20 hz or lower - then eq any small differences so the frequency response is exactly the same and level match so spl is exactly the same - in a blind test you will not be able to tell which is which. You will not be able to pick out the ported box because the resonant damping delay with make no difference whatsoever and it will not be audible. I don't care if you do the blind test inside or outside, you will not be able to pick which is the ported box.

That is my opinion only because I'm not going to go to any length to prove it, and to actually prove it to you, you would have to do the blind test, which you are not going to do because you think your opinion is right.

As far as I'm concerned your opinion is not correct, and I'm not interested in your opinion on this matter unless you can prove it. Resonant enclosure damping delay has NOTHING to do with the paper, NOTHING to do with this thread called "big vs small driver subs", assuming the big vs small drivers are put in properly designed boxes, and serves no purpose.

 

[just a guy]

Your wrong again. The driver dosnt move the mass of air its moving some mass but also using the force to compress the air, which is non linear, the force increases with driver excursion because the air pressure increases, where is that in the equations you don't understand?

I haven't been wrong yet, if you think I have let's see proof.

Simulators use relatively simple equations to derive Mms and Mmd. There's no need to be overly concerned about air compression, simulators are surprisingly accurate. Do you wish to question how simulators can function if they don't consider air compression expressly? And if simulators can function without expressly calculating air compression and still be remarkably accurate, how do you think it's a factor here? There's probably a million factors that have been simplified from real world to the F=ma equation, so the real world is a bit more complex than a simple equation. That doesn't mean simple equations can't be remarkably accurate at predicting real world response even if they leave out a few little factors that make little or no difference.

And as I mentioned, I don't care about the math in the paper at all, not even a little bit. You can disregard the ENTIRE PAPER except the single zoomed in impulse response measurement. That single measurement covers the entire thesis of the paper and everything you need to know about the subject.

Let's see some proof that there's a problem with the measurement or how it was performed. If you can't do that then you are arguing about nothing.

 

[Crashpc]

Sorry. Now I see. I believe air compression nonlinearity is 1) not major problem for directly radiating systems 2) might get to be large problem, because there is so many minor problems which add up to the overal performance, that it´s not even funny to bring just the one, as in the woofer speed document. It´s hard to stay on topic. Really.

 

[Crashpc]

If you make a ported box that has the same frequency response as a sealed box (with the same driver) - and this is not hard to do - and make sure the port tuning is below 40 hz, ideally 20 hz or lower...

Isn´t that one pretty tight specification (to a place where ones senses don´t work that well anymore)?
How can this one disprove anything? I´m speechless. And I´m done with the arguing. (no, I´m not angry. Coool, chilled. It just seems we don´t agre in anything. Circumstances, facts, situation, usability, nothing).
Have a nice day.

 

[just a guy]

Isn´t that one pretty tight specification (to a place where ones senses don´t work that well anymore)?

That's the whole point, I mentioned it several times in case you weren't paying attention. Keep the tuning low, at least 40 hz or lower, ideally 20 hz or lower, and you will not hear any audible delay. I think I said this 5 times now.

THE WHOLE POINT is to keep the tuning at a low frequency where one's senses don't work well anymore. I think I mentioned that at least twice.

If you tune a ported box higher than 40 hz you will obviously have audible problems, that's simply not good design. And there's absolutely no need or even any good reason to tune a ported box that high.

 

[just a guy]

Sorry. Now I see. I believe air compression nonlinearity is 1) not major problem for directly radiating systems 2) might get to be large problem, because there is so many minor problems which add up to the overal performance, that it´s not even funny to bring just the one, as in the woofer speed document. It´s hard to stay on topic. Really.

1. Absolutely not, not until you get to very high velocities and high spl. Simulators don't have any trouble at all predicting real world performance until systems get pushed near their limits.

2. No it's not a large problem, there are many minor aspects and factors that absolutely can be completely ignored while still coming to a pretty accurate prediction of performance. Simulators are remarkably accurate and there's dozens of things they don't consider at all. It's not until the system is pushed near the limits that the sims become unreliable, especially at subwoofer frequencies.

You might find it easier to stay on topic if you didn't change the topic, which is all you have done here.

 

[Crashpc]

That's the whole point, I mentioned it several times in case you weren't paying attention. Keep the tuning low, at least 40 hz or lower, ideally 20 hz or lower, and you will not hear any audible delay. I think I said this 5 times now.

THE WHOLE POINT is to keep the tuning at a low frequency where one's senses don't work well anymore. I think I mentioned that at least twice.

If you tune a ported box higher than 40 hz you will obviously have audible problems, that's simply not good design. And there's absolutely no need or even any good reason to tune a ported box that high.

Nope. You will not have obviously a problem. For example B&C suggested design of 12".bass tuned at around 60Hz sounds very good, tight and fast even with horrendous GD to frequency ratio, while when you tune it down to 42-45Hz as I did with 12TBX100,.it sounds significantly boomier and not really good. My point is that while you avoid complete problematics by pushing it at the edge of hearable spectrum and call it "done", I would like to dig into detail.

 

[just a guy]

If it sounded great tuned to 60 hz and it sounded "boomy" when tuned lower, the problem is the different frequency response, not resonant damping delay. You can discount the room effects all you want but it very likely sounded better/worse with different tuning as a result of room effects and would sound completely different in different rooms or outside. A sub that sounds "boomy" in one room can sound very "lean" and "tight" in a different room. The room dominates perception at bass frequencies, resonant damping delay is a drop in the bucket in comparison.

As far as I'm concerned, tuning a ported box above 40 hz is simply bad design. You can dig into detail all you like but it has nothing to do with the woofer speed paper or the subject of the "big vs small driver subs" thread. This should be in it's own thread called "resonant damping delay audibility thresholds" or something like that.

 

[Crashpc]

If it sounded great tuned to 60 hz and it sounded "boomy" when tuned lower, the problem is the different frequency response, not resonant damping delay.

As I wrote, the delay to frequency ratio was horrendous. Maybe absolute value of delay is more important. But you wrote that tuned higher, it will sound like that, which was not the case. I had also some 18" ClassA woofers, and these sounded nice and tight, at 42Hz tuning, while the 12" subwoofer didn´t sound that good and tight when tuned at 42Hz. It is not in the tuning itself.

You can discount the room effects all you want but it very likely sounded better/worse with different tuning as a result of room effects and would sound completely different in different rooms or outside. A sub that sounds "boomy" in one room can sound very "lean" and "tight" in a different room. The room dominates perception at bass frequencies, resonant damping delay is a drop in the bucket in comparison.

...jadajada - I discount it completely. I played this subs OUTSIDE, so there is no room problem to interfere.

As far as I'm concerned, tuning a ported box above 40 hz is simply bad design. You can dig into detail all you like but it has nothing to do with the woofer speed paper or the subject of the "big vs small driver subs" thread. This should be in it's own thread called "resonant damping delay audibility thresholds" or something like that.

I would like to listen your opinion in this one. I would guess that MOST SUBS are tuned at, or higher frequency than 40Hz. Not yours obviously, and not mine now (18SW115).

 

[just a guy]

As I wrote, the delay to frequency ratio was horrendous. Maybe absolute value of delay is more important. But you wrote that tuned higher, it will sound like that, which was not the case. I had also some 18" ClassA woofers, and these sounded nice and tight, at 42Hz tuning, while the 12" subwoofer didn´t sound that good and tight when tuned at 42Hz. It is not in the tuning itself.

...jadajada - I discount it completely. I played this subs OUTSIDE, so there is no room problem to interfere.

It's frequency response. I would bet that when you changed the tuning the delay time didn't change all that much but the frequency response changed dramatically.

I would like to listen your opinion in this one. I would guess that MOST SUBS are tuned at, or higher frequency than 40Hz. Not yours obviously, and not mine now (18SW115).

I've built only one sub with a 40 hz tuning and none with a tuning higher than that. It was for someone else. 40 hz isn't nearly low enough to cover the music I prefer.

MOST SUBS are not designed properly and not eq'ed properly and don't have flat or even pleasing in room frequency response, so I'm not worried about most subs.

 

[Crashpc]

It's frequency response. I would bet that when you changed the tuning the delay time didn't change all that much but the frequency response changed dramatically.

Possibly.
What I am interested in, in this discussion, is the parameters/aspect assembly causing problems, and assemblies not causing the problem.
Obviously high tuning itself doesn´t cause boomy sound. 42-45Hz tuning itself doesn´t cause boomy sound, tuning lower doesn´t cause boomy sound.
Flat sounding speakers (outside) don´t cause boomy sound, so it is not frequency response alone, or tuning, or GD alone either.

When boomy sound "happens", It mimics some situation comparable car crash - when more factors add up and work together to cause a problem. It would be nice to have rules written down, which will likely to cause problems. I see no problem walking thin line using higher tuning or whatever, if it works.
The B&C design using about 33-34l box tuned at 60Hz is way too awesome for what it is. It produces great amount of SPL and fast tight upper bass. It´s so compact one can put few of these into very small car to transport it with rest of the rig.

MOST SUBS are not designed properly and not eq'ed properly and don't have flat or even pleasing in room frequency response, so I'm not worried about most subs.

That might be true. But there is this "properly designed" interpretation - it hugely depends on ones intentions. Proper for one situation can be failure for another situation/need.

Tuning a subwoofer for a room is good idea that works well. If I knew this years ago, and If I had different goals then...