Experience according to T/S parameters and more

+1 I made that very same mistake trying to save a couple dollars no more from me

... And now, sorry for the doublepost, I needed to divide long answer from the troll flame. Kidding.

Elliot: Sounds like you know something, it just sounds to me the way I wouldn´t understand it the right way if I was beginner. Lets se each "problematics":

Elliot Thompson wrote: What you are suggesting is a compromise in which the majority of builders do everyday. Those builders never mentioned the consequences of making such compromises from a performance standpoint in which I am bringing to your attention. It is not the loudspeakers fault the designer cannot accommodate the woofers requirements in order to achieve optimum performance

Never suggested this.
Speaker requirements are dependant greatly on the whole bunch of parameters. And Vas parameter is not alone, which needs to be evaluated in the system. See horn-loaded systems, or even some manufacturers designs of compact vented systems and free plans. These greatly deviate from what you would expect with certain Vas parameter value, and these are not matching the Vas values yet still achieve great results.

Once you have different motor strenght and quality, the enclosure volume also needs to be very different (even with the same Vas value). Also your intentions might move with your plans for outcome. For example having less response/sensitivity in the low bass can be handled for the smaller box, or even greater sensitivity in the upper bass and greater power handling, because cone of the speaker will not hit the excursion limits. You also get better group delay response. It only depends on how do you want to design your system, and it is not instantly bad or wrong to choose the other way. Frequency response is not alone to be set, It needs to be decided and checked with many more parameters at once.  Once frequency response is the only aspect you look for, I can see why you like bigger enclosures.

Elliot Thompson wrote: The end result is either having a box ring like a bell or offer no bass without a heavy dose of equalisation.

This can be true, or also can not. Depends on more things than Vas parameter.
For example If I simulate 15TBX100 in 60l box, even tho it has over 100l Vas, it will do it´s job down to 40Hz, which is perfectly usable for many people. Equalisation on the bottom end is not a problem. At tuning frequency, the cone movement is very low, and modern speakers handle 1000+Watts of power. That is the intention. See how RCF bass bins are tuned (undertuned). They absolutely expect you to boost it.



Edited by Crashpc - 11 June 2016 at 12:24pm

Ok, now seriously, how do we do it civilized way to not quote each other to death?

I´ll try to..

The compromise - it is generally compromise, but absolutely not frequency response compromise to the box. The reason is obvious. The box volume in certain tuning is what sets maximum sensitivity and output power down there on the bottom bass. No matter what speaker you stick in, there is a limit. With modern speaker, the limit is almost reached, when you don´t f*k things up. So with proper larger speaker, you WONT loose any bass you would have with smaller speaker, and also you gain on other parameters. I will support this on real speaker later in text.


Not knowing frequency response of the speaker without measurement is pretty normal outcome when you don´t measure. What is the point of this? The text you wrote after makes sense, but is only haf of the truth. Also motor strenght and speaker construction will make great changes to this. As I wrote - specifically designed "horn loading" speakers are made with higher Vas value on purpose, and they´re stuck into small chambers for best output. And the output is higher than what ported enclosures give us ==> not a compromise in this regard.

Now, for the "no bass" mistake. See the comparison in the picture below:



B&C 18SW115 vs B&C 15BG100 Both in the same enclosure.

15BG100 is matched to the enclosure as you say, 18SW115 has no bass. Right. Funny.

Here are disadvantages of the larger speaker:
It costs more.

End of disadvantages topic. You could argue about need for equalisation, I tell you what - in room, you need it anyway, even with flattest response speakers.

Now advantages:
Higher sensitivity.
Less power.
Less cone movement.
Less distortion.
Greater maximum output.
Better phase response and obviously GD.
Newer manufacturing technology - goes without distortion to greater cone excurstions.
Better thermal handling - more magnet/basket mass, larger voice coil and smaller enclosure is actually better cooled with ports.


Now to the burning thing which really grinds my gears:
There is no general rule to this, you cannot simply say speakers in smaller enclosure just burn.
Yes, some applications are more prone to it. We are clever guys, we do clever designs, and part of it is thinking about cooling and handling the device so it doesn´t burn. You cannot just discart every horn loaded system, because all of these work in small chambers.

For the cooling of port loaded enclosure: Again, you just need to do something about it, but when you do, you will be able to exploit speaker capabilities without hitting thermal limits in a way you describe.
Firstly, smaller ported box is cooler. It has less air in, so it will change for cooler air faster. The speaker magnet will have cooler air available. It still doesn´t solve cone excursion, right?
Well, for power applications, you just set your low-pass filter lower, so the cone will start to move!
The reward will be lower bass extension, where smaller speaker cannot get, due to cone excursion.

You could again argue that when you don´t have this low bass in music, and run some bass frequencies around port tuning, all this will not help, cone will not move and it will burn anyway, right?
Here is the answer: If one of these burns, the other one will too. Both speakers will have coil ends hanging away from the pole piece and cooling "position". No advantage of higher excursion speaker cooling here. But remember, the larger speaker has larger and meatier voice coil, and propably even some newer cooling techniques implemented. And provides more bass for less power, so you don´t have to push it so much anymore. Pushing less power to the larger coil doesn´t mean what you suggested - burning. But the opposite. Less power compression. Less power again, more output or cooler running again and again.

I still didn´t see anything, what would convince me about your points.
If you want me not just to argue but agree and understand, please feel free to bring in some real life scenario and real speakers. We might get to your points in a more constructive and positive way. Also we might bring each points separately, look at it closer, and make some better than general conclusions. If you have the nerve, don´t hesitate to stand your ground proudly, I still have things to learn, and this is healthy discussion about nice technical stuff. You might be right. If you feel we spam it here, don´t hesitate to use PM.

// I have no idea how this can work. Here is the deal:  My box is tuned at 33Hz. I don´t hear anything under 28Hz, which could mean normal thing - accoustical short under tuning, or my ears are not good for lowest bass. Anyway even in this deep accoustical short at 12Hertz, the floor where it stands is pretty calm, but the ceiling is shaking, ceiling light rattling. Shaking power down to 12Hz. How come? Is there anything about BR enclosures  behavior under tuning frequency I don´t know yet?

Anyway, thank you for great discussion.


Edited by Crashpc - 12 June 2016 at 8:02am

Your picture is false.

Heh, no, the image was not made up artificially to cheat on you guys. Don´t dig yourself a hole with this argument. It is simulated SPL response from both speakers with no altering or cheating.

You should normalize the levels say in 500 Hz for example to see the real differences.

On that I cannot agree. Why should I do that?
Isn´t speaker system made to achieve certain goals, for example certain sound pressure level at certain frequency? Well, both speakers reach the goal, except the bigger one can get input power lowered for frequencies higher than 35Hz. Again, less distortion, les cone movement, less power= less heat, the larger system has better GD and more. There is no harm to the bigger speaker done.

They have same level at 30Hz when larger driver is 3-4dB louder.

Yes, What a catch! Now you focus on it, because it is the detail I´m about. :-)

Hence it will sound like it has less bass, as it does have less bass than the yellow one.

Yes, unless you do your equalization which you need to do in your room ANYWAY. And so we count on that there will totally be some equalization. The point is that larger speaker doesn´t output less SPL than smaller speaker in the same small volume. This claim is debunked right there, The speaker can be then let to output more of the upper range, but it can be avoided easily too. But in the meantime we get so many benefits in other parameters from the large speaker, that it´s not even funny.

Full of assumptions without actual relevance to reality.

Oh, sir, rest assured, that my speakers at home (18SW115 is one of these) which I´m now listening to, are very real. Do you have anything supportive and real for this claim or just blaffing?

Depends so heavily on driver.

Absolutely. I claimed this before you did, and I also encourage my oponents to bring some of these to prove that in certain scenarios, my way is not only way. I even believe in their/your way. I just see no supportive data, no real outcome, and absolutely not generality in the other way people want to suggest, and call it a general way. That I call blaf and nonsense. Not that they cannot be right for particular scenario, They can. See next quote.

Faital 18HP1060 and 15HP1060 use same plateset and same voice coil. Hence it is an example which against your list made it completely invalid argumentation.

Nice example! And I agree. This can happen. What should not happen is people jumping on somebody who uses speakers which are out of your example. :-)

But don´t think I don´t have devil intentions - I would compare those different way. How about 15" model in 70l 45Hz BR box and 18" model in 80l closed box (I take about 10l for good bassreflex space taken out of the BR box). Yes, from 40 to 60Hz, the output SPL would be certainly significantly higher for smaller speaker and there is no denial. There is also no denial that the larger speaker would output more in larger box in this situation. But the distortion, transient response, GD, would be way too superior to the smaller BR box. If you watched some hi-fi crazy people on other forums, they put 21" speakers into closed boxes, and pull 10Hz from it (for hi-fi usage, 105db maximum would be okay). Don´t tell them to use smaller system with bassreflex. It´s all about intentions and performance aspects one is about.

You also don't EQ the bass because of the room. You just don't. When you understand how to tune a system, you understand what you can deal with and what you can't.

On that I would disagree. I do use it for room equalization. It is free solution for few of the problems.  I understand the problematics enaugh. Of course, there is other solution. Damping, bass traps + multisubwoofer application to solve it all. But you need to make your processing anyway, it costs quite some money. You have to set your room for acoustical performance, but in real life, it might be a kitchen (not doable normally), so you don´t have this choice. And it is out of equation in our discussion about the box alone I guess. We´re talking about speaker enclosure response. How do you want to solve steep 8 db peak/dip of the room at 63Hz with single bass cab other than with eq, that I don´t know. Would like to learn that magic (never seen even in magicians solutions).

Your comments about cooling are also with lack of knowledge and understanding. There is no simple model on how cooling works, it depends on where your ports are and how laminar they behave.

Keep civil. We´re speaking technical stuff about speakers. Not personal stuff. I didn´t call you something, so be cool. I will not respond to posts like that again. Completely. I´m out of flame discussions really soon.

Of course there is no simple model and it all depends. But you have it the other way around. The burden of proof is on you guys. You actually claimed that the speaker in smaller enclosure will rather burn. What a drag..

I haven´t heard from professionals about single situation of speaker burned just because the ported enclosure was smaller. When you´re hanging in that situation, It´so reckless driving of the system, that It will burn sooner or later anyway.

It doesn´t matter much if the air flow is laminar or turbulent in the BR port once the flow is similar in amount, and the air somehow gets to the speaker to cool it. The coil doesn´t care what´s around the speaker basket once the air moves there. The motor has its own forced cooling system, so it is close to not-dependent on the outer space once it has air changed. Only absolutely sealed and small horn enclosures positively suffer from this fenomenon. That can be taken as a fact. Nothing more.

Larger coil of my speker, larger basket, and less power to the more sensitive speaker, it´s all brute facts, helping to keep the speaker cooled down. Please do me a favor, attack it in a civil way with technical data and proofs. Don´t argue with non-facts as you did, Pasi...




Edited by Crashpc - 12 June 2016 at 11:41am

Edited by bob4 - 12 June 2016 at 11:46am

Crashpc wrote: Ok, now seriously, how do we do it civilized way to not quote each other to death?

The most we can do is focus on key points.

Crashpc wrote: Not knowing frequency response of the speaker without measurement is pretty normal outcome when you don´t measure. What is the point of this?

The measured frequency response in free-air will allow you to see if the driver is efficient at the given frequencies you are aiming to reproduce. It also tells you if the limiting factor is the loudspeaker or enclosure if you choose to mount the loudspeaker in an enclosure that is smaller than the VAS requirements of the driver.

Below is a measured spot frequency response of a 15-inch woofer in free air from 5 Hz – 10,000 kHz

The free-air frequency response measurement shows the true frequency response of the driver with no obstructions. It also shows that the loudspeaker is relatively flat from 200 Hz – 27 Hz before the driver naturally rolls-off (below 27 Hz) based on its limitations in free-air. If this driver is mounted in a reflex cabinet and cannot offer the same kind of frequency response in the enclosure as it will in free-air, it means the VAS requirements of the loudspeaker is greater than the enclosure can accommodate.

Bear in mind WinISD cannot offer a loudspeaker’s frequency response in free-air. It can only give you a frequency response once a cabinet comes into play. So you are at the mercy of the cabinet’s size to determine the frequency response. This is why VAS is a primary parameter. If you do not know the VAS, you will never know if the woofer is giving you optimum performance or not.  

                                                              

Crashpc wrote: Now, for the "no bass" mistake. See the comparison in the picture below:

The picture is not matched. It is easy for a speaker to play 100 Hz than 50 Hz much less 25 Hz. This is why many rely heavily on HPF.

Crashpc wrote: Now to the burning thing which really grinds my gears: There is no general rule to this, you cannot simply say speakers in smaller enclosure just burn.

This is what I said;

Elliot Thompson wrote: What will happen is the voice coil is going to overheat and burn because the minimum excursion taking place will not be able to cool off the voice coil fast enough when faced greater power handling under long term conditions. The majority of loudspeakers reconed are based upon thermal damage not mechanical damage.

Crashpc wrote: Now advantages: Higher sensitivity. Less power. Less cone movement. Less distortion. Greater maximum output. Better phase response and obviously GD. Newer manufacturing technology - goes without distortion to greater cone excurstions. Better thermal handling - more magnet/basket mass, larger voice coil and smaller enclosure is actually better cooled with ports.

One more time…

Elliot Thompson wrote: What will happen is the voice coil is going to overheat and burn because the minimum excursion taking place will not be able to cool off the voice coil fast enough when faced greater power handling under long term conditions. The majority of loudspeakers reconed are based upon thermal damage not mechanical damage.

You cannot cool the voice coil without a good amount of excursion if your goal is greater maximum output.

Crashpc wrote: Firstly, smaller ported box is cooler. It has less air in, so it will change for cooler air faster. The speaker magnet will have cooler air available. It still doesn´t solve cone excursion, right?

Real world situation

You entered a club 10 p.m. The air conditioner was set at maximum. You are the only one on the dance floor. At 2 a.m. the dance floor is so packed you are bumping into other people. The air conditioner was set at maximum. At what time was the dance floor the coolest?

 

Crashpc wrote: I still didn´t see anything, what would convince me about your points.

I did not see anything that proved to me you have any experience under real world conditions. You are showing simulations on WinISD and not realising that simulations are based on a perfect world in which, you and I do not live in.

Crashpc wrote: If you want me not just to argue but agree and understand, please feel free to bring in some real life scenario and real speakers. We might get to your points in a more constructive and positive way. Also we might bring each points separately, look at it closer, and make some better than general conclusions. If you have the nerve, don´t hesitate to stand your ground proudly, I still have things to learn, and this is healthy discussion about nice technical stuff. You might be right. If you feel we spam it here, don´t hesitate to use PM.

You are more

Edited by Elliot Thompson - 13 June 2016 at 12:03pm