Fact or Crap? There is no replacement for displacement.

[Kvalsvoll]

Question. It's this due to "turbulence"? I mean, non-linearities of the fluid dynamics?

Yes, non-linearities are the reason. As velocity increases, the resistance to flow increases, and this is a non-linear effect. And a small, narrow aperture is worse - narrow channels compress and distort more for same velocity compared to a wider. And at the mouth there will eventually also be problems with too high pressure.

These problems sort of multiply as you go lower in frequency. Also, since the threshold of hearing drops for very low f., it is no point in being able to reproduce those low f. if max spl is too low to be of any practical use.

The consequence of this is that while a very small subwoofer can be made to play the required around 30hz at sufficient level for quite normal-loud levels, the size multiplies when you want full frequency range and full spl capacity.

 

[sarumbear]

Then we see that all practical acoustic transmitters will behave similar for low frequencies, as they are all small compared to wavelength.

The question asked by the OT is on possible difference in low frequency sound quality between small (5-6") and large (12-15") bass drivers. If they all behave the same way what is your point? All woofers are small compared to the frequencies they will work at.

While the intensity is a measure of how much energy is transferred, it is the p(pressure) we hear.

You cannot hear the pressure as it is static. We hear the sound wave, which is is the pressure deviation from the atmospheric pressure.

 

[mhardy6647]

Old audiophiles are like cat ladies, only with subs.

(screenshot from audioasylum)

 

[mightycicadalord]

I voted yay on no replacement. Probably one of the easiest things for me to test. Provided two speakers don't have major issues the larger one will always sound better to me.

 

[Kvalsvoll]

The question asked by the OT is on possible difference in low frequency sound quality between small (5-6") and large (12-15") bass drivers. If they all behave the same way what is your point? All woofers are small compared to the frequencies they will work at.

You cannot hear the pressure as it is static. We hear the sound wave, which is is the pressure deviation from the atmospheric pressure.

A larger driver will make a difference already approaching 100-200hz, and this range is very important for bass definition and tactile feel.

The p(pressure) varies with the signal, it is not static, static pressure is usually omitted in acoustic models, as the static pressure has no significance before entering extremely high pressure (spl) levels.

 

[sarumbear]

A larger driver will make a difference already approaching 100-200hz, and this range is very important for bass definition and tactile feel.

The p(pressure) varies with the signal, it is not static, static pressure is usually omitted in acoustic models, as the static pressure has no significance before entering extremely high pressure (spl) levels.

So you posted an agreement to what I said, which is the opposite of what you said previously???

 

[Kvalsvoll]

So you posted an agreement to what I said, which is the opposite of what you said previously???

I had to go back now, and read. Your post #32 sums up the essentials quite well, as I see it. Nothing wrong there. My point on the radiator surface making a difference is just adding more information about this detail.

And it makes a difference, for bass frequencies, just not for the lowest bass below say 60hz or so.

One system I set up with a larger main speaker with 12" in back-loaded horn, this speaker rolls off the low bass so everything below 40hz is lost. I added a bass-system with 2x very small subwoofers with 6" drivers. This system had nice tactile feel and slam, and could play loud, on normal music with moderate low bass. Crossover was 80hz. If the bass-system had 12", and the main speakers has 6", this would not be a great experience.

 

[dc655321]

A larger driver will make a difference already approaching 100-200hz, and this range is very important for bass definition and tactile feel.

How would this (bold) difference between large/small drivers be measurable? Velocity microphone?

 

[Kvalsvoll]

How would this (bold) difference between large/small drivers be measurable? Velocity microphone?

You can measure it with a normal omni measurement mic, because this relates to directivity, which again shows up in early reflection level. The larger speaker will show a reduction in early reflections, compared to a small one.

 

[ThatM1key]

I had 2 pair's of speakers that had similar bass output technically, A KLH 900B (8 inch) and a Realistic Minimus 7 (4 inch), Both can hit 50hz and literally had the same magnet size. Although the 900B was pure garbage, you didn't need to touch the bass knob versus the Minimus 7, where you needed to crack the bass to max, just get something good. It was almost a replacement for displacement situation.

In which situation, who would blow up first? The KLH 900B ironically enough. I blew up a 900B speaker accidentally, I got gutted it, threw away the parts and used it as a drink holder and as a outdoor chair. I didn't even use close to 50 watts worth of power to them. I have 4 pair's of Realistic Minimus 7, and I initially wanted to blow one dying pair up. Let me tell you, they were pretty damn tough and I never managed to blow them up, apparently 50 watts is nothing to them.

I still believe that a cheap cheap 12-15 inch partsexpress woofer can bass lower then lets say a Polk 6.5inch woofer, but your giving up a lot of quality for that bass perk.

 

[audio2design]

Funny enough similar for cars and speakers. It is all about how much air you move. In a car, you can move air through displacement, RPM, or compressing it (turbo/supercharger). In a speaker, size and throw.

 

[dc655321]

You can measure it with a normal omni measurement mic, because this relates to directivity, which again shows up in early reflection level. The larger speaker will show a reduction in early reflections, compared to a small one.

Thanks.
Your response is a little surprising given that tactility and definition imply vector properties (at least to my mind).

 

[sarumbear]

I had to go back now, and read. Your post #32 sums up the essentials quite well, as I see it. Nothing wrong there. My point on the radiator surface making a difference is just adding more information about this detail.

And it makes a difference, for bass frequencies, just not for the lowest bass below say 60hz or so.

One system I set up with a larger main speaker with 12" in back-loaded horn, this speaker rolls off the low bass so everything below 40hz is lost. I added a bass-system with 2x very small subwoofers with 6" drivers. This system had nice tactile feel and slam, and could play loud, on normal music with moderate low bass. Crossover was 80hz. If the bass-system had 12", and the main speakers has 6", this would not be a great experience.

I do not see what is this related to the topic. You have a horn speaker with a limited low frequency response and you added a subwoofer using small drivers. Do you mean to say large drivers are better suited for mid-bass and low drivers are better suited to sub-bass???

 

[Hiten]

Hope I am not off topic. Even if 5 or 6 inch driver plays low with suffecient level, wouldn't IMD be concern ?

 

[sarumbear]

Hope I am not off topic. Even if 5 or 6 inch driver plays low with suffecient level, wouldn't IMD be concern ?

Why do you think IMD to be any concern on a band limited driver?

 

[Hiten]

Why do you think IMD to be any concern on a band limited driver?

I thought if one is using 5 or 6 inch (2 way) than IMD would be of concern ?

 

[sarumbear]

I thought if one is using 5 or 6 inch (2 way) than IMD would be of concern ?

I read what you said. I was asking why do you think it will be a concern? What is your criteria or reason of concern?

 

[Hiten]

I read what you said. I was asking why do you think it will be a concern? What is your criteria or reason of concern?

for ex. whatever range (Band limited) the woofer is supposed to have in a 2 way the lower end of that range would cause distortion in upper part of that range. Or is it that it will not be audible ? thats what I want to know.

 

[sarumbear]

for ex. whatever range (Band limited) the woofer is supposed to have in a 2 way the lower end of that range would cause distortion in upper part of that range. Or is it that it will not be audible ? thats what I want to know.

As far as I am concerned IMD in a speakers is not a factor. THD is way too higher a value. You can read more about IMD tests in this post.

 

[Hiten]

As far as I am concerned IMD in a speakers is not a factor. THD is way too higher a value. You can read more about IMD tests in this post.

Ok will go through it.
regds