Big subs vs Small subs

[Mr. Widget]

Have you tested them? What was it you didn't like?

I built them in 2006. I don't remember if I took measurements of them or not... I had CLIO back then so I probably did. I just remember being impressed by how much abuse they could take, but subjectively I preferred the sound of JBL's 2245s.

 

[sarumbear]

I built them in 2006. I don't remember if I took measurements of them or not... I had CLIO back then so I probably did. I just remember being impressed by how much abuse they could take, but subjectively I preferred the sound of JBL's 2245s.

Can you try to explain subjectively what was wrong with them?

 

[René - Acculution.com]

I am sure it can be measured, demonstrated, even simulated. We just need a correct yardstick. I'm putting my trust @René - Acculution.com to show us some simulation of transients to combine it with his analysis of Room gain and his work I linked in my previous post, and then see what we can learn with respect to this subject. I'm patient, but I'd like to see big vs. small drivers, does it really matter?

In my opinion, it does. I have no means to prove it, so don't take my word for it. But, my personal experience has lead me to believe that displacement is important and that room is equally contributing to this effect, also diminishing it if one's listening position is not in the right place in the room, or setup is not done right with regards to it.

In my room, and only at MLP, the effect is quite interesting. On good recordings of kick drum, and even more so on some EDM and psy trance music tracks with good dynamic range, I get this effect that bass, the very pressure wave is emanating from within my body, around my solar plexus area, right before I can mentally perceive it as pitch. When I try to measure this with a simple FFT analyzer, what the graph makes of it is just a flat transient encompassing a wide range of frequencies, with equal rise time, and only when the decay starts being plotted, I can see which of the main frequencies were contained within the transient. I suppose it also is either not really quick enough to process it, or there's something more to it.

And it certainly does "feel" like so. Just as a basic, physical kick with no apparent acoustic meaning, or pitch, if you will. The audible perception comes very soon, within milliseconds, but it is delayed and somewhat synchronous with room decay. Without a sub, I no longer have flat bass response at MLP, and clearly something is missing to the effect. And this is only a 12" sealed sub.

Knowing how "slow" bass truly is, I believe this has something to do with the wavefront reaching the body, with the correct phase to produce such an effect. If it has to do with it, then I suppose the displacement would matter?

Interesting. I have heard this from clients too. I am actually working on a article about bass port where I do transient calculations, but I am not sure that it will really resolve this. For given Thiele-Small parameters, the sound field should look pretty much the same for a smaller and a larger cone, although locally there will be a difference. But such two different drivers will probably not have the same T/S, so are we assuming that the are equalized to give the same magnitude and phase response? Or does the difference simply come from the two drivers being fundamentally different? Also, the acoustic impedance seen from the drivers will be different, so perhaps there is something there? Not sure...

 

[Mr. Widget]

Can you try to explain subjectively what was wrong with them?

That was almost 20 years ago... I really don't remember the details, but at the time I had 2245s and Sub1500s as well as this commission project and never pursued another project with 2242s.

 

[audiofooled]

Interesting. I have heard this from clients too. I am actually working on a article about bass port where I do transient calculations, but I am not sure that it will really resolve this. For given Thiele-Small parameters, the sound field should look pretty much the same for a smaller and a larger cone, although locally there will be a difference. But such two different drivers will probably not have the same T/S, so are we assuming that the are equalized to give the same magnitude and phase response? Or does the difference simply come from the two drivers being fundamentally different? Also, the acoustic impedance seen from the drivers will be different, so perhaps there is something there? Not sure...

I believe that at normal listening levels there can be no audible difference between large and small drivers, even though them having different T/S parameters. It's about what is "tangible" at higher SPL. Something measurement microphones are hardly able to pick up. It seems that measuring of loudspeaker cone vibration is not trivial:

https://www.klippel.de/fileadmin/klippel/Bilder/Know-How/Literature/Papers/Measurement_and_Visualization_Cone_vibration_06.pdf

There's also a drag force that loudspeaker cone sees and at higher velocity during transients it seems too be very significant. It can be put into perspective with the drag equation calculator . If assumed that both cones are having the same Cd (drag coefficient) and equal velocity, then the drag force would be proportional to the driver's Sd. Meaning, a 15" driver will see a more than double of drag force than a 10" one would. If they are tracking the same input signal at the same SPL, the cones would have to output the same work, but the smaller cone would need to have more acceleration in order to achieve higher excursion at same velocity. The question is how much. Impulse, step response?

On the receiving end, what our bodies are feeling also has to do with acoustic impedance. What I was able to find is about ultrasound, but sound nevertheless:

Acoustic Impedance - an overview | ScienceDirect Topics

www.sciencedirect.com

This is what I found interesting:

The acoustic impedance, z, of a material is the ratio of acoustic pressure to the associated particle speed (Kinsler et al., 2000). It can be shown that for plane waves this is equal to the product of the density and the speed of sound in the medium. The acoustic impedance at 20 °C for air, distilled water, and bone is 415, 1.48 × 106, and 5.3 × 106 Pa s m− 1, respectively (Hatakeyama et al., 2000). Given that the bulk of soft tissue comprises water, it stands to reason that the acoustic impedances of soft tissues in the body are not significantly different from that of water. Adipose tissue does have a slightly lower acoustic impedance due to its lower density and speed of sound. The major exceptions are the lungs, which have a much lower acoustic impedance due to the vast number of air spaces (0.1 × 106 Pa s m− 1 inflated, 1.4 × 106 deflated Pa s m− 1; Oelze et al., 2008), and bone, which has a higher density and speed of sound and thus a higher impedance (4–8 × 106 Pa s m− 1; Laugier and Haïat, 2011).

Would this also apply to low frequencies?

Also, It is considered that both air and water are Newtonian fluids.

While no real fluid fits the definition perfectly, many common liquids and gases, such as water and air, can be assumed to be Newtonian for practical calculations under ordinary conditions.

But nevertheless, the transition between air and water when we jump into it is something we "feel" most definitely. Water can stop a speeding bullet.

I really don't know if all this would apply, or if this even have something to do with sound intensity level, or room acoustics, for that matter. But subjectively it's the transients from larger drivers, rather than smaller ones is what gives me this tactile feel.

 

[Sokel]

Also, It is considered that both air and water are Newtonian fluids.

While no real fluid fits the definition perfectly, many common liquids and gases, such as water and air, can be assumed to be Newtonian for practical calculations under ordinary conditions.

But nevertheless, the transition between air and water when we jump into it is something we "feel" most definitely. Water can stop a speeding bullet.

I really don't know if all this would apply, or if this even have something to do with sound intensity level, or room acoustics, for that matter. But subjectively it's the transients from larger drivers, rather than smaller ones is what gives me this tactile feel.

I thought the same about water analogy in previous post.
As I think of it more what we must consider as proper is not jumping into water.
We must think of it as if drivers are already into water as they are into air.

 

[theREALdotnet]

I thought the same about water analogy in previous post.
As I think of it more what we must consider as proper is not jumping into water.
We must think of it as if drivers are already into water as they are into air.

I urge you to read the warranty exclusions for you subwoofer first.

Kidding aside, there was a thread about quasi-anechoic measurements that cited a very interesting paper about extreme near-field measurement of loudspeakers. I can’t find it in a cinch, but it expounded on the interesting transitional effects from the surface of the cone to the air it pushes. But, I believe, a point was made that past a transitional zone the cone-air interaction can be considered pistonic and conforming to the simple model everybody uses.

 

[Sokel]

I urge you to read the warranty exclusions for you subwoofer first.

Kidding aside, there was a thread about quasi-anechoic measurements that cited a very interesting paper about extreme near-field measurement of loudspeakers. I can’t find it in a cinch, but it expounded on the interesting transitional effects from the surface of the cone to the air it pushes. But, I believe, a point was made that past a transitional zone the cone-air interaction can be considered pistonic and conforming to the simple model everybody uses.

This one?

http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20%281974-04%20AES%20Published%29%20-%20Nearfield%20Paper.pdf

 

[theREALdotnet]

This one?

http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20%281974-04%20AES%20Published%29%20-%20Nearfield%20Paper.pdf

No, not that one, but this is interesting, too.

 

[audiofooled]

I thought the same about water analogy in previous post.
As I think of it more what we must consider as proper is not jumping into water.
We must think of it as if drivers are already into water as they are into air.

What you are saying may not be too farfetched. The physics may not be so complicated after all. The difference in speed of sound propagation through air, liquid and solids is huge:

Sorry for reposting this, but please lower the volume on your headphones, set the playback speed to 0.25 and start playing from 1:53.

What you may notice is how much faster the sound is traveling through solid ground, how it creates wave pattern like disturbances in dirt particles and how camera mic detects and records sound much slower, no sooner than wave propagation through air reaches it. Essentially SPL, what microphones "hear" and our ears hear.

When I think about it, it is no longer strange to me that at home, perceptually this tactile and audibly meaningless feel comes a bit quicker than I can actually hear it and mentally detect it as pitch. I believe that SPL needs to be high enough to excite the solid floor and propagate through it and other adjacent solids in room which are coupled to it. I mean walls and furniture I am sitting on. As in the video, the tactile sensation seems to be distance and frequency related. It does not necessarily decrease with distance the same way as through air because as explained in the first video the intensity losses through solids and liquids are different. But, admittedly I may be completely wrong, in which case, pardon my ignorance.

 

[Andysu]

big large JBL professional cinema subs

 

[Andysu]

 

[Andysu]

 

[napfkuchen]

big large JBL professional cinema subs
View attachment 279411

How can one enjoy audio in such a mess?

 

[theREALdotnet]

How can one enjoy audio in such a mess?

Turn off the light? Close your eyes?

 

[Deleted member 58722]

Turn off the light? Close your eyes?

How can one enjoy audio in such a mess?

Because you don't listen with your eyes?

 

[Kvalsvoll]

In other words the port resonance has lower Q than it normally is? If I’m not mistaken low Q port design was analysed by R. Small on his Ph.D. thesis.

I now show how the port output contributes to the total output here:

T6-A/T6 Compact Horn Subwoofer

The T6 has been around for some time now, it is a great way to fix the bass as long as you do not require earthquake levels, and the T6-A provides both dsp …

www.kvalsvoll.com

This is how it works:

References to another manufacturers product were mentioned, I found the product page, looking for specifications. It is a small sealed subwoofer, and that is about all that can be retrieved of useful information, as the spec is "105dB" and "11Hz". Which leaves the impression of a nonsense product. But this is also a much simpler design, presumably much less expensive, so not really comparable to the T6. Not meant for the same audience.

It is the acoustic loading that gives the T6 its sound character, it is different, and it is very small. So it is possible to make something that is small, and still has at least some of this exciting sound, BUT it can not play very loud. Because size is directly related to output capacity, it is simply not possible to make a very small subwoofer with high output at low frequencies, regardless of what type it is - sealed or ported or horn.

 

[Sal1950]

Pure subjective experience and opinion here.

Adam,
What's the approx cubic foot size of your listening room?

 

[sarumbear]

I now show how the port output contributes to the total output here:

T6-A/T6 Compact Horn Subwoofer

The T6 has been around for some time now, it is a great way to fix the bass as long as you do not require earthquake levels, and the T6-A provides both dsp …

www.kvalsvoll.com

This is how it works:

View attachment 280907

References to another manufacturers product were mentioned, I found the product page, looking for specifications. It is a small sealed subwoofer, and that is about all that can be retrieved of useful information, as the spec is "105dB" and "11Hz". Which leaves the impression of a nonsense product. But this is also a much simpler design, presumably much less expensive, so not really comparable to the T6. Not meant for the same audience.

It is the acoustic loading that gives the T6 its sound character, it is different, and it is very small. So it is possible to make something that is small, and still has at least some of this exciting sound, BUT it can not play very loud. Because size is directly related to output capacity, it is simply not possible to make a very small subwoofer with high output at low frequencies, regardless of what type it is - sealed or ported or horn.

Thank you for this. Interesting. Very wide response indeed. The widest I had seen do far was this:

Sonus Faber Lumina III loudspeaker Measurements

Sidebar 3: Measurements I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Sonus Faber Lumina III's frequency response in the farfield and an Earthworks QTC-40 mike to measure the nearfield and in-room responses. I measured the speaker's impedance with MLSSA...

www.stereophile.com

 

[AdamG]

Adam,
What's the approx cubic foot size of your listening room?

Wide open floor plan. Not absolutely certain but I think I remember calculating it out before to the tune 8,100 cubic feet. Ballpark.

Here is a calculation done at the time: