Bass direction is audible

[audiofooled]

Good stuff !

I have to admit that I've given up trying to analyze the force of soundwaves that are stronger than just hearing.
I just observe room object movements and feel tactile body vibrations.
It's waaay too complicated I think, to be able to model in a real-world space that isn't some very simple geometric form.

It's crazy the way I've seen objects response to cranking tunes...
Like a roll of paper towels unwinding about 1/4 revolution at a time from Alex Clare's "Too Close", mounting around the corner on a wall 20+ft from speaker/sub stack.
Craziest I've ever seen, a huge drop in the middle of Lindsey Stirling's "Crystallize", reached out 35 feet away and opened a kitchen cabinet in the next room mounted up near ceiling, and plucked a single champagne glass down to the ground. Dozen others unmoved. Same song outdoors will make make a 50ft deck handrail and pickets writh like a snake when it hits. Yes, I did say cranking !

I see the same crazy stuff with wave phenoms, watching them on the lake we look out at. Big rolling waves hit walls one way, waves with breaking crests another.
Combinations, all vectored together, are like moguls on the ski slopes, only they are constantly moving as you trying to ride whatever thru them.

The science of waves, vibrations...too much for this old mellon to master. So I just play with, and enjoy them.

edit: PS, have meant to thank you for the track by Smilk you posted some time back. I really like it and it's a good demo song for my rig. Gives guests some real grins.

Cool, thx!

Yeah, my system is tiny in comparison to yours, it's just happens to be very dynamic, as a result of my quest for what I think is good sound. At first, I was surprised about stuff being displaced from where I left them but later on I started to think about it as a form of distortion. Simply lots of stuff rattling around the house. It took me a while but I've found a solution in having the best of both worlds, i.e. not sacrificing any of the tactile force, but all other stuff remaining silent and still, sort of damped when vibrating. Hand rail still vibrates the same but it's silent and outside anyway.

If you think about it, sound waves pass freely through each other in air, but what happens when they hit a more dense obstacle of a different acoustic impedance you gets waves stacking upon one another, forming bigger ones, standing, bouncing and refracting, as you may observe in water. Human body soft tissue impedance may be similar to that of water. I know nothing about ultrasound for medical purposes, but I think I've read somewhere that gel is used for impedance matching.

Bass is big waves, especially bass drops as quick sweeps containing many frequencies. SPL is what we hear, but the energy has to go somewhere. In my room floor was the biggest problem and I was able to measure what happens to be some sort of feedback of energy coming back from the floor and inducing vibrations in the speaker cabinets, no matter how sturdy they are, or the floor, for that matter. It's distortion, just not audible because all the other stuff connected to the floor are louder than that. Only when you manage to get rid of it you realize that in fact it was audible/tangible. Bass simply regains clarity and definition, also bang on correlation in frequency and tactile feel. It sounds and feels like something in between externalized headphones and outdoor bass. But it takes some homework and it's a real pain in the neck setting it up.

 

[gnarly]

Nice one fella. I love your thinking... And am jealous of your ability to be able to move sh** around your domicile with bass/SPL.
Splendid.

I love that I can play loud where I live but reckon I'd have the cops round sharpish if cupboard doors started opening/loo rolls unravelling etc tho, as I live in the city centre.
(Chuffed that I have the potential/gear to do so however.) One day.

Kudos!

Thank you Sir !! It really is fun at times...I watch many guests go wild over the years.

I've been lucky...cops have only been here twice....
Way less than I've deserved...i have some really nice neighbors it seems...

 

[gnarly]

Cool, thx!


Bass is big waves, especially bass drops as quick sweeps containing many frequencies. SPL is what we hear, but the energy has to go somewhere. In my room floor was the biggest problem and I was able to measure what happens to be some sort of feedback of energy coming back from the floor and inducing vibrations in the speaker cabinets, no matter how sturdy they are, or the floor, for that matter. It's distortion, just not audible because all the other stuff connected to the floor are louder than that. Only when you manage to get rid of it you realize that in fact it was audible/tangible. Bass simply regains clarity and definition, also bang on correlation in frequency and tactile feel. It sounds and feels like something in between externalized headphones and outdoor bass. But it takes some homework and it's a real pain in the neck setting it up.

Good points, (along with the rest of your post.)

I've been kind of lucky with subs (bass). My main room is fairly large and spills into more space. So subs work about anywhere without a lot of work.
Biggest problem is sub-to-sub wavelengths that cancel. Reflections less so.

 

[audiofooled]

Good points, (along with the rest of your post.)

I've been kind of lucky with subs (bass). My main room is fairly large and spills into more space. So subs work about anywhere without a lot of work.
Biggest problem is sub-to-sub wavelengths that cancel. Reflections less so.

You're quite lucky, my room get's easily overpowered (even though not that small), but it likes it's windows open

Wavelengths are less of a problem if the subs are not on the same ground plane, hence variety of bass array concepts.

As far as disturbing the neighbors, I guess I'm lucky as well, but there's a gold mine of information if you search for what the pro sound system engineers are doing about deployment of big systems. A lot can be useful for small systems and home audio.

 

[gnarly]

As far as disturbing the neighbors, I guess I'm lucky as well, but there's a gold mine of information if you search for what the pro sound system engineers are doing about deployment of big systems. A lot can be useful for small systems and home audio.

Yep, I've studied the various cardioid sub deployment used in prosound. Been to Smaart training classes with subs set up in the parking lot, for measuring and listening.
Not really much will help with my setup though here at the lake. Heck, if a neighbor calls the cops I couldn't say to the nearest mile who might have called, the way sound travels over water.

I do look to prosound for learning audio science. Seems so very, very far ahead of consumer audio.
Been a student of guys like Keele, McCarthy, Merlijn, Danley, Gunness, SynAudCon, etc, etc...for quite a while

 

[audiofooled]

I do look to prosound for learning audio science. Seems so very, very far ahead of consumer audio.

I agree. They are indeed far ahead in measurements and modelling. It's just that we don't always understand what can be applicable in domestic situation, or have the means to do so.

 

[Keith_W]

Yep, I've studied the various cardioid sub deployment used in prosound.

I had a debate with a friend about whether cardioid subs make any sense in living rooms. I know that they make sense outdoors or in large concert halls. But I am sceptical if they make any difference in a room where the longest dimension is shorter than a bass wavelength. Am I wrong? I would love to hear ASR's opinion about this.

 

[mcdn]

In my experience subwoofer localisation is mainly due to localisation of distortion products. For example a 40Hz tone may not be localisable on its own, but most subs will generate 10% (-20dB) of tones at 80Hz, 160Hz, etc. It's not clear from most studies if the generated tones are free of distortion or not.

 

[Chromatischism]

I had a debate with a friend about whether cardioid subs make any sense in living rooms. I know that they make sense outdoors or in large concert halls. But I am sceptical if they make any difference in a room where the longest dimension is shorter than a bass wavelength. Am I wrong? I would love to hear ASR's opinion about this.

That aside, you also have the loss of output efficiency which makes them less attractive for those with home theaters.

 

[mcdn]

I had a debate with a friend about whether cardioid subs make any sense in living rooms. I know that they make sense outdoors or in large concert halls. But I am sceptical if they make any difference in a room where the longest dimension is shorter than a bass wavelength. Am I wrong? I would love to hear ASR's opinion about this.

Speak to any LX521/LXStudio owner. We are biased but we love our cardioid bass, even though the cutoff has to be around 30Hz.

 

[NTK]

Speak to any LX521/LXStudio owner. We are biased but we love our cardioid bass, even though the cutoff has to be around 30Hz.

Linkwitz's designs are dipoles, not cardioid.

 

[Keith_W]

Speak to any LX521/LXStudio owner. We are biased but we love our cardioid bass, even though the cutoff has to be around 30Hz.

I am sorry, I do not find your answer satisfactory. It's not that I am not open to the idea of cardioid bass (or dipole bass) being beneficial, but I would like to see some convincing theoretical arguments to support the assertion. To me, all that is needed is for the dipole sub to encounter one wall and its no different to omnidirectional bass.

 

[NTK]

I am sorry, I do not find your answer satisfactory. It's not that I am not open to the idea of cardioid bass (or dipole bass) being beneficial, but I would like to see some convincing theoretical arguments to support the assertion. To me, all that is needed is for the dipole sub to encounter one wall and its no different to omnidirectional bass.

You may want to take a look at Olli Kantamaa's master thesis.

Improving Two–Way Loudspeaker Directivity

Compact conventional two–way loudspeakers radiate omnidirectionally typically at frequencies below 500 Hz and the acoustic directivity of increases with frequency. Such loudspeakers couple with room acoustics efficiently at low frequencies, evoking room mode resonances and early reflections...

aaltodoc.aalto.fi

 

[mcdn]

Linkwitz's designs are dipoles, not cardioid.

View attachment 383081

View attachment 383082

Yes, apologies for getting that mixed up!

 

[mcdn]

I am sorry, I do not find your answer satisfactory. It's not that I am not open to the idea of cardioid bass (or dipole bass) being beneficial, but I would like to see some convincing theoretical arguments to support the assertion. To me, all that is needed is for the dipole sub to encounter one wall and it’s no different to omnidirectional bass.

I think the point is that non-monopole bass has its fans, whether cardioid or dipole. Not even Siegfried could get to the bottom of why, but it does seem a topic worthy of research.

 

[Keith_W]

You may want to take a look at Olli Kantamaa's master thesis.

Improving Two–Way Loudspeaker Directivity

Compact conventional two–way loudspeakers radiate omnidirectionally typically at frequencies below 500 Hz and the acoustic directivity of increases with frequency. Such loudspeakers couple with room acoustics efficiently at low frequencies, evoking room mode resonances and early reflections...

aaltodoc.aalto.fi

Thank you. I am unable to read the actual paper, but I found this interesting:

That abstract does not indicate the size of the room. 80Hz has a wavelength of 4.3m. I can believe that if the room dimension is > 4.3m, it may be beneficial from 80Hz up. But so far I have not seen anything that indicates that when wavelength > maximum room dimension, there is any benefit from any non-monopole design. I have deep respect for you, so I am really hoping to be proven wrong here

 

[Theta]

I was sent this article: Auditory Localisation of Low Frequency Sound Sources (Nastassa, Pulki, Makivirta, AES Convention 154 2023). Unfortunately I only have access to the abstract. I have quoted it in full:



Note that the study was done in an anechoic chamber. The lowest frequency of 31.5Hz is about 10m long, surely this can not be audible in an average listening room?

If this study is correct, it would have implications as to how we should position subwoofers in our listening rooms. Maybe Griesinger's "stereo sub" idea may have some merit. Subwoofer positioning schemes such as Geddes' 3 sub method, or two subs in diagonal corners would need rethinking. Opinions?

EDIT: paper is available for download. See @NTK post here.

It amazing to me the number of serious enginiring papers, patents and test like klippel, all good and worth exploring, but the results do not lead to concrete amelioration in electro acoustics. 90% of all speakers are still crap, and the upper 10% at ridiculous cost are still not better then the high end pro speaker of 50 years ago.

 

[jhaider]

I had a debate with a friend about whether cardioid subs make any sense in living rooms.

Maybe (assumption: "sub" = <100Hz) . Such a sub will excite a different modal pattern, and may be better or worse. The same applies to dipole/OB or any other non-monopole.

It will be a lot less efficient than a standard closed box.

 

[Bjorn]

I had a debate with a friend about whether cardioid subs make any sense in living rooms. I know that they make sense outdoors or in large concert halls. But I am sceptical if they make any difference in a room where the longest dimension is shorter than a bass wavelength. Am I wrong? I would love to hear ASR's opinion about this.

Not if you are at liberty with position of the subs. The rooms modes will swamp any directivity, and they all excite the same amount of modes.

However, monopoles, dipoles, and cardioids do trigger room modes differently. So if one is locked to a certain position of the subs, one might do better than the other.

Oh, one reason why some may see less room modes with dipoles is because of less deep bass that doesn't trigger the lowest room modes and thus it's harmonics. Due to the dipole cancellation.

Cardioids and dipoles will have higher distortion than monopoles BTW.

 

[TheZebraKilledDarwin]

I was sent this article: Auditory Localisation of Low Frequency Sound Sources (Nastassa, Pulki, Makivirta, AES Convention 154 2023). Unfortunately I only have access to the abstract. I have quoted it in full:



Note that the study was done in an anechoic chamber. The lowest frequency of 31.5Hz is about 10m long, surely this can not be audible in an average listening room?

If this study is correct, it would have implications as to how we should position subwoofers in our listening rooms. Maybe Griesinger's "stereo sub" idea may have some merit. Subwoofer positioning schemes such as Geddes' 3 sub method, or two subs in diagonal corners would need rethinking. Opinions?

EDIT: paper is available for download. See @NTK post here.

Finally. Very interesting. When I built my HT I followed the usual HT guidelines for sub placement but could not stand the bass. It felt dislocated and smeared at XO80 and very strange (in the studio our subs are placed at LCR). It also did not sound like in a movie theater. When I tried and placed the sub below center it immediately felt correct and sounded so much better (transients, impulsive behaviour, width and depth changed completely). And REW showed a worse frequency response and not much difference in the time domain...
Afterwards thinking about the discrepancy I could have slapped myself, why I was even surprised: Since I was 16 years old and the first time in a club, I had experienced and known, how tremendously the sound quality improves with reduced distance and with the sub directly in front - and not somewhere on the side and further away. Every feet of reduced distance is audible. Additionally I even had known for a long time that in theatres LCR speakers do not have their channel subs somewhere in the room, but @ LCR. And still I ignored all that.
That was a great lesson to me.