Drunken Thoughts On Bass Reflection

[LewisH]

Hi all, first of all, I recommend everyone completely ignoring this thread because I'm quite "merry". I'm also a novice. However, for those foolish enough to ignore my suggestions, welcome to my poorly thought through nonsense thread. I'm sure we'll allllllll regret what we said here in the morning

Ok, so what I've been pondering tonight is the following:

When you have a bass frequency, the wavelength is quite large. Due to its size, room reflection is guaranteed. Probably even almost immediately. So why not encourage that and pipe the bass output straight onto the floor and assume in the configuration of the speaker that it's reflected? How do we account for that in a speaker configuration? I don't know. I'm a novice. Does it even make a difference? probably. I dunno, I'm a novice.

Ok... 1... 2... 3... now go

I'm sure someone will have something useful to say. Probably that it doesn't matter. Possibly that I should go to bed because I have work tomorrow. Maybe that I shouldn't be drinking wine on a Monday. Well, all valid points... I'm signing out now. Nighty Night!

[billfitzmaurice]

All frequencies are reflected. You may find this of interest: http://ethanwiner.com/believe.html

[LewisH]

Thanks Bill.

...So we ignore it?

[scholl]

Below a certain frequency bass pressurizes the room and becomes omni directional, that's the Schroeder frequency. That comes out to 100-300hz. Starting with Winer's site adding this site Homepage (mh-audio.nl) and reading the Loudspeaker cookbook should arm you with enough information to make you dangerous. LOL

Some subwoofers are downward firing and that increases room coupling. Depending on the room, system and desired bass sound that can be good or bad.

Have fun with your journey.

[billfitzmaurice]

Schroeder frequency is where room resonances dominate, rather than room reflections. Omni-directionality is a matter of the baffle size. Directionally locatable is a matter of the distance between your ears, which must be a significant portion of a wavelength to allow triangulation. Downward firing has no effect on full boundary loading, which occurs when the distance to the boundary is less than 1/4 wavelength, no matter which direction the driver faces.

[charliejone]

Your inebriated ideas on bass reflection may be amusing, but they actually touch on an intriguing idea in speaker design and room acoustics. In fact, reflections can affect how a room's bass frequencies are heard. Low-frequency sound waves are prone to reflecting off surfaces due to their long wavelengths. It's not a typical speaker arrangement strategy to explicitly direct the bass output onto the floor and assume that it will be reflected. Although the floor might cause reflections, it is typically more beneficial to consider the room's overall acoustics and speaker and subwoofer placement to achieve a balanced and accurate sound reproduction.
fnf

[DrewsBrews]

Ever see a video where they excite a plate at different frequencies and pour something like sand on it? It creates different patterns depending on the frequency. Similar thing happens in the room. Dimensions of the room and frequency are what dominate. Where the sound is generated should have an effect, but how do you know what that will do in your specific room?

[billfitzmaurice]

The main concern with long wavelengths is that when the main wave and reflected wave meet at and near 180 degrees apart they cancel. If a sub radiating plane is 1/4 wavelength from the wall behind it a cancellation will occur. If the listener position is 1/4 wavelength from the wall behind him/her there will be a cancellation. Reflections off every surface in the room, including the ceiling and floor, will cause minor cancellations, based on the distance from both the sub and the listening position to said surfaces. Careful sub placement, where the sub radiating plane isn't 1/4 wavelength from the wall behind it and the listener position isn't 1/4 wavelength from the wall behind him/her will help, but the only method to reduce these cancellations to the extent that they're not audible is to use multiple subs, placed in the room so that none of the various cancellations will dominate the overall result.

[AEIOU]

Ever see a video where they excite a plate at different frequencies and pour something like sand on it? It creates different patterns depending on the frequency. Similar thing happens in the room. Dimensions of the room and frequency are what dominate. Where the sound is generated should have an effect, but how do you know what that will do in your specific room?

Chladni Plates.