What's the point of having different kinds of speakers

[Swerd]

Schroeder frequency, see:

http://en.wikipedia.org/wiki/Loudspeaker scroll down to the section on Placement:
"In a typical rectangular listening room, the hard, parallel surfaces of the walls, floor and ceiling cause primary acoustic resonance nodes in each of the three dimensions: left-right, up-down and forward-backward. Furthermore, there are more complex resonance modes involving three, four, five and even all six boundary surfaces combining to create standing waves. Low frequencies excite these modes the most, since long wavelengths are not much affected by furniture compositions or placement. The mode spacing is critical, especially in small and medium size rooms like recording studios, home theaters and broadcast studios. The proximity of the loudspeakers to room boundaries affects how strongly the resonances are excited as well as affecting the relative strength at each frequency. The location of the listener is critical, too, as a position near a boundary can have a great effect on the perceived balance of frequencies. This is because standing wave patterns are most easily heard in these locations and at lower frequencies, below the Schroeder frequency, typically around 200–300 Hz, depending on room size."

Also see
http://en.wikipedia.org/wiki/Room_acoustics
"The way that sound behaves in a room can be broken up into roughly four different frequency zones:

• The first zone is below the frequency that has a wavelength of twice the longest length of the room. In this zone, sound behaves very much like changes in static air pressure.
• Above that zone, until the frequency is approximately 11,250(RT60/V)1/2 (when Volume is measured in cubic feet and 2000(RT60/V)1/2 when Volume is measured in cubic metres),[1] wavelengths are comparable to the dimensions of the room, and so room resonances dominate. This transition frequency is popularly known as the Schroder frequency, or the cross-over frequency and it differentiates the low frequencies which creates standing waves within small rooms from the mid and high frequencies.[2]
• The third region which extends approximately 2 octaves is a transition to the fourth zone.
• In the fourth zone, sounds behave like rays of light bouncing around the room."

Also see http://en.wikipedia.org/wiki/Manfred_R._Schroeder

 

[highfigh]

Thank you

 

[highfigh]

No references at my fingertips, but Toole's book is my primary reference. I could very well be wrong on the specific terms.
edit:
http://www.soundandvision.com/content/schroeder-frequency-show-and-tell-part-1

Like the spelling of his name?

I think we did discuss this- the definition in the link seems familiar and the chance of the professor not knowing about is nil- he was a Physicist.

 

[Swerd]

Spelled Schroeder – pronounced Schrader.

On a side note, I often see people saying that they want theater or pro-style speaker systems for their home theaters. They mistakenly believe that if its good enough for a large theater, it should be great at home.

The Room Acoustics wikipedia link explains why speaker systems meant for theaters or auditoriums should not be used in homes with smaller rooms. The different room dimensions create different frequency zones.

 

[ARES24]

I have a question; In what order would you prioritize the following?

Speakers
Room acoustics
EQ

 

[Swerd]

I'd suggest this priority:

• Speakers
  
  
• Speaker & listener location
  
  
• EQ – for bass below ~200-300 Hz (I've never bothered trying to calculate my room's Schroeder frequency). Use this EQ sparingly in the form of narrow notch filters to tone down bass standing waves caused by wall/ceiling/floor reflections.
  
  
• EQ – above ~200-300 Hz. If really needed, use even more sparingly than EQ for bass. Better (in my room with my speakers) if not done at all. In my limited experience, this tends to stomp on my speaker's mid range performance, which I happen to like better unmodified. I suspect this varies widely with speakers, room specifics, and listener preference.

 

[AcuDefTechGuy]

I have a question; In what order would you prioritize the following?

Speakers
Room acoustics
EQ

1. Room Acoustics. If horrible, nothing will sound good. Plenty of rugs/carpet, drapes/curtains, soft comfy sofas/loungers and pillows are good.
2. Speakers
3. EQ

 

[zieglj01]

I have a question; In what order would you prioritize the following?

Speakers
Room acoustics
EQ

1. speakers
2. room acoustics
3. EQ - mainly under 200 hz
(I am not a big fan of the EQ game and I do not by receivers
based on their room correction tool)

 

[AcuDefTechGuy]

The only EQ I like is Audyssey Dynamic EQ (I turn Audyssey room correction off).

 

[highfigh]

I saw the response from a bunch of crappy 70V Atlas ceiling speakers in the typical boxes change from terrible to flat in only a few minutes when the system designer came in to fine tune systems when I worked for a contractor in the late-'90s. They told us what to install and where, then came in to tweak and commission the sytems. He used rack-mounted White Instruments equalizers, with no controls on the face or rear- only through the JBL software in his laptop. Sounded very good when he was done and the coverage was incredibly even. While it wasn't for home theater, it was used for voice, music and to accompany video. In the right hands, EQ works. In the wrong hands, it doesn't. However, EQ is NEVER the first line of importance in an audio system. Since those rooms were all carpeted, they had known characteristics but when a system is designed, the dimensions are determined, then the materials, then thee construction methods. This is all done before speakers are chosen and in many cases, the wrong ones are used because not enough integrators think about dispersion patterns and acoustics is the realm of even fewer. However, for the real integrators who are full-service, treatment is considered fairly early in the process. They tend to use certain speakers because they're familiar and out of preference, but they do change if the space requires it.