Home
AudioAsylum Trader
High Efficiency Speaker Asylum

Need speakers that can rock with just one watt? You found da place.

For Sale Ads

FAQ / News / Events

 

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.

You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login


Login to access features only available to registered Asylum Inmates.
    By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username:

The Name that you picked or by default, your email.
Forgot Moniker?

 
 

Examples "Rapper", "Bob W", "joe@aol.com".

Password:    

Forgot Password?

 Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:  
Your Email:  
Subject:  

Message Comments

   

Original Message

RE: really? do the math (it's easy!)

Posted by tomservo on March 6, 2017 at 10:09:53:

Hi
The issue is "where does the reverberant field begin".

Picture a low frequency one below the lowest room mode, at these frequencies your room is a leaking pressure vessel and this "containment" of the bass pressure is the only free lunch in audio, "room gain".

Be aware too that a flexing wall or floor etc is also a diaphragmatic absorber and a sink hole at that frequency.

AS soon as you increase the frequency past the first mode, one is in the modal region where a measurement easily identifies large peaks and dips in the response in the room.

The larger the room, the lower the first mode is and the more numerous the modes are as you go higher up. With a large enough, live enough room one can reach the critical distance and the reverberant field at that point no longer has large peaks and dips, the modes are so dense they have averaged out. There is zero voice intelligibility as well as the time information has been completely scattered and all is left is a noise with the same power spectrum as the acoustic power of the source.

That condition is pretty normal in very large spaces and when public address announcements are barely intelligible as a result of the direct sound not being high enough over the "noise" or reverberant sound.

At the dimensions of a living room and typical loudspeakers it is usually the specular reflections close to the loudspeaker which harm imaging the most, and the side walls are often the source.
One way to "see" where absorption will help is to place a mirror on the wall where you can see the tweeter of the closest speaker from your sweet spot and then replace the mirror with a sound absorbing panel, do both sides..
Remember that critical distance and rt-60 are all terms that were originated for and apply in large scale acoustics and do not apply where the modal density is sparse.