Recess on speaker boxes

[legswilly]

I can see the speaker boxes recessed to accommodate the speakers. Is there a reason for this? Does it make a difference to the sound? Using MDF it is easy to do, but say in granite or concrete it is more difficult.


Why would I like to build in granite. I like the look of it and so does the wife.


Thank you for replying.
Werner

 

[ugly woofer]

One word ....diffraction.

 

[Galu]

The benefits of a solid granite enclosure may outweigh the increased risk of diffraction!

If you are not aware, some of the sound bends (diffracts) around the raised surround of a driver and causes a 'disturbance' when added to the direct sound from the driver.

The effect may, or may not, be noticeable depending on the thickness of the driver mounting plates. The thinner the better in your case.

 

[Galu]

Here's more specific information:

Sound waves that bend (diffract) around the driver frame and then reflect off the baffle can interfere with the direct waves from the driver causing peaks and troughs in the sound.

However, the frame would have to be quite thick for that to be of consequence. It's more of an issue with tweeters that produce very short wavelengths than with woofers or midrange drivers.

 

[garrbage]

The benefits of a solid granite enclosure may outweigh the increased risk of diffraction!

If you are not aware, some of the sound bends (diffracts) around the raised surround of a driver and causes a 'disturbance' when added to the direct sound from the driver.

The effect may, or may not, be noticeable depending on the thickness of the driver mounting plates. The thinner the better in your case.

To my view granite have very little (if not at all) benefit as a material for a speaker boxes.
Recessed drivers - for all woofers and most mids, excluding rare 4 or 5 way, difraction from the basket edges is irrelevant as out of range. It is somewhat important for twitters, you may see up to about 1dB picks/dips here and there on a spl curve. I think Zaph or Troels Gravesen had written about it
I recess all of the drivers as it is more aesthetically pleasing, and even for thick woofer frames recessing something 10mm on a 8-10-12 inch woofer or 4-5-6-8 inch mid doesn't do much for phase alignment.