Speaker grills and sound

[BrentEvans]

So, after the wreck, the grilles on the DRs were trashed (they were mosquito screen) so I replaced them with metal. Had a local fab shop make some from 18 gauge punched steel that has about 50% open area, and they look great. The thing is... when I fired the rig up the sound was off. I had to go back and flatten out the EQ significantly (removing 3-4db from most of the PEQ filters) to get them back in shape... so it seems the new grilles helped the response a bit. This is counter-intuitive to me. Any ideas?

[Bill Fitzmaurice]

Any ideas?

Diffraction. See section 1-5:
http://www.jblpro.com/pub/manuals/pssdm_1.pdf

The lower frequencies pass unaltered, the higher frequencies have to make their way around the metal. The result is somewhat flatter response and wider dispersion, but also some loss of high end sensitivity. An extreme example of the use of metal grilles or vanes to alter response and dispersion was the acoustic lens.
http://www.jblpro.com/pub/obsolete/Acou ... amily1.pdf

The diffusers in our HF arrays work on the same principle.

[BrentEvans]

Well that's awesome then. If there's any loss of HF sensitivity, it's imperceptible. Perhaps the ribbons contribute somewhat to that. The main changes I had to make were midrange (3.5-4k) and there was a big hump at 880hz I had to pull down.

I do believe I've just become a big fan of metal grilles!