Proac D48R

Got response from ProAc and Soundorg today and both confirmed that it is the M6 thread size.

Anyone noticed that with the grills left on the D48R, they sound slightly lost in definition, imaging is affected, bass also looses definition. At least this is what I noticed with my D48R with ribbons. The "liveliness" of music simply goes away if you leave the grills "on".I was experimenting with a new position last and discovered this. But with the grills removed, the bliss returned. With the new position I was able to successfully achieve the LEDR Test UP. Also the vocals "lock" in the center now and the music sounds more coherent. Love how the D48S make music!

What you are describing is relevant for almost any speakers I called it ’screening’ affect ,when you are hearing the speakers with the grills on it like you are putting a screen between the twitters and drivers to your ears .The grills are for to protect your speakers from dust or potential damage to the speakers’ components.

This was not an issue when the speaker was new. After 1 1/2 years I notice that any small change to the speaker placement or grill makes a big difference.

Vandersteen and a few others are the only ones I know of who voice their speakers with grills on. I have Vandy Quatro's and the grills have never been off of them and never will be as long as I own them. lol.  I kind of like that part. I have owned Proac's for years and always had the grills off.  Everyone I know who sells them have told me to keep them off.  That's why their beautiful baffle finish is important, lol.