How grills affect?

Back again. I did a late night listening comparison with my Thiel CS1.5s. Since I had to keep the volume down, I can't say much about the anti-diffraction properties of the grilles. (I'm really not sure I could ever evaluate those properties.) However, the speakers did sound better to me with the grilles off, more detail and spatial cues. I took a close look at the 1.5 and 2.3 grilles. I put them against a light and also did the "breath test." They look like they could have been designed better. It seems there could have been less grille material and more space for airflow. When blowing into the grilles, there is a good bit of resistance to airflow. I can't imagine that these grilles could possibly be "acoustically transparent." I suppose that more acoustically transparent grilles become less effective as dust covers and visual blocks.

I think that with my Thiel CS2.3s, the grills have some very small effect on the low-level detail in the music.

Good thought Leoturetsky. I was only thinking about the rounded edges for anti-diffraction. I suppose the grille material could also be part of the scheme.

I like the way JM Lab Utopia series does it. the "speaker grilles" are actually solid wood "speaker protectors." They are to be put in place so that the maid can come through the room and clean things up without damaging the speakers. Of course, this would work well for women and children also. So, obviously, with these speakers you would remove the grilles for listening.

The Thiel CS1.5 grille is unique in that it actually has a sizeable rounded wood frame which gives the front of the speaker ALL of its anti-diffraction properties. In other words, without the grilles in place, the front of the speaker has no rounded corners at all. The Thiel CS2.3s are not like this and I'm sure that very few speaker grilles are designed this way. I never thought about it but the CS1.5 would be a good speaker to experiment with to see if the rounded shape actually makes an audible difference. I have my CS1.5s set up as my main speakers right now so I will try to do this experiment and post some results in the next day or two.