Developing speakers is pretty labour intensive, and even most larger speaker companies don't have their own anechoic chamber (we certainly don't). That said, I am lucky enough to live 20 minutes drive from the Seas factory, and they DO have an anechoic chamber. So we use that extensively during our development.
In addition to that, measurements outside is another useful approach:
Here is a groundplane measurement showing a pretty even bass response from the Saranna. The crossover to the coax is at 170hz, as one can see it's pretty seamless.
I've also built a certainly-not-anechoic-but-still-reasonably-accurate corner in our workshop with quite a bit damping. Comparing it to measurements from Seas, it is probably around +/-2dB down to 100hz. From around 4-500hz and down to 100hz, it shows a level that is probably 1-2dB too low.
Here is the Saranna measured in that corner. The on-axis response is somewhat untidy, while at 15 degrees it is pretty okay.
On-axis:
15 degrees:
![1713517494710.png 1713517494710.png](https://www.whatsbestforum.com/data/attachments/119/119889-89b501ef7ab0dbd6cf6c7bfb2f7b4373.jpg)