If your BH is without a hexagonal tweeter, my advice to you is to get one now.
For Belara BH, the first thing that I asked my workers to carry out is to install a hexagonal tweeter.
It must be directly above the main entrance hole and about 2.5 feet - 3 feet above the monkey house roof top.
For Belara the best position is above the apex of the two roofs.
The height chosen was about 2' 10 inches.
Immediately after its installation I insisted that the roof extension about the main entrance hole to be shorter.
Main reason being to get a much wider flying areas of those birds when they approach the hexagonal tweeter.
You will boost your BH exposure by at least 4 times as compared to not having one.
The Belara case is one of a good example.
The moment the external sound is played for the first time you can see those birds flying at the back will start to fly towards the BH.
They used to pass by at the back and was never interested to fly to the BH since there was no external sound pulling them over.
Now all the sides are with external sound.
A sudden change in sound distribution and obviously there will be a sudden surge of birds coming over the main entrance hole.
I noticed that they not only arrived in bigger numbers but many will attack the hexagonal tweeter.
Every bird that came to inspect the BH on a daily basis will increase your chance of hooking them as your permanent tenant.
I did the same at Bukit Besi a few month back and right now the flying path of birds to that BH is coming from 360 degrees.
It used to be only on the front side of the building.
Trust me on this and try to assemble one and quickly install at your BH roof top.
Have a look at some pictures taken when the tweeter was installed.
Also when those asbestos roofs were cut and removed.