You can conquer the problem of scaring newcomers away by dividing the community into groups of 150 people.
Instead of a 1500-member community, aim for 10 smaller, tighter, communities of 150 members.
The first 150 people to join become Community 1. The door is closed behind them. Only they can open invite new members now. They become a closed unit. The second 150 people to join become the second community, and the third 150 become the third community. etc…
This solves the problem of scaring newbies away, without annoying patronising your current members. Your community is open to benefit newcomers, but closed to benefit your members. Each smaller community might form closer relationships. You might even be surprised by the productivity of 10 online communities working in parallel.
Better still, you can try different strategies on different communities.
Why not give it a try?