Subtracting from a SUM range by the number of positive entries returned?

So I have a Formula like this:

=SUM(SUMIF(A1:A10,">0")-B1)

But I want to subtract the value of B1 multiplied by the number of positive retus from the A1:A10 range.

For example, if only 3 entry's in the rage are valid, I minus by B1 three times.

Any ideas?