  The symplectic blob algebra $b_n$ ($n \in \mathbb{N}$) is a finite
dimensional algebra defined by a multiplication rule on a basis of certain
diagrams. The rank $r(n)$ of $b_n$ is not known in general, but
  $r(n)/n$ grows unboundedly with $n$. For each $b_n$ we define an algebra by
presentation, such that the number of generators and relations grows linearly
with $n$. We prove that these algebras are isomorphic.
