  We define a quantum loop group $\mathbf{U}^+_Q$ associated to an arbitrary
quiver $Q=(I,E)$ and maximal set of deformation parameters, with generators
indexed by $I \times \mathbb{Z}$ and some explicit quadratic and cubic
relations. We prove that $\mathbf{U}^+_Q$ is isomorphic to the (generic, small)
shuffle algebra associated to the quiver $Q$ and hence, by [Neg21a], to the
localized K-theoretic Hall algebra of $Q$. For the quiver with one vertex and
$g$ loops, this yields a presentation of the spherical Hall algebra of a
(generic) smooth projective curve of genus $g$ (invoking the results of
[SV12]). We extend the above results to the case of non-generic parameters
satisfying a certain natural metric condition. As an application, we obtain a
description by generators and relations of the subalgebra generated by
absolutely cuspidal eigenforms of the Hall algebra of an arbitrary smooth
projective curve (invoking the results of [KSV17]).
