diff --git a/gprMax/solvers.py b/gprMax/solvers.py
index 26de9bb8..9a759e94 100644
--- a/gprMax/solvers.py
+++ b/gprMax/solvers.py
@@ -21,7 +21,8 @@ from gprMax.utilities import timer
 from .grid import FDTDGrid
 from .grid import GPUGrid
 import gprMax.config as config
-from .subgrids.solver import create_solver as create_subgrid_solver
+from .subgrids.solver import create_updates as create_subgrid_updates
+from .subgrids.solver import SubGridSolver
 
 
 def create_G(sim_config):
@@ -42,7 +43,8 @@ def create_solver(G, sim_config):
         updates = GPUUpdates(G)
         solver = Solver(updates)
     elif sim_config.subgrid:
-        solver = create_subgrid_solver(G)
+        updates = create_subgrid_updates(G)
+        solver = SubGridSolver(G, updates)
     else:
         updates = CPUUpdates(G)
         solver = Solver(updates)
@@ -52,8 +54,8 @@ def create_solver(G, sim_config):
     # a large range of function exist to advance the time step for dispersive
     # materials. The correct function is set here  based on the
     # the required numerical precision and dispersive material type.
-    #props = updates.adapt_dispersive_config(config)
-    #updates.set_dispersive_updates(props)
+    props = updates.adapt_dispersive_config(config)
+    updates.set_dispersive_updates(props)
 
 
 class Solver:
diff --git a/gprMax/subgrids/solver.py b/gprMax/subgrids/solver.py
index 8cb01e8d..ec5d4db6 100644
--- a/gprMax/subgrids/solver.py
+++ b/gprMax/subgrids/solver.py
@@ -18,7 +18,7 @@ from ..updates import CPUUpdates
 
 
 
-def create_solver(G):
+def create_updates(G):
     """Return the solver for the given subgrids."""
     updaters = []
 
@@ -36,9 +36,7 @@ def create_solver(G):
         updaters.append(sgu)
 
     updates = SubgridUpdates(G, updaters)
-    solver = SubGridSolver(G, updates)
-    return solver
-
+    return updates
 
 class SubgridUpdates(CPUUpdates):
 
@@ -174,6 +172,7 @@ class SubgridUpdater(CPUUpdates):
             self.update_electric_pml()
             precursors.interpolate_magnetic_in_time(int(m + sub_grid.ratio / 2 - 0.5))
             sub_grid.update_electric_is(precursors)
+            self.update_electric_b()
 
             self.update_sub_grid_electric_sources()
 
@@ -188,6 +187,7 @@ class SubgridUpdater(CPUUpdates):
         self.update_electric_pml()
         precursors.calc_exact_magnetic_in_time()
         sub_grid.update_electric_is(precursors)
+        self.update_electric_b()
         self.update_sub_grid_electric_sources()
         sub_grid.update_electric_os(G)
 
@@ -216,6 +216,8 @@ class SubgridUpdater(CPUUpdates):
 
             precursors.interpolate_magnetic_in_time(m)
             sub_grid.update_electric_is(precursors)
+            self.update_electric_b()
+
             self.update_sub_grid_electric_sources()
 
         self.update_magnetic()