diff --git a/src/dartsort/peel/matching.py b/src/dartsort/peel/matching.py
index 6dba2593..289ae47b 100644
--- a/src/dartsort/peel/matching.py
+++ b/src/dartsort/peel/matching.py
@@ -685,7 +685,7 @@ def find_peaks(
             objective[torch.logical_not(unit_mask)] = -torch.inf
         # formerly used detect_and_deduplicate, but that was slow.
         objective_max, max_obj_template = objective.max(dim=0)
-        times = argrelmax(objective_max, self.spike_length_samples, self.threshold)
+        times = spiketorch.argrelmax(objective_max, self.spike_length_samples, self.threshold)
         obj_template_indices = max_obj_template[times]
         # remove peaks inside the padding
         if not times.numel():
@@ -816,39 +816,13 @@ def __post_init__(self):
 
     def convolve(self, traces, padding=0, out=None):
         """Convolve the objective templates with traces."""
-        out_len = traces.shape[0] + 2 * padding - self.spike_length_samples + 1
-        if out is None:
-            out = torch.empty(
-                (self.objective_n_templates, out_len),
-                dtype=traces.dtype,
-                device=traces.device,
-            )
-        else:
-            assert out.shape == (self.objective_n_templates, out_len)
-
-        for q in range(self.rank):
-            # units x time
-            rec_spatial = self.objective_spatial_singular[:, q, :] @ traces.T
-            # convolve with temporal components -- units x time
-            temporal = self.objective_temporal_components[:, :, q]
-            # temporalf = self.objective_temporalf[:, :, q]
-            # conv1d with groups! only convolve each unit with its own temporal filter.
-            conv = F.conv1d(
-                rec_spatial[None],
-                temporal[:, None, :],
-                groups=self.objective_n_templates,
-                padding=padding,
-            )[0]
-            # conv = spiketorch.depthwise_oaconv1d(
-            #     rec_spatial, temporal, padding=padding, f2=temporalf
-            # )
-            if q:
-                out += conv
-            else:
-                out.copy_(conv)
-
-        # back to units x time (remove extra dim used for conv1d)
-        return out
+        return spiketorch.convolve_lowrank(
+            traces,
+            self.objective_spatial_singular,
+            self.objective_temporal_components,
+            padding=padding,
+            out=out,
+        )
 
     def subtract_conv(
         self,
@@ -1238,18 +1212,3 @@ def _grow_buffer(x, old_length, new_size):
     new = torch.empty(new_size, dtype=x.dtype, device=x.device)
     new[:old_length] = x[:old_length]
     return new
-
-
-def argrelmax(x, radius, threshold, exclude_edge=True):
-    x1 = F.max_pool1d(
-        x[None, None],
-        kernel_size=2 * radius + 1,
-        padding=radius,
-        stride=1,
-    )[0, 0]
-    x1[x < x1] = 0
-    F.threshold_(x1, threshold, 0.0)
-    ix = torch.nonzero(x1)[:, 0]
-    if exclude_edge:
-        return ix[(ix > 0) & (ix < x.numel() - 1)]
-    return ix
diff --git a/src/dartsort/util/spiketorch.py b/src/dartsort/util/spiketorch.py
index ddad49b3..26cf0c5b 100644
--- a/src/dartsort/util/spiketorch.py
+++ b/src/dartsort/util/spiketorch.py
@@ -217,9 +217,74 @@ def reduce_at_(dest, ix, src, reduce, include_self=True):
     )
 
 
+def argrelmax(x, radius, threshold, exclude_edge=True):
+    x1 = F.max_pool1d(
+        x[None, None],
+        kernel_size=2 * radius + 1,
+        padding=radius,
+        stride=1,
+    )[0, 0]
+    x1[x < x1] = 0
+    F.threshold_(x1, threshold, 0.0)
+    ix = torch.nonzero(x1)[:, 0]
+    if exclude_edge:
+        return ix[(ix > 0) & (ix < x.numel() - 1)]
+    return ix
+
+
 _cdtypes = {torch.float32: torch.complex64, torch.float64: torch.complex128}
 
 
+def convolve_lowrank(
+    traces,
+    spatial_singular,
+    temporal_components,
+    padding=0,
+    out=None,
+):
+    """Depthwise convolution of traces with templates"""
+    n_templates, spike_length_samples, rank = temporal_components.shape
+
+    out_len = traces.shape[0] + 2 * padding - spike_length_samples + 1
+    if out is None:
+        out = torch.empty(
+            (n_templates, out_len),
+            dtype=traces.dtype,
+            device=traces.device,
+        )
+    else:
+        assert out.shape == (n_templates, out_len)
+
+    for q in range(rank):
+        # units x time
+        rec_spatial = spatial_singular[:, q, :] @ traces
+
+        # convolve with temporal components -- units x time
+        temporal = temporal_components[:, :, q]
+
+        # temporalf = temporalf[:, :, q]
+        # conv1d with groups! only convolve each unit with its own temporal filter
+        conv = F.conv1d(
+            rec_spatial[None],
+            temporal[:, None, :],
+            groups=n_templates,
+            padding=padding,
+        )[0]
+
+        # o-a turns out not to be helpful, sadly
+        # conv = depthwise_oaconv1d(
+        #     rec_spatial, temporal, padding=padding, f2=temporalf
+        # )
+
+        if q:
+            out += conv
+        else:
+            out.copy_(conv)
+
+    # back to units x time (remove extra dim used for conv1d)
+    return out
+
+
 def real_resample(x, num, dim=0):
     """torch version of a special case of scipy.signal.resample