diff --git a/ml4gw/transforms/__init__.py b/ml4gw/transforms/__init__.py
index 74a7eb8..e9cf480 100644
--- a/ml4gw/transforms/__init__.py
+++ b/ml4gw/transforms/__init__.py
@@ -1,3 +1,4 @@
+from .iirfilter import IIRFilter
 from .pearson import ShiftedPearsonCorrelation
 from .qtransform import QScan, SingleQTransform
 from .scaler import ChannelWiseScaler
diff --git a/ml4gw/waveforms/generator.py b/ml4gw/waveforms/generator.py
index bcf4197..d9e27c1 100644
--- a/ml4gw/waveforms/generator.py
+++ b/ml4gw/waveforms/generator.py
@@ -1,11 +1,13 @@
 import math
 from typing import Callable, Dict, Tuple
 
+import numpy as np
 import torch
 from jaxtyping import Float
 from torch import Tensor
 
 from ml4gw.constants import MSUN
+from ml4gw.transforms import IIRFilter
 from ml4gw.types import BatchTensor
 from ml4gw.waveforms.cbc import utils
 
@@ -68,10 +70,7 @@ def __init__(
         self.right_pad = right_pad
         self.f_ref = f_ref
 
-    def get_frequencies(self, df: float):
-        """Get the frequencies from 0 to nyquist for corresponding df"""
-        num_freqs = int(self.nyquist / df) + 1
-        return torch.linspace(0, self.nyquist, num_freqs)
+        self.highpass = self.build_highpass_filter()
 
     @property
     def delta_t(self):
@@ -90,6 +89,30 @@ def size(self):
     def delta_f(self):
         return 1 / self.duration
 
+    def build_highpass_filter(self):
+        """
+        Builds highpass filter object.
+
+        See https://git.ligo.org/lscsoft/lalsuite/-/blob/master/lalsimulation/python/lalsimulation/gwsignal/core/conditioning_subroutines.py?ref_type=heads#L10 # noqa
+        """
+        order = 8.0
+        w1 = np.tan(np.pi * (self.f_min) / self.sample_rate)
+        attenuation = 0.99
+        wc = w1 * (1.0 / attenuation**0.5 - 1) ** (1.0 / (2.0 * order))
+        fc = self.sample_rate * np.arctan(wc) / np.pi
+
+        return IIRFilter(
+            order,
+            fc / (self.sample_rate / 2),
+            btype="highpass",
+            ftype="butterworth",
+        )
+
+    def get_frequencies(self, df: float):
+        """Get the frequencies from 0 to nyquist for corresponding df"""
+        num_freqs = int(self.nyquist / df) + 1
+        return torch.linspace(0, self.nyquist, num_freqs)
+
     def generate_conditioned_fd_waveform(
         self, **parameters: dict[str, BatchTensor]
     ):
@@ -275,4 +298,9 @@ def forward(
         hc = torch.nn.functional.pad(hc, (pad, 0))
         hp = torch.nn.functional.pad(hp, (pad, 0))
 
+        # finally, highpass the waveforms,
+        # going to double precision
+        hp = self.highpass(hp.double())
+        hc = self.highpass(hc.double())
+
         return hc, hp
diff --git a/tests/waveforms/test_generator.py b/tests/waveforms/test_generator.py
index 6ecccd8..5ff53ab 100644
--- a/tests/waveforms/test_generator.py
+++ b/tests/waveforms/test_generator.py
@@ -12,17 +12,7 @@
 from ml4gw.waveforms.generator import TimeDomainCBCWaveformGenerator
 
 
-@pytest.fixture(params=[10, 100, 1000])
-def n_samples(request):
-    return request.param
-
-
-@pytest.fixture(params=[1, 2, 10])
-def duration(request):
-    return request.param
-
-
-@pytest.fixture(params=[1024, 2048, 4096])
+@pytest.fixture(params=[2048])
 def sample_rate(request):
     return request.param
 
@@ -84,7 +74,7 @@ def test_cbc_waveform_generator(
     theta_jn,
     sample_rate,
 ):
-    duration = 20
+    duration = 10
     f_min = 20
     f_ref = 40
     right_pad = 0.5
@@ -163,31 +153,23 @@ def test_cbc_waveform_generator(
             gwsignal_params, gwsignal_generator
         )
 
-        hp_ml4gw_highpassed = high_pass_time_series(
-            hp_ml4gw[i].detach().numpy(), 1 / sample_rate, f_min, 0.99, 8.0
-        )
-        hc_ml4gw_highpassed = high_pass_time_series(
-            hc_ml4gw[i].detach().numpy(), 1 / sample_rate, f_min, 0.99, 8.0
-        )
+        hp = hp_ml4gw[i].detach().numpy()
+        hc = hc_ml4gw[i].detach().numpy()
 
         # now align the gwsignal and ml4gw waveforms so we can compoare
-        ml4gw_times = np.arange(
-            0, len(hp_ml4gw_highpassed) / sample_rate, 1 / sample_rate
-        )
+        ml4gw_times = np.arange(0, len(hp) / sample_rate, 1 / sample_rate)
         ml4gw_times -= duration - right_pad
 
-        hp_ml4gw_times = (
-            ml4gw_times - ml4gw_times[np.argmax(hp_ml4gw_highpassed)]
-        )
+        hp_ml4gw_times = ml4gw_times - ml4gw_times[np.argmax(hp)]
 
         max_time = min(hp_ml4gw_times[-1], hp_gwsignal.times.value[-1])
         min_time = max(hp_ml4gw_times[0], hp_gwsignal.times.value[0])
 
-        mask = hp_gwsignal.times.value < max_time
-        mask &= hp_gwsignal.times.value > min_time
+        mask = hp_gwsignal.times.value <= max_time
+        mask &= hp_gwsignal.times.value >= min_time
 
-        ml4gw_mask = hp_ml4gw_times < max_time
-        ml4gw_mask &= hp_ml4gw_times > min_time
+        ml4gw_mask = hp_ml4gw_times <= max_time
+        ml4gw_mask &= hp_ml4gw_times >= min_time
 
         # TODO: track this down
 
@@ -199,30 +181,28 @@ def test_cbc_waveform_generator(
 
         close_hp = np.allclose(
             hp_gwsignal.value[mask],
-            hp_ml4gw_highpassed[ml4gw_mask],
+            hp[ml4gw_mask],
             atol=5e-23,
-            rtol=0.01,
+            rtol=0.05,
         )
 
-        close_hp = close_hp or np.allclose(
+        assert close_hp or np.allclose(
             hp_gwsignal.value[mask][:-1],
-            hp_ml4gw_highpassed[ml4gw_mask][1:],
+            hp[ml4gw_mask][1:],
             atol=5e-23,
-            rtol=0.01,
+            rtol=0.05,
         )
-        assert close_hp
 
         close_hc = np.allclose(
             hc_gwsignal.value[mask],
-            hc_ml4gw_highpassed[ml4gw_mask],
+            hc[ml4gw_mask],
             atol=5e-23,
-            rtol=0.01,
+            rtol=0.05,
         )
 
-        close_hc = close_hc or np.allclose(
+        assert close_hc or np.allclose(
             hc_gwsignal.value[mask][:-1],
-            hc_ml4gw_highpassed[ml4gw_mask][1:],
+            hc[ml4gw_mask][1:],
             atol=5e-23,
-            rtol=0.01,
+            rtol=0.05,
         )
-        assert close_hc