diff --git a/amodem/dsp.py b/amodem/dsp.py
index b090980..b12554a 100644
--- a/amodem/dsp.py
+++ b/amodem/dsp.py
@@ -107,8 +107,8 @@ class QAM(object):
 
 
 class Demux(object):
-    def __init__(self, src, freqs, sampler=None):
-        self.sampler = sampling.Sampler(src) if sampler is None else sampler
+    def __init__(self, sampler, freqs):
+        self.sampler = sampler
         self.filters = [exp_iwt(-f, Nsym) / (0.5*Nsym) for f in freqs]
         self.filters = np.array(self.filters)
 
diff --git a/amodem/equalizer.py b/amodem/equalizer.py
index bdf71b7..99b1c18 100644
--- a/amodem/equalizer.py
+++ b/amodem/equalizer.py
@@ -28,7 +28,7 @@ def modulator(symbols, carriers=modem.carriers):
 
 def demodulator(signal, size):
     signal = itertools.chain(signal, itertools.repeat(0))
-    symbols = dsp.Demux(signal, config.frequencies)
+    symbols = dsp.Demux(sampling.Sampler(signal), config.frequencies)
     return np.array(list(itertools.islice(symbols, size)))
 
 
diff --git a/tests/test_dsp.py b/tests/test_dsp.py
index 4c8022c..d586c9e 100644
--- a/tests/test_dsp.py
+++ b/tests/test_dsp.py
@@ -5,6 +5,7 @@ from numpy.linalg import norm
 
 from amodem import dsp
 from amodem import config
+from amodem import sampling
 
 
 def test_qam():
@@ -93,6 +94,6 @@ def test_demux():
     carriers = [dsp.exp_iwt(f, config.Nsym) for f in freqs]
     syms = [3, 2j]
     sig = np.dot(syms, carriers)
-    res = dsp.Demux(sig.real, freqs)
+    res = dsp.Demux(sampling.Sampler(sig.real), freqs)
     res = np.array(list(res))
     assert np.max(np.abs(res - syms)) < 1e-12