diff --git a/amodem/calib.py b/amodem/calib.py
index 299f5fb..44fd784 100644
--- a/amodem/calib.py
+++ b/amodem/calib.py
@@ -8,6 +8,7 @@ log = logging.getLogger(__name__)
 from . import common
 from . import dsp
 from . import sampling
+from . import stream
 
 
 def volume_controller(cmd):
@@ -110,7 +111,7 @@ def iter_window(iterable, size):
             yield block
 
 
-def recv(config, src, verbose=False, volume_cmd=None):
+def recv(config, src, verbose=False, volume_cmd=None, dump_audio=None):
     fmt = '{0.freq:6.0f} Hz: {0.msg:20s}'
     if verbose:
         fields = ['total', 'rms', 'coherency', 'peak']
@@ -118,6 +119,8 @@ def recv(config, src, verbose=False, volume_cmd=None):
 
     volume_ctl = volume_controller(volume_cmd)
 
+    if dump_audio:
+        src = stream.Dumper(src, dump_audio)
     result_iterator = detector(config=config, src=src)
     result_iterator = volume_calibration(result_iterator, volume_ctl)
     result_iterator = iter_window(result_iterator, size=3)
diff --git a/amodem/recv.py b/amodem/recv.py
index 5815b34..71f5afb 100644
--- a/amodem/recv.py
+++ b/amodem/recv.py
@@ -194,20 +194,9 @@ class Receiver(object):
         self.plt.title(title)
 
 
-class Dumper(object):
-    def __init__(self, src, dst):
-        self.src = src
-        self.dst = dst
-
-    def read(self, size):
-        data = self.src.read(size)
-        self.dst.write(data)
-        return data
-
-
 def main(config, src, dst, dump_audio=None, pylab=None):
     if dump_audio:
-        src = Dumper(src, dump_audio)
+        src = stream.Dumper(src, dump_audio)
     reader = stream.Reader(src, data_type=common.loads)
     signal = itertools.chain.from_iterable(reader)
 
diff --git a/amodem/stream.py b/amodem/stream.py
index ecadd0f..f6e6d14 100644
--- a/amodem/stream.py
+++ b/amodem/stream.py
@@ -43,3 +43,14 @@ class Reader(object):
         raise IOError('timeout')
 
     __next__ = next
+
+
+class Dumper(object):
+    def __init__(self, src, dst):
+        self.src = src
+        self.dst = dst
+
+    def read(self, size):
+        data = self.src.read(size)
+        self.dst.write(data)
+        return data
diff --git a/tests/test_calib.py b/tests/test_calib.py
index 31a9649..f64b42c 100644
--- a/tests/test_calib.py
+++ b/tests/test_calib.py
@@ -144,8 +144,10 @@ def test_recv_binary_search():
         calib.send(config, buf, gain=gain, limit=2)
     buf.seek(0)
 
+    dump = BytesIO()
     with mock.patch('subprocess.check_call') as check_call:
-        calib.recv(config, src=buf, volume_cmd='ctl')
+        calib.recv(config, src=buf, volume_cmd='ctl', dump_audio=dump)
+    assert dump.getvalue() == buf.getvalue()
 
     gains.append(gains[-1])
     fmt = 'ctl {0:.0f}%'