diff --git a/lasp/__init__.py b/lasp/__init__.py
index becea65..c0fadc5 100644
--- a/lasp/__init__.py
+++ b/lasp/__init__.py
@@ -1,11 +1,10 @@
-from .lasp_atomic import *
-from .lasp_avstream import *
 from .lasp_common import *
+from .lasp_avstream import *
+from .wrappers import *
+from .lasp_atomic import *
 from .lasp_imptube import *
 from .lasp_measurement import *
 from .lasp_octavefilter import *
 from .lasp_slm import *
 from .lasp_siggen import *
 from .lasp_weighcal import *
-from .wrappers import *
-from .device import AvType
diff --git a/lasp/c/lasp_siggen.c b/lasp/c/lasp_siggen.c
index d9610b4..766af76 100644
--- a/lasp/c/lasp_siggen.c
+++ b/lasp/c/lasp_siggen.c
@@ -332,6 +332,13 @@ us Siggen_getN(const Siggen* siggen) {
   feTRACE(15);
   return 0;
 }
+void Siggen_setLevel(Siggen* siggen, const d new_level_dB) {
+  fsTRACE(15);
+
+  siggen->level_amp = d_pow(10, new_level_dB/20);
+
+  feTRACE(15);
+}
 
 void Siggen_free(Siggen* siggen) {
   fsTRACE(15);
diff --git a/lasp/c/lasp_siggen.h b/lasp/c/lasp_siggen.h
index d5ec290..52e7862 100644
--- a/lasp/c/lasp_siggen.h
+++ b/lasp/c/lasp_siggen.h
@@ -46,6 +46,14 @@ Siggen* Siggen_Sinewave_create(const d fs,const d freq,const d level_dB);
  */
 Siggen* Siggen_Noise_create(const d fs, const d level_dB, Sosfilterbank* colorfilter);
 
+/**
+ * Set the level of the signal generator
+ * @param[in] Siggen* Signal generator handle
+ *
+ * @param[in] new_level_dB The new level, in dBFS
+ */
+void Siggen_setLevel(Siggen*, const d new_level_dB);
+
 
 /**
  * Obtain the repetition period for a periodic excitation.
diff --git a/lasp/device/__init__.py b/lasp/device/__init__.py
index 7bd944a..6fde552 100644
--- a/lasp/device/__init__.py
+++ b/lasp/device/__init__.py
@@ -1,6 +1,4 @@
-#!/usr/bin/python3
 from .lasp_device_common import *
-from .lasp_daq import *
 from .lasp_deviceinfo import *
 from .lasp_daqconfig import *
 from .lasp_daq import *
diff --git a/lasp/device/lasp_daq.pyx b/lasp/device/lasp_daq.pyx
index c05854e..8b1039c 100644
--- a/lasp/device/lasp_daq.pyx
+++ b/lasp/device/lasp_daq.pyx
@@ -4,7 +4,7 @@ from .lasp_daqconfig cimport DaqConfiguration
 
 from cpython.ref cimport PyObject,Py_INCREF, Py_DECREF
 import numpy as np
-from .lasp_device_common import AvType
+from ..lasp_common import AvType
 
 __all__ = ['Daq']
 
diff --git a/lasp/device/lasp_daqconfig.pyx b/lasp/device/lasp_daqconfig.pyx
index b1d382f..a34063d 100644
--- a/lasp/device/lasp_daqconfig.pyx
+++ b/lasp/device/lasp_daqconfig.pyx
@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 """!
 Author: J.A. de Jong - ASCEE
diff --git a/lasp/device/lasp_device_common.py b/lasp/device/lasp_device_common.py
index 5cedd8e..40c9bde 100644
--- a/lasp/device/lasp_device_common.py
+++ b/lasp/device/lasp_device_common.py
@@ -1,17 +1,10 @@
-__all__ = ['AvType', 'DaqChannel']
+__all__ = ['DaqChannel']
 from ..lasp_common import Qty, SIQtys
 from dataclasses import dataclass, field
 from dataclasses_json import dataclass_json
 from typing import List
 import json
 
-class AvType:
-    """Specificying the type of data, for adding and removing callbacks from
-    the stream."""
-    audio_input = 1
-    audio_output = 2
-    video = 4
-
 @dataclass_json
 @dataclass
 class DaqChannel:
diff --git a/lasp/device/lasp_deviceinfo.pyx b/lasp/device/lasp_deviceinfo.pyx
index 2ead824..c5e991b 100644
--- a/lasp/device/lasp_deviceinfo.pyx
+++ b/lasp/device/lasp_deviceinfo.pyx
@@ -1,3 +1,12 @@
+# -*- coding: utf-8 -*-
+"""!
+Author: J.A. de Jong - ASCEE
+
+Description:
+
+DeviceInfo C++ object wrapper
+
+"""
 __all__ = ['DeviceInfo']
 
 
diff --git a/lasp/lasp_avstream.py b/lasp/lasp_avstream.py
index 70bfc87..79a0664 100644
--- a/lasp/lasp_avstream.py
+++ b/lasp/lasp_avstream.py
@@ -1,20 +1,15 @@
-#!/usr/bin/env python3.6
 # -*- coding: utf-8 -*-
 """
 Description: Read data from image stream and record sound at the same time
 """
 #import cv2 as cv
 from .lasp_atomic import Atomic
+from .lasp_common import AvType
+from .device import (Daq, DeviceInfo, DaqConfiguration)
 from threading import Thread, Lock
 import numpy as np
-
-class DAQConfiguration:
-    pass
-
 import time
-from .device import (Daq, DeviceInfo,
-                     AvType,
-                     )
+
 
 __all__ = ['AvStream']
 
@@ -28,7 +23,7 @@ class AvStream:
     def __init__(self,
                  avtype: AvType,
                  device: DeviceInfo,
-                 daqconfig: DAQConfiguration,
+                 daqconfig: DaqConfiguration,
                  video=None):
         """Open a stream for audio in/output and video input. For audio output,
         by default all available channels are opened for outputting data.
diff --git a/lasp/lasp_common.py b/lasp/lasp_common.py
index 2125b73..1fb8249 100644
--- a/lasp/lasp_common.py
+++ b/lasp/lasp_common.py
@@ -20,6 +20,7 @@ __all__ = [
     'P_REF', 'FreqWeighting', 'TimeWeighting', 'getTime', 'getFreq', 'Qty',
     'SIQtys',
     'lasp_shelve', 'this_lasp_shelve', 'W_REF', 'U_REF', 'I_REF', 'dBFS_REF',
+    'AvType'
 ]
 
 # Reference sound pressure level
@@ -42,6 +43,14 @@ U_REF = 5e-8 # 50 nano meter / s
 # hence this is the reference level as specified below.
 dBFS_REF = 0.5*2**0.5 # Which level would be -3.01 dBFS
 
+class AvType:
+    """Specificying the type of data, for adding and removing callbacks from
+    the stream."""
+    audio_input = 1
+    audio_output = 2
+    video = 4
+
+
 @dataclass_json
 @dataclass
 class Qty:
diff --git a/lasp/lasp_imptube.py b/lasp/lasp_imptube.py
index 56d471d..f32ec44 100644
--- a/lasp/lasp_imptube.py
+++ b/lasp/lasp_imptube.py
@@ -11,6 +11,8 @@ from .lasp_measurement import Measurement
 from numpy import pi, sqrt, exp
 import numpy as np
 from scipy.interpolate import UnivariateSpline
+from lrftubes import PrsDuct
+from functools import lru_cache
 
 class TwoMicImpedanceTube:
     def __init__(self, mnormal: Measurement,
@@ -22,6 +24,8 @@ class TwoMicImpedanceTube:
                  fu: float = None,
                  periodic_method=False,
                  mat= Air(),
+                 D_imptube = 50e-3,
+                 thermoviscous = True,
                  **kwargs):
 
         """
@@ -60,6 +64,9 @@ class TwoMicImpedanceTube:
             kmax = ksmax/s
             self.fu = kmax*mat.c0/2/pi
 
+        self.thermoviscous = thermoviscous
+        self.D_imptube = D_imptube
+
         self.periodic_method = periodic_method
         self.channels = [kwargs.pop('chan0', 0), kwargs.pop('chan1', 1)]
         # Compute calibration correction
@@ -82,8 +89,9 @@ class TwoMicImpedanceTube:
         # Calibration correction factor
         # self.K = 0*self.freq + 1.0
         K = sqrt(C2[:,0,1]*C1[:,0,0]/(C2[:,1,1]*C1[:,1,0]))
-        self.K = UnivariateSpline(self.freq, K.real)(self.freq) +\
-                1j*UnivariateSpline(self.freq, K.imag)(self.freq)
+        # self.K = UnivariateSpline(self.freq, K.real)(self.freq) +\
+        #         1j*UnivariateSpline(self.freq, K.imag)(self.freq)
+        self.K = K
 
     def cut_to_limits(self, ar):
         return ar[self.il:self.ul]
@@ -94,6 +102,7 @@ class TwoMicImpedanceTube:
         """
         return self.cut_to_limits(self.freq)
     
+    @lru_cache
     def G_AB(self, meas):
         if meas is self.mnormal:
             C = self.C1
diff --git a/lasp/lasp_siggen.py b/lasp/lasp_siggen.py
index 0144d7f..9f8fcd5 100644
--- a/lasp/lasp_siggen.py
+++ b/lasp/lasp_siggen.py
@@ -14,8 +14,10 @@ from typing import Tuple
 import numpy as np
 
 from .filter import PinkNoise
+from .lasp_octavefilter import SosOctaveFilterBank, SosThirdOctaveFilterBank
+from .filter import OctaveBankDesigner, PinkNoise, ThirdOctaveBankDesigner
 from .lasp_avstream import AvStream, AvType
-from .wrappers import Siggen as pyxSiggen
+from .wrappers import Siggen as pyxSiggen, Equalizer
 
 QUEUE_BUFFER_TIME = 0.3  # The amount of time used in the queues for buffering
 # of data, larger is more stable, but also enlarges latency
@@ -89,7 +91,7 @@ class SiggenData:
 
 
 def siggenFcn(siggendata: SiggenData, nblocks_buffer: int, 
-              queues: list
+              dataq: mp.Queue, pipe
               ):
     """
     Main function running in a different process, is responsible for generating
@@ -100,12 +102,10 @@ def siggenFcn(siggendata: SiggenData, nblocks_buffer: int,
     nframes_per_block = siggendata.nframes_per_block
     level_dB = siggendata.level_dB
     dtype = siggendata.dtype
-    eq = None
 
     signaltype = siggendata.signaltype
     signaltypedata = siggendata.signaltypedata
 
-    dataq, msgq, statusq = queues
 
     def generate(siggen, eq):
         """
@@ -119,6 +119,31 @@ def siggenFcn(siggendata: SiggenData, nblocks_buffer: int,
             signal *= 2 ** (bitdepth_fixed - 1) - 1
         dataq.put(signal.astype(dtype))
 
+    def createEqualizer(eqdata):
+        """
+        Create an equalizer object from equalizer data
+
+        Args:
+            eqdata: dictionary containing equalizer data. TODO: document the
+            requiring fields.
+        """
+        if eqdata is None:
+            return None
+        eq_type = eqdata['type']
+        eq_levels = eqdata['levels']
+
+        if eq_type == 'three':
+            fb = SosThirdOctaveFilterBank(fs)
+        elif eq_type == 'one':
+            fb = SosOctaveFilterBank(fs)
+
+        eq = Equalizer(fb._fb)
+        if eq_levels is not None:
+            eq.setLevels(eq_levels)
+        return eq
+
+    eq = createEqualizer(siggendata.eqdata)
+
     def newSiggen():
         """
         Create a signal generator based on parameters specified in global
@@ -156,14 +181,14 @@ def siggenFcn(siggendata: SiggenData, nblocks_buffer: int,
         siggen = newSiggen()
 
     except Exception as e:
-        statusq.put((SiggenMessage.error, str(e)))
+        pipe.send((SiggenMessage.error, str(e)))
         return 1
 
     finally:
-        statusq.put((SiggenMessage.done, None))
+        pipe.send((SiggenMessage.done, None))
 
     while True:
-        msg, data = msgq.get()
+        msg, data = pipe.recv()
         if msg == SiggenMessage.stop:
             logging.debug("Signal generator caught 'stop' message. Exiting.")
             return 0
@@ -174,14 +199,17 @@ def siggenFcn(siggendata: SiggenData, nblocks_buffer: int,
                     # Generate new data and put it in the queue!
                     generate(siggen, eq)
             except SiggenWorkerDone:
-                statusq.put(SiggenMessage.done)
+                pipe.send(SiggenMessage.done)
                 return 0
         elif msg == SiggenMessage.adjustVolume:
             logging.debug(f"Signal generator caught 'adjustVolume' message. New volume = {level_dB:.1f} dB FS")
             level_dB = data
-            siggen = newSiggen()
+            siggen.setLevel(level_dB)
+        elif msg == SiggenMessage.newEqSettings:
+            eqdata = data
+            eq = createEqualizer(eqdata)
         else:
-            statusq.put(
+            pipe.send(
                 SiggenMessage.error, "BUG: Generator caught unknown message. Quiting"
             )
             return 1
@@ -201,11 +229,12 @@ class Siggen:
         )
 
         qs = [mp.Queue() for i in range(3)]
-        self.dataq, self.msgq, self.statusq = qs
+        self.dataq = mp.Queue()
+        self.pipe, client_end = mp.Pipe(duplex=True)
 
         self.process = mp.Process(
             target=siggenFcn,
-            args=(siggendata, self.nblocks_buffer, qs),
+            args=(siggendata, self.nblocks_buffer, self.dataq, client_end),
         )
         self.process.start()
 
@@ -222,11 +251,14 @@ class Siggen:
         Args:
             new_level: The new level in [dBFS]
         """
-        self.msgq.put((SiggenMessage.adjustVolume, new_level))
+        self.pipe.send((SiggenMessage.adjustVolume, new_level))
+
+    def setEqData(self, eqdata):
+        self.pipe.send((SiggenMessage.newEqSettings, eqdata))
 
     def handle_msgs(self):
-        while not self.statusq.empty():
-            msg, data = self.statusq.get()
+        while self.pipe.poll():
+            msg, data = self.pipe.recv()
             if msg == SiggenMessage.error:
                 self.stop()
                 raise RuntimeError(
@@ -239,6 +271,9 @@ class Siggen:
                 self.stop()
 
     def start(self):
+        if self.stopped:
+            raise RuntimeError('BUG: This Siggen object cannot be used again.')
+
         self.stream.addCallback(self.streamCallback, AvType.audio_output)
         self.handle_msgs()
 
@@ -249,9 +284,8 @@ class Siggen:
         self.stream.removeCallback(self.streamCallback, AvType.audio_output)
         while not self.dataq.empty():
             self.dataq.get()
-        while not self.statusq.empty():
-            self.statusq.get()
-        self.msgq.put((SiggenMessage.stop, None))
+        self.pipe.send((SiggenMessage.stop, None))
+        self.pipe.close()
         
         logging.debug('Joining siggen process')
         self.process.join()
@@ -276,4 +310,4 @@ class Siggen:
             outdata[:, :] = 0
 
         if self.dataq.qsize() < self.nblocks_buffer:
-            self.msgq.put((SiggenMessage.generate, None))
+            self.pipe.send((SiggenMessage.generate, None))
diff --git a/lasp/wrappers.pyx b/lasp/wrappers.pyx
index e9e6fa9..536c396 100644
--- a/lasp/wrappers.pyx
+++ b/lasp/wrappers.pyx
@@ -74,7 +74,7 @@ cdef extern from "lasp_python.h":
 __all__ = ['AvPowerSpectra', 'SosFilterBank', 'FilterBank', 'Siggen',
            'sweep_flag_forward', 'sweep_flag_backward', 'sweep_flag_linear',
            'sweep_flag_exponential', 
-           'load_fft_wisdom', 'store_fft_wisdom']
+           'load_fft_wisdom', 'store_fft_wisdom', 'Window']
             
 
 setTracerLevel(15)
@@ -635,6 +635,7 @@ cdef extern from "lasp_siggen.h":
     c_Siggen* Siggen_Sweep_create(d fs, d fl,
                                   d fu, d Ts,d Tq, us sweep_flags,
                                   d level_dB)
+    void Siggen_setLevel(c_Siggen*,d new_level_dB)
     us Siggen_getN(const c_Siggen*)
     void Siggen_genSignal(c_Siggen*, vd* samples) nogil
     void Siggen_free(c_Siggen*)
@@ -659,6 +660,9 @@ cdef class Siggen:
         if self._siggen:
             Siggen_free(self._siggen)
 
+    def setLevel(self,d level_dB):
+        Siggen_setLevel(self._siggen, level_dB)
+
     def genSignal(self, us nsamples):
         output = np.empty(nsamples, dtype=np.float)
         assert self._siggen != NULL