diff --git a/plugins/channel/nfm/nfmdemod.cpp b/plugins/channel/nfm/nfmdemod.cpp
index c64298ba1..edd352e68 100644
--- a/plugins/channel/nfm/nfmdemod.cpp
+++ b/plugins/channel/nfm/nfmdemod.cpp
@@ -80,7 +80,8 @@ void NFMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iter
 			demod = m_volume * m_lowpass.filter(demod);
 			sample = demod * 32767;
 
-			if (!(framedrop & 3))
+			// Display audio spectrum to 12kHz
+			if (!(framedrop & 1))
 				m_sampleBuffer.push_back(Sample(sample, sample));
 
 			if(m_squelchState > 0)
diff --git a/plugins/channel/nfm/nfmdemodgui.cpp b/plugins/channel/nfm/nfmdemodgui.cpp
index 0b314fafd..ed022220e 100644
--- a/plugins/channel/nfm/nfmdemodgui.cpp
+++ b/plugins/channel/nfm/nfmdemodgui.cpp
@@ -163,7 +163,7 @@ NFMDemodGUI::NFMDemodGUI(PluginAPI* pluginAPI, QWidget* parent) :
 	m_pluginAPI->addAudioSource(m_audioFifo);
 	m_pluginAPI->addSampleSink(m_threadedSampleSink);
 
-	ui->glSpectrum->setCenterFrequency(0);
+	ui->glSpectrum->setCenterFrequency(6000);
 	ui->glSpectrum->setSampleRate(12000);
 	ui->glSpectrum->setDisplayWaterfall(true);
 	ui->glSpectrum->setDisplayMaxHold(true);
diff --git a/plugins/channel/ssb/ssbdemodgui.cpp b/plugins/channel/ssb/ssbdemodgui.cpp
index a861e10b2..46544d649 100644
--- a/plugins/channel/ssb/ssbdemodgui.cpp
+++ b/plugins/channel/ssb/ssbdemodgui.cpp
@@ -137,11 +137,10 @@ SSBDemodGUI::SSBDemodGUI(PluginAPI* pluginAPI, QWidget* parent) :
 	m_pluginAPI->addAudioSource(m_audioFifo);
 	m_pluginAPI->addSampleSink(m_threadedSampleSink);
 
-	ui->glSpectrum->setCenterFrequency(0);
-	ui->glSpectrum->setSampleRate(12000);
+	ui->glSpectrum->setCenterFrequency(3000);
+	ui->glSpectrum->setSampleRate(6000);
 	ui->glSpectrum->setDisplayWaterfall(true);
 	ui->glSpectrum->setDisplayMaxHold(true);
-	m_spectrumVis->configure(m_threadedSampleSink->getMessageQueue(), 64, 10, FFTWindow::BlackmanHarris);
 
 	m_channelMarker = new ChannelMarker(this);
 	m_channelMarker->setColor(Qt::red);
diff --git a/sdrbase/dsp/spectrumvis.cpp b/sdrbase/dsp/spectrumvis.cpp
index 1bc9a43f4..21fcc1efd 100644
--- a/sdrbase/dsp/spectrumvis.cpp
+++ b/sdrbase/dsp/spectrumvis.cpp
@@ -60,19 +60,30 @@ void SpectrumVis::feed(SampleVector::const_iterator begin, SampleVector::const_i
 			Real ofs = 20.0f * log10f(1.0f / m_fftSize);
 			Real mult = (10.0f / log2f(10.0f));
 			const Complex* fftOut = m_fft->out();
-			size_t spectrumStart = 0;
+			Complex c;
+			Real v;
+			size_t halfSize = m_fftSize / 2;
 
 			if ( positiveOnly ) {
-				Real logZero = ofs + mult * log2f( 0 );
-				for(size_t i = 0; i < m_fftSize / 2; i++)
-					m_logPowerSpectrum[i] = logZero;
-				spectrumStart = m_fftSize / 2;
-			}
-			for(size_t i = spectrumStart; i < m_fftSize; i++) {
-				Complex c = fftOut[((i + (m_fftSize >> 1)) & (m_fftSize - 1))];
-				Real v = c.real() * c.real() + c.imag() * c.imag();
-				v = mult * log2f(v) + ofs;
-				m_logPowerSpectrum[i] = v;
+				for(size_t i = 0; i < halfSize; i++) {
+					c = fftOut[i];
+					v = c.real() * c.real() + c.imag() * c.imag();
+					v = mult * log2f(v) + ofs;
+					m_logPowerSpectrum[i * 2] = v;
+					m_logPowerSpectrum[i * 2 + 1] = v;
+				}
+			} else {
+				for(size_t i = 0; i < halfSize; i++) {
+					c = fftOut[i + halfSize];
+					v = c.real() * c.real() + c.imag() * c.imag();
+					v = mult * log2f(v) + ofs;
+					m_logPowerSpectrum[i] = v;
+
+					c = fftOut[i];
+					v = c.real() * c.real() + c.imag() * c.imag();
+					v = mult * log2f(v) + ofs;
+					m_logPowerSpectrum[i + halfSize] = v;
+				}
 			}
 
 			// send new data to visualisation