diff --git a/plugins/channel/chanalyzer/chanalyzer.cpp b/plugins/channel/chanalyzer/chanalyzer.cpp
index 38e88fb49..e1f234d4d 100644
--- a/plugins/channel/chanalyzer/chanalyzer.cpp
+++ b/plugins/channel/chanalyzer/chanalyzer.cpp
@@ -71,7 +71,7 @@ void ChannelAnalyzer::feed(const SampleVector::const_iterator& begin, const Samp
 
 	for(SampleVector::const_iterator it = begin; it < end; ++it)
 	{
-		Complex c(it->real() / 32768.0, it->imag() / 32768.0);
+		Complex c(it->real() / 32768.0f, it->imag() / 32768.0f);
 		c *= m_nco.nextIQ();
 
 		if (m_ssb)
diff --git a/plugins/channel/lora/lorademod.cpp b/plugins/channel/lora/lorademod.cpp
index 61f0ca1d7..f2d6a23a5 100644
--- a/plugins/channel/lora/lorademod.cpp
+++ b/plugins/channel/lora/lorademod.cpp
@@ -247,7 +247,7 @@ void LoRaDemod::feed(const SampleVector::const_iterator& begin, const SampleVect
 
 	for(SampleVector::const_iterator it = begin; it < end; ++it)
 	{
-		Complex c(it->real() / 32768.0, it->imag() / 32768.0);
+		Complex c(it->real() / 32768.0f, it->imag() / 32768.0f);
 		c *= m_nco.nextIQ();
 
 		if(m_interpolator.interpolate(&m_sampleDistanceRemain, c, &ci))
diff --git a/plugins/channel/tcpsrc/tcpsrc.cpp b/plugins/channel/tcpsrc/tcpsrc.cpp
index 3b953a83a..5e4438d35 100644
--- a/plugins/channel/tcpsrc/tcpsrc.cpp
+++ b/plugins/channel/tcpsrc/tcpsrc.cpp
@@ -85,7 +85,7 @@ void TCPSrc::feed(const SampleVector::const_iterator& begin, const SampleVector:
 	int rescale = 30000 * (1 << m_boost);
 
 	for(SampleVector::const_iterator it = begin; it < end; ++it) {
-		Complex c(it->real() / 32768.0, it->imag() / 32768.0);
+		Complex c(it->real() / 32768.0f, it->imag() / 32768.0f);
 		c *= m_nco.nextIQ();
 
 		if(m_interpolator.interpolate(&m_sampleDistanceRemain, c, &ci)) {
diff --git a/plugins/channel/wfm/wfmdemod.cpp b/plugins/channel/wfm/wfmdemod.cpp
index 57a550de0..9c224d4ee 100644
--- a/plugins/channel/wfm/wfmdemod.cpp
+++ b/plugins/channel/wfm/wfmdemod.cpp
@@ -80,7 +80,7 @@ void WFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
 
 	for (SampleVector::const_iterator it = begin; it != end; ++it)
 	{
-		Complex c(it->real() / 32768.0, it->imag() / 32768.0);
+		Complex c(it->real() / 32768.0f, it->imag() / 32768.0f);
 		c *= m_nco.nextIQ();
 
 		rf_out = m_rfFilter->runFilt(c, &rf); // filter RF before demod
diff --git a/sdrbase/dsp/scopevis.cpp b/sdrbase/dsp/scopevis.cpp
index 115979833..9bab9af68 100644
--- a/sdrbase/dsp/scopevis.cpp
+++ b/sdrbase/dsp/scopevis.cpp
@@ -90,7 +90,7 @@ void ScopeVis::feed(const SampleVector::const_iterator& cbegin, const SampleVect
 
 			for(int i = 0; i < count; ++i)
 			{
-				*it++ = Complex(begin->real() / 32768.0, begin->imag() / 32768.0);
+				*it++ = Complex(begin->real() / 32768.0f, begin->imag() / 32768.0f);
 				++begin;
 			}
 
diff --git a/sdrbase/dsp/spectrumvis.cpp b/sdrbase/dsp/spectrumvis.cpp
index 3f34dfecc..b8b90763a 100644
--- a/sdrbase/dsp/spectrumvis.cpp
+++ b/sdrbase/dsp/spectrumvis.cpp
@@ -82,7 +82,7 @@ void SpectrumVis::feed(const SampleVector::const_iterator& cbegin, const SampleV
 
 			for (std::size_t i = 0; i < samplesNeeded; ++i, ++begin)
 			{
-				*it++ = Complex(begin->real() / 32768.0, begin->imag() / 32768.0);
+				*it++ = Complex(begin->real() / 32768.0f, begin->imag() / 32768.0f);
 			}
 
 			// apply fft window (and copy from m_fftBuffer to m_fftIn)
@@ -141,7 +141,7 @@ void SpectrumVis::feed(const SampleVector::const_iterator& cbegin, const SampleV
 			// not enough samples for FFT - just fill in new data and return
 			for(std::vector<Complex>::iterator it = m_fftBuffer.begin() + m_fftBufferFill; begin < end; ++begin)
 			{
-				*it++ = Complex(begin->real() / 32768.0, begin->imag() / 32768.0);
+				*it++ = Complex(begin->real() / 32768.0f, begin->imag() / 32768.0f);
 			}
 
 			m_fftBufferFill += todo;
diff --git a/sdrbase/gui/glspectrum.cpp b/sdrbase/gui/glspectrum.cpp
index ceda6182a..928f2be10 100644
--- a/sdrbase/gui/glspectrum.cpp
+++ b/sdrbase/gui/glspectrum.cpp
@@ -353,14 +353,15 @@ void GLSpectrum::updateHistogram(const std::vector<Real>& spectrum)
 	quint8* b = m_histogram;
 	quint8* h = m_histogramHoldoff;
 	int sub = 1;
+	int fftMulSize = 100 * m_fftSize;
 
 	if(m_decay > 0)
 		sub += m_decay;
 
 	m_histogramHoldoffCount--;
 	if(m_histogramHoldoffCount <= 0) {
-		for(int i = 0; i < 100 * m_fftSize; i++) {
-			if(*b > 20) {
+		for(int i = 0; i < fftMulSize; i++) {
+			if((*b>>4) > 0) { // *b > 16
 				*b = *b - sub;
 			} else if(*b > 0) {
 				if(*h >= sub) {