diff --git a/spectrogramcontrols.cpp b/spectrogramcontrols.cpp
index 7dbf4db..2b728e4 100644
--- a/spectrogramcontrols.cpp
+++ b/spectrogramcontrols.cpp
@@ -50,11 +50,11 @@ SpectrogramControls::SpectrogramControls(const QString & title, QWidget * parent
     layout->addRow(new QLabel(tr("Zoom:")), zoomLevelSlider);
 
     powerMaxSlider = new QSlider(Qt::Horizontal, widget);
-    powerMaxSlider->setRange(-100, 20);
+    powerMaxSlider->setRange(-140, 10);
     layout->addRow(new QLabel(tr("Power max:")), powerMaxSlider);
 
     powerMinSlider = new QSlider(Qt::Horizontal, widget);
-    powerMinSlider->setRange(-100, 20);
+    powerMinSlider->setRange(-140, 10);
     layout->addRow(new QLabel(tr("Power min:")), powerMinSlider);
 
     // Time selection settings
@@ -111,7 +111,7 @@ void SpectrogramControls::setDefaults()
     fftSizeSlider->setValue(9);
     zoomLevelSlider->setValue(0);
     powerMaxSlider->setValue(0);
-    powerMinSlider->setValue(-50);
+    powerMinSlider->setValue(-100);
     cursorsCheckBox->setCheckState(Qt::Unchecked);
     cursorSymbolsSpinBox->setValue(1);
 }
diff --git a/spectrogramplot.cpp b/spectrogramplot.cpp
index f994216..be0de17 100644
--- a/spectrogramplot.cpp
+++ b/spectrogramplot.cpp
@@ -143,15 +143,15 @@ void SpectrogramPlot::getLine(float *dest, off_t sample)
 
         fft->process(buffer.get(), buffer.get());
         const float invFFTSize = 1.0f / fftSize;
-        const float dbMult = 5.0f / log2f(10.0f);
+        const float logMultiplier = 10.0f / log2f(10.0f);
         for (int i = 0; i < fftSize; i++) {
             // Start from the middle of the FFTW array and wrap
             // to rearrange the data
             int k = (i + fftSize / 2) & (fftSize - 1);
             auto s = buffer[k] * invFFTSize;
             float power = s.real() * s.real() + s.imag() * s.imag();
-            float magdb = log2f(power) * dbMult;
-            *dest = magdb;
+            float logPower = log2f(power) * logMultiplier;
+            *dest = logPower;
             dest++;
         }
     }