diff --git a/modules/juce_audio_basics/utilities/juce_Decibels.h b/modules/juce_audio_basics/utilities/juce_Decibels.h
index e5eb802622..937cf0a6b7 100644
--- a/modules/juce_audio_basics/utilities/juce_Decibels.h
+++ b/modules/juce_audio_basics/utilities/juce_Decibels.h
@@ -60,6 +60,20 @@ public:
                              : minusInfinityDb;
     }
 
+    /** Restricts a gain value based on a lower bound specified in dBFS.
+
+        This is useful if you want to make sure a gain value never reaches zero.
+    */
+    template <typename Type>
+    static Type gainWithLowerBound (Type gain, Type lowerBoundDb)
+    {
+        // You probably want to use a negative decibel value or the gain will
+        // be restricted to boosting only!
+        jassert (lowerBoundDb < (Type) 0.0);
+
+        return jmax ((Type) gain, Decibels::decibelsToGain (lowerBoundDb, lowerBoundDb - (Type) 1.0));
+    }
+
     //==============================================================================
     /** Converts a decibel reading to a string.
 
diff --git a/modules/juce_audio_basics/utilities/juce_IIRFilter.cpp b/modules/juce_audio_basics/utilities/juce_IIRFilter.cpp
index fedeb759ea..c1e32254db 100644
--- a/modules/juce_audio_basics/utilities/juce_IIRFilter.cpp
+++ b/modules/juce_audio_basics/utilities/juce_IIRFilter.cpp
@@ -23,6 +23,8 @@
 namespace juce
 {
 
+constexpr auto minimumDecibels = -300.0f;
+
 IIRCoefficients::IIRCoefficients() noexcept
 {
     zeromem (coefficients, sizeof (coefficients));
@@ -44,7 +46,7 @@ IIRCoefficients& IIRCoefficients::operator= (const IIRCoefficients& other) noexc
 IIRCoefficients::IIRCoefficients (double c1, double c2, double c3,
                                   double c4, double c5, double c6) noexcept
 {
-    auto a = 1.0 / c4;
+    const auto a = 1.0 / c4;
 
     coefficients[0] = (float) (c1 * a);
     coefficients[1] = (float) (c2 * a);
@@ -67,9 +69,9 @@ IIRCoefficients IIRCoefficients::makeLowPass (double sampleRate,
     jassert (frequency > 0.0 && frequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
-    auto nSquared = n * n;
-    auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
+    const auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
+    const auto nSquared = n * n;
+    const auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
 
     return IIRCoefficients (c1,
                             c1 * 2.0,
@@ -93,9 +95,9 @@ IIRCoefficients IIRCoefficients::makeHighPass (double sampleRate,
     jassert (frequency > 0.0 && frequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto n = std::tan (MathConstants<double>::pi * frequency / sampleRate);
-    auto nSquared = n * n;
-    auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
+    const auto n = std::tan (MathConstants<double>::pi * frequency / sampleRate);
+    const auto nSquared = n * n;
+    const auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
 
     return IIRCoefficients (c1,
                             c1 * -2.0,
@@ -119,9 +121,9 @@ IIRCoefficients IIRCoefficients::makeBandPass (double sampleRate,
     jassert (frequency > 0.0 && frequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
-    auto nSquared = n * n;
-    auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
+    const auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
+    const auto nSquared = n * n;
+    const auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
 
     return IIRCoefficients (c1 * n / Q,
                             0.0,
@@ -145,9 +147,9 @@ IIRCoefficients IIRCoefficients::makeNotchFilter (double sampleRate,
     jassert (frequency > 0.0 && frequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
-    auto nSquared = n * n;
-    auto c1 = 1.0 / (1.0 + n / Q + nSquared);
+    const auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
+    const auto nSquared = n * n;
+    const auto c1 = 1.0 / (1.0 + n / Q + nSquared);
 
     return IIRCoefficients (c1 * (1.0 + nSquared),
                             2.0 * c1 * (1.0 - nSquared),
@@ -171,9 +173,9 @@ IIRCoefficients IIRCoefficients::makeAllPass (double sampleRate,
     jassert (frequency > 0.0 && frequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
-    auto nSquared = n * n;
-    auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
+    const auto n = 1.0 / std::tan (MathConstants<double>::pi * frequency / sampleRate);
+    const auto nSquared = n * n;
+    const auto c1 = 1.0 / (1.0 + 1.0 / Q * n + nSquared);
 
     return IIRCoefficients (c1 * (1.0 - n / Q + nSquared),
                             c1 * 2.0 * (1.0 - nSquared),
@@ -192,13 +194,13 @@ IIRCoefficients IIRCoefficients::makeLowShelf (double sampleRate,
     jassert (cutOffFrequency > 0.0 && cutOffFrequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto A = jmax (0.0f, std::sqrt (gainFactor));
-    auto aminus1 = A - 1.0;
-    auto aplus1 = A + 1.0;
-    auto omega = (MathConstants<double>::twoPi * jmax (cutOffFrequency, 2.0)) / sampleRate;
-    auto coso = std::cos (omega);
-    auto beta = std::sin (omega) * std::sqrt (A) / Q;
-    auto aminus1TimesCoso = aminus1 * coso;
+    const auto A = std::sqrt (Decibels::gainWithLowerBound (gainFactor, minimumDecibels));
+    const auto aminus1 = A - 1.0;
+    const auto aplus1 = A + 1.0;
+    const auto omega = (MathConstants<double>::twoPi * jmax (cutOffFrequency, 2.0)) / sampleRate;
+    const auto coso = std::cos (omega);
+    const auto beta = std::sin (omega) * std::sqrt (A) / Q;
+    const auto aminus1TimesCoso = aminus1 * coso;
 
     return IIRCoefficients (A * (aplus1 - aminus1TimesCoso + beta),
                             A * 2.0 * (aminus1 - aplus1 * coso),
@@ -217,13 +219,13 @@ IIRCoefficients IIRCoefficients::makeHighShelf (double sampleRate,
     jassert (cutOffFrequency > 0.0 && cutOffFrequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto A = jmax (0.0f, std::sqrt (gainFactor));
-    auto aminus1 = A - 1.0;
-    auto aplus1 = A + 1.0;
-    auto omega = (MathConstants<double>::twoPi * jmax (cutOffFrequency, 2.0)) / sampleRate;
-    auto coso = std::cos (omega);
-    auto beta = std::sin (omega) * std::sqrt (A) / Q;
-    auto aminus1TimesCoso = aminus1 * coso;
+    const auto A = std::sqrt (Decibels::gainWithLowerBound (gainFactor, minimumDecibels));
+    const auto aminus1 = A - 1.0;
+    const auto aplus1 = A + 1.0;
+    const auto omega = (MathConstants<double>::twoPi * jmax (cutOffFrequency, 2.0)) / sampleRate;
+    const auto coso = std::cos (omega);
+    const auto beta = std::sin (omega) * std::sqrt (A) / Q;
+    const auto aminus1TimesCoso = aminus1 * coso;
 
     return IIRCoefficients (A * (aplus1 + aminus1TimesCoso + beta),
                             A * -2.0 * (aminus1 + aplus1 * coso),
@@ -242,12 +244,12 @@ IIRCoefficients IIRCoefficients::makePeakFilter (double sampleRate,
     jassert (frequency > 0.0 && frequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto A = jmax (0.0f, std::sqrt (gainFactor));
-    auto omega = (MathConstants<double>::twoPi * jmax (frequency, 2.0)) / sampleRate;
-    auto alpha = 0.5 * std::sin (omega) / Q;
-    auto c2 = -2.0 * std::cos (omega);
-    auto alphaTimesA = alpha * A;
-    auto alphaOverA = alpha / A;
+    const auto A = std::sqrt (Decibels::gainWithLowerBound (gainFactor, minimumDecibels));
+    const auto omega = (MathConstants<double>::twoPi * jmax (frequency, 2.0)) / sampleRate;
+    const auto alpha = 0.5 * std::sin (omega) / Q;
+    const auto c2 = -2.0 * std::cos (omega);
+    const auto alphaTimesA = alpha * A;
+    const auto alphaOverA = alpha / A;
 
     return IIRCoefficients (1.0 + alphaTimesA,
                             c2,
diff --git a/modules/juce_dsp/processors/juce_IIRFilter.cpp b/modules/juce_dsp/processors/juce_IIRFilter.cpp
index 69f99417fc..37bed1e8fb 100644
--- a/modules/juce_dsp/processors/juce_IIRFilter.cpp
+++ b/modules/juce_dsp/processors/juce_IIRFilter.cpp
@@ -30,6 +30,8 @@ namespace dsp
 namespace IIR
 {
 
+constexpr auto minimumDecibels = -300.0;
+
 template <typename NumericType>
 std::array<NumericType, 4> ArrayCoefficients<NumericType>::makeFirstOrderLowPass (double sampleRate,
                                                                                   NumericType frequency)
@@ -37,7 +39,7 @@ std::array<NumericType, 4> ArrayCoefficients<NumericType>::makeFirstOrderLowPass
     jassert (sampleRate > 0.0);
     jassert (frequency > 0 && frequency <= static_cast<float> (sampleRate * 0.5));
 
-    auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
 
     return { { n, n, n + 1, n - 1 } };
 }
@@ -49,7 +51,7 @@ std::array<NumericType, 4> ArrayCoefficients<NumericType>::makeFirstOrderHighPas
     jassert (sampleRate > 0.0);
     jassert (frequency > 0 && frequency <= static_cast<float> (sampleRate * 0.5));
 
-    auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
 
     return { { 1, -1, n + 1, n - 1 } };
 }
@@ -61,7 +63,7 @@ std::array<NumericType, 4> ArrayCoefficients<NumericType>::makeFirstOrderAllPass
     jassert (sampleRate > 0.0);
     jassert (frequency > 0 && frequency <= static_cast<float> (sampleRate * 0.5));
 
-    auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
 
     return { { n - 1, n + 1, n + 1, n - 1 } };
 }
@@ -82,10 +84,10 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makeLowPass (double s
     jassert (frequency > 0 && frequency <= static_cast<float> (sampleRate * 0.5));
     jassert (Q > 0.0);
 
-    auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
-    auto nSquared = n * n;
-    auto invQ = 1 / Q;
-    auto c1 = 1 / (1 + invQ * n + nSquared);
+    const auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto nSquared = n * n;
+    const auto invQ = 1 / Q;
+    const auto c1 = 1 / (1 + invQ * n + nSquared);
 
     return { { c1, c1 * 2, c1,
                1, c1 * 2 * (1 - nSquared),
@@ -108,10 +110,10 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makeHighPass (double
     jassert (frequency > 0 && frequency <= static_cast<float> (sampleRate * 0.5));
     jassert (Q > 0.0);
 
-    auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
-    auto nSquared = n * n;
-    auto invQ = 1 / Q;
-    auto c1 = 1 / (1 + invQ * n + nSquared);
+    const auto n = std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto nSquared = n * n;
+    const auto invQ = 1 / Q;
+    const auto c1 = 1 / (1 + invQ * n + nSquared);
 
     return { { c1, c1 * -2, c1,
                1, c1 * 2 * (nSquared - 1),
@@ -134,10 +136,10 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makeBandPass (double
     jassert (frequency > 0 && frequency <= static_cast<float> (sampleRate * 0.5));
     jassert (Q > 0.0);
 
-    auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
-    auto nSquared = n * n;
-    auto invQ = 1 / Q;
-    auto c1 = 1 / (1 + invQ * n + nSquared);
+    const auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto nSquared = n * n;
+    const auto invQ = 1 / Q;
+    const auto c1 = 1 / (1 + invQ * n + nSquared);
 
     return { { c1 * n * invQ, 0,
                -c1 * n * invQ, 1,
@@ -161,12 +163,12 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makeNotch (double sam
     jassert (frequency > 0 && frequency <= static_cast<float> (sampleRate * 0.5));
     jassert (Q > 0.0);
 
-    auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
-    auto nSquared = n * n;
-    auto invQ = 1 / Q;
-    auto c1 = 1 / (1 + n * invQ + nSquared);
-    auto b0 = c1 * (1 + nSquared);
-    auto b1 = 2 * c1 * (1 - nSquared);
+    const auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto nSquared = n * n;
+    const auto invQ = 1 / Q;
+    const auto c1 = 1 / (1 + n * invQ + nSquared);
+    const auto b0 = c1 * (1 + nSquared);
+    const auto b1 = 2 * c1 * (1 - nSquared);
 
     return { { b0, b1, b0, 1, b1, c1 * (1 - n * invQ + nSquared) } };
 }
@@ -187,12 +189,12 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makeAllPass (double s
     jassert (frequency > 0 && frequency <= sampleRate * 0.5);
     jassert (Q > 0);
 
-    auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
-    auto nSquared = n * n;
-    auto invQ = 1 / Q;
-    auto c1 = 1 / (1 + invQ * n + nSquared);
-    auto b0 = c1 * (1 - n * invQ + nSquared);
-    auto b1 = c1 * 2 * (1 - nSquared);
+    const auto n = 1 / std::tan (MathConstants<NumericType>::pi * frequency / static_cast<NumericType> (sampleRate));
+    const auto nSquared = n * n;
+    const auto invQ = 1 / Q;
+    const auto c1 = 1 / (1 + invQ * n + nSquared);
+    const auto b0 = c1 * (1 - n * invQ + nSquared);
+    const auto b1 = c1 * 2 * (1 - nSquared);
 
     return { { b0, b1, 1, 1, b1, b0 } };
 }
@@ -207,13 +209,13 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makeLowShelf (double
     jassert (cutOffFrequency > 0.0 && cutOffFrequency <= sampleRate * 0.5);
     jassert (Q > 0.0);
 
-    auto A = jmax (static_cast<NumericType> (0.0), std::sqrt (gainFactor));
-    auto aminus1 = A - 1;
-    auto aplus1 = A + 1;
-    auto omega = (2 * MathConstants<NumericType>::pi * jmax (cutOffFrequency, static_cast<NumericType> (2.0))) / static_cast<NumericType> (sampleRate);
-    auto coso = std::cos (omega);
-    auto beta = std::sin (omega) * std::sqrt (A) / Q;
-    auto aminus1TimesCoso = aminus1 * coso;
+    const auto A = std::sqrt (Decibels::gainWithLowerBound (gainFactor, (NumericType) minimumDecibels));
+    const auto aminus1 = A - 1;
+    const auto aplus1 = A + 1;
+    const auto omega = (2 * MathConstants<NumericType>::pi * jmax (cutOffFrequency, static_cast<NumericType> (2.0))) / static_cast<NumericType> (sampleRate);
+    const auto coso = std::cos (omega);
+    const auto beta = std::sin (omega) * std::sqrt (A) / Q;
+    const auto aminus1TimesCoso = aminus1 * coso;
 
     return { { A * (aplus1 - aminus1TimesCoso + beta),
                A * 2 * (aminus1 - aplus1 * coso),
@@ -233,13 +235,13 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makeHighShelf (double
     jassert (cutOffFrequency > 0 && cutOffFrequency <= static_cast<NumericType> (sampleRate * 0.5));
     jassert (Q > 0);
 
-    auto A = jmax (static_cast<NumericType> (0.0), std::sqrt (gainFactor));
-    auto aminus1 = A - 1;
-    auto aplus1 = A + 1;
-    auto omega = (2 * MathConstants<NumericType>::pi * jmax (cutOffFrequency, static_cast<NumericType> (2.0))) / static_cast<NumericType> (sampleRate);
-    auto coso = std::cos (omega);
-    auto beta = std::sin (omega) * std::sqrt (A) / Q;
-    auto aminus1TimesCoso = aminus1 * coso;
+    const auto A = std::sqrt (Decibels::gainWithLowerBound (gainFactor, (NumericType) minimumDecibels));
+    const auto aminus1 = A - 1;
+    const auto aplus1 = A + 1;
+    const auto omega = (2 * MathConstants<NumericType>::pi * jmax (cutOffFrequency, static_cast<NumericType> (2.0))) / static_cast<NumericType> (sampleRate);
+    const auto coso = std::cos (omega);
+    const auto beta = std::sin (omega) * std::sqrt (A) / Q;
+    const auto aminus1TimesCoso = aminus1 * coso;
 
     return { { A * (aplus1 + aminus1TimesCoso + beta),
                A * -2 * (aminus1 + aplus1 * coso),
@@ -260,12 +262,12 @@ std::array<NumericType, 6> ArrayCoefficients<NumericType>::makePeakFilter (doubl
     jassert (Q > 0);
     jassert (gainFactor > 0);
 
-    auto A = jmax (static_cast<NumericType> (0.0), std::sqrt (gainFactor));
-    auto omega = (2 * MathConstants<NumericType>::pi * jmax (frequency, static_cast<NumericType> (2.0))) / static_cast<NumericType> (sampleRate);
-    auto alpha = std::sin (omega) / (Q * 2);
-    auto c2 = -2 * std::cos (omega);
-    auto alphaTimesA = alpha * A;
-    auto alphaOverA = alpha / A;
+    const auto A = std::sqrt (Decibels::gainWithLowerBound (gainFactor, (NumericType) minimumDecibels));
+    const auto omega = (2 * MathConstants<NumericType>::pi * jmax (frequency, static_cast<NumericType> (2.0))) / static_cast<NumericType> (sampleRate);
+    const auto alpha = std::sin (omega) / (Q * 2);
+    const auto c2 = -2 * std::cos (omega);
+    const auto alphaTimesA = alpha * A;
+    const auto alphaOverA = alpha / A;
 
     return { { 1 + alphaTimesA, c2, 1 - alphaTimesA, 1 + alphaOverA, c2, 1 - alphaOverA } };
 }