diff --git a/htdocs/lib/AudioEngine.js b/htdocs/lib/AudioEngine.js
index 298046b..6226825 100644
--- a/htdocs/lib/AudioEngine.js
+++ b/htdocs/lib/AudioEngine.js
@@ -230,10 +230,14 @@ AudioEngine.prototype.getBuffersize = function() {
 };
 
 function ImaAdpcmCodec() {
+    this.reset();
+}
+
+ImaAdpcmCodec.prototype.reset = function() {
     this.stepIndex = 0;
     this.predictor = 0;
     this.step = 0;
-}
+};
 
 ImaAdpcmCodec.imaIndexTable = [ -1, -1, -1, -1, 2, 4, 6, 8, -1, -1, -1, -1, 2, 4, 6, 8 ];
 
diff --git a/htdocs/openwebrx.js b/htdocs/openwebrx.js
index 29dd3e7..7017fc8 100644
--- a/htdocs/openwebrx.js
+++ b/htdocs/openwebrx.js
@@ -29,7 +29,7 @@ var center_freq;
 var fft_size;
 var fft_fps;
 var fft_compression = "none";
-var fft_codec = new sdrjs.ImaAdpcm();
+var fft_codec;
 var waterfall_setup_done = 0;
 var secondary_fft_size;
 var rx_photo_state = 1;
@@ -1942,6 +1942,7 @@ function openwebrx_init() {
     } else {
         audioEngine.start(onAudioStart);
     }
+    fft_codec = new ImaAdpcmCodec();
     initProgressBars();
     init_rx_photo();
     open_websocket();