diff --git a/amodem/equalizer.py b/amodem/equalizer.py
index 9d4bb46..983192e 100644
--- a/amodem/equalizer.py
+++ b/amodem/equalizer.py
@@ -60,6 +60,6 @@ def train(signal, expected, order, lookahead=0):
     return h
 
 
-prefix = [1]*400 + [0]*50
+prefix = [1]*200 + [0]*25
 equalizer_length = 500
 silence_length = 100