Question about Amplifiers & Preamps
Hi! The thumping motion is usually caused by faulty cross-over voltage biasing. What this is is simple; Power amps of high wattage are usually constructed of two similar but opposite polarity amplifiers ;one drives the top (positive) part of the sinusoidal and the other drives the bottom.
The simple causes that need to be eliminated are
1) Earthing :-check earthing to ensure no earth loops
2) Check the Power fuses:- usually, the supply of power to only one part of the amplifier causes thumping motion. The power section in these designs have a positive and negative polarity eg.=80V-0V-(-) 80V
3) Disconnect the speakers and check the power supply Voltages across the output stage sumettry for more details visit
Posted on Dec 04, 2008
Tips for a great answer:
Jan 03, 2014 | Crown I-T8000 2-Channel Amplifier
Sep 20, 2011 | ButtKicker BKA1000-4A Amplifier
Apr 17, 2011 | Crown CE2000 2-Channel Amplifier
Apr 17, 2010 | Krell KAV-300i 2-Channel Amplifier
Jan 17, 2010 | Cambridge Audio Azur 540A Amplifier
Oct 13, 2009 | Rockford Fosgate Punch 1000W Class BD Mono...
Sep 25, 2008 | Amplifiers & Preamps
May 07, 2008 | Amplifiers & Preamps
Apr 07, 2008 | NAD C350 2-Channel Amplifier
743 people viewed this question
Usually answered in minutes!