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Re: Ampeg SVT 3 Pro output has DC

11/7/2005 9:57 AM
R.G.	Re: Ampeg SVT 3 Pro output has DC I used to use a variac too, but I got frustrated with some smart amps that refused to play if their power supply was not right after X delay. If it's a typical class AB solid state, there may well be two driver transistors, one on top and bottom. Some amps use a bootstrap capacitor from the output to a split load for a single driver transistor, but that's pretty old school and rare these days. A bad bootstrap cap could give you a similar problem. You may have a fault in the soft start circuit itself. Is it easy to defeat? What is the power supply to the amp like? Bipolar? How many volts? Can you run it at half voltage through a variac, perhaps by defeating the soft start and using the light bulb? I agree that "SVT" means "Stupid Vicious Thing" by the way.

11/7/2005 9:57 AM

R.G.

Re: Ampeg SVT 3 Pro output has DC

I used to use a variac too, but I got frustrated with some smart amps that refused to play if their power supply was not right after X delay.

If it's a typical class AB solid state, there may well be two driver transistors, one on top and bottom.

Some amps use a bootstrap capacitor from the output to a split load for a single driver transistor, but that's pretty old school and rare these days. A bad bootstrap cap could give you a similar problem.

You may have a fault in the soft start circuit itself. Is it easy to defeat?

What is the power supply to the amp like? Bipolar? How many volts? Can you run it at half voltage through a variac, perhaps by defeating the soft start *and* using the light bulb?

I agree that "SVT" means "Stupid Vicious Thing" by the way. 8-)