Testing Leach Amp, questions about output

wigginjs · 10th July 2004, 08:33 PM

I'm about to start testing my leach amp and my question is this:

Do I need to have R50 and C25 wired in series between the positive output terminal and the negative output terminal in order to test the amp WITHOUT an input signal or output load?

Click here to see the schematic, you'll see R50 and C25 maked with astericks, which means they are located on the output binding posts. I don't have a very good way to connect these components at this time, but the tests I will be doing are without input signal or output load.

Tony · 10th July 2004, 10:56 PM

these are optional if you are merely testing the amps and not connecting the amp to a speaker load yet....otherwise don't forget to put them in when putting the amps in service..

by testing, you mean, checking the input offset voltages and setting the output transistor bias current, right?

Eva · 10th July 2004, 11:07 PM

The amplifier may oscillate randomly without this RC network, with or without speaker load and/or input signal, since one of its purposes is to lo load the output with 10 ohms above audio frequencies in order to limit open-loop gain and improve stability. Try to place the RC network temporally anywhere, connect it between output and power ground

10th July 2004, 08:33 PM	#1
wigginjs diyAudio Member Join Date: Dec 2003 Location: Columbia, SC	Testing Leach Amp, questions about output I'm about to start testing my leach amp and my question is this: Do I need to have R50 and C25 wired in series between the positive output terminal and the negative output terminal in order to test the amp WITHOUT an input signal or output load? Click here to see the schematic, you'll see R50 and C25 maked with astericks, which means they are located on the output binding posts. I don't have a very good way to connect these components at this time, but the tests I will be doing are without input signal or output load. __________________ The Four Chairs DIY Home Theater

10th July 2004, 10:56 PM	#2
Tony diyAudio Moderator Join Date: May 2003 Location: Palatiw, Pasig City	these are optional if you are merely testing the amps and not connecting the amp to a speaker load yet....otherwise don't forget to put them in when putting the amps in service.. by testing, you mean, checking the input offset voltages and setting the output transistor bias current, right? __________________ http://www.elab.ph/forum/index.php?topic=32688.0

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10th July 2004, 11:07 PM	#3
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	The amplifier may oscillate randomly without this RC network, with or without speaker load and/or input signal, since one of its purposes is to lo load the output with 10 ohms above audio frequencies in order to limit open-loop gain and improve stability. Try to place the RC network temporally anywhere, connect it between output and power ground