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6v6 PP choosing between 9k and 12.8k tran

Worked on the amp last night and had good results. First reversing the polarity of the output transformer mains did correct the feedback. Equipment used for this testing, a Fluke 8025B multimeter and a EZ OS-5020 oscilloscope and an AirportExpress for signal generation. I measured the open loop and closed loop gain with the original 2.2K value in place and decided the transformers were acting good enough that I could reduce the feedback voltage some to get a little more gain, with my hillbilly factoring I figure I ended up at about -10dB using 3K for Rf. I saw some signal noise at the low end at higher levels which a .001uF feedback cap cleaned up. Results, I went from (if generous) the original 3.5 Watts, 50 - 20K, to 6.8 Watts clean 50 - 20KHz. It will do 2 Watts clean down to 37Hz. The 1KHz square wave looks good measured with my limited equipment, (side note: The choke that went into this amp came out of my departed Eico 377 Audio Generator) and a 2KHz square wave looked very reasonable. At 1KHz it will do 8 watts without any visible waveform distortion. I'm happy with the results and want to thank all of you who helped along the way. I dedicate this project to Kegger as it was this little amp that originally led me to come to know him on here.

Regards,
Bill Smith

for Kegger
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Thanks Kward, been sitting listening to it, feeding a rebuilt pair of JBL L19's With a big smile on my face. Bruce Springsteen, Darkness on the Edge of Town sounds sublime. I started this out repeating the saying that the iron is the heart of an amp, well I believe the iron is the lungs and the power supply is the heart. I will never be able to afford a Mackintosh or Citation II class of amp, but I got a little home brew race horse here.
 
Amplifiers are basically power supply modulators. All of the juice going to the speaker comes from the power supply, so if thats lousy everything else is too.
 
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