vinta9e
New member
Re: NAD Peavey 6505
http://www.ultimatemetal.com/forum/andy-sneap/254781-just-did-5150-bias-mod.html
Perhaps not the tidiest way I've seen it done but serves the purpose of showing the $1.50 worth in parts. The mod substitutes the 15k resistor with a 10k trimpot and a ~5k resistor in series. The power tubes can now be biased a little hotter. What sounds and feels best to me in these amps is still on the cold side - nowhere near redplating so it doesn't shorten tube life. Just enough that "the shrill is gone".
I don't mean to encourage you to push your hands inside the amp and get zapped to death. Just letting you know that it doesn't take Mr. Dumble to make it happen; it's a routine, half an hour job including tube biasing for any tech worth his salt.
http://www.ultimatemetal.com/forum/andy-sneap/254781-just-did-5150-bias-mod.html
Perhaps not the tidiest way I've seen it done but serves the purpose of showing the $1.50 worth in parts. The mod substitutes the 15k resistor with a 10k trimpot and a ~5k resistor in series. The power tubes can now be biased a little hotter. What sounds and feels best to me in these amps is still on the cold side - nowhere near redplating so it doesn't shorten tube life. Just enough that "the shrill is gone".
I don't mean to encourage you to push your hands inside the amp and get zapped to death. Just letting you know that it doesn't take Mr. Dumble to make it happen; it's a routine, half an hour job including tube biasing for any tech worth his salt.
