Telecaster Guitar Forum - View Single Post - $299 Gibson tube amp

Jaybird · March 11th, 2008, 11:32 AM

[quote=specialty guitars;1150915]Yours is a unique one for sure. I can't imagine lifting that 25uF cap would make it sound "spotty and gargley", when all it does is reduce gain. NFB can be a tricky issue. I do wonder if the .1uF caps made it unstable. Yours is the only one that's had those problems (that we know of), and it's the only one with different value coupling caps. Amp circuits are kind of a "balancing act".

I thought about this and decided to try some other value NFB resistor. First I used a 100k , because the squeal was so intense, I figured the 47k must be way off if what you told me is the case. There was still squeal, but not so immediate or scary sounding. Next I used a 1 meg resistor (overkill?) to just determine if anything stopped the squeal. No squeal, but no noticable difference in the amps sound. So now I think I will hook up a pot and see if I can dial in something. To your ears, just how does the NFB change the tone or sound of the amp, what should I be looking for?

March 11th, 2008, 11:32 AM	#453 (permalink)
Jaybird Tele-Meister Join Date: Nov 2006 Location: California Posts: 184 9 Photos	[quote=specialty guitars;1150915]Yours is a unique one for sure. I can't imagine lifting that 25uF cap would make it sound "spotty and gargley", when all it does is reduce gain. NFB can be a tricky issue. I do wonder if the .1uF caps made it unstable. Yours is the only one that's had those problems (that we know of), and it's the only one with different value coupling caps. Amp circuits are kind of a "balancing act". I thought about this and decided to try some other value NFB resistor. First I used a 100k , because the squeal was so intense, I figured the 47k must be way off if what you told me is the case. There was still squeal, but not so immediate or scary sounding. Next I used a 1 meg resistor (overkill?) to just determine if anything stopped the squeal. No squeal, but no noticable difference in the amps sound. So now I think I will hook up a pot and see if I can dial in something. To your ears, just how does the NFB change the tone or sound of the amp, what should I be looking for? __________________ Blaaaa blaaaaa, waaaaa waaaaa, razzle dazzle, do dah, zzzzzzzzzz.