It seems some people here have a pretty good grasp on amp engineering. I have a KT88 pentode monoblocks that hum 60 cycle. When the input is shorted and the 12ax7 pulled, its totally quiet. My local tech surmises the noise therefore originates before that tube or in the tube.
Amp is a typical wood bread box built on the over the shelf DIY Tube CB. He is mocking up a tube socket he can stick in the existing socket, then power the anode with 5 volts DC, instead of AC.
He is also wondering about the case. Do I need a shielded case. Any thoughts on what to try?
There is a Lundahl input transformer from the single ended rca to the CB.
I have already swapped tubes, shielded tubes, cheated ground, different power cables, different locations in home, isolation transformers, shunyata, isotek, turned off house, ground is 6.7 ohm. I'm pretty sure its an inherent internal noise and I would love to isolate it and get rid of it.
Amp is a typical wood bread box built on the over the shelf DIY Tube CB. He is mocking up a tube socket he can stick in the existing socket, then power the anode with 5 volts DC, instead of AC.
He is also wondering about the case. Do I need a shielded case. Any thoughts on what to try?
There is a Lundahl input transformer from the single ended rca to the CB.
I have already swapped tubes, shielded tubes, cheated ground, different power cables, different locations in home, isolation transformers, shunyata, isotek, turned off house, ground is 6.7 ohm. I'm pretty sure its an inherent internal noise and I would love to isolate it and get rid of it.