Grounding can be very tricky in a high gain amp, moving them or running dedicated grounds to the star point can make all the difference both regarding hum and oscillations. I'd try to simplify it as much as possible, pull the drive tube and try to get the clean channel right. Power down the FET to see if it is the source. Also, see if the hum goes away seconds after you power it off, there's still power in the caps and the heaters are hot.
You have a low voltage of 18.8 if I remember correctly. Now 18.8/3~6.3. So could a three-way voltage divider be a solution? I can see some challenges with running the relays of that, because current draw will vary.
Depends on where I put the voltage divider. Unless I place it at the end of the chain and just use it for the relays, I'm supplying filament current through those resistors, which would mean I'd have to use some pretty big resistors. Just 300mA dropping 12.6V would dissipate 3.75 watts. That also adds to the current that the transformer has to supply.
I like your cradle I did mine with half circle cut out of the outside, and a thumbscrew and allthread for a stop or adjustment. The same for the sliding adjustable bottom. Can't wait to hear it, well I guess I have to wait to hear, so I can. Ha
Not yet. I've been away from the workshop for quite a while. It's been an interesting year for me to say the least. I hope to get back to work on it soon. I finally finished working on my other amp which I designed from the ground up. As soon as I can get back to the shop I'll do a video on that too.
yes that is very cool.
yes i want that kit :) thanks.
i guess it didnt turn out so good or we would have a demo by now.
Looking forward to the $75 amp turn on and play thru demonstration
Grounding can be very tricky in a high gain amp, moving them or running dedicated grounds
to the star point can make all the difference both regarding hum and oscillations. I'd try to
simplify it as much as possible, pull the drive tube and try to get the clean channel right.
Power down the FET to see if it is the source. Also, see if the hum goes away seconds after
you power it off, there's still power in the caps and the heaters are hot.
You have a low voltage of 18.8 if I remember correctly. Now 18.8/3~6.3. So could a three-way voltage divider be a solution? I can see some challenges with running the relays of that, because current draw will vary.
Depends on where I put the voltage divider. Unless I place it at the end of the chain and just use it for the relays, I'm supplying filament current through those resistors, which would mean I'd have to use some pretty big resistors. Just 300mA dropping 12.6V would dissipate 3.75 watts. That also adds to the current that the transformer has to supply.
I like your cradle I did mine with half circle cut out of the outside, and a thumbscrew and allthread for a stop or adjustment. The same for the sliding adjustable bottom. Can't wait to hear it, well I guess I have to wait to hear, so I can. Ha
That was my first idea but I knew I'd never get the channel cut right. How did you cut yours?
@@timkrauseelectronics9245 router
Very nice series!. Does the amp work now?
Not yet. I've been away from the workshop for quite a while. It's been an interesting year for me to say the least. I hope to get back to work on it soon. I finally finished working on my other amp which I designed from the ground up. As soon as I can get back to the shop I'll do a video on that too.