Keep your finger on the heatsink. 
Are you sure all the soldering work is well done?
Is the sound undistorted with your finger on the heatsink? (Apart from the hum)
Are you sure all the soldering work is well done?
Is the sound undistorted with your finger on the heatsink? (Apart from the hum)
Nicely done Hugo!
Good work sg97, very good.
The hum may be due to RF oscillation. Often if a heat sink isn't grounded this may happen. You cannot directly ground your heat sinks, but larger ceramic capacitors to circuit "ground" should clear that up. A scope would have confirmed this (or not).
Good work sg97, very good.
The hum may be due to RF oscillation. Often if a heat sink isn't grounded this may happen. You cannot directly ground your heat sinks, but larger ceramic capacitors to circuit "ground" should clear that up. A scope would have confirmed this (or not).
Please take a pic fom the input socket and the connection to the amp.
I think the amp is fixed. We only need to fix this grounding issue.
It is important to know that there is minimal hum with no TRS connected. That's a good thing.
I think the amp is fixed. We only need to fix this grounding issue.
It is important to know that there is minimal hum with no TRS connected. That's a good thing.
And now it will play with transistors from around 1978 🙂 A Good Year for the Roses err...transistors.