Hi, I have solved after hours the "static hum 100 Hz" Problem. There is a link anywhere in this Thread to that Issue.
So I also canceled the HT+ Supple on the Mainboard and "outsourced" with additional PSU PCB Outcut from the Controlboard. I only outsourced the HT, not 12V DC Supply. This 12V DC Part remained in the Main PCB.
Here are my Summary of recommanded to get rid of Oscillation, Hum and Noise:
- Outsourcing of the HT+ PSU Part at the Mainboard using the small remaining HT+/12 additonal PSU PCB, the 0V connection from the big ReservoirCaps goes in my Build directly to the Star Ground - Grounding of the these Caps on dedicated Connection has caused the most 100 Hz Hum
- Useing the recommanded Grounding Schematic with Pin1 Input to the Ground
- Useing shielded Cables for all Audio Lines like XLR Connections, Instrument Connections/Oszillation Mod, drill all other Cabels especially for ACs, ...
-Do the Oszillation Modifikation, this mod is in most cases absolute Necessary to get rid of the that
- Check the Instrument 6.3 Jack if "To and From" is reversed or try to reverese the Cables if anything feels not common like additonal Hum if using the front Jacks...
- check if you use the OEPs - the Cans should have a connection to the Ground or they are very sensitive!
-Transformers as far as possible away from the Tubes, Audiotransformers, XLRs...
By the way I am not a Electrical Engineer and this Build was really hard to get a propper working Unit. This piece is an excellent sounding Unit, behaved clean sound. Sound very expensive...
And yes, a first Quicktest show that the OEPs have from 60Hz to 20kHz a very linear Frequency Response. Under 55Hz to 20 Hz they are causing a Bass Roll off of about 3-4 dB at Line Mode with Line Level, 0dB 0,775V Output. So you should think about it, if you need this Lowend Range, or you prefer this little extra Preparation for the Mixing....