Recently got a used Decware Zbox. Unit has a buzz in both channels. Checked out all the parts and all parts are good. The internal wiring is a rats nest and may windup redone. But before going there, looking for some basic "quiet" mods that might help. Some of the items I am thinking about
- two 100 ohm resistors to ground each leg of the heater power supply
- reversing the phasing of the heater supply
- adding a choke to power supply
- adding more capacitance to power supply
- converting the AC heater circuit to DC
- adding an OC2 tube to power supply
I'll post some schematics of the Zkit4, which looks very similar to the parts and layout I have been testing. So from a concept model, any mods to make this circuit quieter, should work on the Zbox (no schematic available).
The schematic with the OC2 is an upgrade that is not in place, but certainly worth considering.
I'm including a pic of the current wiring job and another pic where someone already went down this road and cleaned one up.
- two 100 ohm resistors to ground each leg of the heater power supply
- reversing the phasing of the heater supply
- adding a choke to power supply
- adding more capacitance to power supply
- converting the AC heater circuit to DC
- adding an OC2 tube to power supply
I'll post some schematics of the Zkit4, which looks very similar to the parts and layout I have been testing. So from a concept model, any mods to make this circuit quieter, should work on the Zbox (no schematic available).
The schematic with the OC2 is an upgrade that is not in place, but certainly worth considering.
I'm including a pic of the current wiring job and another pic where someone already went down this road and cleaned one up.
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