Hello,
Your comments and advice would be most welcome.
I have a tube preamplifier with the power supply (rectifier tube) inside - the unit is noisy. It has a 50Hz hum and I have tried everything I know to solve the ground loop. A picture of the preamp is attached.
I have decided to separate the power side and the signal side into different chassis' in the hope that this will help.
I will not touch the circuitry or their connecting wires except replace rca wiring and redo the grounding. I'll also replace the 'umbilical' as it will need to be longer. This project is really a separation and rearrangement of the components. The PDF plan is attached. I have not indicated wiring that connects the components as I will keep them intact.
I'm not very knowledgeable but I feel confident that I can do this.
I have a couple of quesitons:
1. Should the PSU chassis be steel or aluminium?
2. Should internal grounding wires be the same wires as the signal wires?
3. I am looking at Jupiter 23awg
4. Which kind of wire should I purchase to use as the umbilcal wire?
Any comments or suggestions would be most helpful.
Gratefully, Bob
Your comments and advice would be most welcome.
I have a tube preamplifier with the power supply (rectifier tube) inside - the unit is noisy. It has a 50Hz hum and I have tried everything I know to solve the ground loop. A picture of the preamp is attached.
I have decided to separate the power side and the signal side into different chassis' in the hope that this will help.
I will not touch the circuitry or their connecting wires except replace rca wiring and redo the grounding. I'll also replace the 'umbilical' as it will need to be longer. This project is really a separation and rearrangement of the components. The PDF plan is attached. I have not indicated wiring that connects the components as I will keep them intact.
I'm not very knowledgeable but I feel confident that I can do this.
I have a couple of quesitons:
1. Should the PSU chassis be steel or aluminium?
2. Should internal grounding wires be the same wires as the signal wires?
3. I am looking at Jupiter 23awg
4. Which kind of wire should I purchase to use as the umbilcal wire?
Any comments or suggestions would be most helpful.
Gratefully, Bob
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Hi Miniwatt,
The unit is not a commercial unit. I bought it for very low dollars and it had the hum. I thought to myself "no problem, I'll be able to solve that". Well, its been a lot more difficult than I thought
I.ve tried every combination possible. I've also tried a Ground Zero.I think there may be induced hum between components. Also, I thought grounding would be easier with two separate chassis - am I correct?
I just tried twisting some wires and the grey wire has just moved to that position accidently - so the hum is not due to that.
Oh, I think you mean the grey cable at the bottom of the picture. Right!
Its connected to the switch on the front panel and continues around the front and other side to the terminal for the transformer. It is sheilded though.
Ok, I'll have a closer look. Thank you,
Hi Bob. The layout seems very poor, input sockets very close to the transformer and the mains power routed all round the chassis and very close to the valve, I'd be tempted to remedy these first. Ground loops are not necessarily easier to deal with using separate chassis, you may even make them larger. It looks like the signal wires are twisted left and right channels together and ground wires run separately, this is not correct, the signal flow and return (gnd) should be twisted together
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It's also possible there are either defective capacitors that need to be replaced,
or design errors that must be corrected. Separating the circuits into different
enclosures might do little or nothing about the hum. Can you get a schematic
from the previous owner?
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