Hello,
I have the intention of building a ThorstenL phono pre as discussed in dc phono
I have bought a toroid transformer and intend to use an RC cascade as the power supply fed by an EZ80. Now is my main question: is it useful to put the power supply (transformer + filtering) in an aluminium box?
I have the intention of building a ThorstenL phono pre as discussed in dc phono
I have bought a toroid transformer and intend to use an RC cascade as the power supply fed by an EZ80. Now is my main question: is it useful to put the power supply (transformer + filtering) in an aluminium box?
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In the mean time, I have built the thing and it works like a charm!
I chose to build it with a toroid transformer (not in a metal box) and an EZ80/81 rectifier feeding into an RCRCRCRCRC cascade. I know this does not give the best results, but I chose to make it tube-purist.
The only thing I can still chase for is a little bit of hum on both channels. it is currently at the same level as the record grain rumble, which means it is not bad at all, but I can hear it and I would like to improve that aspect a little bit.
I chose to build it with a toroid transformer (not in a metal box) and an EZ80/81 rectifier feeding into an RCRCRCRCRC cascade. I know this does not give the best results, but I chose to make it tube-purist.
The only thing I can still chase for is a little bit of hum on both channels. it is currently at the same level as the record grain rumble, which means it is not bad at all, but I can hear it and I would like to improve that aspect a little bit.
You must locate source of humm.
- anode voltage
- heater voltage
- input humm
- microphonics
For input humm when shorting the input to ground humm will disapear.
For anodevoltage humm disconnect ac anode supply to rectifyer while heater voltage is still and listen if humm disapear.
For microphonics touch the tubes and listen if the humm changes.
For heater humm try to determ of the humm is 50 or 100hz.
And post complete schematic incl. power supply as build.
Pictures of the build are always helpfull.
- anode voltage
- heater voltage
- input humm
- microphonics
For input humm when shorting the input to ground humm will disapear.
For anodevoltage humm disconnect ac anode supply to rectifyer while heater voltage is still and listen if humm disapear.
For microphonics touch the tubes and listen if the humm changes.
For heater humm try to determ of the humm is 50 or 100hz.
And post complete schematic incl. power supply as build.
Pictures of the build are always helpfull.
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