• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

PSU question? Going tube rectified

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I'm building this amp
An externally hosted image should be here but it was not working when we last tested it.

The artice says the max output current is 20 ma

Here's the psu
An externally hosted image should be here but it was not working when we last tested it.


I'd like to use a 5U4GB retifier because I have a bunch laying around and a 235-0-235 @270ma transformer. I put some values into PSU designer but I'm not shure about the rectifiers limits? How should I change the capacitors values so that it's within the rectifiers range?
 
Why do you consider it out of range at the moment?

I don't believe PSU II takes tube warm up into consideration when it sims. So you could ignore excess current messages during the first few seconds anyway.

BTW, 100 uF, seems off the charts for a headphone amp.

;)
 
Sure... 150 uF is fine.

MerlinB,

As the the input cap gets larger, the diode conducts for a shorter duration of time (conduction angle). Equal energy, in less time, means more current. Instead of "ripple current"... think of it has "peak charging current". This current kills the diode. Inrush is not a problem because the tube diode wakes up slowly.



;)
 
Hi phn,

Cheap chokes are what happens when your kid throws the cordless phone into the swimming pool or knocks the Weber (popular American outdoor cooking grill) over loaded with ribeyes (expensive and tender beef steak).

Chokes find their advantage ($$) when the wattage levels go up.

;)
 
Yes,

But also you should be looking at ripple voltage as well. Look at the min and max voltages of your final cap. The difference between these two is the ripple voltage and that could be audible. Larger caps will reduce this voltage; buit also increase currents... it is a comprimise you must balance.

Try experimenting with a larger resistor & smaller caps as rdf suggested. If your supply comes out at 240 Volts, that will make very little difference in the sound, if any. A ten fold reduction in ripple could make a real difference.

Do you have a specification for the desired ripple voltage>? What caps were in the original design?

;)
 
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