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Old 26th March 2004, 01:06 AM   #11
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Well the U19 curves seem damn flat! I think we have a winner!

(A winner because it can handle so much voltage with such a high mA.)

Only problem is, the table is of a scale of 1000's of volts!!

According to figure 2 in the same image, at 1000volts you see roughly a 25volt drop from the operating voltage of 825v from 100 to 325mA

Which means that a 500volt supply is likely to come out 25-50volts lighter.

I would probably see performance on par to PY500A...
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Old 26th March 2004, 02:40 AM   #12
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Nope, it still works out below 400volts while running a PY500A into choke. 350volts to be exact, way too low.

I would get the same result with the U19 so both tubes are discarded, unless someone can tell me the maximum capacitance for the PY500A for frontline cap while in bridge? ie. 4 valves to make one 4 diode bridge.

I could try but I think it'll still go below 400v even with a cap infront, and even then I would need 47uF to see 470v!

I tried 8uF and it came to 450v.

Other than that, it's SS ...
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Old 26th March 2004, 05:06 AM   #13
SHiFTY is offline SHiFTY  New Zealand
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IMHO, you should use SS rectifiers. In a SE amp, there is probably more justification for tube rectifiers, but in PP, with the higher power supply rejection ratio (PSRR) you don't need to worry.

I use a couple of plain old 1N5408 in my 807 PP amp. The amp is totally silent, no noise at all. Any high frequency noise is removed by the choke. The power supply is solid as a rock, great regulation. The amp sounds fantastic.

The main problem with a GZ34 or similar is the power supply dips by tens of volts when a loud sound is played. This changes the operating point of all the tubes right down to the preamp and therefore you get distortion.

My idea is to provide the tubes with the optimum operating conditions, ie nice high current power supply.
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Old 26th March 2004, 05:12 AM   #14
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Indeed shifty.

I guess that's a wrap then.

My SS design (frontline cap is 8uF PIO):
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