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Old 16th September 2005, 02:54 PM   #1
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Default choke input ripple level?

I build a 6DJ8 pre with the psu of http://diyparadise.com/preamptutorial.html

I think it's an easy question, but...

How low is the ripple level should be for a B+ of 200VDC?

Is it ok for 10VAC?

I heard hum.. noise about 30cm from speaker and sss.. noise about 60cm.

Thanks for your reply.
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Old 16th September 2005, 06:13 PM   #2
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So.... your hum is lower than the noise floor? This is good.

Of course, we want no hum at all. So we want to find out if the hum is actually from the B+ or another source.

Do you see 10VAC on the 200VDC B+ line? Bad. However it should sound much louder than less than the ssssss.

How are you looking at the 10 volt AC?

Have you actually used 50H chokes???

Need more info, please.

Thanks!
Gabe
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Old 16th September 2005, 06:28 PM   #3
SY is offline SY  United States
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The PS hum should be about half a millivolt.

If you can hear hum, there's too much. My first guess would be the grounding and/or layout.
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Old 16th September 2005, 10:36 PM   #4
amperex is offline amperex  United States
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I prefer nothing more than .001% ripple in the B+ for preamps.
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Old 16th September 2005, 11:16 PM   #5
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to Gabevee,

Thanks your reply.

Quote:
How are you looking at the 10 volt AC?
I use a ditigal multimeter to probe tha B+ and ground.Switch AC and DC to measure it.

Quote:
Have you actually used 50H chokes???
No, I use two 20H chokes and (47+47)uF for each C.

To SY, amperex,

the ripple seem to be toooo big, I will check my solder , ground, and layer first.

Thanks.
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