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Old 22nd August 2010, 03:09 AM   #1
Brit01 is offline Brit01  United Kingdom
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Default Humming from WCF but not SRPP

Used exactly the same power supply for a WCF headphone amp and just got humming from the PSU.

With the SRPP set up, same chassis/grounding etc, dead quiet.
Is the WCF more susceptable to noise?

I do like the SRPP a lot.
Just trying out it with some 5687 now. Loved the 6N6P.
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Old 22nd August 2010, 03:17 AM   #2
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Location: Maui, Hawai'i, USA
SRPP has very good PSRR. How much ripple on your B+?

P
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Old 22nd August 2010, 03:35 AM   #3
Brit01 is offline Brit01  United Kingdom
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not sure in this moment. My PSUII just crashed!!

For the SRPP:

Hexfreds
1uf
1K
200uf
1k
200uf/bypassed with 0.1 MKP10 Wima


Same caps with WCF, just varied resistors for correct B+.
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Old 22nd August 2010, 05:03 AM   #4
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not sure in this moment. My PSUII just crashed!!

'king measure it!

Put a biggazz choke in place of the first resistor. 10H minimum. I use 25H.

P
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Old 22nd August 2010, 01:48 PM   #5
Brit01 is offline Brit01  United Kingdom
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Wish it was that easy to buy a choke. Can't even buy caps bigger than 250V, they have no idea what PIO is, and OPT's forget it.

Well I think I'll just stick with the old trusted SRPP.

(I live in Uruguay!)
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Old 22nd August 2010, 08:37 PM   #6
Brit01 is offline Brit01  United Kingdom
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Default Confused with LM317 and LED bias

I'm running a SRPP and trying out with different CCS on top and bottom cathodes.

Set up a DN2540 on the cathode of the top tube which works nicely.

But I thought I understood how to use a LM317 on the cathode of the bottom tube. Obviously not.
I had a Voltage of 1.21 V on the output of the LM317 with a resistor of 68 ohms.
So about 18 mA no?

So why does it not work? Just get a total distorted mess.

What am I doing wrong?


LED bias: If I have a voltage of 2.2V on the cathode with an LED with 130V on the anode of the bottom tube, how can I work out the current? I realise it sets up a constant voltage source but still confused.

I'm using 6N6P's in a headphone configuration.

Thanks
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