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Old 17th June 2014, 08:40 AM   #471
ahaja is offline ahaja  Poland
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Aaaa ;-) - I thought about preamplifier circuit.

PSU - I don't know where is R3/27R - I don't see schematic ...
Is it after LM reg working as a CCS?
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Old 17th June 2014, 12:08 PM   #472
BigE is offline BigE  Canada
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No. It is on the collector of the transistor.

Edit: No coffee yet....
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Old 18th June 2014, 03:25 AM   #473
BigE is offline BigE  Canada
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Finally got LTspice to work properly.... C3 is a problem for LTspice. It has been removed, and a 10 uF cap has been placed across the adjustment pin to ground. This may be changed to something much smaller, but it works for now.

1.23 volts is now measured across the CCS setting resistor -- seems like the regulator is working.
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Old 18th June 2014, 04:50 PM   #474
BigE is offline BigE  Canada
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It also works, and sounds better, (IMO) with the 10 uf cap removed. C4 is necessary according to Walt Jung.

http://waltjung.org/PDFs/Sources_101_P2.pdf

I also replaced R3 (27 ohm) with a 10 ohm resistor to better match the LT spice model (difficulty converging with 27 ohms).

Last edited by BigE; 18th June 2014 at 05:05 PM.
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Old 19th June 2014, 01:06 AM   #475
BigE is offline BigE  Canada
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Tantalum R3 @ 12 ohms is terrific. ( In my subjective opinion. )
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Old 21st June 2014, 04:27 AM   #476
BigE is offline BigE  Canada
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The oscilloscope says different..... To get current oscillation under control, I went to a different transformer. Now running a single 216 VA 2x18 instead of a pair of 229R24. The 229R24s ought to be enough, but this works..... The 'scope says that under static load, the oscillation is gone. Also,back to the 27 ohm PRP.

The biggest frustration is that LTspice simulates differently from real life... will test the dynamic performance on the scope.

Last edited by BigE; 21st June 2014 at 04:37 AM.
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Old 21st June 2014, 02:16 PM   #477
BigE is offline BigE  Canada
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Do not remove C9 and C10. They reduce sibilance. LT spice says 0.1uF is enough, so that position now has MK1837 caps. Sibilance is reduced.
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Old 22nd June 2014, 01:22 PM   #478
BigE is offline BigE  Canada
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Can we use an NTC as a "slow start" for the LM317/337 regulators?
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Old 2nd July 2014, 11:13 PM   #479
BigE is offline BigE  Canada
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Wima MKP 0.047 uF for C9 C10 is excellent.

May try bypassing the 100u on the phono board.
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