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Old 8th April 2012, 12:16 AM   #611
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If i had to define what iam hearing, i would say it a level of sibilance or maybe even decay. Puzzling. Makes methink possible bad layout ans noise, although i dont know how it is getting through regulator. One of myfavorite artist to test amps woth is Allison Krause. She has tone to her voice that is revealing of amps. It shows up in her voice an dalso on drum snares and brushes. Gonna throw in John scofield, Grace Under Pressure and have a listen., then onto Patricia Barber and Night Club.
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Old 8th April 2012, 12:20 AM   #612
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Why you got that RCRC before L? And not just a permissible C before L if you look at your rectifier's datasheet?
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Old 8th April 2012, 12:43 AM   #613
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You have rclc in you schematic with tube rectifier. I can change easily if you think this is the source of the problem. Ill look at datsheet again, but dont remember seeing that.
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Old 8th April 2012, 02:24 AM   #614
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40uF max for 5U4G. I added an R to drop some voltage and damp the charging peak but not yet another RC cell. Don't know about the sonics and your config but it can be made simpler for a test. First cap value allows you to get less voltage the lower you go by the way.
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Old 8th April 2012, 07:49 AM   #615
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My handbook sais that the total resistance of transformer windings and first cell must be a minimum of 575 ohms [The datasheet mentions 575 @ 1000 V RMS and 250 @ 750 V - the latter is your target]. With a toroid and 100 ohms you are far from that, I suspect.
5R4G.pdf

And 5V AC is the max, can't you dewind (if you understand) a few windings? I have had troubles myself with too high currents/capacitor banks, and in one case one tube arced, in a setting for a 300B amp, while another was OK in the same amp.

If you tap unsymetrical you get bad harmonics too. A resistor bridge between the two legs 1/2 and 7/8 is needed if you don't have a center tap: 2x200 ohm 5 W would be nice, the output from the intersection.
albert
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Last edited by triode_al; 8th April 2012 at 08:02 AM. Reason: additions
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Old 8th April 2012, 11:10 AM   #616
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Salas,
Are you saying 40uF for first stage. In your. drawing there is 470uF. I can easily combine resistors and make into 160R to 4.7uF(i have1 uF or 2) to choke to 40uF.
Triode Al,
570R wouldgive way too much Vdrop and i would not have enough for regulator. Are you saying standard EI trafos have higher internal resistance and help in ths regard? Also, i do not have CT, although numerous schematics have shown non CT configuration, although it makes senses about signal not being balanced. I had planned to wrap toroid with another winding as suggested by KevinK, i guess i could do two and make sure they are balanced.
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Old 8th April 2012, 11:32 AM   #617
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The PSU schematic had 150R to 4u7 to 20H choke (70RDC) to 470u. That gives 220R additionally to the transformer's internal and was enough to smooth out the charging peak on the scope. The tube specs specify a max for the input cap in a CLC.
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Old 8th April 2012, 11:48 AM   #618
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Gotcha,
will measure toroid and make changes and measure with scope. Thanks for explanation
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Old 8th April 2012, 12:55 PM   #619
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Salas,
What's the maximum safe current that your filament regulator can produce in this configuration? I'm considering regulating the filaments in my power amp. I think the KT88's draw around 1.6A. I apologize if I'm getting off topic.
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Old 8th April 2012, 01:22 PM   #620
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I wouldn't use LM317 for 1.6A. 1.5A is its datasheet max on a good sink. LM/LT338A is ample at 5A spec and low drop. Google its datasheet and sink it well if you will use one.
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