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Old 1st October 2012, 07:59 PM   #31
disco is offline disco  Netherlands
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Is that high value for R3 necessary? Did the C3G suffer from oscillation?

Is there no noise issue on the 6C4C cathode with all those LEDs?
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Old 1st October 2012, 09:19 PM   #32
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Quote:
Originally Posted by disco View Post
Is that high value for R3 necessary? Did the C3G suffer from oscillation?

Is there no noise issue on the 6C4C cathode with all those LEDs?
Soldering is ahead of me. That is also my first experience with C3g - so your question is to be answered.
As for LED - I replaced RC cathode bias with LEDs and there was a huge improvement. I did not measure noise though.
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Old 4th October 2012, 11:51 AM   #33
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Link to build thread of filament regulator for 6C4C
LM317 tracking pre-regulator and current regulator
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Old 4th October 2012, 01:13 PM   #34
tinitus is offline tinitus  Europe
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you could light up a house with all those leds
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Old 4th October 2012, 02:00 PM   #35
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I will attach a pic when I fire them.Only 112 per channel See attached pic from other thread.
Click the image to open in full size.

Last edited by yagoolar; 4th October 2012 at 02:04 PM.
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Old 4th October 2012, 02:03 PM   #36
tinitus is offline tinitus  Europe
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just one tad bigger pictures, please
much too small to see anything

hey, btw, thanks to you(partly) I just now realized why voltage drop over the plate resistor should be calculated and added to supply voltage nice to know
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Old 4th October 2012, 02:21 PM   #37
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Quote:
Originally Posted by tinitus View Post
just one tad bigger pictures, please
much too small to see anything
Original post with bigger pictures.
12W Push pull w/6C4C
Quote:
hey, btw, thanks to you(partly) I just now realized why voltage drop over the plate resistor should be calculated and added to supply voltage nice to know
Glad I could help
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Old 6th October 2012, 03:06 AM   #38
tcqanh is offline tcqanh  Viet Nam
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Originally Posted by yagoolar View Post
Recent schematic of the amp. Now assembly.
why don't you use fixed bias for power stage ? it is simple and easy to adjust the operation point.

many people here gave up the LED bias....
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Old 6th October 2012, 07:26 AM   #39
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I am rebuilding the existing amp with LED bias, yet improving / experimenting with some elements i.e. filament power supply and driver stage. I decided to leave output stage bias as is. If I went to fixed bias I would have to change at least mains transformer, add another regulator. And then I would end up with another enclosure, and that would be new amp. I have 2 more projects on the table: SET w/300b and PP w/6C4C. So perhaps then.
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Old 6th October 2012, 10:17 AM   #40
SY is offline SY  United States
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Quote:
Originally Posted by yagoolar View Post
As for LED - I replaced RC cathode bias with LEDs and there was a huge improvement. I did not measure noise though.
It's very low. Figure roughly 0.6-0.7nV/rt Hz per LED and the series string adds as power (not voltage).
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