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Old 13th March 2013, 04:18 PM   #2061
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Anyone know what C7 does?
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Old 13th March 2013, 04:34 PM   #2062
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compensation cap , what else

ensuring your better sleep , when thinkin' about HF in your preamp

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Old 13th March 2013, 04:49 PM   #2063
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C7 is off mine.
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Old 13th March 2013, 04:55 PM   #2064
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Thanks -not so obvious to a newb, after after reading Wikipeadia.

Any ideas why I get voltage oscilliation at output R16/R17 on one channel. Some have suggested removing C7 to prevent oscilliation.
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Old 13th March 2013, 05:09 PM   #2065
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some are having different problems ;

Wayne didn't put it here to make oscillation
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Old 13th March 2013, 05:36 PM   #2066
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I am sure it was put in for good reason. I want to be methodical before pulling, swapping parts arbitriarliy.

If this cap was bad, would it create my symptoms? Same with C9?
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Old 13th March 2013, 05:59 PM   #2067
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according to post #2030 , I can see few things :

increase R28 to have 1V5 across R6 ; then you'll have around 1V across R29

then fiddle with P1 to have 0 at R16/R17 node

increase source resistors for input Jfets , to have 9V4 at Q3 colector


solid caps are rarely culprit of problems , at least not in this range of voltage

all measurements with input gnd-ed

if you make it as Wayne constructed it , it must work


if not - something is ooked in actual physical layout

frankly - I can't keep up with this thread , but it seems that Pearl make more than one Greedy Boy suffer ...... and that's pity , bcs circuit is simple and elegant and easy to grasp
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Old 13th March 2013, 06:44 PM   #2068
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I hate it when my stuff is ooked!
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Old 13th March 2013, 07:22 PM   #2069
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Quote:
Originally Posted by Zen Mod View Post

frankly - I can't keep up with this thread , but it seems that Pearl make more than one Greedy Boy suffer ...... and that's pity , bcs circuit is simple and elegant and easy to grasp
..unless you are Greedy Boy in Training (GBIT), newb. Probably over complicating - comes down to mistake in stuffing,etc. Bad component due to previous mistake. A lot bad ZVP3310s, ZTK450s for a lot of Greedy Boys, GBIT.
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Old 13th March 2013, 10:43 PM   #2070
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Check posts #473 and #647 by Wayne. Based on those, I left out C7.
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