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Old 21st December 2005, 06:40 PM   #121
lineup is offline lineup  Sweden
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Here is a better ORIGINAL Crescendo 1982 schematic scan.
I found the link by searching this forum.
http://img347.imageshack.us/my.php?image=cres1c9wn.jpg

I hope it uses same refering label numbers for resistors as danne uses.
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Old 23rd December 2005, 02:26 PM   #122
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I test my Crescendo today again and i have change the resistors and tody the R15,R16 and R9 gone upp in smoke why, sombody now???
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Old 23rd December 2005, 02:44 PM   #123
Jay is offline Jay  Indonesia
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hi danne,

may be you put 12V zener in place of 3v9 zener? They look similar. The 12V one is slightly fatter, and has higher series number.
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Old 20th February 2006, 03:22 PM   #124
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I hav eproblem whit oscillations in my crescendo somone that can help me+?
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Old 20th February 2006, 04:05 PM   #125
Bensen is offline Bensen  Belgium
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Make sure that your gate resistors are as close as possible to the gates of the MOSFET's! Put a ceramic cap of a few 100n between the + and - rail as close as can be to the FET's.
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Old 21st February 2006, 06:37 AM   #126
AndrewT is offline AndrewT  Scotland
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Hi Bensen,
do you mean drain to power ground? or +drain to -drain?
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Old 21st February 2006, 04:29 PM   #127
Bensen is offline Bensen  Belgium
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Hi Andrew,

No I ment: just placing one ceramic cap between the power rails. And this as close as possible to the MOSFET's.
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Old 22nd February 2006, 07:54 AM   #128
AndrewT is offline AndrewT  Scotland
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Hi,
just as done with opamp bypass!
Never seen this on a power amp.
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Old 1st April 2006, 02:46 PM   #129
refosk is offline refosk  Slovenia
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I had built the original crescendo from 1982, it works fine with low volumes but when I volume it up I get strange distorsions heard like brp,brp,brp when bass is playing. And this bass distorsions are very loud. Can someone sugest me what to look for?
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Old 1st April 2006, 03:56 PM   #130
joensd is offline joensd  Germany
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Maybe P1 is dirty/corroded and so bias current might not be set properly.
Check bias current and if you set it up turn the pot slightly forth and back (that sometimes is enough to "clean" the contacts;
if its too bad and current alters, change it)

Otherwise check all voltages and report back the ones that are not at least similar to the original schematic.
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