DChristie's PL 2000

mlucitt said:
Joe, are those back-to-back 2.2/35V electrolytic capacitors (C47-C50) there to block DC from leaving the preamplifier?
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Yes that is what they are for, you would also benefit from making them larger and non-polar. You can easily get a 4.7uF or larger polypropylene to fit in that area and get rid of those crappy electrolytics. You only need one cap to replace the 2 in series.
 
Gepetto said:
The center tap is just the easiest Lee, either works. When you put them in the 12V legs, you have to double the value (200) to get the result I was looking for in the center tap with 100.
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I have some 220's....
 
Gepetto said:
Yes that is what they are for, you would also benefit from making them larger and non-polar. You can easily get a 4.7uF or larger polypropylene to fit in that area and get rid of those crappy electrolytics. You only need one cap to replace the 2 in series.
Click to expand...


That would make for some long leads where they're at...
 
You have to go from the minus to minus holes, but it'd work....what voltage?
 
Hookay, I'll put em in...

Gotta do Old Chicago with Jani for a bit. Date night..
 
Gepetto said:
That is 3x better than what is in there now. 2.2uF in series with 2.2uF = 1.1uF

I call that a big win
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We don't have DC blocking caps on the outputs of the OPAMPs in the Rev E or Rev G1 Control Boards, right? Why are these caps necessary in the PL2000? Do OPAMPs typically contain DC levels on the output, or is it just a failure mode that we are trying to prevent? Just curious.
 
Yeah, when something goes south in a pre.....that is hooked to a WOPL 700....without caps in line.....shit can get intense..,.
 
mlucitt said:
We don't have DC blocking caps on the outputs of the OPAMPs in the Rev E or Rev G1 Control Boards, right? Why are these caps necessary in the PL2000? Do OPAMPs typically contain DC levels on the output, or is it just a failure mode that we are trying to prevent? Just curious.
Click to expand...

They aren't necessary in an extremely well behaved preamp where the output offset is sub millivolt. They are there...
 
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