My New (old) PL400 --how to upgrade?

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rinman77

New Around These Parts
Joined
Apr 6, 2019
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Hi,
I just received a pretty beat up, but working PL400. The board looks a little different than other ones I've seen posted here. I'm curious what might be my best options for upgrades. I listened to the amp already and I definitely like it, but I'm sure there's room for improvement. It's clear that one of the big caps has been replaced, but I'm not sure as to whether all of the smaller caps are original or not--it seems like some of them might be newer.
I'll be studying some of the threads to try and learn as much as I can. But if anyone is willing, please take a look below and let me know if there's anything particular about this unit that might impact my upgrade choices.
Thanks!

PL400_whole layout.jpg20190414_184213_Name plate.jpg20190414_184423_main board.jpg20190414_191901_main-board-bttm.jpg20190414_184322_the fins.jpg
 
Depends on how far you want to go. New driver board, back plane boards in full comp mode, new LED light board, cap kit , etc....
 
I guess I would start with most "bang for buck", or most "bang for easiest to implement" first, and then go from there.
I would want to focus on sound before aesthetics, and I would consider the back plane as the last thing to tackle because I would want to first hear how it sounds in its original configuration. So given that my thought would be:
  1. Cap upgrade
  2. Control board upgrade
  3. Aesthetics (LED kit, front panel)
  4. the (maybe) Back plane upgrade
Does that seem to make sense? Am I missing something?
Thanks,
 
Easiest to most difficult
Output transistors...
Cap upgrade
Light board upgrade
Control board upgrade
Backplanes

Not going full comp with the backplanes will limit the improvements received however.
 
It was being used in a live sound situation, so 1/4" more common than RCA. They also added a on/off switch on the front.
 
Gepetto said:
Easiest to most difficult
Output transistors...
Cap upgrade
Light board upgrade
Control board upgrade
Backplanes

Not going full comp with the backplanes will limit the improvements received however.
Click to expand...

I know its subjective, but how would you describe the sonic improvement realized by the full upgrade.
 
A state of the art amp that competes with anything in the 10K range. I've owned Spec 2's, SAE 2400, Denon POA 2800, Bryston 4B, and some others I can't remember right now. The bottom line is they sound more "alive" than the aforementioned amps...
There will be some that say the specs don't support my observations, to which I say there are things we hear that can't be measured.......and things measured we can't hear....
 
OK, my next question: is the PL400 version I have compatible with the stock upgrades available?
 
Yes, you may have to drill a couple holes in the backplane to fit the PL14-20 board in place of that PL400C, but it's a piece of cake...the rest should be basic layout and point to point wiring.
 
Do you need to see more than this?
 

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Do you know Eric?
 

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rinman77 said:
Hi,
I just received a pretty beat up, but working PL400. The board looks a little different than other ones I've seen posted here. I'm curious what might be my best options for upgrades. I listened to the amp already and I definitely like it, but I'm sure there's room for improvement. It's clear that one of the big caps has been replaced, but I'm not sure as to whether all of the smaller caps are original or not--it seems like some of them might be newer.
I'll be studying some of the threads to try and learn as much as I can. But if anyone is willing, please take a look below and let me know if there's anything particular about this unit that might impact my upgrade choices.
Thanks!

View attachment 34723View attachment 34724View attachment 34725View attachment 34726View attachment 34727
Click to expand...


If you start a rebuild, pay a lot off attention to instructions and detail. You do not want to take it apart to fix something you missed
or something in that sort. I've had to take the Baclplane's out of mine twice now. And this is after installing the Control board once.
 
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