My New Early Model PL400 w/ 4 Fin Heat Sink

punchback

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#1
First time posting in the Phoenix forums due to my recent acquisition. I've been jonesing for a Phase Linear for a long time. I mainly look on CL and I don't see them too often in the Cincinnati area. One popped up on CL that seemed a good price for an operational unit. So... I’m the proud owner of a new “old” PL400. It seems that it is an early model with a 4 fin heat sink configuration. It also has fuse type lamp to illuminate the meters from the top. This meter illumination apparently prevent me from using the White Oak Audio LED upgrade. Let me know if there is a way to make it work with my PL400. It is operational and has the stock (12pcs) PL909 and (4 pcs) SJ2741? The front panel is rough and has some sort of clear splatter on it. My wild ass guess is the splatter might be floor wax??

I’m looking for suggestions as to what is a must do upgrade. So far the following is what I plan. Let me know if I’m missing anything.
  1. It seems that most everyone upgrades the power rail caps to ~15,000uf @ 100V. I know that WOA offers a kit where they stack 2 caps to accomplish that but I’m not sure they'd work with the clamps that hold the caps in place. I’m kind of looking at the following caps from Mouser. I’m not sure exactly what to look for in a cap such as this… Would it be better to get a 105°C cap (80-ALS80A163KF100) or a cap with a higher ripple current and little lower ESR (871-B41458B9159M000)? Both are almost the same size as the currently installed stock capacitor. Or is there some other reason to get one over the other?
  2. If I upgrade the caps I’ve read where that puts a strain on the bridge with all of the inrush current when it’s turned on. Should I upgrade the bridge? The current bridge is a 200V 30A (MDA990-3) with a date code from 1971. The next step up in current rating at Mouser is only 35A and the next step from that is 50A (905-KBPC5006T)
  3. It goes without saying that I’ll be installing the Watts Abundant speaker protection board.
Future Upgrades
  1. The front face plate is a little rough. I’ll be attempting to clean it up. I see where someone on eBay sells a reproduction. Has anyone used this reproduction and been happy?
  2. Eventually I’d like to install the WOA control board.
What do you think?

PL400.jpg PL4002.jpg PL400SN.jpg

Alan
 

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#2
The price to upgrade a 400 costs the same as the price to upgrade the 700... Get more bang for your buck with a 700... Look at the prices of a 400 on the bay... You can't hardly give them away. In the event you have to sell down the road, you wont get $250 for it... if you have to sell the 700, they go for big bucks... There is a reason. Just sayin
 

punchback

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#3
The 400 boat has already sailed and I'm in it. I'm sure I'll never sell it anyway... Any opinions on the PS caps, bridge (and that bridge mod), and anything else that should probably be done right off the bat?
 

punchback

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#4
I read about a diode latch up mod. Does this apply to all PL's including my early 400? Does back to back mean in parallel?

Changing C6 to 470uf at 50 volts will flatten the lower frequency response considerably. Soldering two 1N4148's back to back on the back of the board to the leads of C6 will prevent random latch up of the positive rail voltage to the speaker outs. So if you change C6 leave about 3/16's of lead sticking out.
 

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#5
The White Oak cap kit will work. Any computer grade cap in the 100 volt range will also work. 80 volters may not as rail voltage can be as high as 85 volts.
A 50 amp bridge is preferable. Bypassed on all 4 legs with .01uf/ 400 volt poly caps.
Don's DC protect is well worth the peace of mind.
White Oak also has faceplates...

The biggest difference will be the control board, it will sound muuuuuuch better. If you romp on that 4 dinner have a fan handy...
 

laatsch55

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#6
I read about a diode latch up mod. Does this apply to all PL's including my early 400? Does back to back mean in parallel?

Changing C6 to 470uf at 50 volts will flatten the lower frequency response considerably. Soldering two 1N4148's back to back on the back of the board to the leads of C6 will prevent random latch up of the positive rail voltage to the speaker outs. So if you change C6 leave about 3/16's of lead sticking out.
No, not parallel. Reverse the polarity of the 4148's to each other , twist leads together , solder , trim to 3/16", bend to 90 degrees and solder to the foil side leads of C6.
The White Oak control board incorporates this change. The factory board really appreciated this. Latch up is a real phenomenon and this eliminates it.
 

laatsch55

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My bad...Joe was working on getting some. PM Gepetto, that's WhiteOak Joe.
 

Fishoz

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#9
Welcome to Phoenix PB.....

I started with a 4finner.....enjoyed it for a year without problems then the itch kicked in. Long story short, no longer have my original PL. Check out the Fishoz build by Lee.

As of now the PL400 Lee sent back is one of the most detailed amps I've heard. Enjoying the shit out of it and never looked back.......although 'Sniff does a lot of tempting with his nice 700b's.
 

punchback

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#10
My bad...Joe was working on getting some. PM Gepetto, that's WhiteOak Joe.
I've already met, so to speak, Joe. I bought a LED upgrade before I realized that I cannot use it on my early 400. He was very understanding of my mistake. I will check with him on the 400 face plate
 

laatsch55

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#12
The 400's are good little amps. I've run 400's and 700's on my Kornerhorns and there is a difference. I can clip a 400 on the K's but not a 700, and for anything below concert levels a 400 is just fine. The 400 will have better residual noise specs, and other than power levels they're pretty much the same on other specs.
That being said.....there is no substitute for headroom...
 

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Yup, plan for the future.... gotta have the headroom. If the ship has sailed, scuttle it, it will save you time and money in the long run.
 

laatsch55

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#14
For some folks Perry a 400 is plenty, and a 400 WOPL is still a pretty impressive amp. To each his own...
 

Fishoz

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Yup...a 400 is plenty for some (satisfied here)....maybe if I were younger I'd go for a 700. Too much time left on Lee's lifetime warranty to give up my 400 though. The 400 has kept me smiling for almost three years now.
 

Gibsonian

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#16
Yep, tons of small amp folks out there think we are nuts for clipping a little ole 250 watter.

To each their own.
 

WOPL Sniffer

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For some folks Perry a 400 is plenty, and a 400 WOPL is still a pretty impressive amp. To each his own...
Dont tell me!..... The OP asked "What do you think? " I told him what I Thunk....... If he want a 400 4 finner, no skin off my nose. Just tryin to pass off what I learned the last few years. You get what you pay for. That's what I learned.
 

WOPL Sniffer

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#19
And clipping will kill equipment.

I just had a guy say "I'll never sell my Emotiva 100 pound super amps. I built him 2 custom WOPL's. His second Emotiva just sold.... Never say never.
 

laatsch55

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#20
Amen. Well aware of what clipping does....and it sounds bad too.
Yeah, I like changing minds with a WOPL too......a lot...
 
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