Newly Aquired PL 400 Early

[Heat-Sinks-R-Cool]

Hi folks, new to this forum...

Got a very nice unmolested PL 400 4 fin. Sent an email to White Oak regarding the control bd and whether or not their board can be used in an early non PL14 control bd unit. I believe my amp has a PL 400c control bd. It looks like the output x-istors and design would allow for the new control bd work as a direct replacment, but I want to make sure.

Also any specific issues with overheating with 4 fin heat sinks that I should know about ?

 

[WOPL Sniffer]

doubling those heat sinks would be cooler

 

[Gepetto]

The control board works in every PL400 built

 

[grapplesaw]

Welcome to the forum
with not much searching here you will find lots of threads giving all the information you need to be successful.
Whiteoaks has lots of goodies for that amp visit their web store.

https://www.whiteoakaudio.com/estore.aspx

( I do not receive any monetary payment for promoting Joe’s stuff, only great support and friendship)

 

[gene french]

doubling those heat sinks would be cooler

built 2 sets ..one for my 400c 4 fin...other for my 4 fin junker to wopl ....
not hard to do...

 

[WOPL Sniffer]

built 2 sets ..one for my 400c 4 fin...other for my 4 fin junker to wopl ....
not hard to do...

Doubling the heatsinks means "Buy an 8 fin"

 

[gene french]

have one of those too...trying not to discriminate...
would love a 700...still lookin...

 

[WOPL Sniffer]

have one of those too...trying not to discriminate...
would love a 700...still lookin...

I just found a 400 II, and a 700 II in boxes in the shed a day or 2 ago. I got too much to do........................

 

[e30m3mon]

I just found a 400 II, and a 700 II in boxes in the shed a day or 2 ago. I got too much to do........................

Add those to that growing to-do list ...

 

[WOPL Sniffer]

Add those to that growing to-do list ...

 

[mlucitt]

built 2 sets ..one for my 400c 4 fin...other for my 4 fin junker to wopl ....
not hard to do...

Gene, you should be in the fin-building business. I'll take two, please.

BTW, the 4 fin units were the earlier variety; what are the Serial Numbers of your two units? Mine is 2225. I also have a Customer's PL400 that was built at the Edmonds, WA factory in October 1973 before the move to Lynnwood, WA in 1974, S/N 1043-070A.

 

[WOPL Sniffer]

have one of those too...trying not to discriminate...
would love a 700...still lookin...

700B/700 II's are not hard to find, but ARE hard to find cheap. You just got to buy one, the prices will do nothing but go up. You are not looking very hard. Or, you could have one of the fine builders here build you one so you don't have to monkey with it. Very expensive but if you look at your amp outliving you/us, $3000 is cheap. We can spend 30 grand on a vehicle which don't last for shit these days.......

 

[gene french]

Gene, you should be in the fin-building business. I'll take two, please.

BTW, the 4 fin units were the earlier variety; what are the Serial Numbers of your two units? Mine is 2225. I also have a Customer's PL400 that was built at the Edmonds, WA factory in October 1973 before the move to Lynnwood, WA in 1974, S/N 1043-070A.

the stock 4 fin is 443-123...123rd unit built in april 73...400c board...i recapped...added joes ps cap kit and led kit and wa dc protect board...
the parts 4 fin is 3059...and had pl14a board...it was smoked...i bought joes chassis and used transformer, meters, faceplate...did the full complimentary kit with ps cap and led upgrade and bigger rectifier as suggested by joe...there is a fabricating shop near....he made them for me...one side is bent...the other side is welded ...he does good work ..was 40 bucks for 4...

 

[gene french]

700B/700 II's are not hard to find, but ARE hard to find cheap. You just got to buy one, the prices will do nothing but go up. You are not looking very hard. Or, you could have one of the fine builders here build you one so you don't have to monkey with it. Very expensive but if you look at your amp outliving you/us, $3000 is cheap. We can spend 30 grand on a vehicle which don't last for shit these days.......

i have noticed...either would suit me...one will come along...and you are right...i aint looking hard....i had to buy another car since i flipped the dodge ....and was almost 2k to repair the dodge...just finished up a whole house furniture/remodel project ... and sent couches out today to be reupholstered...unless a 700 comes along that i cant walk away from...i will bide my time!!
i hate savings dipping...lol
life is good!!!

 

[gene french]

and i am building voigt pipes...forgot about that little project!!!

 

[J!m]

We can spend 30 grand on a vehicle which don't last for shit these days.......

In 1998 I spent $23,300 for my ti and still drive it today.

“I made a few *special* modifications myself.”

 

[Heat-Sinks-R-Cool]

I know it seems obvious that the engineering change from 4 fin to 8 fin would be to fix a heat issue, but are the 4 fins marginal or just a bad design? Did they forget that the ambient temps may not be room (25 c). Seems like Carver (the man) would have figured out the correct sq area. I haven't done a calculation, has anyone figured out how weak they really are? I don't know much of the history, but it seems like the consensus on the board is to upgrade... If anyone knows the service history of these and how many were built before they figured out they needed to add more heatsink, that would be of interest to me...thanks for the replied BTW!

 

[gene french]

and i am building voigt pipes...forgot about that little project!!!

and that little import duty thingy...3k quickly becomes 5k...

 

[Gepetto]

I know it seems obvious that the engineering change from 4 fin to 8 fin would be to fix a heat issue, but are the 4 fins marginal or just a bad design? Did they forget that the ambient temps may not be room (25 c). Seems like Carver (the man) would have figured out the correct sq area. I haven't done a calculation, has anyone figured out how weak they really are? I don't know much of the history, but it seems like the consensus on the board is to upgrade... If anyone knows the service history of these and how many were built before they figured out they needed to add more heatsink, that would be of interest to me...thanks for the replied BTW!

The 4 fin problem is not so much the 4 fins themselves which are adequate except for more severe conditions AND aesthetic appeal. It is more about the innards.

PL was all over the map at that point and you never know what you will find inside the covers. Meter differences, lighting differences, control board differences, no die cast saddle on the transformer, caps and bridge mounted to the sides, back wall holes out of spec, the list goes on.

By the time they did the 8 fin, things settled down and the variability inside went away. Plus you had a better looking heat sink set on the back.

The advice is: There are so many 8 fin units out there, don't settle for a 4 fin nightmare...

 

[WOPL Sniffer]

Doubling the heatsinks means "Buy an 8 fin"

I second that.... NO MORE 4 FIN AMPS

The extra work in getting them completed can be a daunting challenge for the unprepared.