PL 400 renovation cost

S

scottcampthomas

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Apr 9, 2021
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What is the cost (parts and labor) to have a qualified tech totally upgrade the sonic performance of my perfectly functioning but all original PL 400 ?
 
When you ask that question here, we assume that “upgrade” means a complete rebuild- remove everything, replace everything. Only the case and transformer remains original.
 
Billboard said:
If perfectly working, I would just put a DC protection board in it, 400s are not worth upgrading, unless it is of sentimental value.
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You can’t resell it for what you put into it, but if you want to keep it for a long time for yourself, it still makes a damn fine amp.
 
Mark is right, you will have a world class reliable amp, if you are keeping it then may be worth doing. However you must consider the cost, the cost to upgrade a 400 and a 700 is about the same. Most will buy a 700 to upgrade. I have a full WhiteOak 700B and a nearly stock 8 fin 400 with DC protection, and new output transistors.
 
Billboard said:
Mark is right, you will have a world class reliable amp, if you are keeping it then may be worth doing. However you must consider the cost, the cost to upgrade a 400 and a 700 is about the same. Most will buy a 700 to upgrade. I have a full WhiteOak 700B and a nearly stock 8 fin 400 with DC protection, and new output transistors.
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At minimum, new outputs all around and capacitors. DC protection should be mandatory even if you do nothing else, and do it first.
 
Scott, I assume you are talking about the venerable PL400, and not the improved PL400 Series II. The difference in sound between a stock PL400 and one completely rebuilt with White Oak Audio (WOA) parts is phenomenal. The posts above have merit, many think the PL400 is not worth rebuilding. However, I have done the full PL400 rebuild many times and I can tell you, IT IS WORTH IT! Most people do not need more than 200 Watts per channel anyway. With the rebuild you will be getting 250-300 Watts per channel. The difference in sound quality comes mostly from the new Rev G1 Control Board that replaces the original Phase Linear control board that has a faulty design, poor layout, and components that are 40-50 years old. The difference in increased dynamic range comes from the new WOA main Power Supply Capacitors with almost triple the reserve power capacity. The difference in lower noise and distortion comes from the new WOA Backplane Boards that eliminate the vintage point-to-point wiring on the back of the amplifier. The difference in sheer power that will knock you over comes from the 16 new Output Transistors that have much more gain and are more closely matched due to modern manufacturing methods. You really need a pair of decent speakers when you get this upgrade.

I really like the sound of the PL400, it is smoother and less shrill than its big brother, the brute, the PL700. I have both and I can listen to the upgraded PL400 all day; the upgraded PL700 (1000 Watts) is perfect for scaring animals and small children, after a couple of hours listening to live thrash metal bands like Metallica, AC/DC, etc. I'm done.

But its your call...
 
I agree, upgrade that 400 when your ready. You'll have a wonderful amp that you can pass on to the next generation. I have 2 full WOPls a 400 S1 and a 400 S2. Both play way way louder than I'll ever need. I have yet to go past 3/4 volume, too damn painful to my ears, my dog, my cats, my tropical fish in the tank.
 
mlucitt said:
With the rebuild you will be getting 250-300 Watts per channel.
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Is that what we're getting on the 400? I thought it was somewhere between 230 to 250.

I have to add that the 400 doesn't "get tired" with a long session of loud playback. It seems that amps I've had in the past (around 120WPC) seem to diminish in output and "listenability." They more or less got tired of playing. I wonder if it has to do with heat buildup.
 
MarkWComer said:
Is that what we're getting on the 400? I thought it was somewhere between 230 to 250.
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Mark, it is hard to measure. Mostly, I grab a single channel RMS Voltage at the speaker binding posts with the full input level of 1.0 VRMS at 1KHz. Then I use Ohms law to calculate power into 8 Ohms. Oh, and you have to ensure the supply voltage at the outlets is 120VAC (no less than 117VAC).

Both channels driven, would probably be closer to 230-250 Watts per channel, total 500 Watts maximum. But who listens to 1KHz sine waves? Musical power is more transient and dynamic, that is where the Phase Linear amps shine.
 
George S. said:
I agree, upgrade that 400 when your ready. You'll have a wonderful amp that you can pass on to the next generation. I have 2 full WOPls a 400 S1 and a 400 S2. Both play way way louder than I'll ever need. I have yet to go past 3/4 volume, too damn painful to my ears, my dog, my cats, my tropical fish in the tank.
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I don’t like excess volume, either. At 63 years old, my ears are still pretty sensitive.
 
I guess I better give my two cents worth.
I have several 400’s in various places. For average listening throughout the house the 400 is over kill. There is not sound difference from my 700’s or d-500’s. They are lighter to lug around. Less power stress on the circuit’s. I really think for most a 400 is more than you need. It costs less to buy the core and a little cheaper to WOPl and a whole lot cheaper if you tweak the stock one.
Happy listening
 
Thanks everyone,
I assume my PL 400 is a series one. I found the box and it makes no reference to "series 2" . I don't have easy access to the rear of the amp to ck there. I use it with a VTL tube preamp and Sonas Faber Venere speakers. To me, that combination has a wonderful sweet sound, good detail and a spacious soundstage. Having said that, my point of reference is the Dynaco 400 in my other system. I bought both of those amps new in the seventies and haven't obsessed about their sonic obsolescence until now. Back then I thought amps provided primarily the dampening horsepower required to precisely control the speakers as directed and sonically influenced by the preamp and other components. Is adding the DC protection board easy enough for novices ?
 
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