Testing of a stock, and a WOPL 400

[laatsch55]

Got a local 400 in for the conversion to a White Oak board. It's a Ser I with a PL14 A board. Totally stock except for new electrolytics I put in two years ago. She's a cherry too.
We're gonna document this one pretty close.

 

[laatsch55]

Test Conditions,

Bias -left 348 mv DC, Right 350 mv DC
Offset---Left -.002, Right--+.004
Drivers---MJ2741's Date Code---7352
Outputs--XPL909's Date Code---7320

Analyzer---Audio Precision ATS-1DD Last Cal--2008

 

[laatsch55]

THD & N

 

[laatsch55]

Frequency Response

 

[laatsch55]

THD & N 100 watt out put

 

[laatsch55]

Noise floor or SNR, crosstalk, and max output just before clipping

 

[mlucitt]

Lee, what are the idling rail voltages on that bad boy?

 

[laatsch55]

81.2+ and -

 

[mlucitt]

Good enough for a Rev C board! The before and after comparisons you are making will allow us to make some quantitative metrics for analysis of differential parameters that will substatiate the benefits of the Rev C upgrade; or, generate some marketing hype. If we can say THD is improved by 10% or, frequency response (somewhat due to the new outputs) is flatter dy 18%, we have really got something.

 

[soundude]

Lee seems like a solid candidate for a WO upgrade...lee do you have a PDF schematic of the 400 thats clean. can you send to my email when you have a chance.

 

[soundude]

Lee I don't remeber if I asked you but what is the rated VA on the power tranny for the 700?

 

[laatsch55]

2.5KW

 

[laatsch55]

That I don't have John. I think Joe does.
Mark, this one gets the "A" board. And nothing else is being touched, not the grounding scheme, not the PS caps, drivers and outputs will remain the same.

Correction--John I have that and a lot more, PM your e-mail.

 

[mlucitt]

Either WOA board will be a big improvement I bet.

 

[soundude]

Thanks Lee gotta lot of reading....
Question what was the difference between the PL20 and the PL14..

 

[soundude]

Like those Black 700s.....Nice! See they have Joes upgrades too..

 

[laatsch55]

That's what we're fixin to find out. It wasn't bad to begin with, pretty good spec's on this one.

 

[laatsch55]

Thanks Lee gotta lot of reading....
Question what was the difference between the PL20 and the PL14..

they were made cheaper with cheaper components.

 

[soundude]

You mean the 20's were cheaper, seems to me the 14 was first, someone recap that board on the 400...seen some newer caps in the front...

 

[Gepetto]

The PL20 was Phase Linear's attempt to universalize the board between the 400 and 700. Time ran out on that goal with all the acquisition activity going on at the time with the company.

The PL20 was billed as the universal board.

White Oak has finally realized that vision for the amp, a board with the same build out that goes into any power amp of the 400/700 class that Phase Linear produced.