The Worlds First Fully Comp PL 400 Using White Oak Components !!!!!

[laatsch55]

Fully comp runs complementary outputs----NPN/PNP as opposed to a phase inverting driver to have an NPN output amplify the negative half of the sinewave.

 

[kevin]

What is the difference between Full and Quasi?

I really wanted to ask that very same question..... But as I thought I wouldn't understand anyway !!!

 

[orange]

I've been missing something here...is this a completely new design or are you modding the original circuitry to make it so?

Is the last notion why you're having such a fussy time with it?

Was it meant to be that way?

You can make boys into girls and vice versa but they still need electrolysis (and maybe therapy), I am just sayin'

 

[derek92994]

I really wanted to ask that very same question..... But as I thought I wouldn't understand anyway !!!

And I still don't understand. But thought I would give it a shot

 

[Gepetto]

The reason White Oak Audio did this was to answer numerous requests on how do I make my Phase Linear fully complementary? To do so is possible but it becomes a major backwall rewire, so major that you are better off to rip it out and start over. If you rip and start over, it is a lot of work and you still end up with poor quality sockets on the back wall and a major headache to understand the conversion instructions.

Why do people want to do it? Because it creates an amp with almost perfect circuit symmetry in design from the start to finish. Phase Linear really wanted to do this if they had the capability of doing it but in the early 70s when the amp was created, high voltage complementary pair (NPN/PNP) TO-3 transistors were not really available. In order to work around that, PL used a PNP small signal driving an NPN pre-driver followed by an NPN driver in the lower half (negative voltage side) to emulate a high voltage, power PNP transistor.

The last batch of PL400s and PL700s in the Series II were configured as full complementary output stages as the Motorola MJ15024 and MJ15025 had arrived on the scene. This emerged just prior to the end of PL production. The schematics are marked up from the quasi complementary configuration that dominated their product line for many years.

It is a better circuit configuration for a SS Class AB amplifier if the transistors exist to do it, which they do today.

 

[derek92994]

The amps just get better and better thanks to you guys being able to effectively apply those parts that were not available to the original PL guys back in the day. I'm sure there is much more to it as well as you are changing the circuit boards. I have not ever heard a phase linear but sure look forward to the day when I do, its a new "phase" of audio to me

 

[laatsch55]

Derek, I think you'll be pleasantly surprised. It's a big jump in sound quality than what you are used to.

 

[derek92994]

Derek, I think you'll be pleasantly surprised. It's a big jump in sound quality than what you are used to.

Well I have always upgraded in small steps. Thought I might as well make a big leap for a change (glad you put the idea into my head). Even though I will be sitting on these very basic 12 inch speakers to start with, I still think I will hear some difference. JBL Pro series will be in order for the near future. One step at a time. Even saying that, I still get much enjoyment out of my current setup on a daily basis @ 125 watts per channel.

 

[laatsch55]

And it's not just the additional power, it's such CLEAN power. And the PL's have a sound to them that pleases my ear more than anything I've heard to date.

 

[laatsch55]

I've been missing something here...is this a completely new design or are you modding the original circuitry to make it so?

Is the last notion why you're having such a fussy time with it?

Was it meant to be that way?

You can make boys into girls and vice versa but they still need electrolysis (and maybe therapy), I am just sayin'

Steven, we are TAKING SOMETHING THAT IS ALREADY GOOD AND MAKING IT BETTER. iT'S NOT BEING FUSSY, IT'S VERY WELL BEHAVED.

 

[Gibsonian]

Lee are you planning on posting some results from your analyzer on the full comp 400? Maybe you have and I've just missed it.

 

[laatsch55]

Yes Scoptt I am. We are still playing with some values of some components. When it's settled I'll post a complete suite of test results, un-weighted and IEC A weighted.

 

[Gepetto]

Full Comp PL400 Preliminary Test report

Hi Scott
Here are some data taken from a "stock" build of the fully comp PL400 with the PL400_Backplane boards installed.

View attachment Amplifier Test Report_Full_Comp_9040.pdf

 

[laatsch55]

Nice numbers Joe. Sounds a heck of a lot better than the numbers would indicate, after all, how do you measure soundstage??

 

[Gepetto]

Hard to measure Lee, I agree with you. With a little tweaking I think we can get even better results out of this combination. After all this is just the obvious component swap from the quasi to full.

I will be modifying my spice model to make a full comp version too.

 

[kevin]

Well.... When yall get this all finished what is the cost going to be to do this new conversion to a 400 that someone already has ? I cant imagine mine sounding any better. But I know good and well you guys didn't spend all this time and money so they would sound the same !!!! I'd just love to hear one !!!

 

[laatsch55]

Kevin, your 400 already has a Rev A board right?? To use the fully comp option a guy needs the D board.

 

[laatsch55]

Joe, I'm kinda like Scott. When are the 700 back plane boards comin??

 

[Phase Linear Phanatic]

And guess who wants them BAD? ME! I've read about this all week! Amazing. I should have waited for more development before I went WOA on my 700B. A fully comp PL 700B with all WOA boards and DCP? Jaw dropping............... I see big things ahead.............

 

[Gepetto]

Don't get your hopes up for next week. The PL400 project took over 5 months from start to finish. There was a restart in that project though when I dumped the sockets all together and went for the solder in as far more reliable.