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

[laatsch55]

Some preliminary test results------- Crosstalk simply amazing--UNWEIGHTED---105DB, residual noise floor--120 MICRO VOLTS!!!! SNR---=-102db!!

Joe has done something amazing here people!! This is state of the art. That is a 4 sided board, yep 2 layers between the top and bottom. In a 40 year old machine. I don't know if there are 4 layer boards in other audio equipment, has to be , right??



Now!!. to the BIG question------How does it sound?? I haven't turned it off since I plugged it in. A week ago,,,

 

[laatsch55]

Getting "Invalid Attachment" errors on these pics Lee.

Prolly cause I was editing at the time.

 

[laatsch55]

Joe's turn to explain the benefits of fully comp operation, then I'll give a more detailed description on how it sounds.

 

[derek92994]

Prolly cause I was editing at the time.

Roger that.

 

[NavLinear]

BIG GRIN HERE - WOW!!!!!!

 

[jbeckva]

Got me a droolin!!! Makes a rework seem almost easy now!

So Lee... elab a little on the sound! What hits ya in the face about it??

 

[Gepetto]

Fully comp...

With fully comp circuit topology, the positive half and negative half of the signal are amplified through the final current gain sections with symmetrical circuit design through the use of NPN drivers in the plus half of the signal and PNP drivers in the minus half of the signal.

The quasi comp used NPN on the plus half, like the full comp version but the minus half had the PNP driver emulated by a combination of a small PNP transistor coupled with 2 NPN pre driver and driver instead of using PNP devices. When the Phase Linear was initially introduced, this is what the designers had available to design with so they went with it.

In the last of the PL400 and PL700 production, PL did convert to fully comp on a small number before end of life of the product.


Some benefits, amp gain is more equal on the positive and negative half of the signal. In the quasi comp version, the gain of the negative side was always higher than the positive half. The global feedback compensated for this difference however and quite effectively nulled it out.

The bias settings are now extremely close for both positive and negative half. Part of this comes from the use of precision 1% resistors in the bias resistor locations, the balance comes from the symmetrical topology.

The current limit protection circuits are also now fully symmetrical leading to a more balanced onset of protection for each of the plus and minus sides.

Of course with this PL400 Backplane board, the configuration of full comp or quasi comp is easily selected by several components, jumpers and of course the choice of output drivers.

In the full comp versions, the MJ21196 (NPN) is used in the pre driver and driver positions on the plus half and the MJ21195 (PNP) is likewise used in the pre driver and driver positions on the minus half.

The use of these outstanding drivers everywhere leads to a more robust output stage as a side benefit.

 

[Gepetto]

Got me a droolin!!! Makes a rework seem almost easy now!

So Lee... elab a little on the sound! What hits ya in the face about it??

Hi Jer
The genesis of this project was having to redo an entire point to point backplane on a couple of these amps, not fun. I have the backwall mobiles ready for Christmas gifts as a result

 

[laatsch55]

Crossover distortion is gone, Turn on/turn off thump was gone TOTALLY in Rev C , but now it's just a fade to black, 15 minutes later you're wondering what you are listening for...

On "Museum of Consciousness" on track 7 where it sounds like a movie score with the tubas??? Aw jeez, gives me goosebumples...


Bass is more controlled, mids "Cleaner", highs--less hash. And the unexpected biggie?? Larger soundstage!!!! On my limited listening space that's what I noticed first, and it has to be a pretty good size improvement in that particular area to be noticed here.

 

[laatsch55]

Joe!! PL wind chimes, how cute!!

 

[laatsch55]

And a lot of the lyrics that are indiscernable on Shpongle in general, they're getting known.....

 

[jbeckva]

Hi Jer
The genesis of this project was having to redo an entire point to point backplane on a couple of these amps, not fun. I have the backwall mobiles ready for Christmas gifts as a result


View attachment 9944

Ahh, but if I count the number of sockets above, that leads me to believe ya might have something "else" in the works that I can hold out for.. hehe.

 

[laatsch55]

LMOAO!!!!!!!!!!!!!!!

 

[Gepetto]

Lee has more listening stick time on the full comp than I do. I started with the quasi and Lee tackled the full comp at the same time. I have been enjoying the quasi comp for about 2 weeks now. I especially enjoy the black hole of zero background noise you get when you have nice big power and ground planes in the Backplane board instead of the rather uncontrolled point to point wiring.

I also enjoy the one-to-one wiring a lot. It makes the last phase of the control board install a snap.

Kudos to Lee for being the full comp beta test site for this project!

 

[jbeckva]

And a lot of the lyrics that are indiscernable on Shpongle in general, they're getting known.....

With who I work with daily nowadays, I am able to discern quite a few lyrics....

 

[Gepetto]

Ahh, but if I count the number of sockets above, that leads me to believe ya might have something "else" in the works that I can hold out for.. hehe.

That is one that I messed up on Jer and had to redo it from scratch. Hate it when I do that.

 

[laatsch55]

Not to mention all the test points up high and with loops to hold the mini grabbers, A LOT LESS CHANCE of slip prope disasters!! B+,B-, Bias+, Bias-, ground, Output+, Output-, It don't get any better than that, well until Joe comes out with something else....

 

[laatsch55]

So Jer, you and Shiva getting intimate??

 

[laatsch55]

That is one that I messed up on Jer and had to redo it from scratch. Hate it when I do that.

THIS IS THE POST PEOPLE,!!!

 

[laatsch55]

August 12th, 2013, Joe screwed up. Good , beginning to think he was not human...