Full Or Quasi Comp

[TapeHeadOne]

Hello everyone,

I've read in the old PL400II service manual that the units starting with 4A31658 have full comp output stages. Does this mean that when ordering the White Oak PL input board you have to order the full comp board, or can the board be built as quasi comp for MJ15024/25 as well ?

Thanks,

Peter

 

[MarkWComer]

Rev. E can be built in either config, not sure about Rev. G.

 

[TapeHeadOne]

I apologize for being unclear, I know the board can be built either way. But it must be ordered with the correct components (or separately sourced). The question is does a 'full comp' amp require 'full comp' WOPL board or is the designation 'full comp' in relation to the preamp board itself, so can one have a "quasi comp' pre board and a 'full comp' amp ?

Thanks, Peter

 

[MarkWComer]

“Full comp” and “quasi comp” refers to the output stage transistor makeup, “quasi” being all NPN transistors, “full” being a mixture of NPN and PNP. The driver circuit has to be in the proper configuration to feed which ever transistor makeup is used, and the two aren’t compatible. You can build the driver circuit to accommodate a quasi-comp backwall and revise it if you change to full-comp. When you order the driver board, all components for either build are included.

If you mix the two you’re likely to get asymmetric clipping, the negative (or positive, as the case may be) swings of the waveforms of your audio signal may not be presented to your output transistors.

IF you have an amp that was built by Phase Linear as “full comp,” you will make your driver circuit according to the full comp instructions.

 

[orange]

Begs the question...

Full

or quasi-Moto? (Google)?

 

[TapeHeadOne]

Thank you for the iinformation.

 

[Gepetto]

RevE and RevG1 include components in the kit to allow you to build it either way. Builders choice.

 

[WOPL Sniffer]

Why build a yugo when you can have a Lamborghini??? Go full WOPL and skip the old shit....

 

[TapeHeadOne]

It will no longer be necessary. Something went wrong, it caught fire and burnt to a crisp. Cheers, Peter

 

[WOPL Sniffer]

They ARE ticking time bombs until wopl'd.....

 

[Bradrock]

That's worth pictures.

 

[MarkWComer]

Whoa! Sorry to hear that.

 

[Wheel-right]

RevE and RevG1 include components in the kit to allow you to build it either way. Builders choice.

Just wondering can I use either the RevE or RevG1 in quasi comp mode on my 400 without changing the transistors for a while until I can afford to do the Backplane upgrade? It has the original XPL 910s and the RCA 410s.

 

[Gepetto]

Yes, but go easy on those old devices.

 

[Wheel-right]

Yes, but go easy on those old devices.

I'm a low volume kind of guy, rarely go much past the 9 o'clock position on the volume anyway. By the way Gepetto the new Power Caps work fantastic very happy! So I'll have to gather more green and purchase a new board and light setup soon from you. Thanks for helping us keep these great pieces plugged in. Rob

 

[WOPL Sniffer]

I'm a low volume kind of guy, rarely go much past the 9 o'clock position on the volume anyway. By the way Gepetto the new Power Caps work fantastic very happy! So I'll have to gather more green and purchase a new board and light setup soon from you. Thanks for helping us keep these great pieces plugged in. Rob

Those old Tranny's are just waiting to fail. I have piles of the old ones and would never trust them with my new White Oak parts. Retire that thing until you have all the parts to do the full blown upgrade. Your speakers/Control Boards etc..... will thank you. 40 year old transistors are JUNK and should not be trusted.

 

[WOPL Sniffer]

I'd rely on my Boom Box before I trusted the oldy but moldy on my cherished White Oak Audio Parts. Partial upgrades are not even safe.

 

[Wheel-right]

I'd rely on my Boom Box before I trusted the oldy but moldy on my cherished White Oak Audio Parts. Partial upgrades are not even safe.

I know... Tick, Tick, Tick, I just want to listen to it a little while first, got the new power caps, DCP relay in, speakers are fused, fire extinguisher close by. My problem is I'm not knowledgeable enough or equipped to do the transistors, backplanes and such so I have to build the green pile big enough to pay one of you very talented people to do that. That means even more work than I'm already doing. If ya wanna play, ya gotta pay right?

 

[MarkWComer]

I know... Tick, Tick, Tick, I just want to listen to it a little while first, got the new power caps, DCP relay in, speakers are fused, fire extinguisher close by. My problem is I'm not knowledgeable enough or equipped to do the transistors, backplanes and such so I have to build the green pile big enough to pay one of you very talented people to do that. That means even more work than I'm already doing. If ya wanna play, ya gotta pay right?

Not as hard as you think. Look at some vids at youtube.com/user/Mark5W8Comer before you give up.
Not that it’s difficult, but MUST be done exactly and correctly. And you need a few tools and test equipment.

 

[Wheel-right]

Not as hard as you think. Look at some vids at youtube.com/user/Mark5W8Comer before you give up.
Not that it’s difficult, but MUST be done exactly and correctly. And you need a few tools and test equipment.

I've been watching your vids Mark, excellent and a lot of help, my mechanical skills are up to it, need solder practice but knowledge of how everything works isn't my forte, equipment just a multimeter. Not giving up, Thanks for the boost. Old dog, New tricks...