Taking the Plunge Into the WOPL 400-II Pool

laatsch55

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#21
The backplanes do not come with the outputs, although Joe does sell them too. You only need 4 more of the 21196's , as they are what's recommended...
 

e30m3mon

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#23
Ok - thanks for clarifying.
I did some forum-diving today in an attempt to educate myself on what might be needed and the benefits of full comp. A whole lotta good stuff out there !
 

George S.

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#25
No reason to anymore George, a new chassis for 75.00??
Didn't realize the new 700 chassis was priced so reasonable. Will the Series 1 face plate which appears to be two plates fit it? If so, yes, definitely the way to go. Guess I need to research some photos. Thanks.
 

Gepetto

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#26
Ok - thanks for clarifying.
I did some forum-diving today in an attempt to educate myself on what might be needed and the benefits of full comp. A whole lotta good stuff out there !
PM me with your email and I will forward some info...
 

laatsch55

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#27
Didn't realize the new 700 chassis was priced so reasonable. Will the Series 1 face plate which appears to be two plates fit it? If so, yes, definitely the way to go. Guess I need to research some photos. Thanks.
Not sure on the price George...hence the question mark...
 

e30m3mon

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#28
I've been a little busy since my last post. Got the heat pump installed and charged with R410A..it is doing what it is supposed to and keeping the house toasty.

So that enabled me to free up some time to work on the PL 400-II - and of course ordered some more parts. All this talk of Fully-Complimentary amps in the various online fora has been fascinating. Joe's WO kits have been flawlessly executed in their design, component selection and versatility...I had to order the Backplane kit. And I received Don's DC protection circuit - another well executed upgrade package for this old amp chassis.

I'm looking forward to getting started with all this good stuff. I'll update as things progress.
Thanks again for all the support and info, guys.
Al
 

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e30m3mon

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#31
iphone does that for some reason. It looks ok when I click on the thumbnail. Turn your monitor over!
 

e30m3mon

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#32
I got a few free hours to melt some more solder on the WO Backplane boards. I absolutely love the parts selection and engineering Joe has put into this product. The hours assembling have also been therapeutic...a real sense of accomplishment and something of beauty to behold. I'm going to hate closing this box back up.

A pic from last night, will be cutting and installing the spaghetti (wiring) next time I sit down at the bench. Hopefully this picture is not inverted.
 

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mlucitt

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#33
will be cutting and installing the spaghetti (wiring) next time I sit down at the bench.
Don't add anything to the wire lengths that Joe specifies, they are perfect. With one exception, The 22 gauge white and red wires that supply the meter drive to the Faceplate meters will be too short if you opt to pick up that signal from the top of the DCP Relay Board instead of on the Backplane Boards where the Left and Right Speaker Output yellow wires exit the Backplane Boards (Output 1). I use (2) #6 ring terminals under the +L and +R speaker binding post screw heads.

By taking the signal from the "output" of the relay, where the speaker binding posts attach, you are avoiding the meters jumping at Power On/Off. And in the case of a DC transient or loss of AC power, the DCP will disconnect and protect the meters as it disconnects the speakers, as designed by Watts Abundant.
 

e30m3mon

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#34
That's excellent advice, Mark. I appreciate your insight. While these are not the mechanical meters found in the original PL amps, I like the idea of not sending any transients to the Cylon circuits.
 

e30m3mon

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#35
Some pictures of the WO Backplane installation - got a few hours to get the wires cut and soldered onto the boards, and then set into place. I like how Joe reminds us to clean the back side as these will be installed "for the next 40 years". After getting all those wires routed, I never want to take these out! Speaking of which ... Mark's comment about the wires lengths being perfect and not to add anything got me thinking..."damn these wires are long". So I got creative about routing them around the perimeter, bends and such in such a way to keep the AC wires away from the DC wires, and then then keeping the DC ground wires separate from the DC voltage wires, best I could - or so I thought would work well when everything was reassembled. I also recall reading (somewhere) about how critical the wire routing and keeping things tidy inside amplifiers is to keep noise down. I took a shot at how i though all that wire could be best tucked and routed. The good news is the initial phase of bring-up went without a hitch....figured I'd let the capacitors discharge on their own while I got this note out.

Also note I mounted Don's DCP board so I could route the wires that will eventually be connected to it after the backplane is populated and bias set.

Something I have been meaning to ask, and since I will install the drivers in the morning...how critical is it to have transistors paired correctly, by gain I presume? Reason I ask, is that the bottoms of the MJ 21195s are not marked, but (6) of my MJ21196s are labeled "950" and the other (6) are labeled "970". Will it matter which (6) of the MJ21196s I select to use with the (6) MJ21195s ? Guessing these are the gain values for these transistors?
Many thanks guys
Al
 

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Gepetto

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#37
Some pictures of the WO Backplane installation - got a few hours to get the wires cut and soldered onto the boards, and then set into place. I like how Joe reminds us to clean the back side as these will be installed "for the next 40 years". After getting all those wires routed, I never want to take these out! Speaking of which ... Mark's comment about the wires lengths being perfect and not to add anything got me thinking..."damn these wires are long". So I got creative about routing them around the perimeter, bends and such in such a way to keep the AC wires away from the DC wires, and then then keeping the DC ground wires separate from the DC voltage wires, best I could - or so I thought would work well when everything was reassembled. I also recall reading (somewhere) about how critical the wire routing and keeping things tidy inside amplifiers is to keep noise down. I took a shot at how i though all that wire could be best tucked and routed. The good news is the initial phase of bring-up went without a hitch....figured I'd let the capacitors discharge on their own while I got this note out.

Also note I mounted Don's DCP board so I could route the wires that will eventually be connected to it after the backplane is populated and bias set.

Something I have been meaning to ask, and since I will install the drivers in the morning...how critical is it to have transistors paired correctly, by gain I presume? Reason I ask, is that the bottoms of the MJ 21195s are not marked, but (6) of my MJ21196s are labeled "950" and the other (6) are labeled "970". Will it matter which (6) of the MJ21196s I select to use with the (6) MJ21195s ? Guessing these are the gain values for these transistors?
Many thanks guys
Al
No gain matching required at all Al. That is what the emitter resistors do
 

e30m3mon

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#39
Cool! I didn’t realize gain matching was accomplished that way. I had read a lot of comments here and other audio forums, but wasn’t sure. Thanks for clarifying.

Joe, back around 2009/10 I was determined to take a shot at fixing the “ PL paperweight”, as my wife called it, and purchased the replacement qusai-complementary set of outputs and a few other things off ebay in the hopes of putting it back in service. This was unfortunately to become a dead-end effort as work/life interfered. As my interest and time increased, I started reading more about WOA here and well...here we are.
Will it be ok to use those older cans with the fresh ones? I believe they’re still good. I’ve bench tested each and none are shorted, and an old but trusty radio shack transistor tester seems to show they’re still functional.
Thanks again
Al
 
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