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Taking the Plunge Into the WOPL 400-II Pool
- Thread starter e30m3mon
- Start date
- Joined
- Jan 14, 2011
- Messages
- 74,912
- Location
- Gillette, Wyo.
- Tagline
- Halfbiass...Electron Herder and Backass Woof
- Joined
- Jan 14, 2011
- Messages
- 74,912
- Location
- Gillette, Wyo.
- Tagline
- Halfbiass...Electron Herder and Backass Woof
- Joined
- Jan 14, 2011
- Messages
- 74,912
- Location
- Gillette, Wyo.
- Tagline
- Halfbiass...Electron Herder and Backass Woof
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
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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- Joined
- Jan 14, 2011
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- 74,912
- Location
- Gillette, Wyo.
- Tagline
- Halfbiass...Electron Herder and Backass Woof
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.
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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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.
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.
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
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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- Jan 14, 2011
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- 74,912
- Location
- Gillette, Wyo.
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- Halfbiass...Electron Herder and Backass Woof
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
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
No problem using them Al, just wondering where you obtained them.
Having all one date code is a better match than any scheme devised to try and match devices on any other parameter. But if they are good devices, matching does not matter, the emitter resistors provide local negative feedback to neutralize any device to device minor difference.
Having all one date code is a better match than any scheme devised to try and match devices on any other parameter. But if they are good devices, matching does not matter, the emitter resistors provide local negative feedback to neutralize any device to device minor difference.