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Chrome stripping
#1
All chrome parts were dropped off at plater's early this morning to be stripped as I've decided a heated acid strip to be safer, more effective at removing ALL plating layers without destroying threaded screw bosses and other tiny machined mechanical features CNC'd into the case under the top. Bead blasting risks eroding the internal threads in the underside of the cover and packing the remaining soft aluminum threads with grit making all threads feel gritty and coarse when installing/removing screws. It would also tend to leave plating in small, tight corners, recesses & crevices that the blast gun can't get into due to space constraints. Of course I could thread sacrificial machine screws into those threaded bosses while blasting but then that will leave all the magnetic plating layers in all the threaded bores when finished. Sure it would be a small amount to be sure but "zero" case magnetism is my target! Why would I go to the added expense of 100% non-magnetic screws only to thread them into plated magnetic threaded bores!?! And who better to remove chrome plating than by someone who plates for a living since they frequently have to strip and re-do even their own chrome plating work due to errors. Additionally an acid dip leaves the aluminum in its polished state whereas bead-blasting would've left an exceedingly coarse almost smooth concrete-like surface that would have to be brought back to a smoother more acceptable satin sheen. That would add a ton of additional work for me. Of the two two stripping methods available to me this simply makes the most sense and cost runs within 15-20% of each other. The only concession I'm making is time. With blasting I could've dropped it off this morning and picked it up 3-4 hours later. Plater said "3-10 business days."

The 3-4 layers counting chrome on the case and rear cover shield are the most concerning parts to me as they are the only aesthetics displayed when finished. I want to get them out of the way first. Then I can enjoy more 'downhill' work on the remaining few cast parts that go inside or underneath and remain primarily hidden from view. It will also be easier for me to start machine tools into pure softer aluminum than on the chromed parts if no chrome remains as I don't have to punch thru that much harder multi-layer plating first. I suspect the aluminum will return from plater in a darker color than normal state which won't hurt anything as its just a temporary surface corrosive patina left over from the acid bath that will go away after I media blast the fine satin finish sheen similar to the remote knob on the outer surface.

I'm on 'cruise' for the time being not wanting to get ahead of myself but will certainly find things to putter with along the way.

But I won't do any machining until ALL parts are satisfactorily stripped, then I'll machine, media blast for a smooth satin finish, then anodize and reassemble. Today I'm planning rear/bottom-to-top/front convection air pathways. 75% of that airflow over the PCB tops with 40-45% of that airflow directed "thru" the PS and 25% airflow under the primary PCB then all air collected and discharged at top front face of Devialet
Statements in my posts are opinion only, not to be construed as fact. Any projects I engage in are at my own risk! Their outcome cannot be assured and may result in success, small/no change or catastrophic failure. I encourage no one rely on anything I say or do as gospel and to realize your mileage may vary!
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#2
Manoet,

Talk of drilling the cases has me a bit worried as I recalled something that I read in Paul Miller's review of the D-Premiere in HiFi News April 2010.

I quote from that review.....

"As we will discover, the D-Premiere operates at very high frequencies and power - only by sealing these electronics in a gap-free and near enough air-free enclosure can Devialet guarantee the freedom from emissions and interference required for CE compliance and sale in the EU."
D200, Magico S1's, Antipodes DX
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#3
I remember that quote and never quite understood the relevance of it being air-tight in relation to EM radiation. And it's no more air-free inside than outside the case shurely?
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#4
The point is that EMI can escape through surprisingly tiny gaps in the metalwork, as I understand it.

Another thing that concerns me (intellectually at least) is that no doubt Devialet will have used some sophisticated tools to model and optimise heat flow within the enclosure and dissipation to the outside world, all of which will be rendered null and void by these modifications. Still, I suppose it's Manoet's privilege to do whatever he wants to the unit he's bought...
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK
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#5
Ah OK, I'm displaying my ignorance of the subject!
The 'Apertures' section here is quite relevant:
http://learnemc.com/practical-em-shielding
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#6
(05-Aug-2015, 08:11)gray Wrote: Manoet,  

Talk of drilling the cases has me a bit worried as I recalled something that I read in Paul Miller's review of the D-Premiere in HiFi News April 2010.

I quote from that review.....

"As we will discover, the D-Premiere operates at very high frequencies and power - only by sealing these electronics in a gap-free and near enough air-free enclosure can Devialet guarantee the freedom from emissions and interference required for CE compliance and sale in the EU."

One point to note is that the D-Premier, as well as the 240 and 250 that derived from this model, has a very different case to the 200.  In fact, the case is the key difference between the current 200 & 250 models.  The 250's case is designed to provide very efficient transient cooling, however, the case is expensive to make.  The 200 has a cheaper to make case but identical electronics to the 200.  Although the power supply / ADH is configured differently in the 200 to compensate for the difference in the cooling characteristics of the case.
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#7
It would be interesting to know how the 250 case differs. Different materials?
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#8
Just a couple questions I'd like to ask directed at no one in particular then I'll leave others to form their own conclusions. Besides Devialet how many 99% 'sealed' multi heat generating digital components, ie, amp/pre/DAC enclosures have we seen with no provisions for active ventilation or convection cooling? How many digital amp-only enclosures with no ventilation provisions have we seen previously? How much can heat can "flow" inside a small volume, 99% sealed unit? Since air wants to move north when its molecules become excited due to heat where can it go, where exactly does it flow to if its tightly contained? Is it flowing or is it really stagnant and migrating thru radiation or physical proximity and contact from one part to the next? How many other previous systems can we name that have nearly 1:1 component-to-air ratio internally. Why might traditional systems have have well over 5:1, 10:1 or 20:1 air-to-component ratios internally and be ventilated while Devialet has only ~1:1 and sealed?

Whatever I discover will be made public here. If it works, great and I'll tell you. If it remains about the same, no harm done and I'll tell you. If it fails, I gave it my best shot and I'll tell you. If I get stupid lucky and the numbers sound too good to be true tell me a word or series of numbers to write down on a post-it and I'll stick it to the Devialet right below the GUI and snap a pic, post it within 5 minutes and show you! No one's been invited or encouraged to follow me along in duplicating this project alongside me. I post it for other's curiosity, entertainment and salient interests only. Personally I make no guarantees but I also know we can argue many things, however success isn't one of them.

As to EMI escaping; if it opens any of my garage doors unintentionally I'll change their code. If my iPhone rings all the time as it did before with a new unmodified digital amp I'll move it further than 5-6 feet away.

Let's try to keep it in the spirit of fun, innovation, adventure and learning rather than painting a doom & gloom scenario before its finished. No improvement ever came from complacency or not trying something. And holes can be plugged!
Statements in my posts are opinion only, not to be construed as fact. Any projects I engage in are at my own risk! Their outcome cannot be assured and may result in success, small/no change or catastrophic failure. I encourage no one rely on anything I say or do as gospel and to realize your mileage may vary!
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#9
Love your spirit of adventure.
Glad you are going in eyes wide open.
That and the fact that holes can be plugged ease my troubled mind.
Good luck and thanks for sharing.
D200, Magico S1's, Antipodes DX
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#10
(05-Aug-2015, 13:04)Manoet Wrote: Just a couple questions I'd like to ask directed at no one in particular then I'll leave others to form their own conclusions. Besides Devialet how many 99% 'sealed' multi heat generating digital components, ie, amp/pre/DAC enclosures have we seen with no provisions for active ventilation or convection cooling? How many digital amp-only enclosures with no ventilation provisions have we seen? How much can heat can "flow" inside a 99% sealed unit? Is it flowing or is it migrating thru radiation or physical proximity and contact from one part to the next? How many other previous systems can we name that have nearly 1:1 component-to-air ratio internally. Why might traditional systems have have well over 5:1, 10:1 or 20:1 air-to-component ratios internally and be ventilated and Devialet have only ~1:1 and be sealed?

Whatever I discover will be made public here. If it works, great and I'll tell you. If it remains about the same, no harm done and I'll tell you. If it fails, I gave it my best shot and I'll tell you. If I get stupid lucky and the numbers sound too good to be true tell me a word or series of numbers to write down on a post-it and I'll stick it to the Devialet right below the GUI and snap a pic, post it within 5 minutes and show you! No one's been invited or encouraged to follow me along in duplicating this project alongside me. I post it for other's curiosity, entertainment and salient interests only. Personally I make no guarantees but I also know we can argue many things, however success isn't one of them.

As to EMI escaping; if it opens any of my garage doors unintentionally I'll change their code. If my iPhone rings all the time as it did before with a new unmodified digital amp I'll move it further than 5-6 feet away.

Let's try to keep it in the spirit of fun, innovation, adventure and learning rather than painting a doom & gloom scenario before its finished. No improvement ever came from complacency or not trying something. And holes can be plugged!

Actually, there are some positives in the above posts.  If you consider that the difference between the 200 & much more expensive 250 is cooling, if you can improve cooling of the 200, then maybe this is a route to actually increasing the performance some way (or all the way) to 250 levels?  Although how you electronically reconfigure the power supply etc. to 250 settings I have no idea.  Just a thought!
 
Although it may just blow to pieces, of course! Angel
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