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vertically mounted NCC200s?

hammeredklavier

owner of two very cheap hi-fis
I was just thinking nothing's easy is it! :-D

Right, laying out the CAP6s and NCC200s in the amp case I've got leads me to an(other) unforeseen problem: the case has bloody vent slots in the bottom plate! I don't like the idea of mounting the NCC200s over these slots.

Options are 1.) not worry about it, air is good and the amps don't get that hot; 2.) mount the NCC200s vertically on the sides of the case - can't think of a reason not to, can you? 3.) buy a new case!

As I recall, these amplifiers don't get particularly hot even when working hard...

Ta

Alex
 
I prefer the layout of the first picture for future service and ease of assembly.
I would put some thermal paste under the boards and add a thermal switch near one of the boards and it should be fine.
That’s how Naim does it with success.
 
I prefer the layout of the first picture for future service and ease of assembly.
I would put some thermal paste under the boards and add a thermal switch near one of the boards and it should be fine.
That’s how Naim does it with success.
Yeah but Naim amps don't have vents in the bottom... look closely and you'll see the problem.

If it was a solid sheet of metal I'd go for the first layout no messing. Indeed, it's what I originally planned.
 
Can you fit a sheet of 3mm alu to the bottom of the case?
If the case is steel, I would not recommend #1.

I would go far the alu sheet to spread the heat and also put TR5 under the pcb, next to the alu, to help keep the bias stable.
 
Can you fit a sheet of 3mm alu to the bottom of the case?
If the case is steel, I would not recommend #1.

I would go far the alu sheet to spread the heat and also put TR5 under the pcb, next to the alu, to help keep the bias stable.
Yeah I thought about mounting all the goodies on a piece of aluminium anyway, just for extra strength.

Christ. You know those ideas you wish you'd never had!! :-D
 
I would love to be able to claim it was my idea but Naim did the TR5 thing with the NAP200.

I ran a NAP200 clone in a steel case with an alu plate - it worked well, at least on 40V rails. Higher rails = higher dissipation!
 
OK. Blimey, me and my ideas! I'll just build an amplifier, it won't take a min...!! :-D

Right, is there any reason not to do a Naim and put the NCC200s in a separate enclosure, and use the steel one for the power supply? I know it's a bit Heath Robinson but so what?

https://uk.rs-online.com/web/p/general-purpose-enclosures/5173428

Any reason not to do that - apart from it being two boxes instead of one? Think of all that extra isolation etc!

Alex
 
I would keep it in one box.
The transformer, rectifiers and main smoothing caps need to be physically close. The speaker return should be taken from the power star point i.e. when the main smoothing caps join. It all gets very messy with 2 boxes, unless...

Naim get away with 2 boxes by using local power regulators, which means they can make the power star where the 0V references for the regs meet.
 
If you mount those amps to that case, the steel will NOT act as a sufficient heatsink, and the amps will go into thermal overrun and burn-out the power transistors.

I had a similar case (Modushop Pesante) and mounted a large block of aluminum between the amp modules and the base of the case, but still killed them. Here's was my build: https://pinkfishmedia.net/forum/threads/another-avondale-amp.229811/page-3#post-3822995. Note the many posters in that thread warning me of my folly, but I forged cavalierly ahead, and suffered the consequences. :(

You have three options:
  • Buy a cheap heatsink with fins, and figure out some way to mount it to your existing case (perhaps by cutting a hole in one side for the heatsink to poke out). I'm going to try this myself at some point, using some heatsinks that I acquired.
  • Buy a sheet of aluminum to replace the bottom panel. I've successfully done this twice using Pesante cases (e.g. https://pinkfishmedia.net/forum/threads/play-time-nap140-with-smps.254619/page-2#post-4357478). However, it appears the rear panel of your case is welded to the bottom panel, so this probably won't work for you.
  • Buy a different case, like the Modushop Dissipante. This has aluminum heatsink fins on the side, and you can also order it with 3mm aluminum panels for the top, bottom and rear. It's relatively expensive, though. It's too bad that they don't have an aluminum panel option for their cheaper Pesante cases.
 
If you mount those amps to that case, the steel will NOT act as a sufficient heatsink, and the amps will go into thermal overrun and burn-out the power transistors.

I had a similar case (Modushop Pesante) and mounted a large block of aluminum between the amp modules and the base of the case, but still killed them. Here's was my build: https://pinkfishmedia.net/forum/threads/another-avondale-amp.229811/page-3#post-3822995. Note the many posters in that thread warning me of my folly, but I forged cavalierly ahead, and suffered the consequences. :(

You have three options:
  • Buy a cheap heatsink with fins, and figure out some way to mount it to your existing case (perhaps by cutting a hole in one side for the heatsink to poke out). I'm going to try this myself at some point, using some heatsinks that I acquired.
  • Buy a sheet of aluminum to replace the bottom panel. I've done this with success (https://pinkfishmedia.net/forum/threads/play-time-nap140-with-smps.254619/page-2#post-4357478). However, it looks like the back panel of your case is welded to the bottom panel, so this won't work for you.
  • Buy a different case, like the Modushop Dissipante. This has aluminum heatsink fins on the side, and you can also order it with 3mm aluminum panels for the top, bottom and rear. It's relatively expensive, though. It's too bad that they don't have an aluminum panel option for their cheaper Pesante cases.
Unfortunately, this is what happens when I order parts for one job whilst thinking about another! I just measured what plan area I needed and ordered a bloody case, building the amplifier was for another day so I didn't think about what I was doing!

Replacing the bottom plate with aluminium should be pretty straightforward, it's not welded I just propped it up for the photo! Best option?

I'll buy a better case if it comes to it but it seems a waste. As I say, I bought the stuff a while ago and didn't even look at it!

Thanks

Alex
 
I would keep it in one box.
The transformer, rectifiers and main smoothing caps need to be physically close. The speaker return should be taken from the power star point i.e. when the main smoothing caps join. It all gets very messy with 2 boxes, unless...

Naim get away with 2 boxes by using local power regulators, which means they can make the power star where the 0V references for the regs meet.
I need to have a think about that, it's not abundantly obvious to me why the amplifiers shouldn't be in a separate enclosure...
 
If you mount those amps to that case, the steel will NOT act as a sufficient heatsink, and the amps will go into thermal overrun and burn-out the power transistors.

Depends on the supply rails and how you couple the thermal feedback loop via TR5. What rails did you use MIke?

Post #35 in your link covers some of the considerations.
 
It's DIY, you can do whatever you want and my views are only that :)
Sure, and I'm grateful for all thoughts and advice. I haven't built an amplifier before so I'm making this up as I go along!

I didn't worry about heatsinking as much as I should, basically because I don't recall the amps getting all that hot. As for two boxes, I haven't given it any deep thought obviously, but in principle running a wire between two boxes isn't electrically any different to doing it within a box... in principle. I'd rather stick to one box of course.

Alex
 
Replacing the bottom plate with aluminium should be pretty straightforward, it's not welded I just propped it up for the photo! Best option?
Yes, that should be quite easy, as you can use a simple sheet of aluminum cut to size, with holes drilled to match those in the side panels. Get it anodized if you want, but given you'll never see it, I wouldn't bother. Also, the anodizing decreases its heat transfer ability slightly.

BTW, I wouldn't recommend this technique for something like an NCC300, as it puts out quite a bit more heat, but it's definitely adequate for a pair of NCC2x0 boards.

Also, try to keep the input end of the NCC board away from the transformer. Take a look at my build pics for some layout ideas.
 


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