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vertically mounted NCC200s?

Arkless Electronics said:
I thought the same and checked out the cost of making my own... the cost of the aluminium is truly horrific! They will be buying it in much bigger quantities and getting considerable discount of course but to buy in enough sheet aluminium to make say 4 cases would have cost about 60% of the cost of the finished cases from Modushop!!:eek::eek:

Add the cost of getting the metal cut and drilled etc to professional standard by a local engineering firm and I don't believe you could make them for any less.... then there's the considerable labour and hassle involved!

Also in the case (sic) of the larger Dissipante cases with huge heatsinks then similar heatsinks bought in from RS etc are not at all competitive on price compared with the Modushop offerings.

TLDR; I also thought they were charging a fortune for "empty boxes" but after this exercise I have to regard the prices as very fair.
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Yeah, they're not that expensive, as things go these days!

This one then?

https://modushop.biz/site/index.php?route=product/product&path=205_208_269_271&product_id=194

Tallest components are the CAP6 boards at ~ 60mm tall; case depth is 80mm. I don't see any need for more clearance, do you?

Thanks very much,

Alex
 
hammeredklavier said:
Yeah, they're not that expensive, as things go these days!

This one then?

https://modushop.biz/site/index.php?route=product/product&path=205_208_269_271&product_id=194

Tallest components are the CAP6 boards at ~ 60mm tall; case depth is 80mm. I don't see any need for more clearance, do you?
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Yeah, that's what I often use. However, if your rack has the depth, I suggest you go with 400mm, to make positioning things easier. 300mm can be rather restrictive, especially given the space the fins steal.
 
Mike Hanson said:
Yeah, that's what I often use. However, if your rack has the depth, I suggest you go with 400mm, to make positioning things easier. 300mm can be rather restrictive, especially given the space the fins steal.
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Thanks Mike. Yeah I wondered about that myself - I just laid everything out on the desk and I can get it in 360 x 300... but there's not much room for manoeuvre!

Advice taken!

Ta

Alex
 
Right, nearly two years later...!

By the time the new case arrived from Modushop the window of opportunity to spend time building the amp had slammed shut. However, it's about to reopen and last night I finally got round to opening the box and looking at the new case. First thoughts - I'm glad I took Mike's advice and bought the larger one, I think trying to get everything into a smaller enclosure would have been very unenjoyable!

Right, before I get stuck in, a few practical questions.

Boring basic stuff:

Wire guage. I'm shooting in the dark because I don't know what maximum currents they're going to see. I haven't finalised a layout but at a glance it's hard to see any conductor needing to be more than about 20cm long. Even 0.5mm2 hookup wire would only have a DC resistance of 0.007 Ohms over that distance (0.014 Ohm loop). However, from the above thread I'm guessing even that could be enough to cause problems?

I don't want to do a PhD on it but what do people suggest that combines ease of use with electrical sufficiency? If you made me guess I'd say 1mm2, although again at a glance 18 AWG (0.75mm2) seems to be more readily available, at least in smaller quantities.

Insulation type? My feeling is that a floppy silicone wire would be harder to shape than a stiffer PVC one? Is solid core better?

Also before I go any further - siting the NCC200. Those Modushop cases have slots in the bloody base, which I must say I rather hate! The case is too shallow to mount the amplifiers vertically and I don't fancy drilling them for a direct horizontal mount (although I will if I have to) to the sides where the heatsinks are. As I recall, the NCC200s (and Naim amplifiers) don't get particularly hot even when driven quite hard, so my feeling is that it'd be fine to just bolt then to the base, as close as possible to the sides. I don't know, but would tend to think, that the huge fins on the case are a massive overkill for these amplifiers?

Thanks chaps.
 
NO! You really, really want to have the shortest thermal path between the transistors and the fins, otherwise you might as well have got a plain case.

If you drive them hard, the physics is pretty plain - class B is at best 78% efficient, but less in reality, especially on reactive loads, like loudspeakers. If you dump 100W into the load, expect to dissipate 30 or 40W. The key number is the thermal resistance, measured in K/W - lower is better. If your total thermal resistance, made up of fins, bracket, grease, washers and so is 1K/W, you will get 40C rise, which is OK, and the transistors will set at about 60C. But if you go too much above that, they will die. Now, if I understand their website correctly, the fins by themselves are about 0.67 K/W, so you need to use a short high conduction path to connect board to heatsink - sorry, you will need to drill them for directly bolting on.

For wire, I would go with something reasonably fat for the power supply, earth and output. Minimum 1mm2. Everywhere else, anything nice to work with. I am a heretic, and would use co-ax between the input sockets and the board, but that is very un-Naim.
 
Thanks, I had a feeling that'd be the response! Most Naim and Avondale amps just seem to be bolted to the base of a plain case, so I was wondering if it might just make life easier to pretend the case was plain. Hey ho.

I'll probably use 1mm2 RS Pro hook up wire for every except the signal input. Over those distances the contact resistances must be more than the wires!
 
Thanks. My only hesitation is I haven't got a drill press... I'm not too bothered about drilling the heatsinks but I'm not particularly looking forward to setting about the NCC200s with a hand drill. I think the shock might kill me if I manage to drill the heat spreaders perfectly straight!

Still, in for a penny...
 
The NCC200 boards are mounted on a C channel heat sink .
Drill a 3.2 mm (1/8th) hole and tap 2 x 4mm threads that will line up with the bottom of 2 heat sink fins and use a 4mm Allen bolt which will fit in between the fins. Use heat sinc compound and bolt them up.
Alan
 
337alant said:
The NCC200 boards are mounted on a C channel heat sink .
Drill a 3.2 mm (1/8th) hole and tap 2 x 4mm threads that will line up with the bottom of 2 heat sink fins and use a 4mm Allen bolt which will fit in between the fins. Use heat sinc compound and bolt them up.
Alan
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It's the drilling straight bit that concerns me. I'll just use a drill block on the fins, but the heat spreaders on the circuit board...

Plan A is indeed to use M4 hex cap bolts (coming tomorrow), with a tap in the spreader. It might be easier though to drill 5mm holes in the heat spreaders and use washers and bolts rather than tapping (I think there's room). Should make straightness less critical?

The only other thing I can think of doing is using some uneven aluminum angle, maybe 60, 40mm, with the larger side going on the bottom of the spreader and the shorter edge going on the fins. Obviously the angle can be longer than the NCC200.

It's a pain in the ass, to be honest!!
 
Simple, other thing - de-burr all drilled holes (countersink bit, or just use a larger drill rotated by hand in the hole, to de-burr / use fine abrasive on the spreader, to flatten the surface / ensure all resulting burrs-knocked-down) - so that the mating surfaces are decently-flat, before relying on heatsink compound.
 
martin clark said:
Simple, other thing - de-burr all drilled holes (countersink bit, or just use a larger drill rotated by hand in the hole, to de-burr / use fine abrasive on the spreader, to flatten the surface / ensure all resulting burrs-knocked-down) - so that the mating surfaces are decently-flat, before relying on heatsink compound.
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I'll worry about that when I've drilled the holes...

Do people normally remove the spreaders to drill them? It must be awkward as hell with the circuit board attached!
 
hammeredklavier said:
I'll worry about that when I've drilled the holes...

Do people normally remove the spreaders to drill them? It must be awkward as hell with the circuit board attached!
Click to expand...
Ive always built these boards up from PCBs so did the drilling before fitting the output transistors.
If yours are already mounted, its not easy to de-solder all the output transistors and unbolt the heat sincs
If you have a good Vice you can do it
or use the allready drilled bottom of the PCB heat sincs and mount the board hoizontally on the case heat sinc as I did with my Voyagers
Drilling the case heat sinc is done from the inside, or dismantle the case

Alan
 
337alant said:
Ive always built these boards up from PCBs so did the drilling before fitting the output transistors.
If yours are already mounted, its not easy to de-solder all the output transistors and unbolt the heat sincs
If you have a good Vice you can do it
or use the allready drilled bottom of the PCB heat sincs and mount the board hoizontally on the case heat sinc as I did with my Voyagers
Drilling the case heat sinc is done from the inside, or dismantle the case

Alan
Click to expand...
They're used boards, all built up.

I have got a vice but it's still not hard to see drilling them being a disaster!

I'm minded to buy some 2mm 40 x 40mm aluminum angle, and use that to mount the boards to the fins. That way I don't need to drill any new holes in the heat spreaders on the NCC200s.

I can't immediately think of any reason why that'd be bad. As I said earlier, I don't recall these amplifiers getting very hot anyway!
 
Mynamemynaim said:
I usually drill the case heatsink and tap a thread...then just drill another hole(s) though the board spreader heatsink and bolt the two together
In this case with 3 stainless dome head Allan screws per board

https://flic.kr/p/2mnV7Mf
Click to expand...
That actually looks quite similar to what I propose above. It'd basically enlarge the heat spreaders on the NCC200s, using a piece of aluminum angle very similar to the heat spreader in your photo!
 
andrewsutton said:
Hi, where are you?
Someone here might offer to drill your heat sinks and spreaders and tap them.
Click to expand...
Stoke-on-Trent, however I'm a man with a plan!

I've ordered 1m of 40x40mm aluminum angle, 3mm thick. I'll cut this to two 200mm lengths, which will completely span one of the case heatsinks each side. With care, the bottom and front faces of the NCC200s' heat spreaders will be flush with the new pieces of aluminum angle, and with a right good squidge of expensive thermal paste, heat transfer to the fins should be very good. It should also improve the physical robustness of the build.

Let's suck it and see. My A-S500 is all the amplifier I actually need, the whole point of this build was to learn and experiment, and hang the consequences!
 
Right, while I wait for the new parts to mount the NCC200s on, I've got the transformer and the CAP6s bolted down. So far so good.

Now - you can tell I haven't done this before can't you! - looking at the case I've bought and the parts Les sent me, there's another problem isn't there: there'll be no way of knowing whether the amplifier is on or off!

I know it's not the end of the world, but has anyone tried fitting one of those 16mm Heshen switches to a Modushop case with the 10mm front panel?

Heschen 16mm Rectangle Push Button Switch, Latching Type, 1NO 1NC, Red Blue Yellow White Green Orange, 12V LED Lamp https://www.amazon.co.uk/dp/B076WZ2TJJ?tag=pinkfishmedia-21

Might be a tight fit! It seemed like a good idea when I ordered it...

I know it'll work perfectly well with a rocker switch round the back but obviously it's better on the front and it really needs a light doesn't it.
 
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