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Review and Measurements of Hypex NC400 DIY Amp

Xulonn

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Regarding thermal optimization, this is fairly easy to do: you just need to connect the main heatsink of the SMPS to the enclosure, with at least one layer of electrical isolation.
User @rajapruk and myself did it on our build, using a U shaped aluminum bar and two layers of blue thermal tack.
The drop in temperature on that heatsink was significant.

It appears that you have made some good DIY tweaks. My philosophy is that if heat reduction is easy, why not do it? Your use of thermal tack material to provide heat transfer while maintaining electrical isolation seems to be an excellent solution for kits/projects with internal heat sinking and no provided thermal conductive connection to a metal case.

Heat - even lower heat over time - reduces the lifespan of electronic components. That is why, when I recently purchased an RPi3+ and HiFiBerry DAC+ for showing movies at our little local community players theater, I ordered the steel case for it. Enclosing electronics in plastic - an insulator - when heat-dispersing metal is available doesn't make sense to me. After playing a 2-hour 1080p/2-channel audio movie, with video to the projector via HDMI and audio to the sound mixer board/amp, the RPi3+/HiFiBerry unit is barely warm.

I also purchased a Ghent case for a future 70wpc ICEPower 200ASC + 200AS module amp build, but the modules have no heat sinks, so I assume that they don't generate much heat - and I will seldom push the amp to high loads. I postponed my Ghent/ICEPower project when I came across my mint condition 1993 Classé Model Seventy AB amp, but after I buy the modules and finish the Ghent/ICEPower unit, I might replace the traditional linear power supply of the Classé with a pair of good SMPS modules. The Classé barely gets warm in my system, so the PS mod would eliminate mechanical noise and transformer vibration issues, reduce the weight of the unit drastically, and probably reduce power consumption a bit.
 
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JimB

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I thermal epoxied some heatsinks to mine: clear pins on the 'tops' and black fins on the 'sides'. This is a Ghent Ncore-mx4 case. The pins do not reach the cover. I also used high grade thermal paste under my NC400 module. No temperature measurements - sorry.

Since it shows in the side view photo, I'll note that I made my mains cable star quad, shielded.
IMG_3298 crop.jpg
IMG_3299 crop.jpg
 
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BYRTT

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@casual_audio_nerd,

Not that its related to your trouble shooting problem, but think routing of live wire can be improved running it routed and twisted by itself, as it is for now it looks be non twisted and routed as a snake around of the multiple DC wire buntle.

Visuals below should tell what i mean :)

1050a.png


1050b.png


1050c.png
 

restorer-john

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I thermal epoxied some heatsinks to mine: clear pins on the 'tops' and black fins on the 'sides'.

Personally, I think you are asking for trouble down the track. Epoxy always goes brittle, especially on flat surfaces that are constantly under heating-cooling cycles. You will end up with those little heatsinks falling off and rattling around the casework causing expensive (and spectacular) short circuits.
 

JimB

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Personally, I think you are asking for trouble down the track. Epoxy always goes brittle, especially on flat surfaces that are constantly under heating-cooling cycles. You will end up with those little heatsinks falling off and rattling around the casework causing expensive (and spectacular) short circuits.
Well, I certainly hope not! It is at least Al to Al, with low temp cycling and essentially no other mechanical stress. I suppose if they do fall off in 20 years, I'll have a justification to upgrade!!!;)
 
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JimB

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casual_audio_nerd is using an official Hypex kit. Here is the example shown in their instruction sheet:
1569089167473.png
 

JimB

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Can you zoom in on the XLR wiring of both units?
Specifically, for the left amp, I wonder about this connection here - that the two wires on the left should be connected together. Are they?
1569089722872.png
 

casual_audio_nerd

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@JimB - They are. Photos attached.

last night when testing (streaming through the NAD 658 - it was tripping out every 30-40 seconds. This morning, when moved off the top of the 586, case open, XLR unplugged and just power on, it went 5 mins without tripping. Once I plugged the XLR back in and started streaming again, it tropped within a few mins. I need to keep testing without any source connected. I'm also going to reseat the speaker connectors, as I realized it wasn't as neatly/cleanly seated in the gold clamp.
 

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DS23MAN

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You are having a dc problem from your source tripping the dc protection of the NC400. Remember it is dc coupled.
 

JimB

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@JimB - They are. Photos attached.

last night when testing (streaming through the NAD 658 - it was tripping out every 30-40 seconds. This morning, when moved off the top of the 586, case open, XLR unplugged and just power on, it went 5 mins without tripping. Once I plugged the XLR back in and started streaming again, it tropped within a few mins. I need to keep testing without any source connected. I'm also going to reseat the speaker connectors, as I realized it wasn't as neatly/cleanly seated in the gold clamp.
So, my concern has been for the nAMPON enable line. Maybe check for cold solder joints there where it joins the GND/shield lead.
 
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JimB

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So, my concern has been for the amp enable line. Maybe check for cold solder joints there where it joins the shield.
AND, what happens to your status LEDs when it shuts down? You can ask Hypex what they mean.
 

PaulD

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You are having a dc problem from your source tripping the dc protection of the NC400. Remember it is dc coupled.
Apologies if you've already tried this, but a good basic troubleshooting technique is to sweep inputs and then outputs. If the fault follows the swapped inputs then it is before the amp (eg, DC from whatever is before the power amps), if the fault follows the outputs it is the amp.
 

JimB

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Well, I certainly hope not! It is at least Al to Al, with low temp cycling and essentially no other mechanical stress. I suppose if they do fall off in 20 years, I'll have a justification to upgrade!!!;)
Joking aside, I really do hope it will not become a problem. I used Wakefield BT-301, which is optimized for Al - Al bonding, and followed their instructions about abrading and cleaning surfaces. I expect very small thermal gradients here, so very little mechanical stress. But, I have no information about long term "aging".
 

casual_audio_nerd

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Hi everyone. Apologies for the delay in following up here. Life and works sometimes gets in the way of these hobbies!!.I am pleased to report that I seem to have resolved the issue. My plan was to swap inputs/outputs, try different power sources/cables etc. But I first reseated all the cables, ground wire and speaker wire and haven't had a problem since. I *think* I may have been a bit sloppy with the speaker wire connecting to the board in the first attempt, which may have been causing the trip. I'll report back in a week or two but for now, happy days!!
 

DonH56

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I thermal epoxied some heatsinks to mine: clear pins on the 'tops' and black fins on the 'sides'. This is a Ghent Ncore-mx4 case. The pins do not reach the cover. I also used high grade thermal paste under my NC400 module. No temperature measurements - sorry.

Since it shows in the side view photo, I'll note that I made my mains cable star quad, shielded. View attachment 33937View attachment 33938


Sorry if someone already mentioned this, but I just caught the last post (hurray, working again!) and skimmed back to see this. Epoxy alone, thermal or not, is not a reliable mechanical connection. I suggest picking up a bag of nylon nuts and bolts and using them (you'll have to drill some small holes, at least one per heat sink) to make sure when (not if, at least not IME) the epoxy dries out and the heat sinks loosen, they stay in place instead of falling inside the amp to inevitably find the bestest place to cause the mostest damage.

Don't ask how I know this...

You could also fashion clips from spring steel or other hold-downs, but I've found the nylon bolts to work well, self-insulate, and if one should work itself loose over time from thermal cycling or whatever they won't cause any shorts. A touch of the end of the bolt with a soldering iron will melt the threads enough so that does not happen, and they are soft enough to cut or spin off should you ever need to replace them.

FWIWFM - Don
 

JimB

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Sorry if someone already mentioned this, but I just caught the last post (hurray, working again!) and skimmed back to see this. Epoxy alone, thermal or not, is not a reliable mechanical connection. I suggest picking up a bag of nylon nuts and bolts and using them (you'll have to drill some small holes, at least one per heat sink) to make sure when (not if, at least not IME) the epoxy dries out and the heat sinks loosen, they stay in place instead of falling inside the amp to inevitably find the bestest place to cause the mostest damage.

Don't ask how I know this...

You could also fashion clips from spring steel or other hold-downs, but I've found the nylon bolts to work well, self-insulate, and if one should work itself loose over time from thermal cycling or whatever they won't cause any shorts. A touch of the end of the bolt with a soldering iron will melt the threads enough so that does not happen, and they are soft enough to cut or spin off should you ever need to replace them.

FWIWFM - Don
How do you know this? ;) Anyway, you guys are making me wonder. While I expect this industrial product to actually do what it says (it IS a mechanical bond system, that cannot dry out, and has very high sheer strength, in an application with truly little sheer force), still, I don't know anything about it's degradation over time. If it was bad, it shouldn't be in use anymore. But, I could, easily, secure a loop of SS wire around the assembly that would ensure that the little guys could not simply "fall off" and find the sparkingest places available. Anyway, enough about my choices. Back to your regularly scheduled NC400 sonic qualities programming!
 
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