Hypex Ncore

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#8,601
NC400/SMPS600

Hi I built some NC400/SMPS600 amps in early 2012.
I have used them on and off since (I am partial to valve romanticism, but like the detail and bass resolution of the hypex amps... so I go back and forth between my hypex monoblocks and my valve monoblocks on a regular basis 🙂 ), once in a while one of the mono blocks has shut down (thermal?) but always came back on after a short pause.

However my NC400/SMPS600 have now gradually developed an issue. I took the hypex blocs to a friend nearly a year ago (after they had been in use for several months at my home). We could not try them in his house as the mono blocks immediately tripped the house ground-fuse at his apartment.
At home they worked as well as before. So I thought the problem was at my friends house.

Some months ago I loaned the NC400 mono blocks to my son (same house) as the power supply in his Ucd400 amps died (it had been in continuous use for approx. 5 years so that is understandable, I have ordered a new powersupply for his amps).
He used the NC400/SMPS600 mono blocks for some months, problem free, until one day they blew the house fuse, and I have not bee able to get them going since.
Both blow the house groundfuse immediately and sometimes the fuse for the area they are connected.

The fuses blow immediately when the amps mains are turned on. I tried separating the SMPS600 and NC400 in one amp and the fuse did not blow immediately but after 5-8sec (dont remember exact time).

Could both smps600 have blown at the same time? There is nothing to see on the components and all look ok. I have been in contact with hypex support and sent them pictures of my build but they dont seem to have any answers or suggestions for me.
I use phonos not XLRs and no mains ground.
Any ideas?
 
#8,604
Hi Julf, the power plug has 3pin/3wire Nautric, but the ground is not connected as I did not have grounded mains in the house I rented when I built them.
There was a plan to implement the XLRs. But I would need psaudo-balanced as my valve preamp uses phono and my preamp only uses 2 wire power cable.
On the nc400/ input phono: ampon, return and cable screen go to chassis as the phono return is not insulated from chassis.
 
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#8,605
kbergsson said:
Hi Julf, the power plug has 3pin/3wire Nautric, but the ground is not connected as I did not have grounded mains in the house I rented when I built them.
Click to expand...

OK. So again, be very careful, as nothing protects you against live mains in the chassis.

There was a plan to implement the XLRs. But I would need psaudo-balanced as my valve preamp uses phono and my preamp only uses 2 wire power cable.
Click to expand...

Right, but you would still have the benefit of a balanced cable.

I am assuming your source (especially if it is a valve preamp) connects the chassis to the signal ground. Sounds like that causes the mains earth trip switch to trigger - but there might still be something wrong with your smps600's. Do you have a mains isolation transformer available?

On the nc400/ input phono: ampon, return and cable screen go to chassis as the phono return is not insulated from chassis.
Click to expand...

OK, so your chassis is connected to your preamp chassis through the cable screen.
 
#8,606
I think I have found the problem. And I really dont understand how they could function for over a year before starting tripping fuses. I used at first just one SMPS600 for a stereo setup and did that for the first year (2012). I then got the second SMPS600 and did the mono blocks. I remember having a problem where I was living then and measured my way when connecting the Neutrik mains plug. Now I see I had connected L and ground on the Neutrik plug ( and not L & N). I have now connected L & N and the amps fire upp and all lights come on without tripping the fuse. Will test with music now and see if all is ok.
But if all is ok, I cannot understand how they could work ok for a long time connected like this.
 
#8,607
kbergsson said:
I think I have found the problem. And I really dont understand how they could function for over a year before starting tripping fuses. I used at first just one SMPS600 for a stereo setup and did that for the first year (2012). I then got the second SMPS600 and did the mono blocks. I remember having a problem where I was living then and measured my way when connecting the Neutrik mains plug. Now I see I had connected L and ground on the Neutrik plug ( and not L & N). I have now connected L & N and the amps fire upp and all lights come on without tripping the fuse. Will test with music now and see if all is ok.
But if all is ok, I cannot understand how they could work ok for a long time connected like this.
Click to expand...

Could N have been connected through chassis, shield of input cable, and chassis of preamp?
 
#8,608
Yes possibly N came through the preamp. My loudspeakers are effective (Altec 604-8g, using auto formers in crossovers) and dont need much to drive them, the preamp is a well built Leben rs28cx with a solid separate power supply.

Tested them on music now and the sound was sublime. Maybe I have never heard the mono blocks as they should sound, before. 🙂
 
#8,611
nCore 400 blocks doing a good job. The valves awaiting their turn 🙂
 

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#8,613
Agree 🙂 Once I got the crossovers sortet the Altecs play a lot better than many new speakers. The hypexes and push-pull kt88s fit the Altecs well, even if they are 98-99db they need powerful amps. The triode amps (300b) have their force on relatively simple music, like late night jazz and vocal music.
Locomotive breath with the hypexes on full blast is a religious experience 🙂
 
#8,618
Wiring XLR and IEC

Hi just want to get a final ok before wiring.

I will run a short lead from IEC mains inlet earth pin to the chassis for safety.

XLR Pin 1 short lead to chassis
XLR Pin 2 Blue lead
XLR Pin 3 White lead

Signal cable braid and nAMPON wire connect together and fix to chassis
 
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