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Maybe not that good idea? Hypex nc400 and RME ADI 2 DAC fs

Sophoheilip

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A question regarding coupling of dac and amplifier: I have diy components for the nc400 ready, using a irs2092 clone (wondom, formerly sure electronics) at the moment. The source is a RME Adi 2 dac, fed via spidif from the minidsp shd studio.
So analog connections, input and output seem to be DC coupled. Isn't that quite dangerous for the speakers? Sometimes, I get a loud click, sounding like an arc.
I hope you can shed some light on this for me. Maybe the cheap class d module at the moment is the culprit and the offset from the rme is that tiny to do any harm?
I started to turn off the amp first and on last, preventing to damage something.
 

TabCam

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The irs2092 and clones seem far less reliable, depending on the builder of the unit, than the Hypex NC400. I did not experience any pops or clicks with an NC252. If you still hear those clicks, I would suggest to try another amplifier (from a friend or family).
 

solderdude

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I started to turn off the amp first and on last, preventing to damage something.

When you hear no clicks/pops this way there are no issues. One should adhere to this kind of switching anyway.
 

flowjm

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A question regarding coupling of dac and amplifier: I have diy components for the nc400 ready, using a irs2092 clone (wondom, formerly sure electronics) at the moment. The source is a RME Adi 2 dac, fed via spidif from the minidsp shd studio.
So analog connections, input and output seem to be DC coupled. Isn't that quite dangerous for the speakers? Sometimes, I get a loud click, sounding like an arc.
I hope you can shed some light on this for me. Maybe the cheap class d module at the moment is the culprit and the offset from the rme is that tiny to do any harm?
I started to turn off the amp first and on last, preventing to damage something.

Turning the amps on/off last/first is standard procedure recommended by many manufacturers for precisely the reasons you describe.
 
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Sophoheilip

Sophoheilip

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Thanks for all your answers! Next week the NC400 diy will we ready. If a click appears again, I will have to look deeper into it, to find the cause.
 

Burning Sounds

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Clips and pops.. caps draining ? Path of least resistance leading to speakers ?
Possibly. I'm no expert on these amps, but the reason I ask is because my Apollon Audio multichannel amp has had a small turn on pop and a louder turn off clack since new. Strangely, I've just replaced my Mytek ADDA8x192 with an Okto Research DAC8 Pro and the small turn on pop has gone completely. However, the more disconcerting loud clack at turn off is still there. I don't think it is doing any damage, but would like to know for sure.
I'll email Apollon and see what they say - they are usually pretty responsive.
 

Panelhead

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I am only familiar with the RME. But you really should just leave it powered 24/7. If pops, clicks, or other noise continues the power supply is not not rejecting current spikes on the AC line.
The Hypex module has noise rejection designed in. Implementation could contribute to your issue.
 

Burning Sounds

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Apollon answered my email within 30 minutes. Nice to see that quick response even though my amp is out of warranty. They say all the NCxxxmp series have a pop at turn on and turn off. The other NC series do not do this. They are working on a board that will disconnect the speaker outputs at turn on and turn off for these modules. Perhaps some implementations using these modules have already done this hence some folks have this issue whilst others don't. Anyway, Apollon assured me that it won't cause any speaker damage which is what I suspected.
 
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Sophoheilip

Sophoheilip

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I have my NC400 Monoblocks now up and running, but the problem stil persists. I figured out, when switching on or off the Hypex without signal input connected, there is no click or pop. So while that I held the Rme switched off in my hands and got an electric shock. Multimeter showed me 113 V AC (230V Line) between PE and some uncoated metal underneath the device. Measuring directly on the barrel connector of the power supply, either plus or minus, gave the same result. To ensure, there aren't any other devices faulty, I switched off the entire apartment, except one socket for powering the rme. Same result. The ps of my minidsp and another Meanwell wallplug gave me around the same result (111 and 83 VAC). Is this normal for switching power supplies? Or could anyone in the building have a faulty, bleeding power supply?
I mean, this is giving me around 63 V AC on all 3 pins of the rme xlr output, when there is no signal input.:eek:
Would it help to swap all adapters for earth grounded power supplies?
Sorry for the long text, but I would not like to leave out any useful information. And of of cause, thanks for your future help!
 

McFly

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Im struggling to understand where you are getting that voltage.. are you in US? Is your PE a true earth i.e. your earth you're is testing to is definitely a true earth and isnt transposed somewhere in the building... please draw a diagram if you can of where you are getting this voltage. Show exactly what PE you are measuring and what device or power supply you are measuring to.

Be careful, full mains voltage is lethal.

If you are getting it on other power supplies as you say, i suspect youre "PE" isnt infact a potential earth and is just hot.
 
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Sophoheilip

Sophoheilip

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I hope I have captured all the necessary information on this sketch. I found a few power supplies, eg. iPhone charger or some generic 5V wall plugs, where this strange problem doesn't occur.
1586342151846.png
 

basshead

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Hi Sophoheilip. McFly seems to be right here, your PE may be shorted to a line in your house.
This may happen when some of your neighbors want to cheat with electricity bills by shorting a line to a common ground found in the house like steel water pipes. This situation is very dangerous, as you may have lethal potentials on water taps etc.
 

March Audio

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Switch mode psus have emi noise filtering caps to earth from live and neutral. These leak current to earth (chassis or psu negative if no mains earth is connected which is typical of wall wart power bricks) hence the voltage. It can be 1/2 supply voltage. Nothing unusual. There are limits to what current is allowed. If you have ever touched a bit of kit and it sort of feels like it vibrates as you move your finger across it, or a bit of a tingle, then that is this leakage current.

Btw you should only ever hear a very minor click from the NcxxxMP modules at on/off nothing significant at all.
 
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Sophoheilip

Sophoheilip

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Thank you for your posts guys!

Hi Sophoheilip. McFly seems to be right here, your PE may be shorted to a line in your house.
This may happen when some of your neighbors want to cheat with electricity bills by shorting a line to a common ground found in the house like steel water pipes. This situation is very dangerous, as you may have lethal potentials on water taps etc.

I think this can be an option, but shouldn't this trip the RCD? Also measuring PE to neutral with the main fuse off shows no voltage. Some further installation mistake is imo no excluded, as there is a lot of botched up work in this building.

Switch mode psus have emi noise filtering caps to earth from live and neutral. These leak current to earth (chassis or psu negative if no mains earth is connected which is typical of wall wart power bricks) hence the voltage. It can be 1/2 supply voltage. Nothing unusual. There are limits to what current is allowed. If you have ever touched a bit of kit and it sort of feels like it vibrates as you move your finger across it, or a bit of a tingle, then that is this leakage current.

Btw you should only ever hear a very minor click from the NcxxxMP modules at on/off nothing significant at all.

My NC400 is now ready build and running nicely. Never had such a great amp for the money. As you wrote its the same as for the xxxMP, a small click from the ps relay, followed by a tiny plop in the speakers.
As for the power supply: I am planning to take it to work this week, to see if it is behaving the same way. I have read about the leakage currents in smps and did make an experiment, to measure through my body to ground instead the PE pin and the voltage dropped half. So current must be really small. As for the day I touched it, it felt like more than just a vibration. But maybe I had touched an earthed part with the other hand, cant remember.
 
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