I just tried my other pair of ncore/smps and the DC output is even worse.
No speakers connected, no input from dac connected, just 120VAC input connected and the 4 pin from the ncore hooked up to xlr chassis connector (not even connected to metal chassis for testing purposes) and nampon to the bare ground wires of xlr cable and i'm getting 0.58VDC at the output. That's 0.1VDC higher than the other.
Anyone have any insight, this doesn't seem good.
No speakers connected, no input from dac connected, just 120VAC input connected and the 4 pin from the ncore hooked up to xlr chassis connector (not even connected to metal chassis for testing purposes) and nampon to the bare ground wires of xlr cable and i'm getting 0.58VDC at the output. That's 0.1VDC higher than the other.
Anyone have any insight, this doesn't seem good.
OK, let's see. To start with, is that with a load (speaker) connected, or open outputs? Can you try again with the input shorted (input pins 1 and 2 connected together)?
I agree. For me it isn't an issue as I want to be able to shut off the amps remotely anyway, but I can see it would be convenient to have the voltage available. Unfortunately I am not at my workshop right now, so I can't measure if any of the supply voltages are still on when the power supply is in standby, so I guess we have to wait for the Hypex guys to answer that one.
I just wrote to the support at Hypex because I have tried evrything and nothing helps.
Same voltage regardless if it is hooked up to a speaker load or not.
So short pins 1 & 2 and measure the output voltage again?
It's just "Julf" - an old nickname I got 30 years ago, involving a very drunk punk rock band, and some play on words in both Finnish and Swedish... 🙂
It's your speakers, not mine... 🙂
Unless you have a very powerful preamp, it sounds like the amp has switched on.
So you have connected the hot wire on the input RCA to pin1 on the hypex input connector and the RCA "chassis" to pin2? So your RCA connectors are insulated from the metal chassis?
To avoid ground loop hum. You don't want the main ground connection between the preamp and the power amp to go through the signal path.
I know this won't help you right now, but I think it is good to remember that the nc400 is not a kit, nor a product for consumers. Hypex is in the business of making modules (components) for OEM's to integrate into their products. We are lucky that they have kindly provided a way for us ordinary hobbyists to buy the modules. But as any component, it is up to us, as "system integrators/manufacturers" (even if we only make on amplifier) to understand the data sheets and specifications of the components/modules provided by the module manufacturer. And calling the component "hysteric" and getting tired of it is about as helpful as kicking a bicycle and calling it stupid if you don't know how to fix a flat tyre.
So, aside from any technical advice, I really suggest taking the old but true quotation from "Zen and the Art of Motorcycle Maintenance" to heart: "Assemby of japanese bicycle requires great peace of mind".
OK, that is only 50 mW into 4 ohm, but still... You don't happen to have an oscilloscope?
Yes, that is what I would suggest as next step.
Alright shorted pins 1 & 2 on the xlr connector without the input from the dac connected and i'm getting greater than 0.5VDC still.
Hmm. While 0.5V isn't catastrophically high, it is still definitely higher than I would have expected. I guess it would be good to wait for the hypex guys to chime in, unless you can measure the output with an oscilloscope.
Is this normal? What kind of measurements are other guys with ncores getting? I thought I had maybe done something wrong but these are measurements with absolutely nothing connected except the 120VAC power supply. No speaker load and no dac input.
Well it is possible to buy a lot of amplifier modules with no problems. My solution in this funny case could be to use XLR if RCA do not work.
Well, the hypex specs have a maximum of 0.05V, but I assume that is with load (speaker connected). Unfortunately I can't measure my own ones right now, but I remember it was definitely less than what you are seeing.
Do you know if there is something else that could possibly be causing this? It seems strange that both pairs of my ncore/smps have that high of a reading, seems as if I have done something wrong or something is bad on my end for both of them to do that.
I agree - especially if it still stays that high even with the speakers connected. But the amps work OK?
Erlend,
I can understand your frustration. All I am saying is that it probably won't help in solving the problem.
Yes speakers connected and disconnected same dc output. And the amp does work but it still worries me about that high of a DC voltage, don't want to weld my drivers, plus the loud noises when shutting down regardless of what gets turned off first isn't too nice either.
I also just tested the standby connecting pin1 of j1 to the + side of a 9VDC battery and nothing happened.
Well, 0.5V is only 0.06W into 4 ohm, and only goes to the woofer, as the mid and tweeter have a capacitor in the crossover that cuts off the DC.
And the - side of the battery was connected to ground?
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