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Class D Switching Power Amplifiers and Power D/A conversion

Hypex Ncore
Hypex Ncore
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Old 31st March 2012, 02:55 PM   #3201
Erlend Sæterdal is offline Erlend Sæterdal  Denmark
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Join Date: Mar 2007
Hypex Ncore
Quote:
Originally Posted by kbergsson View Post
Threw it together quick and dirty. The amp is now making wonderful and powerful noises on my Altec 604s
Kjartan
And you use XLR ?
 
Old 31st March 2012, 03:09 PM   #3202
robbbby is offline robbbby  Canada
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Join Date: Feb 2012
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.
 
Old 31st March 2012, 03:24 PM   #3203
Julf is offline Julf  Europe
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Join Date: Oct 2011
Location: Amsterdam, The Netherlands
Quote:
Originally Posted by robbbby View Post
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.
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)?
 
Old 31st March 2012, 03:29 PM   #3204
Julf is offline Julf  Europe
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Join Date: Oct 2011
Location: Amsterdam, The Netherlands
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Originally Posted by robbbby View Post
With regards to the standby, is there any place to get that required voltage from smps? I'd hate to have to put another connector on my chassis or run another wire from who knows where just to put it into standby. Would be nice to keep everything inside the chassis with maybe just adding a simple toggle switch on the back or a push button on the front.
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.
 
Old 31st March 2012, 03:34 PM   #3205
Erlend Sæterdal is offline Erlend Sæterdal  Denmark
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Join Date: Mar 2007
Hypex Ncore
Quote:
Originally Posted by Julf View Post
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.
 
Old 31st March 2012, 03:41 PM   #3206
robbbby is offline robbbby  Canada
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Quote:
Originally Posted by Julf View Post
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)?
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?
 
Old 31st March 2012, 03:51 PM   #3207
Julf is offline Julf  Europe
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Join Date: Oct 2011
Location: Amsterdam, The Netherlands
Quote:
Originally Posted by Erlend Sæterdal View Post
Thank Mr. Julf
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...

Quote:
Well this with oscillating and dc will not happen so I will forget that.
It's your speakers, not mine...

Quote:
I have connected evrything in the right mannor and there is still no sound. I can measure a very small signal with my voltmeter at the output and also hear a very small signal in the speakers
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?

Quote:
In the datasheet it is recommended that the RCA is not isolated ! For what reason ?
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.

Quote:
This is really an hysteric amplifier and I am tired of it allready.
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".
 
Old 31st March 2012, 03:53 PM   #3208
Julf is offline Julf  Europe
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Join Date: Oct 2011
Location: Amsterdam, The Netherlands
Quote:
Originally Posted by robbbby View Post
Same voltage regardless if it is hooked up to a speaker load or not.
OK, that is only 50 mW into 4 ohm, but still... You don't happen to have an oscilloscope?

Quote:
So short pins 1 & 2 and measure the output voltage again?
Yes, that is what I would suggest as next step.
 
Old 31st March 2012, 03:54 PM   #3209
robbbby is offline robbbby  Canada
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Join Date: Feb 2012
Quote:
Originally Posted by Julf View Post
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)?
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.
 
Old 31st March 2012, 03:57 PM   #3210
robbbby is offline robbbby  Canada
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Quote:
Originally Posted by Julf View Post
OK, that is only 50 mW into 4 ohm, but still... You don't happen to have an oscilloscope?
no scope, i'm not a big electronics guy as you can probably tell
 

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