Not to get too far into this here, but I'm interested in simple schemes because when I considered implementing something, it appeared an additional power supply (of some sort) would be required as the standby features require a voltage to hold them there. Perhaps someone can just refer me to another forum or website that might deal with such ideas? For now, I use a Digital-Loggers Iot Relay to switch the mains from my other trigger systems. I use very short mains cords, but it's still a kludge.
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Review and Measurements of Hypex NC400 DIY Amp
- Thread starter amirm
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There was a really, really long nc400 thread on diyuaudio. The SMPS suspend indeed needs an active signal to turn off, but a low-power 12 V supply is not hard to arrange. The nCores themselves have the reverse logic, so no separate supply is needed if you are OK leaving the power supply on.
Ok, will open one today and see if I can locate the source.
Ok, looked into it with more detail:
So thats interesting!
The 'sound' at 450/500/550 Hz almost goes away when the cover is removed.
By moving the microphone close to the pcb's and scanning the components its clear the 1050Hz is coming from the output coil of the NC400.
The 450/500/550Hz is coming from the transformer of the SMPS600.
These sounds are amplified by the cover somehow.
The cover hoovers closely over the transformer, I suspect the metal of the cover gets effected by the field of the transformer and then gives this sound...
Question now is, how to solve this. (preferably without having to rebuild it in a new case
)Instead of a trigger you could also use a master-slave power strip. This is what I do because my Quad 606-2 only has its power switch on the back. My ADI-2 is a bit too frugal for the sensor in the power strip, but combined with an always on Chromecast Audio it just crosses the threshold.
Indeed, I also use a master-slave strip to switch on my NC400's.
The built-in mechanism does a soft start instead of a somewhat brutal total, instantaneous on/off switch.
Got home, so now I have access to the data sheets. The nAMPON input takes a voltage between 2.65 and 3.3 V that turns on the amp (pulling it down to 0 turns the amp off). On the SMPS600, the SMPS Standby input takes a voltage between 3.3 and 12 V that puts the amp into standby.
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@Hayabusa
Torroidal tranformers in linear supplies can have their core quickly saturate with even small dc offset on the power feed. One of my amps does this and removing the cover significantly reduces the audible hum from the supply. In this case a dc offset eliminator such as the emotiva cmx-2 helps eliminate it.
https://emotiva.com/products/cmx-2
Torroids are susceptible because their cores have very little margin against saturation from dc. I don't know how susceptible smps are to dc offset but thought I'd mention it as s possible avenue to explore further.
Torroidal tranformers in linear supplies can have their core quickly saturate with even small dc offset on the power feed. One of my amps does this and removing the cover significantly reduces the audible hum from the supply. In this case a dc offset eliminator such as the emotiva cmx-2 helps eliminate it.
https://emotiva.com/products/cmx-2
Torroids are susceptible because their cores have very little margin against saturation from dc. I don't know how susceptible smps are to dc offset but thought I'd mention it as s possible avenue to explore further.
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From the block schematic of the SMPS600 I see that the mains are directly rectified and that the transformer is in the DC/DC converter after that. So I guess DC on the mains is not causing this.
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Perhaps the cover resonates around 500Hz. With it attached normally, does the noise disappear if you touch it lightly? If so, just add a small amount of damping material to the inside of the lid.
Thanks! I have tried it:
It changes a little, I have now applied some felt on the inside of the lid.. It reduces by 1 dB or so... Problem is that the area that resonates also has ventilation holes, and I don't want to close them... Seems I have to live with the sounds the amp produces.. Its not noticeble while playing music.
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Can you feel the vibration on the case when it’s on? vs. when it’s off? The tactile sensation may be present when you run your fingers gently across the case.
Perhaps you try remedy apply some sound deadening material to an appropriate place on the steel or aluminium casing.
Like car doors or loudspeaker cabinets that have their own natural resonance, metal may have it own. There are products on the market that you can apply to reduce this. I use bituminous felt ($) but one can use branded commercial products like Sonic Barrier ($$) or Whispermat ($$$)
Perhaps you try remedy apply some sound deadening material to an appropriate place on the steel or aluminium casing.
Like car doors or loudspeaker cabinets that have their own natural resonance, metal may have it own. There are products on the market that you can apply to reduce this. I use bituminous felt ($) but one can use branded commercial products like Sonic Barrier ($$) or Whispermat ($$$)
I could not feel tactile vibration. I have now closed the holes of the lid to see if the internal temperature would stay low enough, this seems to to be the case (only +2 degrees C). So I will indeed try to get some of material you propose and stick it under the lid, to see what that does
Have you tried heavy objects on top of the amp to see if that helps?I could not feel tactile vibration. I have now closed the holes of the lid to see if the internal temperature would stay low enough, this seems to to be the case (only +2 degrees C). So I will indeed try to get some of material you propose and stick it under the lid, to see what that does
Big alert !
@Audiophonics is releasing an assembled NC400 Amp. It'll be called PA-S400NC.
Double SMPS600 PSU! So it would deliver as much as monoblocs kits.
1490€ inc VAT, so quite more expensive than their PA-S500NC... but still on par with two NC400 DIY kits from Hypex (699€ each)... and at least, it is assembled already. Is that the first NC400 DIY implementation to date?
@Audiophonics is releasing an assembled NC400 Amp. It'll be called PA-S400NC.
Double SMPS600 PSU! So it would deliver as much as monoblocs kits.
1490€ inc VAT, so quite more expensive than their PA-S500NC... but still on par with two NC400 DIY kits from Hypex (699€ each)... and at least, it is assembled already. Is that the first NC400 DIY implementation to date?
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Nice! Very interesting.
The internal layout of the Audiophonics implementation looks nice to me, with separate power supplies, and plenty of distance between the two pairs of amps and power supplies. Does anybody else have any comments on the apparent quality of that layout?
I hope that they also make it available with a North American power supply.
I hope that they also make it available with a North American power supply.
Wonder how much the external heat sinks are really needed...
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