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Pop/crack on power up, followed by audible tweeter hiss

Hey there, looking for a little advice before throwing money at this issue. I recently installed an integrated amp (nuprime ida-8) in my 2.1 system. When I power up the amp I get a pretty loud pop/crack noise from the speakers followed by a hissing noise from the tweeters that's quite obvious near the speaker and just audible from my listening position. This happens regardless of input, mute toggling, and is independent of the volume level. The amp is plugged directly into the wall (tried multiple outlets). I've been googling, and ruled out some things:

-Disconnected everything on the amp other than power and the l/r speakers
-Unplugged everything else in the house, shut lights off etc
-Made sure the speaker wires weren't touching anything
-Tried two different amplifier units
-Tried 'cheater' plug on the amp power cord

None of this had any effect. Previously I had a pure class-d integrated for a time that was dead silent. I'm in a fairly old apartment building so I don't have any control over the wiring. Is the next step to think about power conditioners or some other device? Any input appreciated. Thanks. 
artishard116
meerzistar
232 posts
 
One of my aging Canadian class D amps sounds pretty rude upon powering up and down. It sounds perfectly well other than at those times. I had a hunch discharging caps might be the cause at power off, it does an almost typical sounding "pop" but its accompanied by harsh static or crackle. Ive grown used to with other amps that went on working well into the future. Never had one make a noise during power up, and its not a pop Im not even sure how to describe it other than brief and nasty. Im tempted to buy new caps and wire them in and take a blind crack at it anyway to see what happens.   
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meerzistar
232 posts
 
Whatever are you meaning ebm? 
mervinpearce's avatar
mervinpearce
15 posts
 
I have a NuPrime IDA-8 and yes it has a pop on startup and that I live with but does not hiss at all.  It is dead quiet even at full volume with no source playing of course.  It has a problem have it seen to.
georgehifi's avatar
georgehifi
10,312 posts
 

You probably have a different version of output filter to the OP. Some other Class D manufacturers changed theirs every 12 months V1 V2 V3 all output filter changes, just to keep owners interested. 

Resulting in different amounts of hiss,, less or no hiss = lacks detail and top end extension, distant. Much hiss = lots of detail, harshness, and extension, in your face. Other versions somewhere in the middle.

This is the crux of the class D, the "switching frequency noise" is still too low to be filtered out without effecting the audio band. When the technology comes in the future to get the "switching frequency" and it's noise up 5-10 higher so then the filters can do their job many octaves away from the audio band, then we'll see class D's take over and bury linear amps.


Cheers George       

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