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Pink noise and pop from Levinson 333 amp

Please help. My ML333 amp makes a pop sound on the speakers when switch to ON from Standby -- I can hear the relays clicks inside the amp then follow by the pop (sometimes it pops going to Standby from ON). Worse yet, when it's IDLE (amp ON but not playing music) I can hear the amp puts out pink noise on the upper-mid and high drivers (my guess is 2kHz and up) when my ears are 2 feet away from the speakers. The noise (hiss?) is there with or without the preamp connected. Does anyone know what are the problems? It shouldn't be the from the main power because I don't get this problem on my Denon home-theater receiver. Thanks in advance.
krellcast
abstract7
541 posts
 
I would disconnect your pre-amp cables to the amp, then turn it on. If either of these problems persist when the pre-amp is not connected you should send the amp back to Levinson. My guess is the pop will still be there--I am not sure about the hiss--but you want to know so that you can give that info to Levinson when you send it back. I hate sending things back for repair (no music for a while), and Levinson will tell you it will be 3 weeks before you get it back--but in general they are much faster. I got most of my stuff back inside a week and almost always inside 2 weeks.
jacpiii
9 posts
 
If you using single-ended connections, make sure the XLRs are shorted with the shorting pins that came with the amp. Not using the pins definitely causes the pops.
ericbee
42 posts
 
Lets address each of the problems one at a time.
1. backround hiss.
While extremely annoying, this is unfortunately normal. It is the noise floor of the amp. Some are worse than others and worse still, some are almost silent. I have heard 2 of the same amp in the same system, one with noticeable backround noise and one with none. Really annoying and as far as I know, unfixable. The way to tell for sure if it is the amp is to disconnect all interconnects from the preamp and the amp (only 2) power it up and if you still hear the hiss from the tweeters, it's the amp.
2. relay clicking
Also normal on Levinson amps. The relay clicks when it powers on or on from standby. This is nothing to worry about.

3. Popping sound
This seems to be the real problem and should not be happening. If the unit was purchased from a local dealer, bring it to his listening room and see if it happens there. It should if it's the amp and if it does'nt, then you can trace the noise back to somewhere else. Very possibly could be the preamp.
krellcast OP
2 posts
 
I am using single-ended RCA connections and shorted XLR pins 3 & 1 using the U-pins from Madrigal. The pops and hiss are there when I disconnect inputs from the preamp. So it's issolated to the amp. I'll try to float the ground tonight.
1) Would the pops hurt the speakers? It's not loud pops, just typical normal listening level. I'm not sure how large is the surge voltage that makes the pops.
2) How can we tell if the background hiss is not amplified when music is playing? My ears can't tell that. I guess I should borrow a scope.
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