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Humming and static noise, Plinius SA 100 MkIII

Hello. I am currently using a pair of Plinius SA 100 MkIII's as mono blocks to power my B&W 802D's. First the amps have a slight hum when on and sometimes they are very quiet. More importantly, when I turn the volume up all the way without a signal from source, there is a very noticable high frequency hiss like radio signal distortation at the speakers. I have tried many things including changing preamps, cables, cords, etc but nothing worked. These amps generate 400 watts as mono so with the volume turned up all the way the noise may not be abnormal.

I would appreciate if any one with similar issue has an answer for me. I love the amps but the noise level is a bit too high. Note: in normal listening volume the noise is very low and not noticable at all only at vey high levels the noise is very noticable. Thank you.
espoverload
espoverload OP
14 posts
 
I appreciate everyone's input. I could accept the noise is from the amps and move on, but I have tried 2 different brand amps and they all produce the same noise at different levels, so something in my system such as power source, is introducing the distortion and the amps amplify the noise. The only thing I haven't been able to try is to use the XLR connections. But my current preamp does not have balanced outputs and I don't want to invest in a new preamp, cables, etc and still have the noise. I have a home theater room with dedicated 20 amp circuit. I'll move the Plinius to that room to see if it makes a difference. After that, I have to decide to keep the amps and live with the distortion or sell and buy something like Pass Labs or Classe. The reason I originally purchased the Plinius was because it is the only amp that I know of which has a clas A and A/B selector.

BTW, when I was using my other amps to test the noise level even my wife noticed the very poor sound quality compared to the Plinius. So the chalenge continues. Thanks
rleff
1,065 posts
 
Are you using balanced or RCA inputs?
misternice's avatar
misternice
339 posts
 
Hi with my mk3,rca gives a hum and a small power surge,when i turn on the pre.Balanced it dissapears.I couldnt sell my 250.
espoverload OP
14 posts
 
I am using unbalanced S.E. RCA. My preamp does not support XLR outputs. I don't want to buy a new preamp, cables, etc and still have the same problem. unless someone has done this and got rid of the distortion. Again, I am not concerned with the hum as it is not always there. My concern is the very noticable distortion at the speakers, which may be caused by other factors and not necessarily the amp. Thanks
gande
2 posts
 
I have a SA50 and a SA102 and they both have the same buzzing sound when running in class A. they are dead quiet when running in class A/B though. The amps don't buzz when nothing is connected to the input or when the mute switch is activated, there is also less buzzing when a tube pre is connected.
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