2. tech-talk
  3. 1176609128

added amp...now hiss from spkr's

Addd an amp to the mix. SS multi-ch. Had no problems prior in relatively simple rig or atleast I did not notice. After making connections to recv'r(now used as pre/pro) I noticed a slight hiss/static like sound comimg from mids on my spkr's. So the process of elimination/isolation began. Long story short, I narrowed it down to the hiss/buzz coming from spkr's with only the amp connected. Nothing else...no interconnects no nothing. That cancels out cable problems, bad dvd player, etc, etc. Just power cable plugged in and wires going from amp to spkrs. When powered on it makes the noise. Amp runs quiet as far as I can tell when putting ear next to it. What's the deal? Tried diff outlets, diff spkr...makes no difference. When taking amp out of the mix and connecting spkr's to recvr, there is no noise at idle. Amp plays fine/sounds fine but the noise, although slight, is bugging me to pieces. Amp was shipped to me and had shifted cady/catty corner while in it's factory packaging which is pretty substantial. Perhaps it took a hit/drop...weighs about 80 lbs! Could something have gotten jared loose...a transformer which it has two of and quite large. Or is it the nature of the beast to output some noise when at idle? Thank you.
mnnc
aball
2,018 posts
 
Some amps have noise at idle and there is no way to fix it. Zero feedback designs are most prone to this problem, of course, and so will always be noisier than those with some feedback. If it was coming from your woofers it could be sub-optimal grounding but from your mids, it is the amp IMO. As long as you don't hear it at all from your chair, I would overlook it.

Arthur
hens
173 posts
 
I have recently noticed the exact same problem from my amp in my bedroom system. The amp is an 80 watt class A and with nothing else connected other than speakers, there is a hum from the mid/bass and a hiss from the tweeter - doesn't change with the volume control. The hum is audible from about 1 metre from the speaker. Unlike your situation, however, I can hear a very slight hum from the amp itself as soon as I swith it on from standby.

Hooked the amp up to less efficient speakers (85db compared to 90db) and whilst the hum remained, it was much lower.

Not audible from the listening seat, but just knowing the hum is there is frustrating and reduces my enjoyment of the music! I think if this is normal from this amp's design, that is very poor.

I'm returning the amp to the retailer to check while still under warranty.
plato
1,543 posts
 
It's probably considered "normal" from a ss-multi-channel amp. Many multi-channel receivers and amps do it. It seems to be the nature of the beast. The more efficient your speakers are (and the closer you sit) the more you will notice it.
More to discover