The noise at times bothers me more than other times just listening to the speakers, but if I plug in audio technica headphones (which I've found to be easy to drive) the hiss becomes unbearable.
Reasons for this:- do you happen to control the volume on your source (e.g. computer) rather than on your receiver? For best performance, set your sources to full (or near full) volume and control loudness with your receiver. Otherwise you'll unnecessarily amplify noise.- your receiver has a defect- you're super sensitiveI don't think build quality should be a problem with this amp. It has a claimed SNR of 95dB which is good imho.edit: Be sure to disable all DSP or headphone enhancement, somtimes they add a notable amount of noise.
Some equipment information:The HK 3490 is rated at 120 Watts per channel.In the Stereophile magazine test of the Linn Majik 109s:My estimate of the Linn's B-weighted sensitivity was significantly lower than the specification, at 85dB(B)/2.83V/m.
There are two possible sources in the receiver of the noise that is bothering you. It is either coming from the power amps, or it is coming from the peamps or pehaps a little bit of both. Don't dismiss the possibility that the noise is environmental, like HVAC noise or a lamp or something like that.(1) Turn the receiver off. Still hear the noise?(2) If the noise follows the setting of the power switch, then to determine where in the receiver it comes from:(3) Disable the connection between the receiver's preamp and power amp. There seem to external jacks and switches that relate to this. Do you still have noise with the power amp inputs shorted? If so, you need less efficient speakers, or to move them further away from you, or some such.(4) If the amp is sufficiently quiet by itself but you get noise when it is connected to the preamp, then you need to reduce the sensitivity of the power amp. This can be accomplished with the external in/out jacks and in-line attenuators Part Express's line of in-line attenuators
Quote from: PhantmShado on 12 April, 2012, 03:40:13 AMThe noise at times bothers me more than other times just listening to the speakers, but if I plug in audio technica headphones (which I've found to be easy to drive) the hiss becomes unbearable.Bypassing the amplifier and plugging the headphone directly into the soundcard output socket mutes the hiss?
@OP: Are you sure this isn't tinnitus, i.e. "ringing" in your ears? Serious question, as I have very high-frequency tinnitus myself, and it occasionally changes into a sort of hissing sound. Your comment about the hiss becoming worse when you put on headphones (which will block out some degree of external sound, depending on the 'phones) - and also about being slightly louder in the right channel - brought this to mind.If you don't hear the hissing anywhere else, and it is especially noticeable through headphones, then it does indeed sound like the HK has a rather high noise floor *and* you're particularly sensitive to it.I had a Kenwood receiver back in the early 90's that I bought brand new (which likely had published noise specs similar to the HK), and even with the volume all the way down, I could easily hear hiss from the tweeters of my Boston Acoustics bookshelf speakers from about 18" away.My Marantz NR1601 receiver that I bought a couple years ago, OTOH, is essentially dead silent - even with the volume at a normal playback level (~-26 dB through speakers or -20 dB through headphones), there is no audible hiss whatsoever through headphones (also Audio-Technicas, FWIW), and I have to have my ear nearly on the faceplates of my Dynaudio Audience 52's tweeters to hear any hiss from them.
Ok, I pulled the jumpers connecting preamp and amp and on both my living room and desk unit as I was curious. The hiss situation remained unchanged on the living room amp. However, listening to the desk speakers, the hiss rose to a regular music volume on removal of the jumpers. It was also still just the right channel though while the left remained very quiet.
Quote from: PhantmShado on 12 April, 2012, 10:01:20 PMOk, I pulled the jumpers connecting preamp and amp and on both my living room and desk unit as I was curious. The hiss situation remained unchanged on the living room amp. However, listening to the desk speakers, the hiss rose to a regular music volume on removal of the jumpers. It was also still just the right channel though while the left remained very quiet.If I get this right, your receiver's background noise was unchanged but still objectionable after you pulled the input to its power amp, but the noise was only objectionable in the right channel?It's axiomatic that the channels of a stereo power amp should be audibly identical. What happens if you switch the channels in the speaker wiring?It is possible that the difference you hear is either due to the speaker or its acoustical environment.If I am understanding what you wrote, when you pulled the inputs to your desk speakers, their noise level increased greatly, but again the channels were different, and again only the right channel was objectionable or was most objectionable.What happens if you swap the locations of the speakers, L & R?Is there a possibiliity that the high frequency response of your L & R ears varies?
I have two HK 3490s. The one I use in the living room where I am far away enough from the speakers I don't detect the hiss mainly has noise on left channel. When I disconnected the jumpers that noise was unchanged. For the one on my desk where the speakers are close enough the hiss bothers me, the noise is mainly on the right channel. Upon removal of the jumpers that right channel noise got much louder, while left remained nearly silent.