If the noise is only audible with your ear very close to the tweeter, it is probably no big deal. If it is audible from the seated position, it is something to investigate, but probably not any reason to panic.
However, if only ONE speaker is making the noise, that is a bit unusual. Note: it is definitely not the speakers' "fault" because they will only produce any noise that is already being sent to them from something else.
My guess would be a slightly noisey tube somewhere in the system, perhaps if your amp has tubes in it. It may go away as the tubes "break in", OR, it may get worse. These changes will point to a tube for sure.
Overall, if the noise is not audible during music playback, don't get depressed. Just enjoy your new system for a week or two, and see what happens. If it is still there or getting worse, try switching the interconnects between left and right, at the AMP (turn it off first!) If the noise moves over to the other side, it's probably the preamp's fault. Otherwise, I would suspect the amp.
The amp is solid state, so if a tube's the problem, then the preamp's the culprit. The preamp is a preowned unit (in basically mint condition), so a bad tube wouldn't necessarily surprise me. Again, though, the hum is very slight, and it doesn't really bother me. Once music is playing, it goes away, with barely a hint left in silent portions of the music. I just thought it odd that I heard it on one side and not the other.
...it's quite unusual that just only one speaker produces hum.
Try to switch all of the sources off or switch between each other and hear if there will be the noise
If the noise is being produced from any of the source you can contact your dealer and explain the situation
Less likely it will be a "tube break-in" in your tuner nor break-in of your SCD-1
The hum could be 60Hz from the power line and it's audiable from base-midrange driver. The tweeter can produce a 60hz claps that sound like a motorcycle if you will put your ear firmly to the tweeter. In this situation only both speakers can be affected. So if you place an ear firmly to the other speaker's tweeter -- you'll know for sure.
Sometimes the digital source components have very high output signal that can overload the input of the preamp (escpcially tube) and cause an offset violation of the input circuit of it. In this case you should try to use tape input instead of dedicated CD.
Andrew- With mono amps, it is always a possibility that you have a slight ground loop problem, particularly if you already know that there is a grounding issue with the house. Also, other devices that are on that A/C circuit can easily manifest noise onto the line that feeds only that amp (assuming you're using different outlets/circuits to power the two mono amps). Lights, refrigerator, fans, TV, computer, etc... can all be culprits.
If you think it's the pre-amp, simply swap the output cables at the back. If the noise appears in the other channel, then it 'could be' simply a tube issue.
Try not to sweat the small stuff, and enjoy the music.
Just my .02
Start swithching things around, amps, interconnects, preamp channels, etc. You should be able to narrow it down to the culprit.
Also, having a dedicated line will definitely improve all aspects of your playback. I am bi-amped and have 2 30amp lines for my amps and one 20amp line for my front end. Having three dedicated lines would be wonderful, but you will notice a big difference with even one. .... But, it might not solve your problem.
Best of luck!
Unless it's an SFL-1 pre or other with one tube, switch the tubes and see if the noise follows to the other speaker. If so, you might want to replace the noisy (microphonic) one. It's also very possible that one channel noise is a dirty tube pin contact, removing and replacing the tube, carefully, will usually clean the contact. Use a soft cotton cloth to handle the tube. In any case, the first upgrade I have always done with tube components is the tubes themselves. If you have "modern" tubes you are in for a treat when you try NOS or lightly used 60's and 70's vintage RCA, Mullard, etc. See NOS threads here and at Audio Asylum. AA won't do 3 letter searches though so you need to input type: 12ax7, 12au7, 7316, whatever. Hope this helps, let us know.
Duh, just noticed it's an Sonic Frontiers pre. Cleaning the tube pins still might help.
Andrew, I would have to say it is likely a grounding problem. I was getting a hum from my amp, even though I installed a dedicated line. Turned out to be my front porch light was not grounded, changed the fixture, made sure it was grounded, problem solved. Good Luck.
I had a problem like this before. I had hum coming from one of my speakers. After hours of trying to figure out the problem I figured out that there was something wrong with one of my rca cables. I was using solid state gear. I hope this helps
You say that the hum is present with the pre in standby - this would tend to exonerate it, and everything before it. Try disconnecting the input leads to the power amp, then turn it on - if the noise is gone, it may have had something to do with the interconnects here. (Make sure the cables are not in close proximity to AC cords, then swap the leads right for left - if the noise moves with the cables, suspect a faulty wire/rca jack connection.) If the noise is still present, turn off the amp, reverse the speaker leads right for left at the amp, and power it up again - if the hum stays in the same speaker, you may have an AC cord too close to that cable. If the noise moves to the other channel, suspect the amplifier itself (possibly its input jacks). You could try using a substitute amp (borrow if necessary) to check this. (It is unlikely that a noise you describe as a "hum/buzz" could originate in the loudspeaker itself [driver, crossover], so its seeming presence at the tweeter only could point to the speaker cable in a biwire setup, but the super-steep crossover on this model could seem to produce the same effect when fed a noise signal above the crossover frequency.) And if all this sounds like too much hassle, well, this is what dealers are supposed to be for!
In my previous post, I realize, I may not have given enough consideration to the description "dual-mono" of the amplifier. I am not familiar with this model, but if it is truly thus - that is to say, all the way back to the wall with 2 power cords - then grounding issues could indeed be in play, even with the noise present in only one channel. Best of luck!
I had this identical problem with a counterpoint SA 1000 preamp and it turned out to be a bad tube.
Andrew, If your preamp is in standby then its not the preamp.
The focus should be the amplifier. You mentioned that your amplifier is dual mono.
It is possible that the slight hum you hear is due to the output transformer exhibiting vibrations from your AC source. That would explain the reason why you are only hearing it out of one channel and not the other. Its not a big deal at all from the way you described it, but if you feel like playing detective here is what you can do.
listen during different hours over the next week or so. See if the hum goes away during late hours. If it does then its the AC coming into the outlet. You can also try plugging into a line conditioner or a grounded outlet.
Either way I would not classify this as a problem.