The power supply source is humming--buzzing? what does that mean?

possibly the microphone needs more power than your sound card can supply although I cannot imagine as the duet is a good piece of equipment.
Is the duet USB bus powered?
Have you tried another cable? Possibly one wire is defective which means that phantom power will superpose the audio signal. In this case you might hear a hum. By the way this results in 6dB of signal loss. This is why XLR plugs have 3 wires. If connected with a 1/4" jack it has to be a stereo plug (tip, ring, sleeve)

Background 50 or 60 Hz buzz can be radiated from nearby wiring or conducted. Grounding is important but that can also be a cause. I suggest you search accidental hum loops.

Poor or faulty power supply regulation or smoothing can inject a mains hum into audio. This would need checking with an oscilloscope which could also be used perhaps to help search for the source.
Radiated hum can be picked up and injected into high gain amplifier inputs and long leads, poor screening and impedance mismatch can make things much worse.

I haven't helped much but I hope I have given you food for thought and further research.

Have you looked at the manuals?

http://www.retrevo.com/search?q=sony+nx810

A TV won't run external speakers directly. Besides, the TV-related audio should originate at, say, the cable Box, and go straight to your (presumed) AV receiver for the best possible decoding and reproduction.


Buzzing is an analog phenomenon and is NOT carried by optical cable in any case.

Buzzing is usally AC line noise leaking into an un-shielded cable somewhere or a floating ground. If the AC plug is reversible, try that. Sometimes the buzz is from an attached device. Make sure all audio cables are plugged in tightly at each end and routed away from or at right angles to any power cords and away from other sources of strong magnetic fields like TV's. I've also seen variable track lights induce noise but it's usually minor.

Try rotating the power cord in the wall outlet.

If it still buzzes with no cables or anything external attached there's an internal problem.

Disconnect the input(s) and see if it hums in the absence of an audio source. A bad audio cable shield or unwisely-routed audio cables will allow entrance of unwanted signals from external power sources, magnetic fields, even dimmer-controlled track lights. Sometimes, simply reversing the orientation of the ac power plug can eliminate humming.

Reverse the cables Left to Right to see if it stays with the cable or the input channel. Follow it back to the source, isolating in the same manner. Eventually you will find the entrance point of the hum. Frequently a cable's ground will oxidize over time and simply removing and reattaching the cable with a twisting motion will re-establish the shield.

Buzzing is usally AC line noise leaking into an un-shielded cable somewhere or a floating ground. If the AC plug is reversible, try that. Sometimes the buzz is from an attached device. Make sure all audio cables are plugged in tightly at each end and routed away from or at right angles to any power cords and away from other sources of strong magnetic fields like TV's.

Disconnect the input(s) and see if it hums in the absence of an audio source. A bad audio cable shield or unwisely-routed audio cables will allow entrance of unwanted signals from external power sources, magnetic fields, even dimmer-controlled track lights.
I've also seen variable track lights induce noise but it's usually minor.

Try rotating the power cord in the wall outlet.

If it still buzzes with no cables or anything external attached there's an internal problem.

When the speaker is connected only at the power line does it makes this noise?

• If it does it's an internal amplifier's ploblem and you have to check out some fittings (electrolytic capacitorsat the power supply, power supply transformer, voltage stabilizers e.t.c.)
• If the speaker is quiet you have to check your external wiring because there is a loop ground. That means that one "ground level" line is connected at the ground by two or more cables (e.g. the audio ground and the grond from the mains power source) In this case disconnect the second (and the 3rd e.t.c.) grounding point.

In case of a problem or clarification, don't hesitate to post me a reply.
If you are satisfied, rate my solution with the "thumbs".

Thanks and regards
Please kindly rate this solution
Stelios
direct FixYa link: http://www.fixya.com/users/technical114

If I understand this correctly: with NO input or cable attached it hums; with an RCA cable attached it works. (What does 'some' mean in this regard?)

You say that connecting the RCA cable improves its sound. That tells me you're supplying a ground through the RCA cable for stray voltage in the sub.

It seems there may be a basic power issue if it hums with no input. Sometimes a given power source in a home may be wired differently than others or may insufficient grounding, which can result in hum. Try reversing the sub's power plug or move it somewhere else.

Since the sub contains its own electronics it is also susceptible to strong external magnetic fields. Keep it and any signal cables leading to it some distance away from other electrical devices like TV's.

Iassume you mean you hear the buzz independently of the audio program - simply connecting the cable causes the buzz?

If tanything in the mix is powered from different AC sources you may have a different ground potential. Sometimes manipulating the orientation of one or more ac plugs will solve hum problems.

The 2200 uF capacitor in the power supply has gone bad and the humming is a 60 Hz from the rectification of AC to 18 vDC.  Either get a new power supply or take apart the power supply and replace the bad cap.

Best way is with balanced audio lines. Use either XLR or TRS cables IF your devices have those connections.

Also, do NOT use light dimmers as these are often a source of the higher frequencies that cause buzz.

Also power ALL the interconnected audio devices from a single source outlet rrather than from mulltiple building receptacles.

Hi chupetin2

If the problem is present with ONLY the speakers connected, that is no other powered devices like subs, or input/output cables, it will be a power supply problem inside the amp. If you have electronic fault finding skills, there will probably be a capacitor in a regulated rail that has failed.
If you do have a sub connected, be sure it is powered from the same mains source as the amp, or at least a GPO that is on the same phase. Different phases will induce mains hum, as will multiple earths. Try also temporarily moving the amp(whilst monitoring the hum) from where it is sitting and see if the hum is being induced into the amp by any other devices

Happy to talk to you more about this. Just ask:)

regards
robotek