Tips for removing induced noise

[PassionForSound]

Hi all,

My office is a very noisy place it seems. Can anyone provide me with some tips to remove induced noise?

With interconnects attached and the volume around 50%, there is definite hum from the system. It doesn't happen if I take the setup elsewhere in the house.

Are there any ways to prevent the interconnects from picking up this noise? I am using high quality interconnects and have tried a few different ones.

 

[4krow]

Makes me wonder if your office has an electrical problem concerning grounding. Another thought would about any copiers/computers, etc. that may be introducing noise. Lastly, cable management can have an effect on this sort of problem. What kind of power filtration do you use?

 

[earwaxxer]

I agree with Greg - ck for the dastardly SMPS's.

 

[grufti]

Are you following the forum usage of "hum" vs. "noise" vs whatever? In other words are you hearing something like 120Hz? If that is the case then my first guess would be something related to grounding. What is your source in the office vs. your source elsewhere in the house?

Have you tried shorting plugs on the input? There is a sticky on shorting plugs somewhere on the forum. You can exclude the interconnects, if the noise is still there with shorting plugs in place.

 

[PassionForSound]

I've done lot's of testing and trouble-shooting to confirm that the issue is noise induced into the interconnects (I nearly took back my DAC because I was blaming it at first!)

Everything remains identical if I setup outside my office. My laptop is the source (via USB) and I'm not using any power filtration wherever I go.

Power supply is a major issue in my office because I have to run an extension across the length of the office in order to have power at my desk. This means power boards for my DAC, Crack, laptop, a pair of active speakers, printer, and monitor.

Have tried unplugging individual devices to see if one of them is the culprit, but no luck. It might be the power board setup or the extension lead I guess.

What is SMPS? And any further suggestions coming from this information about my less-than-ideal power setup? Do you think I should move my desk closer to the power to remove the extension lead?

 

[Paul Birkeland]

Listening to your DAC powered through USB by your laptop with the charger not plugged in should yield the most likely chance of hot having noise.

What are the interconnects in question?

 

[PassionForSound]

Thanks CB, I'll double-check to be 100% sure, but don't think the charger is involved as there is no problem using this exact setup in other rooms even with the charger plugged in.

My interconnects are a range of different high quality options including Tara Labs, Neotech and Stinger. There is no discernible difference to the level of induced noise with any of them. There is also no discernible change if I move the interconnects around while connected (i.e. it doesn't seem to be that they are touching or close to a cable which is creating the noise)

 

[earwaxxer]

A 'SMPS' is a switched mode power supply. What one would usually associate as a 'wall wart'. They could be much larger boxes, often hooked up to laser printers etc. They are very high frequency oscillation devices that emit noise that can be picked up by sensitive electronics. They can also feedback noise into the A/C line.

 

[PassionForSound]

I have a number of SMPSs in my office. I think I tried unplugging them all with no change to the noise though. I'll go back and double-check.

I'm getting the impression that there's not much I can do other than fiddle with power cords, etc. Are there any techniques or devices to better shield interconnects or filter the power in a room?

 

[grufti]

I still don't buy the "noise induced into the interconnects" thing. Even with unbalanced connections "inducing noise" into the interconnects is not easy to do. Connecting a resistor across the inputs with a shorting plug would answer the interconnects question once and for all.

Since you have already done a lot of trouble shooting this one might be one of the easier exercises: take your office power cord setup into a "safe" part of your house and connect just your DAC, Crack and laptop with and without its power supply: hum or no hum? If no hum, then take that exact same setup back to your office and plug in: hum or no hum?

 

[VoltSecond]

I've done lot's of testing and trouble-shooting to confirm that the issue is noise induced into the interconnects (I nearly took back my DAC because I was blaming it at first!)

Everything remains identical if I setup outside my office. My laptop is the source (via USB) and I'm not using any power filtration wherever I go.

Power supply is a major issue in my office because I have to run an extension across the length of the office in order to have power at my desk. This means power boards for my DAC, Crack, laptop, a pair of active speakers, printer, and monitor.

Have tried unplugging individual devices to see if one of them is the culprit, but no luck. It might be the power board setup or the extension lead I guess.

What is SMPS? And any further suggestions coming from this information about my less-than-ideal power setup? Do you think I should move my desk closer to the power to remove the extension lead?

I hate chasing noise. It becomes frustrating fast.
* So the noise is the same inside and outside the office.
* Are there CFCLs or other fluorescent lights nearby? ( Yep, been burned by that.)
* Is the monitor the same as in the other room? ( Monitors can be quite noisy.)
* If the laptop is powering the DAC off of internal power does the buzz go away? With nothing plugged into the wall at all, you can partially eliminate the location.

 

[PassionForSound]

Recap:

1.) Noise only inside the office
2.) Identical setup (except for extension lead and exact power wall socket) elsewhere has no problems
3.) Noise not affected by unplugging any other devices incl. monitor, laptop charger, active speakers, etc. I.e. Even if the DAC and Crack are the only devices plugged in, the issue remains

I'm thinking this must be an issue from the extension lead. Perhaps it's time to remodel my office in the name of sound!

 

[Paul Birkeland]

I still don't buy the "noise induced into the interconnects" thing. Even with unbalanced connections "inducing noise" into the interconnects is not easy to do.

This is actually pretty easy, it's one of the experiments we did when evaluating the Bottlehead interconnect.

Just press your interconnect up against a power transformer and orient it until you get maximum hum, then you can compare different interconnects by positioning the cables the same way.

 

[grufti]

We just differ on what we consider "not easy to do". I consider pressing the interconnect against a power transformer something that is not terribly common or easy to do.

I still don't buy the "noise induced into the interconnects" thing. Even with unbalanced connections "inducing noise" into the interconnects is not easy to do.

Just press your interconnect up against a power transformer and orient it until you get maximum hum, ...

 

[grufti]

I was trying to get to that aspect of your configuration.

1.) Reduce the variables. You have made a lot of progress doing that.
2.) Experiment with the remaining candidates. For example: use another extension cord that you plug into a "safe" outlet outside your office and plug your humming office setup into that extension cord. Hum or no hum? You have eliminated earth ground problems with your office outlet.
3.) Use another extension cord in your office. A typical contractor type grounded extension cord from the nearest Home Depot/Lowe's/... or your garage is fine. Plug in DAC, Crack, laptop. Hum or no hum?

Recap:

1.) Noise only inside the office
2.) Identical setup (except for extension lead and exact power wall socket) elsewhere has no problems
3.) Noise not affected by unplugging any other devices incl. monitor, laptop charger, active speakers, etc. I.e. Even if the DAC and Crack are the only devices plugged in, the issue remains

I'm thinking this must be an issue from the extension lead. Perhaps it's time to remodel my office in the name of sound!

 

[PassionForSound]

Great suggestion re running a cord from elsewhere, grufti. I'll give it a go and report back.

 

[jrebman]

Just curious if you have an outlet tester?  If so, does the office outlet look to be wired to code?

Also, if you do find the interconnects to be the problem, you may want to try the BH interconnects as they are fully shielded from end to end.

And how close to the amp does the video cable from the laptop to the monitor run?

Definitely try a long extension cord to an outlet outside the room and if the hum disappears, do check that the outlet in the office is wired correctly.  You wouldn't belive how common this is even in a house where one guy did all the wiring.

-- Jim

 

[4krow]

I second the wiring reversal thing. I will have to admit making some stoopid mistakes with wiring, all by myself.

 

[PassionForSound]

Hi all,

I've been gone a while and completely re-arranged my office in that time which worked a treat... at first.

After being able to use my Crack perfectly last week, I made 2 small changes this morning and when I powered up there is worse 50Hz noise than ever.

What I changed: placed Playstation 3 on shelf next to DAC and Crack. Moved HD650s and headphone stand to shelf below the Crack. (Connections to PS3 are optical (to DAC), power and HDMI)

When I noticed the noise had returned, I unplugged the PS3 (power only) to see if this was the cause, but the noise remained.

How could this occur?

 

[PassionForSound]

Sorry about the immediate addition, but thought to roll the tube to see if this had any effect. It seems my beloved Mullard 6080WA was the cause.

Will it rectify itself or does this mean dead tube?