High pitch noise in reference monitor

[hardminder]

Hi, here's my problem. I am hearing a really high pitch (15-16 kHz or so, yeah the kind that old folks couldn't hear) hiss in my monitors. It is pretty subtle but at that frequency, it's really irritating. It seem to be louder in the left channel but that could be my hearing as well. I ran a few tests and made some observation that could easily lead to a conclusion but I'm not really sure what's going on. Here is what I observed and tested:

- The volume of the noise doesn't change if i change play with the volume and it's still present when the volume is off.

- The noise disappear if I use a Mic cable (weird right?).

-I bought brand new unbalanced speaker cables, same thing.

-I'm not hearing the hiss with my headphones plugged into the same sound interface.

-I don't know if it can be the issue, I'm thinking it might. I have a lot of gear plugged in the same power outlet (I just can't hardly do it differently). In the same power outlet I have : the 2 speakers, my focusrite interface, 3 computer monitors, 2 computers (rarely running together), my keyboard, a lamp, an external USB drive and that's about it. I'm surprised I didn't even blew a fuse yet honestly...

So here are my questions:

-I really don't want to use mic or instrument cables right?
-If you guys think it's the power outlet thing, what piece of equipment should I plug where if I somehow find a way to access a second outlet.
-Is it something else?

Thanks a lot for your time and knowledge!

[Mike Stranks]

What are the speakers and what is your interface?

If you can you need to be using balanced cables between your interface and your speakers - cables with connectors like this:



or this

[hardminder]

What are the speakers and what is your interface?

Yeah sorry I forgot to mention

Speakers: Mackie HR824
Interface: Focusrite Scarlett 18i6

and I'm using 1/4 jack cables

If you can you need to be using balanced cables between your interface and your speakers

Why are you suggesting I might need using balanced? Is it because of the same outlet/ possible interference thing? And what do you mean ''like this''. Any XLR or Stereo 1/4 cables or is there a specific detail I'm missing in this pictures?

Thanks a lot !

[Eddy Deegan]

If you can you need to be using balanced cables between your interface and your speakers

Why are you suggesting I might need using balanced? Is it because of the same outlet/ possible interference thing? And what do you mean ''like this''. Any XLR or Stereo 1/4 cables or is there a specific detail I'm missing in this pictures?

Balanced cables are far less susceptible to noise and interference from the surrounding environment. The images are all of balanced cables. Some people see a balanced jack and think 'stereo' but that makes no sense in this context; it's balanced!

If you're not using balanced cables, try them. If you are, and you confirm as much, it means that the lack of balanced cables can be ruled out as one very possible cause of the problem.

(15-16 kHz or so, yeah the kind that old folks couldn't hear)

I can't and although I can be grumpy, pine for 'the good old days' on occasion and have a bit of strategic grey here and there I'm not exactly old

[Mike Stranks]

Those were just the first pics I found... you can use any XLR cable and any TRS-TRS cable, but remembering cheap is not always cheerful!

Just looked at pics of your gear... seems like the TRS-TRS option is the one to go for.

[James Perrett]

15-16 kHz or so, yeah the kind that old folks couldn't hear

Nor could many recording engineers in the 80's judging by the number of releases that featured a 15kHz accompaniment to the music from video monitors in the studio.

[Sam Spoons]

Just to add (and assuming you are in the UK) your whole rig, with everything running probably draws less than about 4A* so you are unlikely to be getting close to fuse blowing time. Running everything off a single socket is usually the best way to minimise the likelihood of earth loops causing noize.

* that would be equivalent to around 8A in the US, FWIW my 6kW PA system draws only about 6A in 'real world' usage.

[hardminder]

Balanced cables are far less susceptible to noise and interference from the surrounding environment. The images are all of balanced cables. Some people see a balanced jack and think 'stereo' but that makes no sense in this context; it's balanced!

Yeah, I don't know why I said stereo, I just meant to say 1/4 cables. But still, I didn't know you could use balanced cables for monitors. So I guess, in my situation, balanced cables should be used for everything (bass, guitar and mics included) except maybe for line inputs that requires short cables ?

(15-16 kHz or so, yeah the kind that old folks couldn't hear)

I can't and although I can be grumpy, pine for 'the good old days' on occasion and have a bit of strategic grey here and there I'm not exactly old

Haha , I didn't say you're old if you can't ear it, I said if you're old you can't ear it. Two different things. If you don't have any legs, you can't walk but you might be unable to walk even if you have your two legs...

Thanks a lot for your advise!

[hardminder]

Just to add (and assuming you are in the UK) your whole rig, with everything running probably draws less than about 4A* so you are unlikely to be getting close to fuse blowing time. Running everything off a single socket is usually the best way to minimise the likelihood of earth loops causing noize.

* that would be equivalent to around 8A in the US, FWIW my 6kW PA system draws only about 6A in 'real world' usage.

Thanks for that. I'm not in the UK though, I'm in Canada. The fuses are either 15, 20 or 30 (not sure on which my gear is, the fuses identification is all messed up). But still, if it's 8A as you're suggesting I'm not blowing it but might be closer than you sated (if I'm on the 15A fuse). Thanks, good to know!

[Sam Spoons]

In real life I doubt your gear is drawing anywhere near 8A TBH. 15A should be plenty.

WRT cables, you need balanced cables (TRS or XLR) between your interface and Mackie monitors and for any mics. You will need TS (i.e. normal guitar cables) between guitars and the interface and probably also between the keyboards and interface. TRS cables may work with guitars but won't give any benefit (and will often simply not work at all). Some keyboards have balanced outputs but most do not, if yours does then balanced TRS cables are worth using, if not there will be no benefit and, as with guitars, they may not work at all.

[Martin Walker]

Some keyboards have balanced outputs but most do not, if yours does then balanced TRS cables are worth using, if not there will be no benefit and, as with guitars, they may not work at all.

However, if you're routing unbalanced keyboards into a mixer or audio interface that has balanced inputs, it's also possible to make up a special pseudo-balanced cable that may result in lower background noise if it breaks a ground loop.

SOS did at one time offer their own specially made leads through their on-line shop, although sadly they can no longer get them made: https://www.soundonsound.com/help/sos-special-cables

So, most people have to solder up their own - here's a handy diagram that encapsulates what you need to do:

pseudo-balanced cable image.jpg (23.96 KiB) Viewed 1289 times

I've made up quite a few over the years for my own small studio, where they are perfect for connecting mains-powered (and earthed) keyboards/synths to already earthed mixers/interfaces.

Martin

[Bella Roma]

FWIW I've had 2 separate experiences with high pitched buzz out of my monitors. In the 1st case it turned out to be a blown cap. Since you're hearing it in both monitors, it's probably not bad caps in both. In the 2nd more recent case, I plugged into a different power strip. Originally they were on the same strip as my PC. I then plugged them into a different strip and voila, the noise disappeared. Both strips are using the same outlet in my case, but just switching from the PCs power strip to the other worked. May not solve your issue but possibly worth looking into if you haven't already.

[Drew Stephenson]

WRT cables, you need balanced cables (TRS or XLR) between your interface and Mackie monitors and for any mics. You will need TS (i.e. normal guitar cables) between guitars and the interface and probably also between the keyboards and interface. TRS cables may work with guitars but won't give any benefit (and will often simply not work at all). Some keyboards have balanced outputs but most do not, if yours does then balanced TRS cables are worth using, if not there will be no benefit and, as with guitars, they may not work at all.

To paraphrase
"You should always use balanced cables where you can, but you can use unbalanced cables if you must. But you should always use unbalanced cables where you should, but if you must use balanced cables this may cause some problems, but it may not, in which case use common sense, but not as a replacement for cables. This shouldn't cause any problems but it might, in which case you mustn't and should use what you must use, but not what you must only if you can't. That's a another fine must you've got us into."

[Hugh Robjohns]

Is that from Boris?

[Hugh Robjohns]

There's been a lot of discussion, but you cracked it right at the beginning, even if you didn't know why.

The noise disappear if I use a Mic cable (weird right?).

Not weird at all. The noises were due to ground currents, which are very normal. And when using unbalanced cables, those ground currents flow along the wanted signal's ground reference, and thus get added into the audio signal to become audible.

By using balanced cables, no part of the audio signal travels in the ground anymore, and thus no added noise signals.

You may often use an XLR-XLR cable with a microphone, but it is just a screened, balanced cable that can be used with mic or line-level sources -- but the critical part was that it is a balanced cable. As others have said,m you can get balanced cables with male and female XLRs at each end, or one or both ends could be replaced with TRS ('stereo') jack plugs -- and various other three-contact plugs are also used in different applications. Any of these would work: you just need the right connectors for you equipment.

-I bought brand new unbalanced speaker cables, same thing.

Because they were unbalanced, meaning only two connectors, one being a ground reference which picks up the ground currents.

-I'm not hearing the hiss with my headphones plugged into the same sound interface.

Because the interference isn't coming from the computer via the USB, but is instead getting directly into the speakers via the audio ground connection.

I have a lot of gear plugged in the same power outlet...

This is a good thing, as it minimises the voltage differences of the mains safety ground terminal in the various equipment, and thus minimises the noisy currents flowing around the mains grounds. Always plug gear into the same outlet, or a plugboard ...

-I really don't want to use mic or instrument cables right?

balanced cables (mic, balanced line) yes. Unbalanced cables (instrument leads) no!

H