Speakers humming.

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ste20man

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Hi all, this is my first post.

My soundcard has only one output, a singe 3.5mm jack. It's a generic audio card not one of the better ones. I.e. There is no L + R (RCA) out. Just the single 3.5mm jack.

I have a pair of KRK Rokit 5's that have RCA / TRS / XLR input options.

Currently I am using a 3.5mm cable that splits into two (L+R) RCA connectors.

The problem that I am having is that I am experiancing a hum through the speaks that I can't get rid of. I need to get rid of this and am looking for advice.

With a single 3.5mm jack, can I get a clean signal with this type of soundcard? From what I can tell might not 'output' a balanced signal(?), and so I would need to get a new one even before I get a new cable.

Will just getting a new balanced cable eliminate the hum from the speakers?

Is it even possible to get a 3.5mm jack to split TRS / XLR / Balanced lead?

Can anyone help me with this 'cos I don't know what I'm doing(a bit obvious :-) ).

Thanks for your time, Ste.
 
The source of your hum is probably an earth loop (or ground loop if you're on that side of the Atlantic). The earthing system on a lot of computers (particularly laptops) can cause this when you hook the output up to another piece of gear also connected to mains power (and earthed).

Buying an adaptor cable from 3.5mm jack to some form of balanced connector still won't give you a balanced output...jut the unbalanced rubbish the from the inbuilt in sound card connected to only one of the two pins on the TRS/XLR side.

Unfortunately, I can't give you a definite, single step fix.

The first thing to try is an external USB sound card. This will help your quality immensely anyway and it will USUALLY fix the hum...but not always. Step two if you still have a problem is isolating transformers, one per channel.

Bob
 
Work through it, try plugging a music player into your current setup - mp3 - 3.5 jack - phono - speakers. Does it still hum? then try using a different power outlet for the speakers still humming? try a different cable....

It is often a simple fix, but I have to say on board sound cards are not good. Save up and get an interface.
 
I have just tried my ipod and the sound is crystal clear. Had it next to the power supply and nothing seemed to interfere. Used same the 3.5mm to same RCA's in the back of the Rokit 5's and it was great sounding. Not sure what this means, maybe there is something wrong with the soundcard? Maybe its creating some interferance of some kind?

Seems strange that the Ipod works perfectly and the PC doesn't.
 
It's an earth loop--check the hum, you'll find it's at 60 Hz. If your PC is a laptop, unplug the power supply and run off batteries for a minute. You'll find the hum goes away when the laptop loses it's primary route to earth. With a built in sound card you still may get some electronic noise (because the inside of computers are noisy places) but the hum should go.

If so, my suggestions above will work.
 
In that case it sounds like an issue stemming from your laptop and sound card setup. What type of end does the power cord of your laptop have on it when you plug it into the wall? I was having trouble with noise from my laptop through my receiver and speaker system, and realized it was ground loop interference stemming from having the receiver and laptop on the same circuit. I used a ground lift adapter to take care of it. It eliminates the ground from your laptop power cord when you plug it into the wall, and only costs about 5 bucks for two adapters.

Be aware this is by no means a professional fix, and some consider it to be a little dangerous. (use wikipedia and search for 'ground lift')
Nonetheless, I would still eventually invest in a USB soundcard or interface. mAudio makes some inexpensive and pretty reliable ones.
 
Speakers are humming?
You've got to teach them the words! :D

I've only got the same that reverbdk has suggested in fact my Dell laptop is a three prong on the power supply and I have been running it for a long time with a ground lift plug to solve my humming/buzzing problem.
 
Cheap soundcards do this humm thing. The fix is to get a better sound card. The cabling doesn't help much either. Factor in that the inside of a computer is an electronically noisy environment, which also contributes to the problem.

I ran into the same issue when I plugged my computer into my 150W stereo with 4' Magnepans on it. Even with RCA to RCA cabling the noise as it was persisted. I got a better soundcard (Delta 44) and the noise all but went away. Although not technically, if I crank the volume while NOT outputting any content, and put my ear right up to the speaker, I can hear noise. Even with a good soundcard. But in terms of enjoyment, that's an acceptable noise level since I wont be cranked up and that close in a typical listening scenario.

Sure you could try really expensive cabling, run on batteries, and maybe some form of faraday cage to shield your soundcard from it's environment. And it MIGHT help, some. Or just get a better soundcard IMO.
 
You could cable it from a 3.5mm (line out) to TS (unbalanced) outputs. 3.5mm Y cable to RCA, probably an RCA to RCA cable for reach, and an RCA to TS adapter (large mono headphone jack looking thing 1/4"). But if you get a better soundcard, it will likely have TRS outputs (balanced). And you can run a TRS to TRS cable. (as designed).

Your typical 3.5mm wire is unbalanced. And is subject to cell phone handshakes and other interference. Which could be part of your noise problem if said cable runs across a CRT monitor, near an LED light bulb (that's on), wireless network card, or other influences. In our modern electronically noisy environments.
 
Thanks for all your advice, this is a great forum. :-)

I have a tower PC, not laptop, and am thinking of getting 2 ground lift plugs. If it has worked for you then I guess it should be more than alright for me until the time I invest in a USB interface. I live in the UK using 3 prong plugs.

Can I ask another question regarding the overall power supply?

I have in this room everything that needs mains power coming from one outlet. My PC, Printer, 360, TV and Speakers running from one socket. I have two extensions and probably about 10 plugs using that socket. Everything is working fine, just the speaker hum(teach them the words lol). There is no lack of power.

Will 2 ground lift plug fitted to the two speakers' plugs' still do the job in spite of this? I hope so because I can't move from this room as all others are in use and there are no other sockets for me to use.

If I get a M-Audio Fast Track Pro Sound card for example, would this cut out the noise that I'm expriancing? Are they conected to the PC by USB? Would there be any chance that I would still have interferance with the box itself? EM interferance maybe?

Do you think it's worth me going for the ground lift plug. I have read that these should only be used as a tempory basis.

Sorry for the extremely noob questions.
 
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It needs to be said that lifting the ground on any electrical device designed to use an external ground can be a very dangerous way of proceeding. The ground is there for a reason.
 
What Bobbsy said - even your puny 120v will hurt :) the earth is there for a reason, try another outlet ie if you run an extension cable from a separate ring (cooker socket) and plug the speakers into that. if it still hums its not a ground loop - unless the wiring in your house is bad.
You can get socket testers that will identify bad earth.
You could get a decent second hand USB interface and have much less hassle and better long term results.
 
Ok, I'm gonna get an seperate extention and run the speakers off that. See what happens. I'm thinkin about getting a USB interface. I have the money so I guess I'm gonna to research a bit and see what is out there. This would be the final piece of kit that I need for my home studio. Quite exited about getting one as I do want to record vocals and guitar as well as having a better and more quiet line to my speakers. Would like to say goodbye to the buzzing finally.

All top advice from everyone.
 
I think they make power strips that have some kind of method for cleaning up a power source. Of course this is probably half the price of the interface. I think it's your Pc you need to plug into a clean source, not the speakers. You should't have that problem when using an interface. But seriously plugging those monitors into a cheap sound card is just terrible!

My KRK's hum if I turn on the overhead room light that is on a dimmer. So I try not to do that :p
 
There's power conditioners and UPS's. And inverters to clean up the power supplied. I've got all devices that run on batteries at the point of capture, so I avoid a lot of these issues just with that. Plus no fan noise and such. Not without other issues though. Motor boating / phantom power / having to charge and swap batteries / additional weight of the gear that is just battery weight. But when you travel, you never know IF they'll be power on location, IF you'll have enough cords to reach it, or IF it's any good. Plus that whole middle of a corn field thing. My first tethered gig was in a bowling alley. And it didn't turn out well. Never mind that just plugging in an Iron blew the fuse, repeatedly. I got a field recorder shortly after that. Very shortly.

I think that you should just get a USB interface, or a soundcard with a breakout box. If that doesn't solve your issue, then start looking at other things. Just my opinion...

Definitely get some shielded cables and grounded power supply. Running plugs from other outlets in the same room probably wont help much IMO. They're probably all on the same fuse in the box and the same wire too. Flip that fuse in said box, and find the nearest outlet that's on a different fuse, and pull from that one to distribute the load. If you smell something burning, like the burning filter on a cigarette kind of smell, you've definitely got too many power hungry things on one plug. If the wire of the extension cord from the wall is hot to the touch or visibly melting, same thing. Add up the amps and watts. 1A = 120W or something like that. If you've got more than 1000W on that wire, danger Will Robinson.... Even more than 500W is pushing your luck IMO. Bear in mind that your desktop is probably 350W PSU (or higher). Slap on a 450W HDTV. And some 225W (each) studio monitors. And in this old trailer, Mmmm, something's burning.
 
Thanks for all your advice.

I still feel a bit over my head here but will do some reading to get some further info as well. Thanks again, really appreciate it, Ste. :0)
 
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