POLYMAN Posted June 17, 2006 Share Posted June 17, 2006 i recently bought myself a powered mixer and i noticed a loud hum when i plug my external laptop soundcard into it.i tried different leads,etc into it but the hum never went away.i never got a hum from my non-powered mixer.i just got a new soundcard which had balanced outputs and i thought that this may be the cure for the hum as my old soundcard had unbalanced outputs.i still had the same problem. what the fuck can i do to cure this bitch.i'm pretty new to doing live stuff with a computer and i have a few more gigs lined up i got to sort this stuff out quick.do i need a DI box?learning about this stuff is proving to be quite expensive. Link to comment Share on other sites More sharing options...
pylonbitch Posted June 17, 2006 Share Posted June 17, 2006 sounds like ground loop., what you need is a di with a ground lift circuit. 30 odd quids for a passive stereo box. problem solved. Link to comment Share on other sites More sharing options...
BCM Posted June 17, 2006 Share Posted June 17, 2006 I had this - is your laptop plugged into the mains when you put it into the mixer? Just try unplugging it and run on batteries.... Link to comment Share on other sites More sharing options...
POLYMAN Posted June 17, 2006 Author Share Posted June 17, 2006 BCM hats off to you man that running just off batteries did the job.though i would prefer being able to run off the mains.will what logan five said about the ground loop DI thing enable me to do that.it certainly seems like it must be a mains related problem. Link to comment Share on other sites More sharing options...
Guest DrHat Posted June 18, 2006 Share Posted June 18, 2006 why does my soundcard hum because it doesn't know the words *rimshot* Link to comment Share on other sites More sharing options...
Guest maoam Posted June 18, 2006 Share Posted June 18, 2006 i fixed this by wrapping some tape around the ground pin of my laptop psu so it wasnt getting connected. from a safety aspect i felt ok about it since my laptop case is plastic if a short does occur. to be safe plug it out as soon as your finished with it, or take the tape off. its a quick and dirty solution but it means you dont have to worry about batteries running out. needless to say dont do this if your laptop has a metal case. Link to comment Share on other sites More sharing options...
Guest DrHat Posted June 18, 2006 Share Posted June 18, 2006 i had a hound loop problem once - my dog wouldn't stop chasing her tail *rimshot II* Link to comment Share on other sites More sharing options...
pylonbitch Posted June 18, 2006 Share Posted June 18, 2006 BCM hats off to you man that running just off batteries did the job.though i would prefer being able to run off the mains.will what logan five said about the ground loop DI thing enable me to do that.it certainly seems like it must be a mains related problem. yes it should. i wouldn't advise running your lappy without the earth pin connected. Link to comment Share on other sites More sharing options...
Guest iep Posted June 18, 2006 Share Posted June 18, 2006 indeed, never have anything near you that has it's pin removed *rimshot III: return of the rimshot* Link to comment Share on other sites More sharing options...
foresense Posted June 18, 2006 Share Posted June 18, 2006 i'm having a similar problem on a smaller scale - the humming isn't very loud, so i don't mind that much. i've read that running all connected equipment from the same mains connector (with a splitter) would also do the trick, but i can't really hear a difference. Link to comment Share on other sites More sharing options...
foresense Posted June 18, 2006 Share Posted June 18, 2006 ooooh and i think my appartment isn't grounded.. i live on the second floor you see. *rimshot IV: rimshots gone wild* Link to comment Share on other sites More sharing options...
Fahz0r Posted June 18, 2006 Share Posted June 18, 2006 it's what soundcards do; make sound... Link to comment Share on other sites More sharing options...
Fahz0r Posted June 18, 2006 Share Posted June 18, 2006 btw, if you both have an internal and a PCI/External soundcard, turn off the internal, it'll shut up the humming (but i think everyone is smart enough to do so) Link to comment Share on other sites More sharing options...
Guest maoam Posted June 18, 2006 Share Posted June 18, 2006 lol yeah i'm still not 100% comfortable with removing the ground pin, we should really be considering something like this http://www.zzounds.com/item--EBTHE2PKG Link to comment Share on other sites More sharing options...
mcbpete Posted June 20, 2006 Share Posted June 20, 2006 Baaah, flipping buzzing noises. Here's a recording from my setup coming out from my Vinyl->Preamp (NOTE rename to .flac as I can't upload the file with the proper extension). I've tried unplugging my laptop (I use an external soundcard) and moving the record deck to another power socket but still with the buzzing. When the deck is turned off there's no buzz at all (with the preamp still on) and moving the record manually gives perfect unhumming output, although that's obviously not ideal as I don't have the skills to keep up an exact 33rpm turnage :grin: . There's a constant high buzz which is quieter in the mix, but a lower buzz sound which increases in amplitude as the tone arm reaches the middle of the deck. Anyone have any ideas, would picking up these ground loop isolators help ? Why does the low noise get louder as the tone arm reaches the middle ? Pete... Link to comment Share on other sites More sharing options...
pylonbitch Posted June 20, 2006 Share Posted June 20, 2006 sounds like there's something in the deck motor that's transmitting at vhf. what you need is shielded cables. interestingly, and slighltly o/t, there was a spate of people who got sky dishes fitted, who werte recieving a ghost image of their sky over channel 5 for a while.. this was because the frequencies sky was broadcast on, after being converted through the low noise block unit, were almost bang on channel 5, and disreputable engineers were fitting boxes with unshielded coax, so the cables were acting as trancievers... solution... shielded cable. pete, i don't think, from your description, that you're experiencing ground loop hum...i could be wrong... check the frequency of the hum... in the uk, ground loop hum is usually about 50Hz, but this isn't set in stone. Link to comment Share on other sites More sharing options...
mcbpete Posted June 20, 2006 Share Posted June 20, 2006 I've just checked the waveform out and it seems as if I'm getting a sine-esque buzz at 50Hz and multiples thereof (which slowly fade out as the frequencies increase) which seem most visibly (and thus audible) from 50 Hz -> 350 Hz, but looking at the spectral view the harmonics (I guess that's what you call them) you can see slight bands right up to around 1800Hz. The high pitched buzz sound appears to be around 15630 Hz. Stoopid record players with their electricities and everything. Link to comment Share on other sites More sharing options...
pylonbitch Posted June 20, 2006 Share Posted June 20, 2006 TRY A GROUNDLIFT CIRCUIT... YOU CAN GET A CHEAPASS ONE FROM MAPLIN THAT'S DESIGNED FOR CAR STEREOS, BUT IT DOES THE JOB... IF IT SOLVES THE PROBLEM, INVEST IN A HEAVY DUTY DI WITH A GROUNDLIFT. IF NOT, TRY SHIELDED CABLES. sorry for shouting. i sory. i mad mistak. Link to comment Share on other sites More sharing options...
mcbpete Posted June 20, 2006 Share Posted June 20, 2006 Ok, cheers for the help boss. Will give the ol' thing a try in the very neat future Link to comment Share on other sites More sharing options...
Guest Promo Posted June 20, 2006 Share Posted June 20, 2006 POLYMAN, does it make a nice tune? Or does it just go dum di dum dum dum? :laughing: Link to comment Share on other sites More sharing options...
mcbpete Posted February 28, 2008 Share Posted February 28, 2008 Bump: Well I got myself a spanking new turntable (Pro-ject debut iii), and a spanking new preamp (Cambridge 640p) but I've still got the stoopid 50Hz noise issue. I only hear it when the stylus is in contact with the record (i.e. when I'm using it !) but is silent otherwise so I doubt it's the preamp that's the issue (infact when the turntable is off the preamp output gives about -58db noise which is pretty nice). Also it doesn't matter if the laptop is powered by mains or battery either. But attached is both a .wav and spectral view of a recording when the needle is stuck in the final lock groove: As you can see, there's quite a bad bit of 'hum' noise at 100Hz but there are clear lines at all multiples of 50Hz. Would a ground loop isolator definitely solve this or are there more arcane things afoot ? Link to comment Share on other sites More sharing options...
Guest hahathhat Posted February 28, 2008 Share Posted February 28, 2008 run it through some reverb n delay and release it as ambient Link to comment Share on other sites More sharing options...
Guest greenbank Posted February 28, 2008 Share Posted February 28, 2008 hmm, i have a similar problem with my new setup - but its a faint buzzy (almost beelike) hum that doesn't sound like mains, only present when my external usb audio card is running into the mixer so it's something to do with that being present. theres also no noise from the soundcard + computer alone, only when it's going into the mixer does the noise start. signal chain is: computer (desktop, no way does it sound like a good idea to lift the ground on that, earthing is good!) -> usb cable -> edirol ua-25 -> decentish twin rca cable -> mackie mixer -> decent xlr cable -> pair of HR624s all run off one plug, i think thats supposed to help? any suggestions? i think it's something to do with the rca being non shielded then everything after that in the chain is shielded? Link to comment Share on other sites More sharing options...
mcbpete Posted March 3, 2008 Share Posted March 3, 2008 As you can see, there's quite a bad bit of 'hum' noise at 100Hz but there are clear lines at all multiples of 50Hz. Would a ground loop isolator definitely solve this or are there more arcane things afoot ? UPDATE: I'm pretty sure this aint a ground loop now. If I record the deck whilst it's in the lock groove and then remove the power to the turntable, the frequency of the buzz/hum slows from the 100hz down to 0hz over about 2-3 seconds, therefore I'm guessing its the motor vibration that's being picked up by the cartridge. Now how on frigging heck mc.shite do I solve this one out ? Link to comment Share on other sites More sharing options...
Guest Max Posted March 3, 2008 Share Posted March 3, 2008 i had the problem with an old soundcard (creative) too. the newer ones (digidesign, m-audio) did the job. i'm relating that to better cables and different connection types. that won't help you on the short way though and logans tip should be both, easiest and cheapest way to solve the problem and may prevent you from getting the problem on any device. once again, its always a pleasure to read loganfive. Link to comment Share on other sites More sharing options...
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