Getting rid of hiss/ hum

[nvisibl]

I've done the obvious of getting good quality audio cables, seperating them away from power cables. None of my synths etc.. have any noise coming from them though there is some hiss/hum from the mixer/ monitors and definately the sound card.

Tascam DM24 mixer
Roland DM5 Monitors
Edirol UA-25 Soundcard

Do I just need to put up with some hiss/ hum and perhaps EQ out of the mix as best I can?

[ten]

I had a few rumbles and hums so I replaced all my cables with balanced ones and it fixed the problem. Someone told me its best to find the cause and actually solve it but in my bedroom setup thats really not an option.....balanced cables did the trick and everything is working fine now.

ten

[jasedee]

Im guessing that it might be originating from your computer. Sometimes there is a bad grounding within.

From the computer, to your soundcard, through your mixer, then through your monitors.

Do some trouble shooting.

Unplug your soundcard from your mixer, see if the hum is still there.

go straight from your soundcard to your monitors, to check if it is the mixer....

Good luck!

:)

[AlexHall74]

Also, look into purchasing an EbTech Hum Eliminator, they cost $59 US.

It's a very simple box, 2 in/2 out (1/4", balanced or unbalanced).

http://www.sweetwater.com/images/items/Hum-large.jpg

I had hiss/hum (60 HZ groundloop I think) in my system (P4 2.4 GHZ, M-Audio 2496, Behringer UB 1204, Behringer 2031A Monitors) and thought it might have been the Behringer gear.

Then I purchased balanced cables to conncet the whole mess together and still had hum, so I think my problems was along the lines of what Jasedee just described.

Once I bought the EbTech, I connected two 1/4" patch cables (1 ft. cables used to connect guitar FX boxes) to my Control Room Outs (I don't use the main outs on my DAW mixer) and into the IN ports of the EbTech. Then I connected the OUT ports of my EbTech to my 1/4" TRS cables that go to my 2031As.

My signal chain is dead silent now and I can crank my system and hear no hum.

This device is about $200 cheaper than anything using Jensen transformers and works damn well.

Good luck!

-Alex

[nvisibl]

Thanks a lot for the ideas guys :idea:

[markdavidson]

Actually the issue is probably with impedance. Most synths output unbalanced signals. Most pro level audio interfaced have balanced inputs. Unbalanced lines top out at -10db and balanced lines top out at +4db. What you need is a line level shifter.

http://www.ebtechaudio.com/lls-2.jpg (http://www.ebtechaudio.com/lls-2des.html)

It is a passive device that removes the ground hum as well as adjusts the volume leve and matches your impedance to your interface. I got one of these and it solved most of my hiss/hum problems, except one and it was a cheapo synth that was noisy from the start. Unfortunately, the only thing it doesn't fix is a noisy synth.

[nvisibl]

Thanks Mark... the Hum eliminator from our resident Elvis above is a line level shifter too as far as I could make out from the text.

I'll look into these, cheers guys.

[nvisibl]

ps the majority (but not all) of the hiss/hum is coming from my soundcard.
Edirol UA25, External device.

Any further ideas how to quiten this thing?
Or
Do you think it would be worth my looking at a new soundcard?
Or
Are they all pretty much the same with regards to noise, my last Soundblaster Live was a loud bugger.

[nvisibl]

I find hiss/noise is created when I attach either the Ti or Triton to the PC via USB. So the main hissy pissy culprits are the soundcard, Ti and Triton (when USB'd).

Do you reckon the Line levellers will be able to strip the hiss that is caused by the above from their audio outputs?

Excuse my rattling on about this, just looking to make sure I hit the nail on the head and reduce the noise appropriately.

Cheers

[jasedee]

What about if you use a different USB cable, or a different USB port.

Troubleshooting....go through and rule out ALL possibilities

[grs]

I find hiss/noise is created when I attach either the Ti or Triton to the PC via USB. So the main hissy pissy culprits are the soundcard, Ti and Triton (when USB'd).

Do you reckon the Line levellers will be able to strip the hiss that is caused by the above from their audio outputs?

Excuse my rattling on about this, just looking to make sure I hit the nail on the head and reduce the noise appropriately.

Cheers

I'd use a second computer (not set up or anything) and substitute it and plug in the USBs and see if you get the same interference. Other wise, check to see if you can try a new power supply in the first computer. I had trouble once hard wiring an analog output of an RME device on a laptop to a mixer but when I used ADAT light pipe to an AD / DA the problem went. There was definitely no way that laptop was meant to be grounded into the audio chain.

[nvisibl]

Thanks very much for your feedback and ideas guys.

I've just stripped everything down and started bottom up.

The only thing that I haven't done is tried a different computer... the PC I have Dell Dimension 5000 is quite new and a decent model/ spec, though I know that doesn't bring any guarentees about anything. Thew thing I like about it most is its silent operation, you can hardly tell that its switched on.

Heres my findings with all gains mid way on the Tascam DM24 mixer, level sliders at maximum and main volume at maximum. Each unit was tested one at a time seperately whilst all other units totally disconnected.

Roland DS-5 Active Monitors

These hiss slightly anyway without any audio connection.

They produce sigificant hiss when balanced or unbalanced audio cables are connected directly from the mixer (Tascam DM24) main outputs. Theres no power cable cross overs or anything like that, cables are about 1 metre long and have their own space.

Edirol Sound card

Both balanced and unbalanced audio cables tested - drastic hiss.
USB'ed to PC - tried different USB slots, front, back and on additional USB PCI hub. No difference.

Supernova

Both balanced and unbalanced audio connections tested - slight hiss, not too much. Hard to notice through normal useage, though it would be great to have complete silence as all adds up in the final run.

Fantom XR

USB cable doesn't cause any hiss.
Both balanced and unbalanced audio cables tested - significant hiss.


Virus Polar

USB cable causes slight hiss, tried different cables and ports, no difference.
Both balanced and unbalanced audio connections tested - slight hiss.
Hard to notice through normal usage. Though again would be great to reduce to silence.

Korg Triton

USB cable causes significant hiss, tried different cables and ports. No difference.
Both balanced and unbalanced audio connections tested - significant hiss.

------------------------------------------------------------------------------
The audio cables used are of good quality. I cant remember the makes but I made sure at the time that I got the best that was going in relation to feedback received in the Sound on Sound forum. Costly buggers.

Theres not much scope for crosstalk in general as the cable runs have plenty of space away from power cables and i've also further sheilded them with plastic tube type corrugation.

Tascam DM24, solid and silent.


What do you see as my options being to reduce the hissy pissyness?

New PC? New USB cables? Are there any specific USB cable types that should be used? Which aspects of what I am dealing with here will the line levellers above help out with?

Thanks a lot, greatly appreciated :idea:

[grs]

If it is normal hiss, you just need to gate the tracks that arn't playing anything. I had to do that with the Virus b, the TI has way less hiss.

[Hollowcell]

Unfortunately there only way out is to spend a bit of cash. Although a certain level of noise is acceptable - noise to signal ratio.

But if there is too much noise at low levels then I'd be looking for other stuff first.

I'd check for a gain setting on the back of those monitors though. I'm not familiar with them at all, but there could be something. Getting noise with nothing conected isn't great at all. Even gains or room compensation switches shouldn't cause an audible hiss though (specially with nothing conected).

Sound card noise has many variables indeed. I had trouble with a network card once. And my SCSI card always causes noise when it's accessing the sampler. Power suplys, poorly placed cables ect...Pull the sucker appart and put it back together is an idea - vary the positions of cards.

I know you said the levels were mid-way on your mixer, but how about your preamps? If the onboard pre's are cranking then they could put out a bit of noise. Mmmm, but you did say the Tascam was quiet....

How is your grounding? Does your house have properly grounded outlets. Here in Japan I had to run a cable out the window to ground my gear.

Other than this (and everything else that has been brought up), I can't think of anything else.

Hope you get it sorted.

[nvisibl]

Thanks for your feedback guys.

For the kit items effected by the USB connection I think i'll just pull out the USB cables during recording. Good enough I suppose. :idea:

Changing the Gain on the monitors unfortunately makes no difference. :?

The Soundcard is the bugger. :evil:

I might try an outboard USB hub and see if that makes a difference for the soundcard. :?:

I've no idea about power grounding etc.. with my home, wouldn't know where to look or what to look out for. :?

more or less a brand new PC, perhaps I should have got one of those PC's specific for Music making :?:
http://www.carillondirect.com/clnweb/index.jsp?country=UK

How does one know when to use balanced or unbalance audio jacks :?:

[grs]

How does one know when to use balanced or unbalance audio jacks :?:

Read the manuals.

[nvisibl]

Ok, thanks dude :wink:

Does anyone know if the hum eliminators affect the quality of the sound signal in any way? i.e the sound that you want to keep.

I know that I am kicking the arse out of this here with silly noob like questionings. Please excuse me, and thanks again to you all for taking the time to respond.

[Hollowcell]

Where are you living? Most houses in most countries will have 3 prong power-outlets (here in Japan they don't :? ).

If the outlets have 3 prongs, then chances are the house is grounded (or you'd hope so anyway).

One tip to avoid ground loops (so I've read - I'm no expert), is to run your monitors and your mixer off the same out let. Because I had to make my own grounding setup, all my gear grounds off the same line.

Your soundcard is the biggest problem by the sounds though.

Not sure if eliminators will take something away from the signal - never used them myself.

[nvisibl]

One tip to avoid ground loops (so I've read - I'm no expert), is to run your monitors and your mixer off the same out let. Because I had to make my own grounding setup, all my gear grounds off the same line.

I'll give that one a try, thanks man.

[nvisibl]

How does one know when to use balanced or unbalance audio jacks :?:

Read the manuals.

Unless i've missed it somehow I cannot see any reference in the Ti manual defining wether the Audio connections are balanced or not.

Same with the manuals for:

Triton EX
Fantom XR
Supernova

Anyone? :? :oops:

[Timo]

[Ground Loops (http://www.soundonsound.com/sos/1994_articles/aug94/groundloops.html)]

[Computer/soundcard audio noise (http://www.soundonsound.com/sos/nov04/articles/computerproblems.htm)]

[nvisibl]

Thanks a lot Timo, really helpfull :idea:

[Wandering Kid]

but all the access virus models can only accept unbalanced connections?

using balanced connections shouldnt solve anything because you will get no benefits from them. For ten's problem i imagine his unbalanced cable runs were just absolutely horrific.

could it be the global input level on the synth? try it on the access virus by going into the CTRL menu and increasing the input global parameter to maximum. notice how everything becomes hissier and the LFOs actually emit an audible high pitched squeal around 8000 hz.

on my virus b i have never really been able to get rid of the hiss or the squeal completely, even with this parameter on 0, althoguh it is greatly reduced than when it was on 127.

[AlexHall74]

Good to see you WK; long time no see on the forum.

Cheers Bro! 8)

-Alex

[Khazul]

Does your mixer have a dedicated record bus, otherwise you will be getting summed hiss into the computer which is going to make life unpleasent.

The cables I use for connecting unbalanced outs to my mixer balanced ins seems to be very good at minimising hiss and hum.

Basically what I do is use a decent quality balanced mic cable, at the unbalanced (synth out) end, I connected cold and ground to R and hot to T, then normal TRS connection at the other end. With decent balanced inputs that can cope with asymnetric balanced signals, this yields the kind of noise immunity your get with balanced connections.

The other suggestiuon is about how you wiring you mains up.

Ensure that everything has roughly the same length path to ground (actually its the resistance to ground and therefore the voltage drop on the ground that matters). Dont connect some gear to a distribution block, which also has another distribution block pwering on gera in it. INstead use a star arrangement so all the lengths to ground are roughly the same.

Also use much thicker cable then the current of your gear would demand - this is just to ensure you have a good thick connection to ground.


If all else fails - try searching "ground loop", "mains hum" and othger suitable phrases - there loads of articale on the net about studio wiring to minimise the kind of problem you are experiencing.

If you in the USA, then you might need to provide a common ground point. 2 pin mains over there is a complete nightmare for audio installations.

[nvisibl]

Thanks for your feedback folks.
Ended up it was a groundloop issue.

What a pain in the arse it was to troubleshoot.. I got there in the end though.

:idea: