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stopping guitar hum for recording

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stopping guitar hum for recording

Postby rec-tec » Fri Jun 13, 2014 6:18 am

hi all

whenever i try to recording electric guitar i notice when i solo the guitar track there is always a little hum which ranges from alot (unusable) to just a little (annoying)

is there a gizmo that i can plug the guitar into that sits in between the guitar and the recording device - would a DI box help - or is it just something inherent in guitar circuits?

help/advice (as always) appreciated

cheers

RT
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Re: stopping guitar hum for recording

Postby Hugh Robjohns » Fri Jun 13, 2014 9:10 am

This is usually caused by the natural sensitivity of single-coil guitar pickups to ambient electro-magnetic fields.

You'll probably find that if you orientate the guitar in different directions you'll get different levels of hum. You might also find that if you turn some things off in the room you'll reduce the levels of hum.

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Re: stopping guitar hum for recording

Postby rec-tec » Fri Jun 13, 2014 10:48 am

thanks for that hugh

i did notice one time - if i put my bare foot on the jack that stuck out of the fx unit i was using that the hum significantly reduced (groundloop? - not really sure what that is, but...)

i will try your suggestion

cheers

RT
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Re: stopping guitar hum for recording

Postby ef37a » Fri Jun 13, 2014 12:57 pm

rec-tec wrote:thanks for that hugh

i did notice one time - if i put my bare foot on the jack that stuck out of the fx unit i was using that the hum significantly reduced (groundloop? - not really sure what that is, but...)

i will try your suggestion

cheers

RT
AARRRRGH!!!! That sounds as though you have no earth on the system (you cannot, by definition have an earth "loop" with just a guitar and an interface unless said interface is separately powered perhaps.)

What country are you in RT? If UK get an electrician in to check the mains wiring. In the meantime, do not "experimentally" touch bare metal objects! Actually peeps,NEVER do that!

On the wider point of guitar hum. Been a while since I tried it but if you set a Strat for -20dBFS on a modest strum, you will be lucky to get the noise below -70dBFS. But I shall have another look.

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Re: stopping guitar hum for recording

Postby Jack Ruston » Fri Jun 13, 2014 1:26 pm

Yeah just turn yourself and the guitar, and keep turning until you find a quiet (er) angle. DON'T do that thing with putting your bare foot on some metalwork to get rid of the noise. That's how people get fried!

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Re: stopping guitar hum for recording

Postby ef37a » Fri Jun 13, 2014 1:30 pm

Jack Ruston wrote:Yeah just turn yourself and the guitar, and keep turning until you find a quiet (er) angle. DON'T do that thing with putting your bare foot on some metalwork to get rid of the noise. That's how people get fried!

J

Yeah! The BEST one is when they say "If I hold THIS and then touch THA........!"

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Re: stopping guitar hum for recording

Postby Hugh Robjohns » Fri Jun 13, 2014 2:51 pm

rec-tec wrote:if i put my bare foot on the jack that stuck out of the fx unit i was using that the hum significantly reduced

It would help to know what your entire recording system comprises.

The grounding with the foot thing suggests to me that your recording system has no ground reference. This is common when using battery-operated units and standalone recorders.

If all your mains-powered equipment is 'double insulated' (it will have a box-within-a-box symbol on the power unit) or battery-powered, it has no connection to the mains safety earth. In that situation everything 'floats' and the cable screens essentially act as aerials to pickup any stray interference going.

The solution in such cases is to engineer a deliberate ground connection to the mains safety earth from the sleeve of one of the signal jack connections. If this sounds like the case for you, let me know and I'll explain how to achieve this safely.

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Re: stopping guitar hum for recording

Postby rec-tec » Fri Jun 13, 2014 3:35 pm

thanks hugh

my guitar goes into a (jack) strymon timeline (mains powered) then into a (jack) us144 (usb powered) or motu 828mk3 (mains)then (usb) computer - etc

cheers

RT
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Re: stopping guitar hum for recording

Postby Hugh Robjohns » Fri Jun 13, 2014 3:50 pm

If the computer is a desktop model it will be class 1 with a mains earth connection, and the whiole system should be grounded through that. But if it's a laptop it's probably class II (double insulated) and so the whole system will be earthless -- which is what it sounds like you have.

You can get a safe grounding plug here:

http://www.groundology.co.uk/earthing/earth-connection-plug-uk

You'll then need to make up a lead -- single wire -- with a 4mm plug to go into the mains adapter plug, and wired to the sleeve of a suitable plug to connect with an unused audio socket on your interface.

You could use an ordinary mains plug, but you should take GREAT care to insulate the live and neutral pins inside the plug, just in case the earth wire comes loose and starts floating about in there!

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Re: stopping guitar hum for recording

Postby rec-tec » Fri Jun 13, 2014 4:18 pm

hi hugh

yes - it is a laptop - so i think you are correct

i am hopeful that this will fix it and am most grateful for your advice (as ever)

i always get great advice on this site

cheers - hugh

RT
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Re: stopping guitar hum for recording

Postby rec-tec » Fri Jun 13, 2014 4:28 pm

just purchased the plug thingy

so will report back with feedback (and hopefully no hum!)

cheers

RT
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Re: stopping guitar hum for recording

Postby 10K-DB Music » Sun Jun 22, 2014 11:23 am

I always use a "Noise gate",,,for live or studio. Makes things much less complicated.
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Re: stopping guitar hum for recording

Postby The Elf » Sun Jun 22, 2014 12:06 pm

10K-DB Music wrote: I always use a "Noise gate",,,for live or studio. Makes things much less complicated.
Live, yes. Studio, never.

A gate can ruin an otherwise perfect take. If you need a gate to record then there's something wrong higher in the signal chain, whch should really be fixed it properly at source. If you do still need to gate, then do it AFTER recording, not as you record.
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Re: stopping guitar hum for recording

Postby 10K-DB Music » Sun Jun 22, 2014 12:22 pm

The Elf wrote:
10K-DB Music wrote: I always use a "Noise gate",,,for live or studio. Makes things much less complicated.
Live, yes. Studio, never.

A gate can ruin an otherwise perfect take. If you need a gate to record then there's something wrong higher in the signal chain, whch should really be fixed it properly at source. If you do still need to gate, then do it AFTER recording, not as you record.
Ok,,point taken. Thanks
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Re: stopping guitar hum for recording

Postby 10K-DB Music » Mon Jun 23, 2014 12:19 am

Heres a trk using Noise gate on all trks,,except drums. I guess using a NG in studio is a subjective application,,similar to using your "favorite" mic,,or gtr,,its the end result that we all have to live with that matters,,at least for me anyways. The threshold setting on a NG is critical thats for sure,,just one mans opinion. https://soundcloud.com/scooter261/clouds-10k-db web page soundcloud
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Re: stopping guitar hum for recording

Postby The Elf » Mon Jun 23, 2014 8:42 am

A noise gate is a useful tool in many instances - and drums are where I would use them most often!

But modern editing and silence stripping has removed much of the requirement for the humble noise gate in the studio. Putting a gate on a guitar is fine, but if that guitar is going to fade off at the end of the song the gate is going to either cut the fade or begin chattering - not good. Much better to edit the gaps out and fade the guitar off at the end. Why mess around finding exacting threshold settings when you have scissor and fade tools to do the job perfectly and permanently?

Only when editing is onerous (e.g. drums) is a gate maybe a better solution nowadays.

I don't see gates as being particularly fetishistic in the way of mic's and such. A gate is pretty much a gate. They are devoid of character, at least since the days of hardware.
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Re: stopping guitar hum for recording

Postby The Elf » Mon Jun 23, 2014 9:24 am

Like the song, BTW. Great drumming too - heck what a tragic loss...
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Re: stopping guitar hum for recording

Postby grab » Mon Jun 30, 2014 6:44 pm

Mains grid frequency (50Hz or 60Hz) is *very* stable. In the UK, supplies are guaranteed to be between 47Hz and 52Hz (at least they were when I was working on national grid stuff about 15 years ago), and generally they'll be a lot closer than that. So if you fire up the parametric EQ on your DAW, you can use pretty aggressive notch filters with stupidly high Q factors (i.e. a really needle-like dip in the curve) so that you only touch that frequency and you're really unlikely to take out any actual notes. This is one time where you really have to be able to type in the frequency - mixing "by ear" doesn't cut it. Generally you'll find that you'll also have some harmonics in there too, so add more sharp notches at 100Hz, 150Hz, etc., until you've killed it off.

Of course it's better if you can stop it happening in the first place...
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