hi all, first time poster here. i'm writing cause i'm having some serious hum issues here in my studio space.
basically, i have a portable rack for laptop recording, and i've noticed that my all my rack pieces induce audible hum in the signal path. i think it's a combination of transfomer or power supply issues along with electrical issues (guitars pick up serious noise as well).
for example, if i use the great river pre, and turn on the altec and sytek pres that are adjecent to it on the rack, i can hear hum being added to the signal. turn them off, and the hum lowers. the ampex pre also has these problems. i've recorded this too, just to make sure it's in the path.
however, i've noticed that my furman power conditioner and my motu and digi rack pieces are the biggest culprits - man do they cause the pres to hum! if i move these even just partially out of the rack, the hum significantly reduces.
anyways, these issues have been driving me nuts, and would appreciate some feedback. living in nyc with overloaded electrical lines doesn't help, but still, any suggestions would be great. i've checked the groundings on all my outlets, told the photographer downstairs to turn off all his equipment so i could test, turned off all the lights, monitors, etc.
like, if i use three-to-two prong adapters for all my gear into a single power condition, could the possibly eliminate hum issues, or am i just setting myself of for shoackage?
thanks!!
Electrical Hum Problems - Help!
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Professor
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Never remove a safety ground - it is there for your safety. Especially when you're having weird issues with the power lines. doesn't that seem slightly silly? Kinda like maybe lamenting that you can't hear the radio while you're in the shower, so you'll decide to take a bath with the boombox on the edge of the tub?
The usual cause of "ground loop" hum is from the different voltages on the chassis of various electronic devices. Every chassis has a little juice hanging on it, and when one chassis is connected to another with a different voltage through the ground wire on an audio cable, then current begins to flow across the ground line as the two different "ground planes" try to balance each other. The current flowing in the ground creates a magnetic field which induces current flow on the inner audio cables which is amplified inside the system. Same principle as a transformer.
The two potential cures for this is to break the ground connection between the two devices (cut the sheild on the balanced lines) or to add a more attractive ground between the two devices. (That second one could be as simple as a nice RCA cable with a thick braided copper sheild pulled between two unused connections - and it doesn't even matter much which connections since the cable is just there to be a more attractive conductor for the ground plane currents.)
BUT...
with all that said, I really doubt this is your problem.
I think those circuits really are all overloaded - dangerously overloaded. I don't know why it hasn't tripped the breaker yet, but be thankful.
Without knowing the wiring of the building, you won't really know which outlets are on that circuit. Perhaps you could find the breaker for it and flip it off so you can just walk around and see what outlets are on that switch. I might find that there is way too much hanging on that one breaker while another breaker may have only one 'mouth' to feed.
Since you are increasing the noise in the signal path every time you kick on another piece of gear, even if it's not in the signal path. That may mean the breaker is feeding out 15, 20 or even more Amps through a 10 or so Amp circuit. Like I said, it really should have blown already.
If you can pull out your refridgerator or stove or something, you could plug all the gear into one power strip and run an extension to that outlet and see if the buzz remains. If not, it's power. If so, then it's possible the circuit isn't as empty as we'd nope, but more likely that it really is your gear creating the hum.
-Jeremy
The usual cause of "ground loop" hum is from the different voltages on the chassis of various electronic devices. Every chassis has a little juice hanging on it, and when one chassis is connected to another with a different voltage through the ground wire on an audio cable, then current begins to flow across the ground line as the two different "ground planes" try to balance each other. The current flowing in the ground creates a magnetic field which induces current flow on the inner audio cables which is amplified inside the system. Same principle as a transformer.
The two potential cures for this is to break the ground connection between the two devices (cut the sheild on the balanced lines) or to add a more attractive ground between the two devices. (That second one could be as simple as a nice RCA cable with a thick braided copper sheild pulled between two unused connections - and it doesn't even matter much which connections since the cable is just there to be a more attractive conductor for the ground plane currents.)
BUT...
with all that said, I really doubt this is your problem.
I think those circuits really are all overloaded - dangerously overloaded. I don't know why it hasn't tripped the breaker yet, but be thankful.
Without knowing the wiring of the building, you won't really know which outlets are on that circuit. Perhaps you could find the breaker for it and flip it off so you can just walk around and see what outlets are on that switch. I might find that there is way too much hanging on that one breaker while another breaker may have only one 'mouth' to feed.
Since you are increasing the noise in the signal path every time you kick on another piece of gear, even if it's not in the signal path. That may mean the breaker is feeding out 15, 20 or even more Amps through a 10 or so Amp circuit. Like I said, it really should have blown already.
If you can pull out your refridgerator or stove or something, you could plug all the gear into one power strip and run an extension to that outlet and see if the buzz remains. If not, it's power. If so, then it's possible the circuit isn't as empty as we'd nope, but more likely that it really is your gear creating the hum.
-Jeremy
right now everything is plugged into one item- the power conditioner. so if that's grounded, i was wondering if i should not have all the other pieces going into it be grounded, and if that's perhaps something that's inducing hum.
there are two main circuits in the studio. i found this out last year during a blackout in my neigborhood.
but, right now my major concern is regarding the power conditioner, motu, and digi piece. for example, if i take the motu piece out of the rack and move it around in the air, when it's closer to a pre that is turned on, especially on the power cable side, i can hear hum entering the signal path.
nothing is connected to the motu other than the power cable when i'm doing this.
basically, i think i have some kind of shield issue with these three devices. i mean, if i keep the furman, motu, and digi pieces away from pres, everything is fine, but it's a major inconvenience. have people had luck opening up the items and isolating the stuff inside with rubber or copper tape?
there are two main circuits in the studio. i found this out last year during a blackout in my neigborhood.
but, right now my major concern is regarding the power conditioner, motu, and digi piece. for example, if i take the motu piece out of the rack and move it around in the air, when it's closer to a pre that is turned on, especially on the power cable side, i can hear hum entering the signal path.
nothing is connected to the motu other than the power cable when i'm doing this.
basically, i think i have some kind of shield issue with these three devices. i mean, if i keep the furman, motu, and digi pieces away from pres, everything is fine, but it's a major inconvenience. have people had luck opening up the items and isolating the stuff inside with rubber or copper tape?
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I'm Painting Again
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you could seperate them with with distance or perhaps a mu-metal barrier..I dont know how expenisive or available that is..but it should solve your problems..you basically need to seperate the items that create magnetic fields from the ones that are sensitive to them..there might be other things affecting your system too..you have to work em all out..but i think you have a pretty good idea of what you need to do..you could also invest in a premium hospital grade isolation transformer and a range of power "band-aids"..I think Joel H. has a good setup power-wise in his NYC studio..you might ask him what hes doing..I remember being impressed by his power "approach" from his posts a long while ago..
thanks for the replies! where can i find mu-metal barriers?
i beginning to think that furman is pretty crappy. not surprising considering they are so lightweight for 15 to 20A pieces.
out of all my pres, this is most interesting with in the sytek. the first two channels are very affected by the furman, which is three spaces away, and the last two channels, espcially the fourth one, is very sensitive to whether or not the motu or digi rack is turned on. i think b/c the power supplies/transformers are all on the same side.
as for the altec, it just hums like a madman with the interfaces and furman. the other pres seem to tolerate better cause of the distance.
i beginning to think that furman is pretty crappy. not surprising considering they are so lightweight for 15 to 20A pieces.
out of all my pres, this is most interesting with in the sytek. the first two channels are very affected by the furman, which is three spaces away, and the last two channels, espcially the fourth one, is very sensitive to whether or not the motu or digi rack is turned on. i think b/c the power supplies/transformers are all on the same side.
as for the altec, it just hums like a madman with the interfaces and furman. the other pres seem to tolerate better cause of the distance.
If all your gear is mounted in one rack, try pulling everything out so they aren't touching each other and see if the noise is still there. If the noise goes away, get some rack isolation tabs.
I had this problem once with my guitar effects rack and the iso tabs fixed it.
I had this problem once with my guitar effects rack and the iso tabs fixed it.
my band: Mission 5
i pulled out the motu and digi, holding each so nothing was touching the rack, and the hum seemed more sensitive to distance as opposed actually touching the rack space. but i'll pull everything out and see what happens.
if someone can point me towards a place that sells the mu-metal barriers or the isolation tabs (found those at musician's enemy) that would be great, but not sure if any store in nyc carries them - maybe dale pro audio?
i also saw those rack isolation transformers, but i'm reluctant to add things to the signal path.
maybe i'm obsessing over something that is just reality. lol.
if someone can point me towards a place that sells the mu-metal barriers or the isolation tabs (found those at musician's enemy) that would be great, but not sure if any store in nyc carries them - maybe dale pro audio?
i also saw those rack isolation transformers, but i'm reluctant to add things to the signal path.
maybe i'm obsessing over something that is just reality. lol.
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I'm Painting Again
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mu-metal is what they used to make the cases for the old school tape machine heads out of..
I know this could work as a solution for you but I have no idea how practical or expensive it would be..just an idea..I would consult a real tech before going out to look for mu metal suppliers in other words..there might be a simpler fix or something..Mu-metal is a nickel-iron alloy (77% nickel, 15% iron, plus copper and molybdenum) that has a vey high magnetic permeability. Permeability is represented by μ, the Greek letter mu.
The high permeability makes mu-metal very effective at screening magnetic fields
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joel hamilton
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What is the ground in your studio?
To get us off of NYC ground (which is noisy as HELL) we had two big copper spikes driven into the ground in the basement, that all the star grounded outlets go to...
That goes to a couple of different conditioners for each rack of stuff. For example, in the gigantic tube compression rack (about 30 compressors, all vintage, big tube thingies of various types) there is a giant tripp lite thingy... with all the goodies: filtering, line voltage regulation, the whole shebang...
For the rack with the 160A's and XT's and X's and 1176 and distressor type stuff, there is a simpler furman type thingy, but still with voltage rwegulation... Same for all the other stuff like FX and other compressors and EQ racks.
None of these things even touch the city power ground. Straight to the earth.
We also use wood racks with wood cleats so no ground loops via rack rails at all....
To get us off of NYC ground (which is noisy as HELL) we had two big copper spikes driven into the ground in the basement, that all the star grounded outlets go to...
That goes to a couple of different conditioners for each rack of stuff. For example, in the gigantic tube compression rack (about 30 compressors, all vintage, big tube thingies of various types) there is a giant tripp lite thingy... with all the goodies: filtering, line voltage regulation, the whole shebang...
For the rack with the 160A's and XT's and X's and 1176 and distressor type stuff, there is a simpler furman type thingy, but still with voltage rwegulation... Same for all the other stuff like FX and other compressors and EQ racks.
None of these things even touch the city power ground. Straight to the earth.
We also use wood racks with wood cleats so no ground loops via rack rails at all....
i don't know actually, it's a practice space for bands and stuff, but i have the same problem at home ? would a voltage regulator help with hum-creating rack gear like the interfaces? it's especially annoying with the furman, cause i bought it thinking it would reduce some ac noise and centralize the power center without using power strips, but instead there's transformer hum bleeding into the signal path.
it's not so much a problem when recording amps and stuff cause of the sound level source, but when recording a violin with a low power mic like a royer going into the pre, i have to move the interfaces away from the other gear, and not use the furman - then the hum disappears and i can only hear a little hiss from the pre which is normal.
i'm going to get those rack isolators to start, and maybe move the furman and interfaces off the rack permanently.
it's not so much a problem when recording amps and stuff cause of the sound level source, but when recording a violin with a low power mic like a royer going into the pre, i have to move the interfaces away from the other gear, and not use the furman - then the hum disappears and i can only hear a little hiss from the pre which is normal.
i'm going to get those rack isolators to start, and maybe move the furman and interfaces off the rack permanently.
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joel hamilton
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I keep the interfaces and drives FAR away from anything else, especially tube gear, I dont know why, but it seems to "receive" the EFI bullshit that the converters love to spray.. quite well.tubeman wrote:i don't know actually, it's a practice space for bands and stuff, but i have the same problem at home ? would a voltage regulator help with hum-creating rack gear like the interfaces? it's especially annoying with the furman, cause i bought it thinking it would reduce some ac noise and centralize the power center without using power strips, but instead there's transformer hum bleeding into the signal path.
it's not so much a problem when recording amps and stuff cause of the sound level source, but when recording a violin with a low power mic like a royer going into the pre, i have to move the interfaces away from the other gear, and not use the furman - then the hum disappears and i can only hear a little hiss from the pre which is normal.
i'm going to get those rack isolators to start, and maybe move the furman and interfaces off the rack permanently.
I even wound up with a rack shelf with nothing on it above the coverters in my rack, just as another chunk of metal between the AD/DA rack and the rest of the gear, with the external clock and a DL bay for switching all 24 I/O from the tape machine to PTHD in two seconds...
i think yours is one of those balanced power ones. mine is one of those cheapo 15 pound ones. i read a good tip somewhere. If you can hold a power conditioner with one arm, don't buy it. Unfortunately, I didn't heed the tip.
I think Furman cost cut with the tranformer and shielding of it's cheaper units. I noticed that the AR 1215 and ar 15 have toroidal transformers, which still emit interference, but not nearly as bad as cheap ones.
The tranformer specs are missing in the PL series manual, so I'm assuming these units use the cheaper versions.
I'm about to go to a remote location to record a chorus, when they are on break I will do more testing with the different electrical sources and see if the furman and interfaces still emit the same amount of noise.
I think Furman cost cut with the tranformer and shielding of it's cheaper units. I noticed that the AR 1215 and ar 15 have toroidal transformers, which still emit interference, but not nearly as bad as cheap ones.
The tranformer specs are missing in the PL series manual, so I'm assuming these units use the cheaper versions.
I'm about to go to a remote location to record a chorus, when they are on break I will do more testing with the different electrical sources and see if the furman and interfaces still emit the same amount of noise.
hi all. i'm thinking of trying a diy emi shielding experiment with the 828, 002, and the furman.
i'm thinking of using some copper tape that i have for guitar pickups, wrapping them in electrical tape, and placing them under the transformers.
is this stupid? and if not, how would i properly ground this?
i'm thinking of using some copper tape that i have for guitar pickups, wrapping them in electrical tape, and placing them under the transformers.
is this stupid? and if not, how would i properly ground this?