iMac/firewire interference?

[colton]

UPDATE is further down. PLEASE READ



Hey everyone, long time lurker here.

I'm been having a pretty big problem with a noise/interference/ground issue over the last few days and I was wondering if anyone would care to share some advice if you have experienced something similar. I've searched and read through these threads so far, but I'm still left puzzled:

http://www.ultimatemetal.com/forum/equipment/654250-mac-pros-firewire-problem.html

http://www.ultimatemetal.com/forum/production-tips/553042-hum-ground-noise.html

http://www.ultimatemetal.com/forum/production-tips/525108-please-help-me-my-noise-problem.html

http://www.ultimatemetal.com/forum/...lectrical-gurus-emi-noise-my-home-studio.html

http://www.ultimatemetal.com/forum/equipment/577876-7500-hz.html


I just do this for myself, I'm not an audio engineer by any means. Anyway, here goes...

Up until recently I've been mixing on headphones since my room wasn't properly treated, but that's been slowly changing over the last few days. I decided to take out my Yamaha HS50M/HS10W monitors again since I'm finally getting bass traps put up. So before I was going to proceed any further, I went to Home Depot and bought this - http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

Everything was good, the two yellow lights lit up and matched the "correct" configuration. This was by plugging it straight into my electrical outlet. I also tested the ones in my kitchen and my living room in my apartment. Everything was grounded. So I started to plug things in one by one. I begin with just my monitors. I plugged the AC cable that came with them into my electrical outlet and turned them on. The result was the kind of hiss you'd expect, nothing crazy at all. So then I plugged the power strip (surge protector) into my electrical outlet and plugged the monitors and subwoofer into the power strip and turned everything on. The result was the same, so everything is going smoothly so far. I then proceeded to plug in my interface (M-Audio Firewire 410) via the DC adapter that came with it into the power strip, connected the monitors to the subwoofer via balanced XLR cables and then went from the sub ins to outs 1 & 2 in the interface via XLR to 1/4"TRS. However, the line outs on the M-Audio Firewire 410 are unbalanced, so I should be using an XLR to 1/4"TS cable instead, but the problem I'm fixing to get to wasn't there, so I thought the cables obviously aren't the culprit right now. I've already ordered a pair of XLR to 1/4"TS cables anyway, so I'll have them just in case... Anyway, after doing all of this everything was still going smoothly. So I connected my interface to my computer (iMac Intel Core 2 Duo) via firewire 6-pin to 6-pin, plugged my computer into the power strip and that's when the annoying interference started to occur. My computer isn't even on at this point. When I do turn it on, the noise is still there. So I think I've found the culprit, but I'm still unsure. Is it the firewire cable or something in the iMac? I don't have another firewire cable to test at the moment, but that's my next step. I also have the funds now to upgrade to a better interface with balanced outs, but before I do I want to make sure I know where the problem lies because I have another issue with my guitar pickups picking up a shit load of interference the closer I move the guitar to my computer screen. Any help would greatly be appreciated, this is bumming me out quite a bit. Pretty sure I have electrical and audio hum problems

 

[::XeS::]

It's a ground loop but it's also related to something like the cpu (in my hackintosh something improved when I deactivate some cpu features).
In fact lot of mac pro's have the same problem and iMac as well.
For example my ground loop start from the socket 3 of my multisocket (if I connect the Diago Powerstation to power up my pedals on that socket, my amp has the noise)...and I usually plug my monitor on that socket. But if I disconnect the firewire cable from the computer, the noise disappeared....so it's a pain in the ass to find where the fuck it starts.
Anyway a good PSU and a Furman-like device should solve the problem...

 

[jeid]

I had the noise issue on my setup (27" iMac/HS80M's) and the fix was in the monitor cable for me. I use balanced cables and I snipped one of the wires in the XLR end, plugged it back in.. no noise. Jarkko had the same problem and after I said to try that, his noise also disappeared. It is a CPU issue from what I gather.

 

[::XeS::]

Yes it's a cpu/ground noise issue

 

[Danny Drama]

Yeah, I've had the same thing with various Mac Pro's and various interfaces that people have bought here to use. I personally use Ensembles and have never had a problem with those.

 

[colton]

cheers for the replies so far everyone.

It's a ground loop but it's also related to something like the cpu (in my hackintosh something improved when I deactivate some cpu features).
In fact lot of mac pro's have the same problem and iMac as well.
For example my ground loop start from the socket 3 of my multisocket (if I connect the Diago Powerstation to power up my pedals on that socket, my amp has the noise)...and I usually plug my monitor on that socket. But if I disconnect the firewire cable from the computer, the noise disappeared....so it's a pain in the ass to find where the fuck it starts.
Anyway a good PSU and a Furman-like device should solve the problem...

Yep, sounds like the same dilemma I'm facing. As soon as I disconnect the firewire cable from the computer, the noise disappears. I'm confused as to how this is a ground loop problem if I have good ground? I assumed those little devices can't tell everything, so I shouldn't rely too heavily on their results. When my XLR to 1/4"TS cables and new firewire cable come in, I'll test those out and see if the problem is still there. If it is, what kind of PSU or Furman device are you talking about? My apologies for all of the beginner stuff. You really discover how much you really know about this stuff when you're forced to deal with the bare essentials, haha. My first reaction is that I just want to sell this interface already and get the Profire 610 or a Saffire Pro 24 so that way I can use balanced cables in every part of my chain up until I plug my guitar in. I plan on doing that anyway once I figure out how to fix this issue, if I can. I also fear something could be wrong with my fireport on either my interface or my computer. I've never hot plugged anything, so I don't see that being the problem as far as I know. Anyway, thanks again so far. I'll keep you guys posted when I get those cables.

 

[::XeS::]

Ground loops are really annoying. If I connect the monitors in another wall socket, different from the one I use for all my stuff, the noise disappear...So these noises usually start somewhere and they travel through all the gear and you never know where it really is.
A good PSU (in case of blackout etc...) and a voltage/current stabilizer like furman or similar is usually a good start to clean the electric signal but a good and dedicated electric system is the only way to avoid these problems.
I still have an annoying noise with low latency in my system...at 1024 samples everything's silent but the more I go down (128 or below) the more the noise is audible and irritating.
Don't know if it's a common problem with low latencies or if it's a firewire related problem (or a shitty drivers issue).

 

[colton]

So those cables are backordered. Won't be getting them for another 2 weeks

In the meantime I decided to unplug all of my equipment except for my iMac. I opened Device Settings in Cubase and changed my my input to Built-in instead of the Mic-In, created a stereo audio track and clicked on the monitor button. Immediately noticed the peak meter value on the audio track jump up to around -75db, so I increased the gain on the input channel by about +40db just to hear it what it was.

This is the result: https://dl-web.dropbox.com/get/Noise Test/buil-in_input_noise.wav?w=1b196b69

The same thing occurs if I don't adjust the gain in Cubase and instead, turn up my input volume under system preferences > sound. This is with nothing plugged into the line out of my computer. It's primarily coming from the left side. Is this kind of interference normal?

Now, when I change the input to the built-in microphone the iMac has, I can see the meters in Cubase working when I talk. But the second I click on the monitor button on my audio channel, I get this terrible LOUD ringing/hum noise that shoots all the way up to 0db. This doesn't happen if I monitor through any pair of headphones plugged into my iMac. What's the technical stuff I'm missing here to explain why that happens? I'm genuinely curious because even though all of this is driving me crazy, I'm actually having some fun by learning from it all. Thanks guys.

 

[006]

If you can, try using different wall outlets for some things. Specifically, try plugging the iMac into a different outlet. I actually have everything of mine plugged into the same place. I have my iMac, monitors, external audio hard drive, podxt pro, profire2626 and motu 8pre all plugged into a Furman power conditioner, then that is plugged into a surge protector power strip, which goes into a plug on the wall.

If using a different outlet doesn't help, try something like this, or really anything on this page. They are all a nice chunk of change but they totally work.

Now, when I change the input to the built-in microphone the iMac has, I can see the meters in Cubase working when I talk. But the second I click on the monitor button on my audio channel, I get this terrible LOUD ringing/hum noise that shoots all the way up to 0db. This doesn't happen if I monitor through any pair of headphones plugged into my iMac. What's the technical stuff I'm missing here to explain why that happens?

I think that is just feedback happening since when you switch to headphones it doesn't do it.

 

[Danny Drama]

Now, when I change the input to the built-in microphone the iMac has, I can see the meters in Cubase working when I talk. But the second I click on the monitor button on my audio channel, I get this terrible LOUD ringing/hum noise that shoots all the way up to 0db.

That's probably the monitors and the built in mic being in close proximity I'd have thought? The mic will be picking up the monitor output, which then gets output on top of the original which is then picked up again by the mic and so on.

 

[colton]

UPDATE: I purchased the Ebetch HumX moths ago and that solved the noise issue with my monitors, but not the guitar. I took my guitar/cable/countryman 85 over to 006's place and we concluded that something might've been wrong with my guitar pickups wiring (Mike - or did we? ). But recently I upgraded my gear and the same problem(s) still exists. New computer, interface, and guitar. I've also spent so many hours reading up about ground loops, EMI interference on this forum and various others but I'm still left a little confused. It's become an unhealthy obsession at this point that has prevented me from doing a lot of things I need to get done and I would greatly appreciate help from anyone. Here are some clips I've provided in a folder of the noise I'm referring to. They were done in January when I was using a Firewire 410 and a Jackson at the time. The ones with all of the noise/interference are me moving my guitar around, putting it close to the screen, away from it, tapping the back of the neck, etc. and then one clean DI track of me playing.


http://dl.dropbox.com/u/55705193/iMac:pickup test/Guitar>Countryman>Legion(default)_Impulse.wav
http://dl.dropbox.com/u/55705193/iMac:pickup test/Guitar>Countryman>Legion(default).wav
http://dl.dropbox.com/u/55705193/iMac:pickup test/Legion_Mellowmuse (default).wav
http://dl.dropbox.com/u/55705193/iMac:pickup test/DI_test.wav
http://dl.dropbox.com/u/55705193/iMac:pickup test/Legion_Mellowmuse_nothing_connected.wav
http://dl.dropbox.com/u/55705193/iMac:pickup test/Legion_nothing_connected.wav


Here is a quick DI clip done in a different house with my current set-up last week if anyone wants to see if it's usable. Was recorded a bit too hot, but that shouldn't make a difference in my case.

http://dl.dropbox.com/u/55705193/sad_face.wav


My current set-up:

iMac 21.5", 10.6.8, 3.06 GHz Intel Core i3, 12GB of RAM
Profire 2626
Countryman Type 85
Schecter Hellraiser C1
Beyerdynamic DT 770 Pro Headphones
Planet Waves instrument cable

My computer and interface are plugged into a Belkin surge protector which is plugged into my wall outlet. My guitar is plugged straight into a DI box using a Planet Waves shield 1/4" instrument cable and then out of the DI box into the XLR ins of the Profire. I still get the same noise problem if I remove the DI box from the chain and use the instrument ins of the Profire. I never bothered with the Furman power conditioner because I wasn't sure how this would help in my case. I should also note that when I point one of the ends of the guitar cable at the adapter for the profire, with the other end plugged into the instrument input, that's when the hum is the worst. Could the adapter be the culprit? This is all I can think of because the plug that comes with it only has 2 prongs, so there's nowhere for the noise to go, unless I've completely misunderstood something.

Problems I think I have - ground loop and EMI interference. Can anyone confirm this for me please?


I only get the huge 60hz spike when I plug in a 1/4" unbalanced guitar cable into the profire. Pulled up a frequency analyzer in Cubase and there it was. When I turn the volume on my guitar all the way down, the noise goes away. I plugged in a cheap Sennheiser mic with a balanced XLR cable and no noise/interference. Is this because the plug on the adapter for the profire that goes into my outlet doesn't have a ground pin on it, so there's no place for the audio noise to go? Is that what causes the ground loop? As soon as I plug my guitar in with the volume knob on it up, then that's when I get what I think is EMI noise. When I touch the components on the guitar when I'm not playing, the noise is still there. There are no cracks or pops when I do this, and this is a brand new guitar. I can move around in my chair but it's still way too much noise/interference that would still be in the DI track anyway.

A recap of what I've tried so far:

Different guitars and pickups - both active and passive.
Different cables (from cheap ones to brand new $50 Mogami and Planet Wave ones)
Different rooms and outlets in my condo
Different house - 35 miles away!!!

To be clear a little noise doesn't bother me as I know it can either be edited, gated, or automated out. But this has to be abnormal. I know so many people on this board use a set-up nearly identical to mine and I've never heard the amount of noise I get in any of the DI tracks you guys have posted. Please help me, as this has prevented me from doing anything recording related for the past year almost and is negatively affecting my life right now. What else need to be done/tried? I sincerely appreciate any help. Thanks.

 

[egan.]

What are the chances you have ethernet running to your computer?

 

[colton]

Don't believe I do.

I'd just like to make sure this is RF/EMI noise or a ground loop. I'm guessing the former? Only way I can think to pin point it would be to buy a Digital EMF Meter and walk around.

 

[006]

Man, wish I knew what to do in this situation but I'm at a total loss at this point, I've just never had to deal with any of this

 

[mickrich]

I had something like this on my home setup with macbook pro and m-audio firewire interface.
I could "hear" mouse movements etc.
I put an ART DTI between audio interface outputs and monitors and it completely sorted it out.
http://www.thomann.de/ie/art_dti.htm

 

[colton]

Man, wish I knew what to do in this situation but I'm at a total loss at this point, I've just never had to deal with any of this

can I come over sometime and plug my set-up into your outlet? seriously though... only way to know my rig is hum free right?

 

[egan.]

Don't believe I do.

I'd just like to make sure this is RF/EMI noise or a ground loop. I'm guessing the former? Only way I can think to pin point it would be to buy a Digital EMF Meter and walk around.

I asked b/c I had a crazy GL issue that I thought was emf and it was a loop caused by my cable line. Seriously. After months of pulling my hair out I discovered that I had no guitar noise if I unplugged my tv on the other side of the house. Then I figured out I could get rid of it pulling the cable line. I put an iso on my cable line and the whole problem went away. Crazy right? Nowhere near the audio path and no direct connection to anything in my DAW. The loop was ground --> tv--> to cable split--->cable modem --> to router ---> to computer via ethernet --> ground.

 

[::XeS::]

Crazy

 

[arv_foh]

I asked b/c I had a crazy GL issue that I thought was emf and it was a loop caused by my cable line. Seriously. After months of pulling my hair out I discovered that I had no guitar noise if I unplugged my tv on the other side of the house. Then I figured out I could get rid of it pulling the cable line. I put an iso on my cable line and the whole problem went away. Crazy right? Nowhere near the audio path and no direct connection to anything in my DAW. The loop was ground --> tv--> to cable split--->cable modem --> to router ---> to computer via ethernet --> ground.

that is the most insane ground loop I've heard, thanks for sharing

 

[colton]

I asked b/c I had a crazy GL issue that I thought was emf and it was a loop caused by my cable line. Seriously. After months of pulling my hair out I discovered that I had no guitar noise if I unplugged my tv on the other side of the house. Then I figured out I could get rid of it pulling the cable line.

Gave this a shot. Unplugged my router, cable, tv. No luck

I honestly don't know if the problem is the gear or the power, because I'm using new gear now and even drove to my mom's house and the noise was still there. I didn't think to unplug her router/cable though.