iMac ground noise problems

I have been using an iMac with a FA-66 for a long time and am getting tired of the poor signal quality I get when recording audio (at best -80dB, at worst -60dB when for some reason the iMac causes trash on the ground ; it might also depend on the power line itself). And don’t tell me about the scrrchh scrrrch I sometimes get on my monitors when scrolling a webpage.

This problem is documented all over the place on the internet and it appears that the ground on which the USB / FW connectors are is very dirty and receives all kind of crap from the videocard or LCD or backlight… I have tried other audio interfaces (Mackie and M-Audio) from colleagues and as expected the problem did not disappear.

I bought my iMac 4 years ago and time to replace it is coming… Anybody here had success using good quality audio with a USB/FW interface on a recent iMac? Or using tricks like a backup-battery? I’d rather avoiding lifting the ground…

Oddly enough… My iMac is also 4 years old (First of the aluminium ones). No noise problems here with a Firewire Apogee Duet.
I have read of those same noise problems though. Supposedly its a ground loop issue, and in many cases using a ground loop isolator fixes it.They are transformer based, right? So not lifting the ground in the regular sense, I think…

My former Mac (iMac CoreDuo 2.0 GHz - yes, theres no 2 in between) was just fine with my Line6 UX, while its not the fanciest Gear out there it has a S/N better than my Mixer…there are some Noise Problems with the MacBook Pro even when its running on Batery so i stuck to the iMac.

I had a Focusrite Saffire Pro 40 for a recording an Acoustic Session which was also without any noticeable Noise on the MacBook and the ancient iMac. I always make sure that all Recoding Gear (Mixer, Outboard, Interface, Mac) are plugged into the same Multiple Jack and are using the same Fuse.

I Just replaced it with a brand new iMac (MC814D/A) and everything is still fine. Expect my Neck hurts due to the huuuuge Display :wink:

@ fcd72

I found that doing the exact opposite worked for me. I used a Presonus Firestudio for a while and had TONS of noise, sometimes barely pulling 60dB of headroom when recording at 24 bit. I found that If I kept the presonus firestudio and all the audio gear on a completely separate circuit breaker, so essentially had to have extension cords running all over the place!

It is a really annoying problem. You’d think with Macs being considered the platform most suited for audio work that they wouldn’t make such crappy circuits that bleed signals from the cheap power supplies and graphics cards, and for as much as you spend that you wouldn’t have such a problem.

A ground loop isolator might fix the noise bleeding through the monitors ; assuming it is going through the common ground between the speakers and audio card. But it won’t help during the recording (protocol: FA-66 is connected to the iMac and no other connection. I press ‘rec’ and get noise with a -60dB level). Maybe it’s my audio interface getting old…


yeah, it seems that apple gear gets more and more in the consuming corner than in the producing area… i’d be interested if the MacPro has the same issues.

On a related note: any recommendation for a not too expensive USB interface (to use with my girlfriend’s MacBook which should have a cleaner ground when running on batteries) with a good SNR (background noise when no input connected < 88dB)?

For cheaper, but not disposably cheap interfaces, I like MOTU. Solid drivers (usually with very good Mac support too), and as good a quality of sound as you could hope for, given the price. Not that i’ve used the entire range! But if I was looking to get an inexpensive interface now, I think thats what I would go for myself.
Perhaps look at the MicroBook and Audio Express.

+1 for a ground loop isolator. Any sort of hum eliminator (cheap ~$20 out here) works well for this type of stuff

Assuming you just want 2 inputs, you could always use a Zoom H2, it has a stereo line in, and works as a 24 bit interface and has a fantastic S/N ratio. Any zoom product would be good, you could try the R8/16/24, they are all USB with good quality and are fairly affordable.

An apogee duet would be nice too, but they are pretty pricey!

Try a Line 6 Pod UX1. Im totally satisfied with latency, noise et al + i got a Waldorf Attack Lite + PPG Plugin :wink: + Ableton Live for free. And it has a High Z + Symmetrical Micro in and Latency free Monitoring. Works without a Hassle from 10.4.82 till 10.7.2

capacitors in your interface? reheat the smd? Four years and I assume you used it alot.

The new Focusrite Scarlett 2i2 looks really nice for the money but not many features. Your getting your money in pre-amps and A/D, not a bunch of crap you wont use. Also I loved my Mackie Onyx Satellite though it recently took a dump on me, it was 7 years old. I will probably get another one as you can find them for under $100US new. Great Control Room features! Both these units are only 2 channel though. My iMac is 5 years old and never had issues but I always run my music gear through a Furmann Power Conditioner.