Ground loop!...

[chorus7]

Hi Guys... Wondering if anyone could help me out... I'm running a Mac Book Pro with a M-Audio UNO USB to Midi into my Synthesizers.com Q104 Midi/CV converter... Now when I plug it in I get white noise introduced into my audio? When I go into my audio without the UNO there is no noise... So its the damn Mac USB! So my question is can anyone recommend a ground loop isolator? Or a work around the Mac USB noise? I'm worried that the ground loop isolator will impact the sound? oh and my sound card is the Apoggee Duet... Many thanks in advance...


Joe

[runningonair]

To be honest, you really need to give more detailed information, maybe a diagram.  You need to show all of the device and exactly what is connected to what using what.

Doesn't sound like a power based earth loop, I would expect hum if that were the case.  You could try to isolate earth by using batteries in those devices that take them (just as a test to track down the cause).

I used to have lots of problems like this when I used hardware.  It's a real pain.

[Kane solo andata]

I agree, Grounding problems are always a hum as opposed to a noise, generally

I had a heap of ground loop issues when I first started setting up to make music, now I'm a real stickler for checking everything at every point to make sure I don't run into that problem again,

Try isolating things if you can, like if you can run the cv converter via usb power, run everything off your macs battery and see if the sound still persists, if it does, it aint a ground loop and you have bigger issues...

Also try plugging your whole setup into one powerboard and then plug that into different outlets throughout your house or a friends house to test. I once lived in a house that only had grounding issues in the room I chose to setup in.

But yeah. my guess is bad m-audio gear.
If it is a ground loop I'd actually hazard a guess it's your synths power supply, probably some badly wired 9v or 12v powerpack...

[chorus7]

Many thanks guys for the info! I tried a bunch of different thing and it kept happening, I tried running on just the battery of the Mac and it reduced the noise but it didn't take it away...

So I remembered I had a powered USB mult, which I hooked up and voila! it took away the noise  Now that said I also had to wiggle the Midi connector to the .com system to take it away completely so I think it was a combo of an underpowered USB port and a bad wiring job on the Midi/CV converter...

I'm in a temporary room with my studio since my permanent studio is being built as I type this  so I'll have a more controlled setup soon...

Again many thanks for the help!...


Joe

[Kane solo andata]

Glad it worked out,
Nothing worse than bad noise (as opposed to good noise )

I remember having to run every sound we had through a dc offset to get rid of the inherent noise we had in our early set up!

[chorus7]

Yeah it felt like a needle in a hay stack  ...

I still think the USB's on the Mac are the real villain! I'm finally going to walk away from a laptop with the new studio...


Joe

[haesslich]

my macbook pro came with two plugs for the power supply: one not-grounded (with a "euro-connector" as the non-grounded connectors are called here) and one grounded (for grounded central europe power plugs). i usually use the non-grounded for reasons of simplicity, but this can cause grounding problems when using USB powered devices. the external powerplugs of usb soundcards are usually not grounded here, just the "euro connector", and if the laptop itself isn't grounded either, grounding issues might happen (also when the soundcard uses usb bus power).
is your laptop operated with a grounded power supply - or do you have the choice? (i've the choice on my macbook, but my previous sony had only not-grounded powersupply while the dell latitude i use at work only has grounded connection)

[chorus7]

I'm using the grounded 3 prong plug... A friend of mine suggested this as well, so I might dig out the two (ungrounded) one just to see if anything happens...But part of me doesn't want to mess with anything since its working now  ( I'm afraid I'll jinx something )...

Joe

[Phijel]

I still think the USB's on the Mac are the real villain!

You're not alone with this, I also had trouble with powered usb hubs before, and even with the native usb and firewire ports on my previous macbook pro before it starts to make random saw noises through my fireface and finally dies completely (motherboard is fried apparently) it just won't start anymore.

I hope you're not on that path !

ph

[chorus7]

Man I hope not either ( time to back up some files! )... This is my work computer as well 


Joe

[haesslich]

( time to back up some files! )

a wise man once said: "if you've only one copy, you don't really want to keep it."
let me add that this is true even if you've two copies but both in the same place ;-)