annoying hum

[arkmabat]

My interface came with this thing you clip around the USB wire. Supposedly reduces hum.

[damonvargas]

There is no hum though when I use the cable that came with the interface. In order to run it into the iMac I have to use a different cable along with the apple FireWire to thunderbolt adaptor. Then, I get humming right away!

[camsr]

For most intents and purposes, Thunderbolt is the same thing as Firewire. Yeah, they changed a little of this and a little of that, but they do the same exact thing. I was hoping long ago to get a Thunderbolt enabled interface, but it turned out they changed the standard then to use an electrical connection. Using optical thunderbolt would be a guaranteed way to avoid this nasty scenario. After switching to using TOSLink (optical SPDIF) the noise floor of my monitor is incredibly low.

[BertKoor]

There are three types of FireWire connectors. Found on http://forum.videohelp.com/threads/3041 ... unding-Fix :

I also found Apple sells Thunderbolt-FireWire adapters with the FireWire side having 9 conductors:


Your hum will probably go away if somewhere along the line the smallest 4-pin FireWire connector is used, since that lacks the offending ground conductor. It also lacks AC power, but you already have an AC adaptor for that. Maybe you can use a combination of cheap FireWire adapters to/from the mini format.

My interface came with this thing you clip around the USB wire. Supposedly reduces hum.

Probably ferrite beads which form a LPF. They prevent the cable picks up RF interference which are higher frequencies, such as clicks when the fridge switches on. Since USB is digital, it doesn't do much agains hum induced by a ground loop. But it can cure some data transmission problems.

[damonvargas]

There are three types of FireWire connectors. Found on http://forum.videohelp.com/threads/3041 ... unding-Fix :

I also found Apple sells Thunderbolt-FireWire adapters with the FireWire side having 9 conductors:


Your hum will probably go away if somewhere along the line the smallest 4-pin FireWire connector is used, since that lacks the offending ground conductor. It also lacks AC power, but you already have an AC adaptor for that. Maybe you can use a combination of cheap FireWire adapters to/from the mini format.

My interface came with this thing you clip around the USB wire. Supposedly reduces hum.

Probably ferrite beads which form a LPF. They prevent the cable picks up RF interference which are higher frequencies, such as clicks when the fridge switches on. Since USB is digital, it doesn't do much agains hum induced by a ground loop. But it can cure some data transmission problems.

the adaptor at the very bottom of your post is what i use to go into the iMac. before that is a 6 pin to 4 pin cable i believe. you can lookup the Presonus Firebox from 2005 if you want, it only allows you to use firewire, no other option. So, anyways, to summarize all this. There are 2 cables connected to each other in order to connect the interface into the iMac. The 6 pin to 4 pin cord and the apple thunderbolt adaptor. I guess i could try apple support and see if they have any advice on how to decrease the hum. It is such a strange mix of cables connected to each other that i may be stuck dealing with the hum till i buy a new interface.

[Stanoli]

This is my set up. Computer and monitors are going into a channel strip which goes into the wall. The power ac adaptor to my interface goes directly into the wall and does not touch the power strip.
Now, how do I break this loop you are talking about? Maybe I'll try taking the monitors out of the power strip?

Thanks for your help, appreciate it.

I had that problem once and I got rid of it with connecting the cables of the Computer and the monitor into different wall sockets.
Just try all combinations with the cables and the wall sockets, may`be it works.
Good luck

[BertKoor]

Well I think you currently don't have any 4-pin connection in the adapter string. The FireBox has the regular 6-pin fw connector. The Apple adapter provides the 9-pin version. So the next adapter is 9 to 6 pins. So stil an uninterrupted ground to form a loop.