chassis ground: what is this?

[igloo]

Ok, I've read the rane balanced cable wiring and seen the diagrams at their technical notes: http://www.rane.com/note110.html

It may be because I'm not a native speaker, but what exactly is tying the cable shield to the metal chassis right where it enters the chassis??

What I understand from this is the following. Let's say I want to connect an Akai sampler (which has balanced outputs) to my Metric Halo audio interface (which has switchable balanced, line, mic and unbalanced inputs).

I should build my interconnect cable using twisted pair cable (Mogami or other) and wiring the TRS connectors as per the diagram. In able to follow the directions, I should remove the cover of my sampler and wire the internal connectors' shield with a tiny cable; drill a hole in my sampler's metal encasing and attach the cable to this hole using a small screw with a toothed washer, thus completing the "chassis ground" diagram. Am I somewhere near the actual truth??

How about if my sampler has 8 balanced outputs? I should do the same and tie the 8 internal shields with 8 separate cables to a single point in the chassis ground?

Is the chassis grounding also achieved by tying the shield to, say a metal rack enclosure? I read somewhere that this may or may not be true, depending on the rack/rails type of metal and paint job.


On another subject. What is the correct way of chassis grounding (or any type of grounding) for gear that uses wall warts? I mean, there is no ground prong, and many of these decives are unbalanced, so the internal connectors don't have a shield. I have a Pignose amp, anda Korg N5 with wall warts. i know the wall warts should be as far away from audio lines. But is that it? If I wire all my studio with the star grounding technique, should I have a separate circuit and outlet for this type of devices? should this separate outlet be tied or not to the common ground for the rest of my studio??

Thanks for any help on this matter!

Regards,

Rodrigo Montfort

[igloo]

I'm also shopping for a replacement for my house's electrical panel box (Load center). It uses 3 pole current. I'm trying to figure out the capacity and type of panel box I should get.

The current configuration is the following (All Square-D):

House Central Air Conditioning: 3 pole Circuit braker 70 AMP

House Power supply: Switch with a couple of 60 AMP fuses 250 V each

Studio Air Conditioning: Double Thermomagnetic Circuit braker 30 AMP

Studio Power supply: Single Thermomagnetic Circuit braker 20 AMP



As you can see it's a mess. I'd like to replace the Switch with a Thermomagnetic Circuit braker for the House. (what type? Double 60 AMP?) I'd like to beef up the studio power supply's circuit (at least 30 AMP), and add two new circuits: Studio lighting and Computer/Peripherals.

Proposed configuration:

House Central Air Conditioning: 3 pole Circuit braker 70 AMP

House Power supply: Double Thermomagnetic Circuit Braker 70 AMP

Studio Air Conditioning: Double Thermomagnetic Circuit braker 30 AMP

Studio Power supply: Double Thermomagnetic Circuit braker 30 AMP

Studio Lighting: Double Thermomagnetic Circuit braker 20 AMP

Computer/Peripherals: Double Thermomagnetic Circuit braker 30 AMP


What do you think?

I asked an electrician and he recommended a 3 phase panel box 100 AMP rated. Do you think that'd be enough?

Thanks for any help!


Rodrigo Montfort

[Aaronw]

Are you saying your house has 3 phase power?