Chycki Tube DI grounding arrangement

[Bo Hansen]

Ray,

In your case where you have a transformer balanced output, and will use a balanced transmission, it may suffice and be safest with only capacitor in series with the pin-1.

A 100 ohm resistor in paralell can sometimes burn up, if a connected guitar amplifier get temporarily shock or short circuit problems.

In my ground loop circuit has the two diodes several functions, including to rescue the resistor to burn.

Larger mains transformer in guitar amps and related equipment, usually have better insulation between primary and secondary windings and core. I'm more afraid of the little cheap transformers manufactured in China and Tawain.

--Bo

 

[Mondy]

Hi Bo

Ok that’s sounds like good thinking! I will go for the following if you agree…

1. Mains earth permanently bonded to DI chassis at mains lead entry point

2. Mains transformer installed (this will be a European made first grade UL1411 listed toroidal transformer to EN61558/1) with earth screen also bonded to chassis mains earth point. This transformer will be fused in the primary live connection with a chassis mounted fuse and holder. 

3. Uninsulated ¼” input jacks used (so sleeves permanently bonded to DI chassis) and common 0V connection taken to one connection point as per the Chycki wiring plan

4. Metal XLR output socket bolted to chassis with Pin 1 connected to one of the XLR mounting bolts via 0.1uF 250V rated film capacitor.

Can you let me know if I have this straight?

Cheers

Ray

 

[Bo Hansen]

Ray,

Sure, it seems like an ok solution.

Yes, it's a good idea to use a better quality and safe toridal mains transformer, and connect this in a safe manner with a correct fuse.

Unfortunately, even if you use the 0.1 uF capacitor, my 4 component ground loop circuit or a ground lift switch, in series with XLR pin-1, you can still have ground loop problems, if you use one input jack to feed a mains earthed amplifer.

--Bo