Reducing Hum and Noise

[Bonsai]

I've updated the presentation on my website covering hum and noise issues. This deals with single ended interconnect systems, but you will also get some benefit if you use balanced interconnects.

Ground Loops

 

[NealJ]

Thanks for this. To have something explained and illustrated so well is a godsend for novices like me. Your effort is much appreciated.

 

[Bonsai]

🙂

 

[fredbloggstwo]

Thanks for this. To have something explained and illustrated so well is a godsend for novices like me. Your effort is much appreciated.

+1 - whatever you skill level may be.

Thanks Bonsai

Regards

Mike

 

[johnmarkp]

Bonsai,

Great stuff, I have been fighting a low level noise problem for months. This will help my find and cure the problem.

John

 

[eldad]

Thanks Bonsai

 

[VictoriaGuy]

Thanks!
It took me a minute to find the article- the link is:
http://hifisonix.com/wordpress/wp-content/uploads/2019/02/Ground-Loops.pdf

 

[fredbloggstwo]

Hi All,

One technique that I now stick to rigidly, particularly for low-level signal test equipment, is to put the mains transformer, rectifier diodes and initial smoothing caps (but no regulator) in their own metal external case that is bolted to the mains safety earth and not connected zero volts.

I then use an umbilical cable to the equipment case proper where it connects to the power supply/regulator.

I float the euipment case (which is also lined with screening mesh) and have a grounding lug connected to it. I then connect 0V to a 4mm post so I can bind the case and 0V explicitly at one point. If necessary I can also bring a mains earth to the ground lug from a main interference unit (I do a lot of low level measurements and heavily filter the mains to keep the mains-borne rubbish out)

This has always given me good results and flexibility whilst maintaining safety.

Regards

Mike

 

[VictoriaGuy]

I float the equipment case (which is also lined with screening mesh) and have a grounding lug connected to it. I then connect 0V to a 4mm post so I can bind the case and 0V explicitly at one point. If necessary I can also bring a mains earth to the ground lug from a main interference unit

Mike-
I don't understand...your 'equipment' case is not necessarily connected to the 'mains earth' (aka AC safety ground)?
It's not a big deal if you have only low-voltage solid state circuits inside, I suppose, but not a good idea with higher voltage (tube) gear.

Also, I think that residential wiring is 'different' in the UK from our standards in N. America, so that can affect what is considered safe.

 

[fredbloggstwo]

Hi VictoriaGuy,

If you think about it, putting the transformer, diodes and caps in a seperate case and linking that to an equipment case, is the same situation as using a wall wart.

Regards

Miike

 

[VictoriaGuy]

Hi VictoriaGuy,

If you think about it, putting the transformer, diodes and caps in a seperate case and linking that to an equipment case, is the same situation as using a wall wart.

Regards

Mike

If the wall wart was producing 400volts DC?

 

[fredbloggstwo]

If the wall wart was producing 400volts DC?

Mine aren't because I dont' build equipment using valves.

 

[BigE]

The walwart can pass 12 amps?