SMPS Noise and Ground Loop Issues with JLH Amplifier – Need Filter Advice

Jump to Latest
umut1001

umut1001

Member
Joined 2007
hiendparadise.com/
#1
Hi everyone,

I am building a 4-channel JLH amplifier powered by a 24V Meanwell LRS-150-24 SMPS for a FAST system (2x SB34NRX75-6 woofers and 2x 4-inch full-range speakers). However, I am experiencing high-frequency switching noise and ground loop issues.

While searching for solutions, I came across two different SMPS DC filters on DIYAudio:

  1. ACA Power Supply Filter
  2. PO89ZB Filter
I noticed that these two filters use very different inductor values. One has 2.2µH, while the other uses 180µH. I’m trying to understand why there is such a big difference and which one would be more suitable for my JLH amplifiers.

I also have 10pcs of white and yellow toroidal cores that, as I recall, produce 100µH with 22 turns. Can I use these for an SMPS DC filter? Additionally, I have some 27µH (13x13mm green) inductors.

Would these components be useful for reducing switching noise and ground loop issues? I also have many different capacitors to make pi filters.Any advice, filter schematics, or suggestions would be greatly appreciated!

Thanks in advance!
 

Attachments

  • 20250228_233032.jpg
    20250228_233032.jpg
    654.3 KB · Views: 41
  • 20250228_232811.jpg
    20250228_232811.jpg
    462.7 KB · Views: 40
#5
steveu said:
When using SMPS you have to understand common mode noise. You need a common mode choke between the PS and audio ground. You have to filter the ground side as well as the hot. The line side of the PS needs a common mode choke on hot and neutral (not ground) and a safety ground is not optional because it is also a zero-volt reference.
Click to expand...
I think i can find common mode filter in my country(importing become very very expensive and restricted in Turkey) and make filters myself.Is it better to use 4 LC dc filters(one filter for every amp) or only one filter is enough for all? I think bias will be 4A totally.
 
#6
I found this filter in my storehouse. Can I use it after 24v output ? DCR also seems good. Should I connect earth to case? Sorry I do not know much about filtering and and gnd loops a bit complicated for me.
 

Attachments

  • 20250301_143805.jpg
    20250301_143805.jpg
    492.9 KB · Views: 27
  • IMG-20250301-WA0015.jpeg
    IMG-20250301-WA0015.jpeg
    402.8 KB · Views: 23
#7
steveu said:
When using SMPS you have to understand common mode noise. You need a common mode choke between the PS and audio ground. You have to filter the ground side as well as the hot. The line side of the PS needs a common mode choke on hot and neutral (not ground) and a safety ground is not optional because it is also a zero-volt reference.
Click to expand...
Amy Alice and PO89ZB and amp camp amp filter does not use common mode filter?
 
You must log in or register to reply here.
Top Bottom