Tube DIY Asylum

I put the SMPS in a external shielded box. No noise at all. (nt)

172.11.32.65

Chip647

In Reply to: RE: Anyone use 5V switching power supply for 300b filament? posted by Tre' on March 28, 2024 at 14:40:51

Follow Ups:

Yes, that would work. Shielding. (nt) - Tre' 15:34:19 03/29/24 (7)
.
Have Fun and Enjoy the Music
"Still Working the Problem"
- Well, no... - Triode_Kingdom 17:17:58 03/29/24 (6)
  The DC output of these regulated supplies is very dirty. Check with a scope, and you'll see it. There may be exceptions that have more rigorous internal filtering, but they're few and far between.
  - Most of the crud is well above 20kHz (nt) - Chip647 13:09:37 03/30/24 (3)
    - But not all, and even the energy above 20kHz is too close - Triode_Kingdom 18:24:38 03/30/24 (2)
      So it mixes with the desired signals to create random IM distortion all through the audio band. Shielding and filtering are usually both required to resolve this problem.
      - Like anything, there are tradeoffs - Chip647 09:53:51 03/31/24 (1)
        
        In Reply to: RE: But not all, and even the energy above 20kHz is too close posted by Triode_Kingdom on March 30, 2024 at 18:24:38
        
        For a 1.2 amp 5V supply, I agree it is not the absolute best solution to use a SMPS as they are not too difficult to build if you have the right transformers.
        
        But simply using a decent SMPS in a remote box through a 2ohm/10,000uf RC filter into a Rod Coleman V9 regulator, is very functional and dead silent. If builders are struggling with the dreaded 120hz noise and don't have the taps to generate 8 volts of DC for the regulator, it is definitely a workable solution.
        
        RE: Like anything, there are tradeoffs - Stephen R 01:24:01 04/07/24 (0)
        
        In Reply to: RE: Like anything, there are tradeoffs posted by Chip647 on March 31, 2024 at 09:53:51
        
        Yes, I did this and lived with happily. SMPS into Coleman Regs to GM70s. One thing against, was mine were in close range to other stuff.
        
        I went linear with Rob's suggestion from his website and it was way better for what I was after.
        
        But at a big disadvantage in size, weight and cost.
        
        Technically I was always concerned about the high order products mixing with the audio. Just didn't feel the right thing to do at such a sensitive part of the circuit.
  - RE: Well, no... - Tre' 07:56:17 03/30/24 (1)
    I meant that shielding would work against the airborne RF that these things produce.
    
    I think the rest could be handled with additional filtering but all the filtering in the world won't stop the airborne stuff. Once it's there, it's there.
    
    Tre'
    Have Fun and Enjoy the Music
    "Still Working the Problem"
    - Agree (nt) - Triode_Kingdom 18:25:15 03/30/24 (0)
      nada aqui

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