Tube DIY Asylum

RE: What would you use to fill in the air gap of a SE OPT?

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In Reply to: RE: What would you use to fill in the air gap of a SE OPT? posted by Tre' on February 26, 2024 at 06:51:54

"move the "I" over tight against the "E"?

Quality transformers don't use EI laminations anymore, they use C-cores or even better. Just my opion.

Follow Ups:

RE: What would you use to fill in the air gap of a SE OPT? - Tre' 19:01:29 02/26/24 (9)
OK so how do you close the gap on a C-core?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
- RE: What would you use to fill in the air gap of a SE OPT? - Best audiotransformers 10:12:28 02/27/24 (8)
  like this:
  In the middle you see the -in this case- very small gap.
  
  Edits: 02/27/24
  - RE: What would you use to fill in the air gap of a SE OPT? - dave slagle 13:51:37 02/27/24 (7)
    actually, even if precision ground the gap is still substantial compared to an R-core, toroid or an alternately stacked EI lamination.
    
    dave
    - RE: What would you use to fill in the air gap of a SE OPT? - Best audiotransformers 00:53:44 02/28/24 (5)
      For a SE transformer we need a airgap, even for a push-pull output transformer is an airgap (small) better then no airgap.
      I don't see any bennifits* for EI laminations and for input transformers, line or mc where there is no dc, toroids are the best choice in my opinion.
      
      *for any EI lamination core is a much better c-core, toroid or r-core available. EI is just outdated
      
      Edits: 02/28/24 02/28/24 02/28/24
      - RE: What would you use to fill in the air gap of a SE OPT? - dave slagle 07:00:42 02/28/24 (4)
        
        In Reply to: RE: What would you use to fill in the air gap of a SE OPT? posted by Best audiotransformers on February 28, 2024 at 00:53:44
        
        everyone is welcome to their opinion. now some really small 80% nickel R-cores would be yummy.
        
        dave
        
        RE: What would you use to fill in the air gap of a SE OPT? - Best audiotransformers 07:55:55 02/28/24 (3)
        
        In Reply to: RE: What would you use to fill in the air gap of a SE OPT? posted by dave slagle on February 28, 2024 at 07:00:42
        
        I doubt if the 80% nickel R-core will be ever made, there is no need for it. There are already better solutions on the market.
        Because you seem to like 80% nickel cores, look for ultraperm 10 cores. I used them in the past and they are really nice cores. I still have some for less critical projects.
        
        Edits: 02/28/24
        
        RE: What would you use to fill in the air gap of a SE OPT? - Best audiotransformers 12:01:51 02/28/24 (2)
        
        In Reply to: RE: What would you use to fill in the air gap of a SE OPT? posted by Best audiotransformers on February 28, 2024 at 07:55:55
        
        "actually, even if precision ground the gap is still substantial compared to an R-core, toroid or an alternately stacked EI lamination"
        
        Really? Cores can be polished to a micron scale and the quality of the best EI laminations is so much worse then what is available in C-cores that it makes no sense what you are telling.
        
        RE: What would you use to fill in the air gap of a SE OPT? - dave slagle 13:51:09 02/28/24 (1)
        
        In Reply to: RE: What would you use to fill in the air gap of a SE OPT? posted by Best audiotransformers on February 28, 2024 at 12:01:51
        
        an alternately stacked EI core will have more than double the gap area of a comparable c-core. It is the area in combination with the actual thickness of the gap that determines the effective gap. The whole reason toroids have suce small effective gaps is the large surface area of the mating faces that compromise the gap. Of course you could go for a unicore but I have yet to see those used in audio.
        
        dave
        
        RE: What would you use to fill in the air gap of a SE OPT? - Best audiotransformers 14:12:15 02/28/24 (0)
        
        In Reply to: RE: What would you use to fill in the air gap of a SE OPT? posted by dave slagle on February 28, 2024 at 13:51:09
        
        The lowest gap is in output transformers not the most interesting subject. The quality of the material is by far more interesting and EI has the lowest quality of all transformers cores.
        Because SE amplifiers always need a airgap c-cores are one of the best cores to use for those amplifiers. For Push-pull there is the problem for un-ballanced tubes. So the discussion about the lowest airgap is not so important here.
        For mc or mic transformers where no dc is involved it is important to have the lowest coreloss. Here are toroids the best solution. No airgaps and the lowest coreloss materials are available. EI are just rubbish here.
    - RE: What would you use to fill in the air gap of a SE OPT? - Triode_Kingdom 22:45:42 02/27/24 (0)
      "even if precision ground the gap is still substantial"
      
      Exactly right. And closing it up magnetically is like trying to put Humpty Dumpty back together. :)

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