Tech Square

Posted by Russ57 (A) on March 02, 2006 at 10:28:50

In Reply to: Any X former experts? posted by Granholm on February 26, 2006 at 09:53:22:

That is a 2 by 38VAC, 625VA transformer. Dual 117VAC primary. If you contact them they will normally wind for whatever voltage you want for litte to no extra money. So getting 42 or 45 volt secondary should not be a problem.

Yes I would get a screen and no I would not get cobalt. It almost always helps to have a transformer capable of 150 to 200% of actual current draw. I can offer no science for this but can say it certainly sounds better to me.

Don't overlook good, fast, big caps with nice slew rate times. It has been a long time since I built solid state stuff but back then Siemens sikorel was a fantastic cap. Hard to find, not many sizes, and not cheap, but performance/specs much better than anything else. But time marches on and they might not be the best anymore.

Russ

• Might get in trouble as my main is 230V AC ;o) nt! - Granholm 12:32:09 03/02/06 (0)
  In Reply to: Try Amveco #AA56252-038 posted by Russ57 on March 2, 2006 at 10:28:50:

  nt!
  
  

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• Re: Try Amveco #AA56252-038 - Granholm 11:41:39 03/02/06 (2)
  In Reply to: Try Amveco #AA56252-038 posted by Russ57 on March 2, 2006 at 10:28:50:

  Hi Russ57,

  Was thinking og RIFA PEH 169 or 200 series. But yes the Siemens was very hot back then and I think they still are. But the Aerovox T-power I am using is not to bad eigther! Though they are only rated at 63 voltage wich "only" allow secundary AC to be 2x42VAC (59,xxDC).

  What I was wondering was if there would be even the sligthest benefit from adding even more VA (Actually only A)?? As I have space enough for an toroide up to 3000VA rating (standard build).

  What is your experience with cobolt?

  Have Fun.
  
  

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  • Re: Try Amveco #AA56252-038 - Russ57 12:18:17 03/02/06 (1)
    In Reply to: Re: Try Amveco #AA56252-038 posted by Granholm on March 2, 2006 at 11:41:39:

    Yes, in my experience having a transformer capable of more current than you need makes a nice difference, but I see no point in going past 200%(I guess for you that is about almost 1,000VA tops?). One advantage is that the larger a transformer is the better it's regulation, the difference between loaded and unloaded voltage. So I think it makes for a stiffer supply. Cobalt's big advantage is lower core loss. That is not important to you unless you plan to own a power company and have a bunch of transformers:) Cobalt will have a bigger inrush current and that will already be a problem using "doughnut" transformer. So for the inrush reason I say don't bother with cobalt. Save the fancy core materials for audio coupling transformers such as those used in tube amps. Even then I'd suggest M4 and/or nickel.

    Actually an EI style transformer will not couple high frequency hash on the AC line as well as a "doughnut" type. But they tend to put out more electrical fields and are physically larger. Personally I like EI better.

    
    Russ
    
    

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    • I have heard that before (EI is better) - Granholm 12:29:45 03/02/06 (0)
      In Reply to: Re: Try Amveco #AA56252-038 posted by Russ57 on March 2, 2006 at 12:18:17:

      But what if I ad endcaps?? Would this not prevent some of the stray fields? Or would it also deteriate the sound?

      Have Fun
      
      

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