• butt in w/another question - Sector-7G 18:41:56 10/26/02 (1)
  In Reply to: Question about Using Low DCR Power Xfrmrs in amp circuits posted by Ian L. on October 12, 2002 at 16:23:57:

  Hey-Hey!!!,
  Just for sake of discussion, let's take a big power trans, nice low secondary DCR, say 4 ohms across 440 vac, and a primary with DCR of less than an ohm. For a choke input filter and a Class A biased power section running at least 200 mA and voltage about where I want it, is there any down side to the excess current available? I tried the beast with a resistive load and it put out an amp with less than 10% voltage drop. So far the only drawback I see is size, it weighs about 10 kilos, just like the output trans...
  regards,
  Douglas
  
  

  ---

  • No downside. - gdahl 21:15:30 10/27/02 (0)
    In Reply to: butt in w/another question posted by Sector-7G on October 26, 2002 at 18:41:56:

    Should sound superb! Best way to get great dynamics and deep soundstage (assuming an otherwise good circuit).

    Gary Dahl
    
    

    ---
• Thanks for the answers guys , 't helps . (nt) - Ian L. 22:37:54 10/18/02 (0)
  In Reply to: Question about Using Low DCR Power Xfrmrs in amp circuits posted by Ian L. on October 12, 2002 at 16:23:57:

  Thanks Guys , Everything you've said makes sense .
  
  

  ---
• Re: Question about Using Low DCR Power Xfrmrs in amp circuits - gdahl 15:12:28 10/17/02 (0)
  In Reply to: Question about Using Low DCR Power Xfrmrs in amp circuits posted by Ian L. on October 12, 2002 at 16:23:57:

  Hi Ian,

  I think that when people suggest looking for a low DCR secondary, they really mean they are looking for a power transformer with low temperature rise and good regulation. As MQRacing so aptly explained, low DCR isn't by itself a measure of quality. A good power transformer is unlikely to have high DCR, but it takes more than low DCR to make a good power tranny!

  The true goal, a power supply with low output impedance, is truly worthwhile. If a power transformer has good regulation, the ouput voltage will be close to the nominal value even when there is little or no load. Since it is often hard to find a power transformer with good regulation, sometimes people look instead for a transformer that has excess current capacity and a low-DCR secondary, in order to lower the supply's output impedance. Unless the transformer also has good regulation, the output voltage will be too high. The other unfortunate side effect is too much fluctuation of the output voltage as the load changes.

  Gary Dahl
  
  

  ---
• Re: Question about Using Low DCR Power Xfrmrs in amp circuits - MQracing 21:53:07 10/16/02 (1)
  In Reply to: Question about Using Low DCR Power Xfrmrs in amp circuits posted by Ian L. on October 12, 2002 at 16:23:57:

  Hi Ian and Kevin:

  Hope you don't mind me making a comment on this subject.

  RE: low DCR in power tranneys several thoughts come to mind.

  1) most DCR measurements your see are of the windings cold and not at operating volts and currents. The "hot" windings can be signficantly higher. And there is not a relationship that the lower the cold DCR then, ipso facto, the lower the HOT DCR will be.

  2)the DC resistance of the copper circuit is only one of several IMPEDANCES in a power transformer. By itself, even taking into account point 1 stated above, the DCR of the copper winding could well be (in some designs) the smallest impedance of the transformer overall. The impedance of the core assembly can and does in some designs swamp the loss mechanism of the DCR of the copper circuit.

  And these core losses will be present in any trans made on the planet. Thing is a trans with a real, real low copper DCR but built on a junk core could still have a cumulative impedance that is much, much higher than another specimen built on a better core but which has, as an example, a slightly higher DCR in it's copper circuit.

  Point is that DCR vastly underdescribes what is important in a power transformer is considered solely and exclusively as a barometer of quality in a power transformer.

  MSL
  
  

  ---

  • Re: Question about Using Low DCR Power Xfrmrs in amp circuits - KevinC 03:33:24 10/17/02 (0)
    In Reply to: Re: Question about Using Low DCR Power Xfrmrs in amp circuits posted by MQracing on October 16, 2002 at 21:53:07:

    Here, here! Well said!
    
    

    ---
• Re: Question about Using Low DCR Power Xfrmrs in amp circuits - kevinc 05:21:49 10/13/02 (0)
  In Reply to: Question about Using Low DCR Power Xfrmrs in amp circuits posted by Ian L. on October 12, 2002 at 16:23:57:

  Well, Ian, I will attempt an answer to the first question. For Class AB designs a lower DCR transformer will result is less "voltage bounce" under transient load, so I would expect better dynamics to come as a result. However, for a Class A design, the validity of the "rule" is a bit harder to provide a technical prop for.

  I'll leave the other questions to others. I've never made a comparison such as is suggested, so I have no practical experience.

  Kevin
  
  

  ---

This post is made possible by the generous support of people like you and our sponsors:

Schiit Audio

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---