• RE: are there any Marchand Xover enhancements that you would suggest ? - Satie 09:55:22 04/25/15 (5)
  In Reply to: RE: are there any Marchand Xover enhancements that you would suggest ? posted by pictureguy on April 25, 2015 at 00:22:27

  That is not a bad idea but FREDs are what my modster friend uses as they do the job better than old style diodes.
  

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  • RE: are there any Marchand Xover enhancements that you would suggest ? - pictureguy 10:39:17 04/25/15 (4)
    In Reply to: RE: are there any Marchand Xover enhancements that you would suggest ? posted by Satie on April 25, 2015 at 09:55:22

    In what way 'better'?
    
    I'd love to take a SCOPE and see the swithcing noise generated by various diodes.
    Too much is never enough
    
    

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    • RE: are there any Marchand Xover enhancements that you would suggest ? - Satie 11:51:14 04/25/15 (3)
      In Reply to: RE: are there any Marchand Xover enhancements that you would suggest ? posted by pictureguy on April 25, 2015 at 10:39:17

      I never asked him so I will have to ask when I get a chance.
      
      He does use a scope to help track down problems and to see what "changed".
      
      I don't know how much of what a FRED does over a traditional diode is less switching noise, but switching noise would not be eliminated by a parallel cap or cap to ground.
      
      Even with FREDs he adds chokes everywhere in the PS where feasible.
      

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      • RE: are there any Marchand Xover enhancements that you would suggest ? - pictureguy 14:10:09 04/25/15 (2)
        In Reply to: RE: are there any Marchand Xover enhancements that you would suggest ? posted by Satie on April 25, 2015 at 11:51:14

        Copied from the PASS DIY site.
        
        Per Pass DIY SITE.
        
        Rectifiers.
        Yeah, sure, rectifiers are important, after all, the AC has to get converted to DC, but I don't like the fast recovery types that some audiophiles have raved about. Fast recovery means that they withstand many amps and volts in a tenth of a few nano-seconds, something we don't see very often on the old 60 Hz AC line. They are essential element in switching power supplies, but for regular "linear" power supplies, I much prefer SLOW diodes, and we create them by placing small capacitor circuits across the diodes, which greatly reduces radiated noise.
        
        
        This is the reason I asked. Believe your guru? Believe Pass? I have no idea. Just asked a question:
        Too much is never enough
        
        

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        • RE: are there any Marchand Xover enhancements that you would suggest ? - Satie 14:49:33 04/25/15 (0)
          In Reply to: RE: are there any Marchand Xover enhancements that you would suggest ? posted by pictureguy on April 25, 2015 at 14:10:09

          I can say that is a reason some use tube rectification and gas diodes but my modster friend does like his FREDs. I don't doubt that Pass is right about switching noise reduction with slow diodes, I also don't expect my modster friend has the slightest issue with existing noise levels in his tubed and vinyl centric system. Those are way below what is inherent in this source and gain devices. His main noise reduction step was to use a MM cartridge. A step I readily took myself.
          
          He dud have a hum issue that he traced back to the filament power supply on his preamp's phono stage which he powers separately through a separate tranny and regulator board.. So he put a choke on it and got a cleaner regulator and it solved the issue. He says it easily covered the cost of the scope that showed him where the hum was coming from.
          
          
          

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        • RE: are there any Marchand Xover enhancements that you would suggest ? - Davey 14:40:07 04/25/15 (0)
          In Reply to: RE: are there any Marchand Xover enhancements that you would suggest ? posted by pictureguy on April 25, 2015 at 14:10:09

          Nelson is of course correct. Standard diodes are just fine....you can use RC snubbers on the diodes if you like, but even those are not really necessary with line-frequency applications.
          These are not SMPS supplies we're dealing with here.....just simple linear-regulated +/- supplies delivering low current.
          
          Dave.
          
          

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• To be honest,... - MWE 07:05:38 04/25/15 (0)
  In Reply to: RE: are there any Marchand Xover enhancements that you would suggest ? posted by pictureguy on April 25, 2015 at 00:22:27

  I don't know enough about this in-depth to evaluate your question. I found the FRED sub idea on an old AA post. Perhaps someone with deeper electronics background can comment.
  
  Mark in NC
  "The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
  
  

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