Tech Square

Posted by cheap-Jack (A) on March 01, 2006 at 07:59:15

In Reply to: Good! And some more details! posted by Granholm on February 28, 2006 at 12:26:10:

Hi.

But your power iron is only rated for 300VA, so the best you may be able to get is 120Wrms/channel assuming the overall efficiency is 80%
(PSU+class D power modules).

Where you get 94% efficiency that high for your moduls. What switching topology was used there?

Why you need so high power anyway? Certainly not for normal home use or your neighbours will surely complain you let alone your family.

If you really want it for certain PA use, then you got to replace a
higher VA power transformer with higher B+/B- voltage required by the module design. Say if you really want to get 2x200W/8R, then
you surely need a power iron rated not less than 500VA with B+/B-
to fit the modules. Otherwise, the power iron will get overloaded, causing B+/B- voltage drops & hence O/P power.

The filter caps & bridge rectifiers got to be beefed up accordingly.

c-J

• Dead end? - Granholm 12:36:37 03/01/06 (2)
  In Reply to: More VA power, more O/P power. posted by cheap-Jack on March 1, 2006 at 07:59:15:

  Hi c-J

  My original intend was to get a new power iron! I know I would not get full power with what I got!

  I also do not need the power to be kicked out of my flat ;o)

  But I want it for dynamic headroom! If you listen to uncompressed music like classical music there are much more dynamic information in the music that is realy putting strees on the amp. Therefore I want a solution with the current modules that leaves no limmit at all. No matter the cost.

  I don't know the actual design but only 18-20W is disapated in a modules at full power (290W) and it can be decreased further by adding a seperate gate driver supply) You might find more information here: http://www.lcaudio.com/index.php?page=70

  So back to my original question! What would be the optimal parameters/materials etc. for a state of the art torodial X-former?

  Would I have any sonic benefit by oversizing the X-former to as much as 3kVA? Ore would there be other more important parameters (guage of wire, core material, shielding etc)

  I know that the rest need to follow! I already have 2 rectifier bridges capable of 35A 400V and the current capacitors are not bad at all. But I might need new ones if I should go for higher voltage (if this would add any positive sonic results). And maybe even more capacity is needed? Currently I have 4x10.000uf. With a class-D amp that almost only draw power when music is pressent this should not be bad at all.

  Have fun.
  
  

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  • Not yet. (long) - cheap-Jack 13:14:09 03/01/06 (1)
    In Reply to: Dead end? posted by Granholm on March 1, 2006 at 12:36:37:

    Hi.

    Browsing over the specs sheet you linked, you can boost up O/P power of the module to 200W/C & 350W/C by raising B+/B- to +/-65V & to +/-80V respectively. This will need a 500VA & 875VA power iron, EI or pancake type regardless.

    But who needs such high power for home audio?

    Dynamic headroom is not decided by O/P power alone. Too high power, too high damping factor delivered to speaker systems of high efficiecny only 'freeze' up the speakers. It can make things worse.

    I play classical music, LP, CD & DVD-audio 95% to the time & my power amp is only 35W+35W & "dynamic headroom" is never a problem to me.

    Why? Speaker impedance & efficienct matching & the driver pre-amp
    never overdrive the power amp.

    Headroom is the max. power O/P delivered by the amps before clipping. Gain should be just enough to give the enough power & sound pressure levels SPLs to your ears so that there will be amble of headroom reserved for dynamic climaxes.

    Before you go further, tell me what pream you are driving the modules & what setting of the volume control you get for your
    SPL you are happy with.

    Higher the volume setting, say beyond 12:00 hrs, better will be the dynamic headroom available & more enjoyable will be the music.

    This is my sonic experiences, shared with many other audiophiles.

    c-J
    
    
    

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    • Not that long ;o) - Granholm 13:25:55 03/01/06 (0)
      In Reply to: Not yet. (long) posted by cheap-Jack on March 1, 2006 at 13:14:09:

      Hi,

      Thanks for your reply! My preamp as an acttive design (have been using various passive as well - ELMA attenuators 24 step) The volume nob is a multiturn so there is no 12.00 setting. But ther is a damping scale in the display and I normaly have a damping of about 40db and down to 24db at some classical recordings whan I am home alone.

      My initial request was also if I would get any benefit of beefing up the toroide and I was not sure my self this was the way to go. But as VA is not the only important factor I still look for information of what would make the best toroide? I can have one custom made and can choose my self how it should be made. Many owners of the ZapPulse have experienced improvement in sonic quality by using bigger toroides but to my knowledge bigger is not always better. Hence the question about best quality! If bigger is not the way to go then what?

      By the way thanks for your patience ;o)

      Have Fun
      
      

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