Tech Square

Posted by Granholm (A) on February 27, 2006 at 12:42:04

In Reply to: I'm not a whatever expert. posted by cheap-Jack on February 27, 2006 at 12:25:24:

Sorry for not explaining well enough.

The power used by the amp is in idle (no music signal what so ever). This is about 10W for each chanel (stereo amp = 20W). But it is capable of supplying 2x300W to the speakers if the supply voltage is about +/-65V.

I Already have an 300VA teroide from the shelf (2x42V AC). But want to build this as extreem as possible. I don't mind spending a few hundred $$ or more if I can get just a marginal improvement. And I have heard from others with similar amps that increasign the VA of the X-former can improve sound.

The manufacturer I have contact to can do almost any design but they are not into audio (or at least not over the top - totally lost in space kind of stuff).

I have physical space to place a teroide as big as an of the shelf 3kVA in my current box and would not mind to have one made that big if this is the only design parameter that would ad to the quality. I dont think this is the case and therefore my question!

Please ask again if I still not make any sence...

Have Fun

• You want to post the specs of the amp.. - cheap-Jack 13:00:38 02/27/06 (9)
  In Reply to: Might not have been all that clear ;o) posted by Granholm on February 27, 2006 at 12:42:04:

  Hi.

  so that I can know more about it before I can comment?

  c-J
  
  
  

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  • Here thay are! - Granholm 13:13:26 02/27/06 (8)
    In Reply to: You want to post the specs of the amp.. posted by cheap-Jack on February 27, 2006 at 13:00:38:

    Hi cheap-Jack,

    Thanks for your time! The spec is at the bottom of this page: http://www.lcaudio.com/index.php?page=70

    I only use the amp modules and not the predetor PSU. In stead I use 2 T-Power 10.000UF 63V for each module at the moment. And the 300VA +/-42V AC Teroide.

    I am planning on upgrading the PSU and maybe later use the 700XE http://www.lcaudio.com/index.php?page=75 that in most regards are some what similar to the Zap Pulse 2.3SE.

    Have Fun
    
    

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    • Are this the spec you need? - Granholm 10:16:22 02/28/06 (6)
      In Reply to: Here thay are! posted by Granholm on February 27, 2006 at 13:13:26:

      Output Power 8 Ohms: 200 Watts RMS
      Output Power 4 Ohms: 400 Watts RMS
      Output Power 2 Ohms: 750 Watts RMS
      Output Power 1 Ohms (+/-58V 20-20.000 Hz): 1000 Watts RMS
      Peak Current 0,6 Ohm 100 Amperes 1mS
      Distortion THD < 0,2% 8 Ohms Nom. Load
      Distortion THD 0,04% 1 Watt RMS
      Frequency Response 0 - 150.000 Hz +/- 3dB
      Input Impedance 17 kOhm +/- 1%
      Output Impedance 5,5 Milliohm (70 Hz)

      My current supply is one toroide (2x42V AC 300VA) After a pair of rectifier bridges follows to 4 T-Power electrolytic capacitors at 10.000uF each.

      If you need any further information please ask!

      Have Fun
      
      
      

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      • Yes, I got it now. - cheap-Jack 11:15:56 02/28/06 (5)
        In Reply to: Are this the spec you need? posted by Granholm on February 28, 2006 at 10:16:22:

        Hi.

        So, what power O/P you want? What speaker impednace you are driving?

        With your 300VA power iron, taking 80% as overall efficiency, the max O/P power you can get would be around 120Wrms/channel theoretically assuming 2x42V were high enough for the power modules.

        See if this would help.

        c-J
        
        

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        • Good! And some more details! - Granholm 12:26:10 02/28/06 (4)
          In Reply to: Yes, I got it now. posted by cheap-Jack on February 28, 2006 at 11:15:56:

          Hi,

          To answer your questions first.

          The P/O should be as much as I can get from the amp for maximum dynamic headroom. Though I might stay on my current capacitors that are rated at 63V wich would limit the max output to some degree.

          My speaker impedance is 8 ohm with some areas going down to 6.

          The efficiency is somewhat around 90-94% for the ZapPulse and it would run fine on voltages from 35 to 75V DV (+/-).

          I would not mind skipping my 63V capacitors for an 80V pair to go for the higher current but I am not sure if the sound would improve by doing this!

          Ny my ultimate goal is not getting the amp to sound louder but better! (More controle, dynamic headroom, less noice... ei more natural)

          Have Fun
          
          

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          • More VA power, more O/P power. - cheap-Jack 07:59:15 03/01/06 (3)
            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

            
            
            
            

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            • 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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    • Sorry, I missed the specs. Pls re-post. (nt) - cheap-Jack 07:32:53 02/28/06 (0)
      In Reply to: Here thay are! posted by Granholm on February 27, 2006 at 13:13:26:

      .
      
      

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