Amp/Preamp Asylum

• I am strapping my two PF M7A amps. - tubesforever 00:32:54 10/13/05 (3)
  In Reply to: My two Berning EA-230's are back! posted by whitese on October 12, 2005 at 21:04:34:

  

  If you strap on the 8 ohm load you are actually providing a 16 ohm load to the speakers which changes their crossover's characteristics.

  So you want to strap at 4 ohms to show the proper resistance to your 8 ohm speakers.

  Hope this helps!

  By the way, I just love my amps strapped. Purists tell me this doubles my noise, but I never run much past a few watts anyway.

  Cheers!
  
  

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  • "If you strap on the 8 ohm load you are actually providing a 16 ohm load to the speakers which changes..." - jeffreybehr 09:00:11 10/13/05 (2)
    In Reply to: I am strapping my two PF M7A amps. posted by tubesforever on October 13, 2005 at 00:32:54:

    "...their crossover's characteristics."

    REALLY? Does 'strap' mean parallel? Paralleling a stereo amp's output channels HALVES the output impedance of the amp and combines the power. If the Berning's power rating was 30WPC, he now has 60WPC amps into half the labeled impedance. This doesn't change the speaker's crossover's characteristics any more than driving the speaker from one channel's 4- v. 8-Ohm terminals.

    It DOES, of course, change the amp's ability to drive various speakers, and experimentation is certainly in order.
    
    

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    • Here is the skinny on the mono - tubesforever 23:28:06 10/13/05 (1)
      In Reply to: "If you strap on the 8 ohm load you are actually providing a 16 ohm load to the speakers which changes..." posted by jeffreybehr on October 13, 2005 at 09:00:11:

      The PF M7A was designed as a stereo or mono amp. Providing 4 ohm, 8 ohm and 16 ohm taps.

      So strapped into mono this stereo amp simply requires that I run the amp from the 16 ohm taps in parallel in order to supply 100 watts per channel RMS with 400 watt peaks.

      Running any speaker designed at a specific resistance either above or below dramatically effects the crossovers. Just review any crossover chart displaying 4 ohm and 8 ohm crossover values and you will see what I am saying.

      Interestingly enough, many cheap 70's and 80's speakers sounded best on my 16 ohm taps. So what the heck was going on there? Probably the corrosion of the copper increased the resistance. That is my guess.

      Cheers!
      
      

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      • "Just review any crossover chart displaying 4 ohm and 8 ohm crossover values and you will see what I am saying." Huh? - jeffreybehr 11:18:26 10/14/05 (0)
        In Reply to: Here is the skinny on the mono posted by tubesforever on October 13, 2005 at 23:28:06:

        Those are the DRIVERS, tubes, not the output taps of the amp.
        
        

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