Unity-gain "amp" for high-efficiency speakers

[mudihan]

Has anyone tried using a unity-gain "amp" with, say, 8A current output capacity (essentially just a buffer stage) to drive high-efficiency full-range speakers (say, 100db sensitivity) out of your typical DACs with a solid 2v output? I.e., the set up would be just a digital source with a 2v output ==> high-current buffer ==> crossover-less, high-efficiency, full-range speakers.

I am considering using a buffer as way to minimize noise and simplify/shorten signal path. But I am not sure whether the lack of any voltage gain will work in terms of plain loudness and musical dynamics.

[rayma]

The 2Vrms output on an 8R speaker would be 1/2 W, and only 1/4 A current.
No need for much of a buffer, it would be voltage limited.
You'd likely still need some voltage gain.

[woody]

Well here are 2 designs for that the FAOW and the MOFO. Here is a link to the FAOW.

FAOW

[mudihan]

Originally Posted by rayma

The 2Vrms output on an 8R speaker would be 1/2 W, and only 1/4 A current.
No need for much of a buffer, it would be voltage limited.
You'd likely still need some voltage gain.

Thanks. Very informative. I just found out that my DAC has Vpp of 5.7v at full scale output, which appear to translate to 4Vrms. I think I may be in the real low end of the doable zone.

[indra1]

5.77Vpp is 2V RMS.

[OldDIY]

#2734
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[mudihan]

Originally Posted by indra1

5.77Vpp is 2V RMS.

You are right. Used the wrong calculator and put 5.70v as Vmax instead of Vpp.

[MarsBravo]

5.7Vpp renders approx 2.0Vrms. You need a bridge to reach 3.8Vrms.
{ 5,7pp = 2.85p => * 0.707 = 2.0Vrms (sine wave) }


several synchro-posts!

[MarsBravo]

If Vmax is 5.7, then what is Vmin? 0.0V? Then it's still 2Vrms.

[mudihan]

Originally Posted by MarsBravo

If Vmax is 5.7, then what is Vmin? 0.0V? Then it's still 2Vrms.

I believe the calculator assumes that Vmin would be negative 5.7v, i.e., Vmax is half of Vpp.