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-   -   Unity-gain "amp" for high-efficiency speakers (https://www.diyaudio.com/forums/solid-state/366490-unity-gain-amp-efficiency-speakers.html)

mudihan 20th January 2021 06:33 PM

Unity-gain "amp" for high-efficiency speakers
 
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 20th January 2021 06:38 PM

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 20th January 2021 07:13 PM

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

FAOW

mudihan 20th January 2021 07:17 PM

Quote:

Originally Posted by rayma (https://www.diyaudio.com/forums/solid-state/366490-unity-gain-amp-efficiency-speakers-post6497025.html#post6497025)
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 20th January 2021 07:21 PM

5.77Vpp is 2V RMS.

OldDIY 20th January 2021 07:25 PM

http://forum.vegalab.ru/attachment.p...5&d=1450782964#2734
?????? ????????? ?????????? - ???????? 137

mudihan 20th January 2021 07:27 PM

Quote:

Originally Posted by indra1 (https://www.diyaudio.com/forums/solid-state/366490-unity-gain-amp-efficiency-speakers-post6497085.html#post6497085)
5.77Vpp is 2V RMS.

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

MarsBravo 20th January 2021 07:29 PM

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 20th January 2021 07:31 PM

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

mudihan 20th January 2021 07:33 PM

Quote:

Originally Posted by MarsBravo (https://www.diyaudio.com/forums/solid-state/366490-unity-gain-amp-efficiency-speakers-post6497106.html#post6497106)
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.


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