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.
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.
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.
No need for much of a buffer, it would be voltage limited.
You'd likely still need some voltage gain.
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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.
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!
{ 5,7pp = 2.85p => * 0.707 = 2.0Vrms (sine wave) }
several synchro-posts!
I believe the calculator assumes that Vmin would be negative 5.7v, i.e., Vmax is half of Vpp.
You 'believe'... and 'the calculator assumes'... that's what I doubt.
Naming the half of Vpp as Vmax is confusing, name it Vp instead.
So still the question: what are the measured/actual/real voltages from the DAC output? Is this DAC running on +/-6Vdc (+/-5.7 Vpp out) or +6/0Vdc (+5.7Vpp out)?
1/2√2 is only valid for sine waves, but in general accepted for common (audio) signals.
See attached.
Attachments
It’s not a fancy discrete Class A amp, but you could use a couple of TPA6120A2 Class AB unity gain headphone amp chips in parallel and drive 8ohms. Those chips can have up to +/-15v rails. Capable of 700mA each so 1.4A when in parallel. Probably would drive 100dB sensitive speaker more than loud enough. These chips have phenomenal performance specs with regards to noise and distortion.
https://www.ti.com/lit/ds/slos431b/slos431b.pdf
https://www.ti.com/lit/ds/slos431b/slos431b.pdf
More Class-A Amplifiers
Skip to the second half for something like what you're looking for.
If you go to the main page and ctrl+f "power buffers" he's got more posts on the topic.
Skip to the second half for something like what you're looking for.
If you go to the main page and ctrl+f "power buffers" he's got more posts on the topic.
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