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Audio Buffer – unity gain link stage/headphone amp with ultimate output drive capability

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pma

pma

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What does it look like into say a 10 k load plus a small capacitance?

Virtually same as into 1Mohm.

I placed the PCB to the Modushop box to make a headphone amplifier.

BUF2_headamp.JPG


Edit: 115kHz square response + rise/fall time added

headamp_115k_sq.png
 
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pma

pma

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I made a measurement with RightMark SW, a comparison between Topping D10s-E1DA Cosmos loopback and the same with the Audio Buffer inside the loop.

buffrep_chart.png


Frequency response
fr.png


Noise level
ns.png


Dynamic range
dr.png


THD
thd.png


IMD
imd.png


Crosstalk
ct.png


We can see that the Audio Buffer makes no audible degradation. If we explore THD spectrum of individual measurements, then with Audio Buffer inside the loop we have cleaner spectrum with much less high order harmonic distortion components. This because the output stage of the Audio Buffer is able to give much more output current and operates at higher idle current than the output opamp of the D10s DAC.
 

restorer-john

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The in band ripple is more than I would expect. I presume it is the D10s.

Nice buffer Pavel. :)
 
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pma

pma

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The in band ripple is more than I would expect. I presume it is the D10s.

Nice buffer Pavel. :)
Thank you :).
The in band ripple is mostly from D10s, but also from E1DA. We pay for the very steep filters in both devices, the price of almost no mirror images.

Even more ripple for 44.1kHz Fs.
fr.png

Buffer open photo (as tested)
Buffer_photo_small.JPG
 
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