But PCM played great with this NC500, so maybe an issue with DSD playback rather than the output stage drive problems 😕
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I have good volume control with PCM and HQplayer. With PCM cranked to max it hardens a bit just the same. Full blast is just too loud.
Then it goes to show that it is not a drive issue but some digital clipping occurring within HQPlayer-AKM processing. So I would think even adding buffer or external volume will not help here.
What about your Mirus DAC with HQPlayer in direct DSD mode?
I thought it was just the output stage working too hard. It doesn't sound terrible, just a bit more strained sounding. It's the same with Jriver. Even with PCM, going over about 75% volume it doesn't sound as good. But twice as loud with the buffer sounds smooth as silk. This is why I'm thinking it's the output stage doesn't have enough current to drive those amps with ease at higher volumes.
I never tried the Mirus direct buffer less to the amps. It was fine in SDMdirect. But I had the volume control in the chip.
Ok, I was wrong about drive issues then and you will really need a buffer for your NC500. Maybe you can get Sonny to do a special output stage with more drive to match and in this way eliminate extra buffer stage in the chain
I already have a very good discrete class A buffer for the NC500's. But for use with Sonny's DAC, it would be nice to just have this buffer stage built on to his output board. It's a real bruiser capable of 200ma current with still only 0.0005% THD+N
Here's the noise floor plot for it:
I'm gonna try out Sonny's preamp board with 12db gain. Combined with his output board, should be plenty of juice. Then I'll compare it with his R2R analog volume to my buffer using HQplayer volume control with PCM.
Should be interesting.
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Not to mix up threads just a small info here.
The output stage single ended with an max sink current of 10mA. I did not see that the first time looking on the datasheet, but 8K resistor from the output terminal to the input generates close to 10mA current draw under worst conditions.
The preamp output stage is push-pull for the same reason...
BR
Sonny
looks cool!
It's like a Diesel engine with 1200NM of torque in a Honda Civic! Just barely idling under peak load conditions 🙂
Discrete output stage : Sink is 7mA, source is >50mA but then the transistors enters non linear Hfe region.
For the preamp it is +/-200mA with good result. But i have not yet done an distortion test at these loads. But it drives a pair of B&W P7 very well.
Ok, based on your previous post of the NC500's sinking 10mA into the output stage, it's entering into the non linear Hfe region then when I turn it up to maximum?
Your preamp should handle this task with ease then. 🙂
Why not build the same capability as preamp into the output stage? This would have solved the drive to NC500 nicely for Mike
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