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Difference between different Hypex NCore models and input buffers?

March Audio

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Just a general comment, if you do a look around the net at various power amps their gain is very typically around 26dB. Very rarely beyond the range of 21dB to 29dB.
 

March Audio

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Typical HiFi preamplifiers have rated outputs (SE) of 1-1.5V for a 150mV input. Obviously, if you put in 2.0V you will swing some very high voltages out of the good ones. I've had preamps that would swing up to 35V prior to clipping and most in my collection will easily swing 10-15V, all with extremely low output impedances. My Accuphase is rated at 1 ohm on the SE (RCA) jacks and 600ohms (correct) on the balanced (300+300) and it will happily swing 12V RMS out the RCA jacks. But the volume pot is around a 3pm to do that.

The issue is "typical" domestic preamplifiers would be a poor match in terms of volume pot position/range with a 12.4dB gain power amp. The buffer IS required to bring these amplifiers to a more typical overall gain. It's not rocket science.

Of course there are exceptions, but I expect few modern pre-amps would have supply rails beyond +-15V or +-18V because of the supply limits of the op amps, so thats an absolute max of 10.6 or 12.7 V rms assuming they can swing rail to rail which may not be the case. I would also be wary of their distortion levels at that voltage.
 
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restorer-john

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Of course there are exceptions, but I expect few modern pre-amps would have supply rails beyond +-15V or +-18V because of the supply limits of the op amps, so thats an absolute max of 10.6 or 12.7 V rms assuming they can swing rail to rail which may not be the case. I would also be wary of their distortion levels at that voltage.

True enough. Most of the "normal" domestic preamps are using +/-15V or +/-18V regulators.

My old Perreaux SA-33 will achieve greater than 20V due to the very internal high rails, and at negligible distortion. And a Kenwood L07C preamplifier has +/-47V regulated rails (the transformer is a 97V CT) and <10ohm output impedance. Consider these preamplifiers don't use off the shelf ICs.

Lch L07c output buffer:
1590992685606.png
 

boXem

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Of course there are exceptions, but I expect few modern pre-amps would have supply rails beyond +-15V or +-18V because of the supply limits of the op amps, so thats an absolute max of 10.6 or 12.7 V rms assuming they can swing rail to rail which may not be the case. I would also be wary of their distortion levels at that voltage.
Depends the topology of the preamp.
Fully differential, or whatever it is called, allows to theoretically double the output with the same rails, at the cost of doubling the hardware and complexity for volume control. As usual, tradeoffs, tradeoffs...
 
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