Yes, I wouldn't call it clipping either though it is being driven out of its comfort zone. Marantz and at least some Denon's start to run out of juice so to speak at 1.4 volts. That is okay if you use their matching amps because they put out rated power at 1.4 volts input. So you just need an amp that is going to put out enough power with a 1.4 volt input signal.
If you are talking about the threshold of audibility, I don't think we know enough to really say whether 1.4 V, 1.5 V or even 2.0 V would make a difference to most people or for most applications. But by definition (unofficial I guess as this is just a bobby, not regulated, no fixed standards etc.), clipping is considered by one or more of the following conditions:
Wiki:
-
Clipping is a form of
waveform distortion that occurs when an
amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its
power rating.
Elliot Sound:
- An amplifier is said to be clipping when the output signal attempts to exceed the supply voltage. Since the supply voltage defines the absolute maximum peak output voltage from the amp, the signal will be clipped or 'cut off' if the input signal level is too high. For normal testing purposes, a sinewave is the most common test signal used, but this only tells part of the story.
So Amir may or may not be technically incorrect by the above definitions, but it is
misleading as it would imply that in this example, one may interpret 1.4 V as the "maximum" voltage the pre out can attain at distortions level that is clearly at or above the threshold of audibility that pretty much all other test benches including Stereophile and Audioholics would use between 0.1 or even 1% THD and that is -60 to -40 dB. We should also be reminded that when people see the word "clip" they would think at that point, distortions would become very bad, audible and would deteriorate literally rapidly, not just visudally/graphically as it is in these examples. That is absolutely not the case for any of the Denon/Marantz AVRs measured on AVR, then you still see 75 dB SINAD or 0.018% THD+N at 2 V, that is 43% higher than the ASR labelled "clip" point, that makes little sense.
By other measurement, including Amir's you can see that if he had measured the pre out at higher voltage, THD+N did not reach the point where it would really dropped down to the -60 dB level.
Below is the "amps driven" based on his measurements on the first X4700H, in which SINAD was much worse due to an operational issue that iirc, was due to the "downmixing" issue. I picked this one because in this one he did measure at voltages well pass 2 V.
In this graph, you can see clearly my point about why the 1.4 V, or 1.6 V is not the clipping point. The 2nd graph below, that was for the updated measurements when Amir realize the way he measured it the first time had resulted in lower SINAD because of the downmixing issue. In this graph you can see that he used a different scale, and did not measured up to above 2 V. If he had, you will most certainly see that the unit wouldn't have drop below 70 dB SINAD until at least 3 V. In this one, don't we think the clipping point for the X4700H's pre out should be more like 3.6 V?
Why are we penalizing the preamp/dac by labelling them clipping at a lower voltage only because it did so much better at the lower voltage? What if the unit manage 120 dB up to 1 V and then start to drop visually quick from 1.4 V to 95 dB at 2 V, are we to still label the 1.4 V as "clip"?
Now take a look of the NR1510 he just measured:
Here you see at below 0.5 V, SINAD was barely above 70 dB, yet he wouldn't consider it as clipping, and he didn't!
So, Amir has been consistent in referring the "clip" point as when he sees SINAD drops quickly, or what he called "precipitously". That's fine if a) all of the DUT's pre out voltage vs SINAD follow the same slope, but they don't, and b) if he, or us are to just eyeball the slope of the drop then we need to compare graphs using the same scale. We all know by changing scales of a graph, we can often create delusional effects, though unintentionally. And again, as I mentioned above, should we really label a DUT clip at 1.4 V if such graphs show very high SINAD (for AVR), such as 115 dB SINAD but drop from 1.4 V to 95 dB at 2 V?
I have also used one of his measurements on an Arcam to illustrate my point further, that is why the way he defined the clipping point could be misleading.
In this case, he did not use the term "clip" for the 0.9 V point, that is great, and it would encourage the reader to actually look at the numbers and judge for themselves whether this kind of pre out vs SINAD curve will meet their power amp requirements.
Now if he had measured this AVR10 up to 1 V only, then would he have labelled the 0.9 V point "clip"? My guess is yet he most likely would base on his track record.
In this weirder case, SINAD dropped "precipitously" from 0.9 V as Amir might say, but note that it actually turn around at above 1 V.
