I don't see why. Overall the new measurements are pretty much what one would expect. The tube amp is getting into trouble a bit earlier than the SS amp, and clipping a bit more softly. Otherwise they are very similar. Nothing like the original measurements that had the 007t in trouble vastly earlier.Stax aficionados will bring in the war chest now
0.2% distortion is where both amps start to dominate over HP distortion. That is -54dB. Usefully the SR-303 has a sensitivity of 100dB at 100V. Given we have a load of 100kΩ*, 100V is 10mW. The HP distortion graph for the 313 goes into clipping at about 114dB = 500V. The amplifier graph for the 313 shows it reaching -54dB distortion at a hair over 100mW, or closer to 320V. So the numbers are not wildly off. Either way it is pretty much at the limits of the power rails, whihc is what we expect. The 313 is in the usual SS near vertical take off of distortion, so there is wiggle room for picking your points.
The HP driven by either of the two amplifiers reaches about the same distortion at 3% aka -30dB. This doesn't match anything on the amplifier only distortion, and I would suspect we can safely assume we are past useful measurements in the clipping area. We may be clipping the HP.
If we look at the lower levels, we can see at the LHS, that both amps are driving the HP at about 0.05% distortion: -66dB and at 104dB SPL, which would be a hair past 10mW on the original amplifier graph. At this point the 007t originally measured at about -44dB distortion, which is something of a gap to the -66dB measured driving a HP. Indeed the 007t never measured -66dB distortion at any drive level in the first measurements. The best it ever did was -58dB. So the gap is minimally 8dB, and from the numbers, about 22dB.
The new measurements might not please the tube fanatics, but they don't show that the 007t amp in much worse a light than one might reasonably expect.
* The load is a bit ambiguous. The AP actually presents 100kΩ per leg of its differential input to ground, plus capacitance. So it may be more accurate to take 200kΩ. Capacitance doesn't make much difference at 1kHz, but becomes the dominant load near the top of the range. This is all very ball park, so I'm not worrying right now. If the graph was generated assuming 100kΩ the derived voltages will still be correct even if the power delivery isn't.
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