Australian Hi-Fi

Laboratory Test Report

- Steve Holding

Newport Test Labs measured the frequency response of the Capri S2-SC as extending from less than 1Hz right up to 277kHz –1dB, and from less than 1Hz right up to 301kHz –3dB, which is an incredibly extended frequency response — far more than you will ever need. The extension at high frequency was assisted by the fact that despite those 1dB and 3dB downpoints, the lab measured the frequency response of the Capri S2-SC as being flat-out to 100kHz, after which it started a slow rise that peaked at +5dB at 170Hz before falling to the tabulated down-points. If you combine the –1dB downpoints with the +5dB peak, this puts the overall normalised response at <1Hz – 277kHz ±3dB.

The frequency response of the Jeff Rowland Capri S2-SC within the audio band is shown in Graph 1, and you can see that it is essentiall­y ruler-flat given the extreme vertical scaling used (0.5dB per division). The response is only 0.1dB down at 5Hz and 0.25dB up at 40kHz. Channel separation (not shown, but tabulated in the accompanyi­ng test result chart) was an extraordin­arily good 130dB at 1kHz, and even at the extreme ends of the audio band was well into three figures, being 111dB at 20Hz and 114dB at 20kHz. You’ll never, ever, need more separation between stereo channels than is on offer here!

Channel balance was also spectacula­rly good — one of the best the lab has ever measured, I believe — with a difference in gain between the two channels of only 0.002dB (at 1kHz). Interchann­el phase was perfect at and below 1kHz, registerin­g a perfect result, but was 0.4 degrees out at 20kHz. This is only of academic interest (and likely related to that high-frequency rise noted earlier) as it will have absolutely zero effect on sound.

Graph 2 shows the total harmonic distortion of the Jeff Rowland Capri S2-SC, as measured by Newport Test Labs. Although there are three distortion components visible at 2kHz, 3kHz and 4kHz, these are actually residual distortion components from the lab’s signal generator, so the Capri S2-SC has added no distortion of its own to the output. This means that any distortion components that may be present are more than 120dB down, which, when expressed in the usual percentage terms, means that each would contribute less than 0.0001% to the total. As for that total, Newport Test Labs measured THD+N at 0.002% — far, far lower than would ever be required for perfect music reproducti­on.

You can also see on Graph 2 that lowfrequen­cy mains noise (the almost invisible peak at the extreme left of the graph) is close to 100dB down, so it should not come as a surprise to see that Newport Test Labs measured the overall signal-to-noise ratio of the Jeff Rowland Capri S2-SC as 95dB A-weighted. This is an outstandin­g result, not least because it’s referenced to a very low voltage (500mV). If the lab had used a higher reference, the S/N ratio would easily have exceeded 100dB.

Graph 3 shows IMD, and you can see there are two sidebands to the test signals: one at 18kHz that’s 115dB down (0.00017%) and the other at 21kHz that’s 112dB down (0.00025%), while there are two difference signals down at 1kHz and

2kHz that are 113dB down (0.00022%) and 124dB down (0.00006%) respective­ly. Although the Jeff Rowland Capri S2-SC has levels of IMD that are measureabl­e (just!), they’re not levels that would be audible under any circumstan­ces.

Newport Test Labs also measured the Capri S2-SC’s response to a 1kHz square wave, the result of which is shown graphicall­y below as an oscillogra­m. As you can see, there’s an overshoot caused by that peak in the high-frequency response at 170kHz, but otherwise the square wave is perfectly reproduced.

Newport Test Labs measured input sensitivit­y as being 99mV for 500mV out, which puts gain at 14.1dB (Jeff Rowland specs it as 14.0dB). In a rather clever move, Jeff Rowland has arranged the circuitry so that when the volume control is set to 85.5 there is no gain applied at all (so 0dB gain). Therefore, 100mV at the input will give 100mV at the output.

The review sample of the Jeff Rowland pulled nearly 15 watts from the 240V wall socket, which is around three times what the company

specifies. That said, the preamplifi­er still ran cool enough that it could safely be used in an enclosed space.

Overall, the Capri S2-SC delivered exemplary results on Newport Test Labs’ test bench. It’s an outstandin­g performer.

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