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Great article by Mr. Austin on why measurements are important.
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Posted on November 19, 2020 at 08:48:15 | ||
But what happens if measurements do not characterize the real world performance of the DUT? Stereophile currently does steady state amplifier power measurements. Long ago, they used the Miller Research Amplifier Profiler to characterize the short term peak performance of an amp. Presumably, these measurements more closely correlate with the transient nature of music. Hi-Fi News still uses the Miller profiler. It seems that a test regimen should be an evolving process that seeks to correlate subjective sonic impressions with test results. |
Renewed the subscription.., posted on November 20, 2020 at 23:50:33 | |
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Joined: June 3, 2006 |
to Stereophile for two more years. I think JA Two is getting close to One Bill |
RE: Renewed the subscription.., posted on November 21, 2020 at 18:59:05 | |
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Joined: June 3, 2006 |
Thanks PAR. But I am too far away from Brooklyn and Long Island to grab a good beer! Cheers Bill |
RE: And..., posted on November 26, 2020 at 18:16:11 | |
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Joined: January 18, 2002 |
E-Stat said: "why some like THD or SINAD have little to no correlation with what we hear." True, while the human perceptual system has a wide tolerance to THD and SINAD, let's not get too extreme and suggest "little to no correlation". As per the blind test results using purposely distorted audio linked below, the overall results based on 55 respondents who felt they could hear a difference, there was a preference for distortion less than 0.3% (-50dB) being "better" sounding. While DACs and most good amplifiers can achieve better than this, many speakers would not be able to claim this level of low distortion (across the whole audible spectrum). While it's not necessarily the end-all-and-be-all of technical measurements, it's good to keep in mind that low THD/high SINAD does correlate with low nonlinear distortion and in general I think it's nice to aim for <0.1% (-60dB) as a reflection of a "transparent" source device which will likely be well received as being good sounding. Obviously formal blind testing recommended to better understand/verify this. Obviously this is a generalization. As with most human characteristics distributed over a "normal" curve, some audiophiles might actually prefer more distortion, while others demand even lower distortion.
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RE: You're most welcome, posted on November 28, 2020 at 22:31:33 | |
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E-Stat said: "To believe that artificially added distortion bears any resemblance to the far more complex reality of reproducing music. Enjoy your parlor games. :)" Not sure if this is a fair assessment, man... Kinda rude in fact. Maybe you can provide some decent intellectual discussion? Surely you must think at some high level, like say 3% or 5% THD actually is audible, right? If so, then there must be some kind of threshold whereby audiophiles do care about high-enough-fidelity playback? ------- Archimago's Musings: A 'more objective' audiophile blog. |
Do you ever , posted on November 29, 2020 at 05:25:53 | |
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Joined: May 12, 2000 Contributor Since: April 5, 2002 |
evaluate audio gear by listening to high quality recordings? I find that approach provides far more insight to understanding how a DUT fares reproducing live, unamplified music than simplistic numerically based tests. It's easy to score well on THD based tests-just dial in boatloads of corrective feedback! Which to these ears results in compromised real world performance. Years ago, there was a jerk here (since banned) who referenced a distortion perception test he referred to as "audiophile repellent". He posted his results and assumed no one would accept his challenge. I bettered his ability using the headphone output of a basic laptop and modest Shute IEMs. The THD threshold was in the several percent range IIRC. Boring recording. Boring test. Been there, done that. Wasted time. edit: I located that post here. -36 db relates to 2.5%. |
That was definitely above the threshold of rudeness :) (nt), posted on November 30, 2020 at 22:15:25 | |
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Location: Orange Co., Ca Joined: September 19, 2001 |
nt |
RE: Might be worth reading..., posted on December 2, 2020 at 06:34:20 | |
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Joined: May 12, 2000 Contributor Since: April 5, 2002 |
Might be worth reading via the link below. I am quite familiar with Putzeys and his work - along with using one of his Ncore amplifiers for the garage system. Arguably, his designs are the best switchers available today. While it has a wonderful midrange, I find the top end is compromised as compared with the VTLs. But it works great with New Advents and having 300 watts/channel on hand provides nice headroom. Lots of bang for buck but have no interest with it driving the stats in the main system. As well, you might want to ask yourself this: If a product can't perform well on "simple" sine-wave tests, how is going to perform well under supposedly more complex conditions? It's not a case of inherently linear design not performing well on sine wave tests. Rather - how many zeroes to the right of the decimal point actually improve the listening experience? Nelson Pass has demonstrated that such an assertion has reality bass-ackwards. Designs using boatloads of cascaded feedback do downright poorly on complex conditions. Here is a visual from the referenced article: As for me, I'll pass (pun intended!) on introducing complex distortion products for which the ear is more sensitive. Some feedback can be good, but lots is not necessarily better when the objective is determined by what you hear - as opposed to what you see on paper. Which is likely why I am not a fan of op amp based designs as they have complex topologies and rely upon large amounts (>40db) of corrective feedback. Have you ever replaced such with discrete FETs and compared the differences? I found them very enlightening with a Music Hall DAC where I replaced three TI chips almost three years ago with Burson FETs. My home theater/MC system uses Emotiva and Oppo products with TL072 and 5532 op amps, respectively. The result is neutral, but opaque sounding as compared with the Audio Research combination used upstairs which are zero feedback, class A designs using matched JFETs and triodes in the case of the SP20. |
RE: And..., posted on December 5, 2020 at 19:56:07 | |
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Joined: May 12, 2000 Contributor Since: April 5, 2002 |
They have a lot to do with what you hear. Raise them up high enough, you'll hear them. If you're referring to Electrophonic brown goods gear, sure. Which is what I started with in 1970 as a kid. ;) The tests performed by the "deceitful sorcerer", however, have little to do with what you actually hear with high end gear. Lower them anymore and it really doesn't matter. Once again, we agree. What my experience tells me, however, is those who pursue extreme levels on paper compromise overall sound quality in the real world. Switchers and op amp based devices are not yet ready for prime time in the highest quality systems. |
RE: Might be worth reading..., posted on February 6, 2021 at 14:48:50 | |
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Location: Front row center Joined: November 30, 2011 |
Thats some pretty low distortion numbers by 80's standard .. :) |
A component or speakers or cables sound different in different rooms to different people. Hel-loo! Nt, posted on February 14, 2021 at 13:22:36 | |
Nt |