Probably any knowledgeable analog tape professional is aware that the long-outdated 15 in/s IEC2 recording and playback equalization standard (formerly known as NAB) has serious issues in the regions approaching both frequency extremes. This was established more than four decades ago and lab measurements and the findings of expert listeners remain in solid agreement. I don't recall this as ever being controversial. You could easily repeat the tests today.
So, if someone is reporting that they prefer the sound of the IEC2 15 in/s equalization standard over that of the IEC1 15 in/s standard (formerly known as CCIR), my own first instinct and suspicion would be to look closely at their equalization chain, both in recording and playback.
Just as a carefully and correctly performed measurement of a phono stage's accuracy in tracking the RIAA curve is an essential first step to revealing, quantifying and distinguishing why different phono playback electronics can have audibly different sonic characters, so too it is with analog tape. Arguably, even much more so.
Unlike the case with vinyl pressings (the consumer medium), a series of calibration tones were placed on each master tape reel by recording professionals who wanted to be certain that playback could always be performed with the exact needed complementary equalization.
It's long been accepted that even mild response anomalies are disqualifying in high-end audio. (Or that they ought to be.) No knowledgeable or serious listener would ever accept a randomly adjusted graphic equalizer being inserted into their playback system. But that's what you might be doing if you connect after-market tape playback electronics to a repro head without verifying that the system plays back a calibration tape with acceptably flat response.
In my work, using a measurement protocol with one-twelfth octave resolution (typically measuring over nine or ten octaves with one hundred or more discrete frequencies) I observe certain accepted professional tape playback electronics designs that can routinely align to a given equalization standard to within about one-half a db, from 40 Hz to 22kHz.
Distressingly, I have also measured evaluation non-professional units that cannot be brought closer than eleven dB at some points. Caveat emptor. Any readers of this forum who are thinking of purchasing specialized tape playback electronics would do well to first verify the performance of the unit. At the very least, be certain that what you are buying closely tracks your specified equalization curve with the repro head supplied.
So, if someone is reporting that they prefer the sound of the IEC2 15 in/s equalization standard over that of the IEC1 15 in/s standard (formerly known as CCIR), my own first instinct and suspicion would be to look closely at their equalization chain, both in recording and playback.
Just as a carefully and correctly performed measurement of a phono stage's accuracy in tracking the RIAA curve is an essential first step to revealing, quantifying and distinguishing why different phono playback electronics can have audibly different sonic characters, so too it is with analog tape. Arguably, even much more so.
Unlike the case with vinyl pressings (the consumer medium), a series of calibration tones were placed on each master tape reel by recording professionals who wanted to be certain that playback could always be performed with the exact needed complementary equalization.
It's long been accepted that even mild response anomalies are disqualifying in high-end audio. (Or that they ought to be.) No knowledgeable or serious listener would ever accept a randomly adjusted graphic equalizer being inserted into their playback system. But that's what you might be doing if you connect after-market tape playback electronics to a repro head without verifying that the system plays back a calibration tape with acceptably flat response.
In my work, using a measurement protocol with one-twelfth octave resolution (typically measuring over nine or ten octaves with one hundred or more discrete frequencies) I observe certain accepted professional tape playback electronics designs that can routinely align to a given equalization standard to within about one-half a db, from 40 Hz to 22kHz.
Distressingly, I have also measured evaluation non-professional units that cannot be brought closer than eleven dB at some points. Caveat emptor. Any readers of this forum who are thinking of purchasing specialized tape playback electronics would do well to first verify the performance of the unit. At the very least, be certain that what you are buying closely tracks your specified equalization curve with the repro head supplied.
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