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Mastering Vinyl

Reply #75
No contortions at all.

Bullshit.  If it weren't bullshit then you'd have said it in your first post rather than ridiculously stumble over yourself parsing words to save face.  I'll put money on it that few if any third-party observers see this otherwise.

I'm not going to answer the rest of your off-topic omniscience about my level of understanding regarding analog tape recording or to what degree the tapes were (mis-)used during the process described in that paper.

My stern warnings to analog scott are equally applicable to you: be constructive or leave.  Test my patience and you will see your posting privileges curtailed.  This is topic is not a debate over analog vs. digital.

EDIT: More off-topic posts binned.  If you want them split into a separate discussion, PM either myself or another moderator/admin.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Mastering Vinyl

Reply #76
No contortions at all.


For independent iconfirmation of my claims about how analog tape can be used as an equalizer and compressor, please refer to the following document:

A typical set of detailed specs for a typical magnetic tape that might be used professionally

Please turn to page 3 and refer to the lower illustration entitled "Input Level versus Output Level at frequencies 1 kHz, 10 kHz and 16 kHz (12.5 kHz at 7 1/2 ips)
and tape speeds 30 ips (76.2 cm/s), 15 ips (38.1 cm/s) and 71/2 ips (19.05 cm/s)."

Perhaps most dramatic are the input/output curves for  7 1/2 ips operation. Note that the reference level for all curves is -10 dB. This means that all measurments were referenced to a recorded level of -10 dB. In general, the input and output track each other pretty well up to 4 dB @ 1 KHz, but only up to -2 dB at 10 KHz and only -4 dB at 12.5 KHz.  This means that the tape functions as a variable low pass filter with a sliding inflection point that decreases as recorded level increases. Now notice the corresponding curve for 1 KHz. This time the tape's input/output characteristic is reasonably linear up to maybe +5 dB, but that it smoothly becomes progressivly more nonlinear with inputs up to +18 dB. 

What the charts don't show directly is that the curves shown are for the tape when it is optimially biased. Using more or less bias than is optimal will generally increase the nonlinear effects.

A related question relates to what recorded levels were actually used. One guide is the recorder spec sheet which frequently used a reference level of +12 dB.  This shows a general expecdtaion that the recorder be routinely used in such a way that the tape was rather ninlinear at 1 KHz and highly nonnlinear at 10 KHz.

If we plotted a similar set of curves for a $20 sound card, all of the plotted lines would fall on the straight diagonal, given that we set FS = +18 dB.

My point is not about some presumed superiority of digital but rather that strong audible frequency response variations with changing recording levels are typical for analog tape, and completely unexpected to modern day techs who only have experience with digital.

Analog tape's nonlinear properties were in many cases a good match to the LP. Tape tended to smoothly remove or attenuate signals that might cause miscutting and/or mistracking on a LP. You can only imagine what happened when people started cutting LPs from digital masters that lacked the preconditioning that was automatic and inherent in magnetic tape. Because of the complex nature of the frequency versus level nonlinear attenuation of analog tape, simulating it with simple analog equalizers and compressors is non-trivial.

Furthermore, if you were to design an analog tape simulator, any particular simulator design whose performance  resembled a certain analog tape at a certain speed, would only be anythng like exact for that tape when it was biased in a certain way.  IOW a good analog tape simulator should have a number of strong adjustable variables - tape speed, tape type, and tape bias. Tape coating thickness and tape head track width are weaker variables.

Mastering Vinyl

Reply #77
..... I probably should be reading this thread, shouldn't I.

Mastering Vinyl

Reply #79

*IF* you cut a vinyl LP from a hypercompressed master, *THEN* you will either get very little playing time per side *OR* you have to seriously limit the levels which compromises the (already woeful) S/N ratio available from vinyl.

Seems to be that many new releases are very loud, come on double-LPs even thought they are only 45 minutes long (Ray Lamontagne's new album is about 10 mintues per side on vinyl I think), and cost more.

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