Sep 2, 2011
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    1. Trio
      Part 3 of 3
      Now in the digital realm, that oscillator remnant is still there as part of the music content, or at least that is how the processor sees it unless there is some limiter action to attentuate it or remove it, it will affect how the music sounds overall because the audio level of that oscillator signal is actually as loud as the actual music signal. This is likely why you cannot switch it off.

      If in the analog realm it may just be the way the amp was designed for best overall performance- if the frequency response of the system is that high that it includes the range of frequency the bias oscillator- you do not want that delivered to your speakers because it just ends up as heat in the voice coils.
    2. Trio
      Part 2

      However the reason it is not able to be switched off for tape may have to do with the algorythm that is part of the if digitally based firmware of the processor used, or provides the best overall results of the software/processor combination because when tape is played back normal speed, the bias oscillator that was needed for the actual efficient transfer of energy to magnetize the tape, that bias signal is recorded as well. And some high speed recording decks will reveal this bias signal if you play with the controls in such a way as to bring that oscillator frequency down into the audio spectrum by getting the tape to record at what it sees as normal recording speed of 1 7/8 IPS, but fast forwarded while it is recording- on normla playback it becomes evident that it is there, otherwise it well above the range of hearing. Some inexpensive decks will do this too when recording, if it will allow you to use the fast forward "cue" feature, it often able to be heard.
    3. Trio
      The recording bias for Metal tape, chrome, or regular is a different animal from equalization, but does have some affect on the dyanmics of the recorded material. The ms, ns, and so on are the time factors, most likely for the same or similar reasons of an FM limiter stage.

      And no, none of the equalization or time factors are going to be the same by their nature.
      This is part 1
    4. Trio
      Not sure which post this is supposed to apply to. There have been a number of equalization schemes applied in the US and elsewhere. NAB equalization was sometimes used for tape playback circuits due to some people recording broadcast media signals, (which have some dynamic compression to remain within FCC regulations). But before standardized schemes were adopted, manufacturers of had their own which is very evident with 78's; so many early Hi-Fi systems had an adjustable "Contour" to adjust for those 78's. The "Standard" dynamic compression modes are most often the switchable EQ options on older stereo tube integrated amps, but if you have a more "modern" parametric EQ, installed between preamp stage and power amp stage, this is always in circuit. If the other compensation equalization is added (turning those on) the effects are somewhat additive or subtractive depending where your settings are.
      I am still not sure which thread this is in reference to.
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