I had a few odd thoughts the other day that I would like to discuss.
To put it short, I've been thinking about the concept of playing audio backwards at the mastering/cutting phase.
Let me outline my train of thought:
A basic fact we all know is that any kind of audio consists mostly of transients (= fast impulses) and a decay tail. So in the natural order of a sound, and the corresponding electrical signal you have at first a short burst with a very high slew rate, followed by a decay phase with a much slower one (well, I don't know if slew rate is an appropriate term to describe the decay phase, but you probably get what I mean).
As an electromechanical system, any cutterhead is subject to inertia, which it always has to overcome. It's easier for the needle to stop back to the center point than to accelerate and follow a transient signal. Another limiting factor is the inductance of the voicecoils.
By cutting backwards, the head would first cut the decay tail that is slowly rising, accelerate to the peak, and then slow down really fast during the transient.
I'm not sure if it would be an advantage, but another side- effect of this method is that compression with slower attacks could be applied. Maybe this would result in more subtle compression?
I suspect it would be possible to improve quality by cutting "backwards", because:
- influence of voice coil inductance on transients is decreased
- influence of inertia on the moving parts is turned to benefit
- more accurate signal tracking
- increased thermal performance because heat builds up slower -> system has more time to dissipate it
disadvantages:
- you would have to cut from inside out
- you would have to rotate the cutterhead 180°
- you would have to reverse platter turning direction
- you would have to calculate your starting point in advance, or allow for a gap between the edge of the record and the starting groove (this might look odd, but turn out to be a benefit in regards to stamper robustness)
My question to the old trolls:
1. Has anyone done this kind of "backwards processing"? (I mean only the mastering part, not cutting)
2. Has anyone done "backwards cutting"?
3. Does this make any sense at all?
![Twisted Evil :twisted:](./images/smilies/icon_twisted.gif)