HiDRA (High Dynamic Range Analog) What if . . . ?

[cbdb]

Circling back for a moment to the user-friendliness question, HiDRA could provide recording technicians one very unique and valuable user-friendly feature: it could eliminate the need for re-takes.

Usually not necessary with good performers but all you need to do is send the signal -6db (-10db if your really woried) to another track (that can be erased after). I used to do this when I recorded cartoon voices. (Some lines had over 20db dynamics! (whisper to a scream)).

[Bill F.]

how fast are you switching tracks?

In post, laying down the control track, you can switch whenever and as often as you like to achieve your goals.

If you wrote computer software to automate it, you would have to include parameters beyond level thresholds, such as switching lead timing, logic to prevent switching events from piling up on each other, logic to jump multiple tracks in a single switching event if need be, etc.

all you need to do is send the signal -6db (-10db if your really woried) to another track (that can be erased after).

Cool! Sounds like you're already doing two thirds of what I'm proposing! The HiDRA control layer takes the final step by combining the best of both tracks--the first track for its higher gain during all but the peaks, and then switching to the -6dB track for uncompressed peaks--without incurring generational losses.

[cbdb]

So the switching is done manually. Sounds like a lot of work. If you automate it you could use the rec head on playback to "look ahead" and switch the tracks just before you need it, so its not switching on signal rise (think drum hit) but right before it.

[Thunau]

I have recording background and some photo editing background. What Bill F is describing is not analogous to HDR photography. It would be, if you didn't compensate for the different recording levels. But once you compensate for the varying recording levels you only gain S/N ratio- which on the studio side is already as good as the playback gear so no real gain there.
If you don't compensate for the varying recording levels than you would have effect analogous to HDR- you bring up stuff that otherwise is lost, while not clipping the loud parts. If you automate the levels so that it all flows fairly nice you have a device analogous to a compressor or AGC (automatic gain control).
The only difference is, compressors and AGC devices work post mic preamplifier, but I recall seeing a device that actually combined compressor and mic preamp in one unit where the VCA actually served as microphone gain element.
But seeing how a good mic pre circuit achieves 130dB S/N ratio, even with 30dB of headroom you can get a nice and quiet recording. Then use a compressor or AGC unit to level the program for maximum enjoyment.
Also, there are downward expanders that push the noise down when no signal is peresent. These are the anti-compressors and they work very well in many processes including Dolby and DBX noise reduction systems.

[diy4]

This has been done before, do a search for "3M Dynatrak" .

In the early sixties 3M used a 1" 8-track recorder with 4 pairs of high and low tracks. No control track is needed, the level on the tape is detected and makes the switch automatically.

It didn't catch on because new tape formulations improved noise levels, Dolby A was just around the corner, and hey, it costs twice as much. But the idea is certainly valid. Lots of great tunes were recorded this way.

edit: The trend for several years now has been to wider tape tracks, e.g. 1" 2-track. This lowers noise and distortion. Sounds great!

And no, this method isn't compression at all.Nothing to do with it.

[Bill F.]

If you automate it you could use the rec head on playback to "look ahead" and switch the tracks just before you need it, so its not switching on signal rise (think drum hit) but right before it.

An excellent idea, of the caliber I was hoping for on this forum!

[Bill F.]

Diy4,

Fascinating--thanks! Will google!

Maybe it's time to dust off old tech pinnacles like this now that expectations for dynamic range have evolved, and see how the best of analog stacks up against modern digital.