Floppy Disc Delay

Started by Electron Tornado, October 02, 2017, 12:11:24 AM

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Electron Tornado

It looks like this has been out for over a year, but a search on here gave no results. This is an interesting delay:







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"Corn meal, gun powder, ham hocks, and guitar strings"


Who is John Galt?

thermionix

Neat idea!  Would 5 1/4" offer greater fidelity, or speed range?

Electron Tornado

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"Corn meal, gun powder, ham hocks, and guitar strings"


Who is John Galt?

anotherjim

Should have grabbed some 8" drives & discs when they were around...



Mark Hammer

I've got both 3-1/2and 5-1/4 units (single-sided!) in the garage.

In answer to Thermionix's question, no.  While it makes sense that one's first inclination would be to equate large recordable surfaces with the difference between 1/8", 1/4", and 1" or 2" tape, mag-storage drives don't work like that.  In many respects, it was the development of more precise stepper motors and read/write heads that allowed fitting the same digital information into smaller and smaller spaces.  That is, the space required to stick 1k worth of data on an 8" unit was much larger than the space required to store 1k on a 3-1/2" unit, because the head wasn't as precise and the stepper motor could only budge the head over in bigger steps.  I would imagine the plastic frame that the smaller diskettes came in also permitted a more reliable recording surface, that facilitated precise and predictable movement.  The larger 5-1/4 and 8" sizes weren't as "floppy" as the name suggested (i.e., they wouldn't droop if you held them by the corner), but they were not as mechanically rigid, by virtue of their size.  In some respects that kind of flexibility compelled requiring a big area to store a track, such that one could return to it on command.

The single-sided 5-1/4 drives I have would let you store up to 90k on one side, while the later 3-1/2 units could pack in 1.44meg in a much smaller space.

As a recording medium, they should, I theory, provide much longer life than the more traditional tape loops of Echoplexes, Copicats, and such, simply because the tape-transport mechanism is harder on the tape than a disc drive is on the diskette.  Bear in mind that loop tape has to be pulled, with a certain amount of counter-pull to stabilize it.  Those counter-forces are part of what contributes the wow-and-flutter to tape delay, and would be missing from a disc-based delay.

If the data is recorded and read in digital fashion, with accompanying A->D->A conversion, then they would provide suitable means for yielding delay, but then the goal of even considering them is in search of another means to provide what mag tape provides.  If one is searching for the "sound of mag tape", then a disc-drive would not likely yield the desired result.  A better medium might be those little answering-machine cassettes (which I think T-REX has already done).

duck_arse

we weren't allowed to TOUCH the 8" drives, only the engineer could open and mount them. and I don't think they cost 1500 euro squid equivs each, even back in 1978.

so they is doable, but needs a microcontroller? bah.
don't make me draw another line.

anotherjim

Do it have to be anything digital?
I thought I saw the idea of using dictation recorder heads & electronics and the floppy drive only has to spin the disc. You'd use the disc as if a tape loop. Diameter & spin speed = delay time.
Then again an 8inch disc could be taken out of the envelope and used on a turntable for a more visual thing with longer delay & switching speed?

Mark Hammer

With tape, the location of an analog signal is given directly by the form: the tape passes over the head and that part of the signal can be found there.  With a disc, there is the matter of how to move the read/write head such that content can be relocated for playback at some later point.  Don't confuse mag discs with vinyl ones.  On vinyl, the location of content is given by the grooves and a pre-ordained movement of the cutting stylus and resulting grooves.  Mad discs ain't like that.

thermionix

Quote from: Mark Hammer on October 02, 2017, 09:42:48 AM
In answer to Thermionix's question, no.  While it makes sense that one's first inclination would be to equate large recordable surfaces with the difference between 1/8", 1/4", and 1" or 2" tape, mag-storage drives don't work like that.

I was thinking more about circumference and speed, such that for a given RPM, the "intelligence" could be spread over more recording surface, like faster mag tape, rather than wider.  This of course assumes we're talking about reading and writing at the outer edge of the disk.  You know, the first track on an LP side sounds better than the last.

However...I didn't realize this was a digital delay, I thought they were using the floppies as a substitue for mag tape, recording audio instead of ones and zeros.  So, disregard.


PRR

Long long ago, mass quantities of used-once *computer* tape came into the surplus market. Audio folks tried to use it for (analog) audio. The oxide is very different. Digital is optimized for extreme flux, analog is optimized for the mid-range of flux. Horrible distortion. (Hmmmm.)

Heads too are very different.

So try it. Figure how to keep the motor spinning. Hack the head to record AND playback.... ah, you can't do both at once, as you need for audio delay. (You could do a Repeat.) I suppose you could steal another head, but mounting is tough and tight.

I see that CloudsHill has done a LOT of mechanical fabrication for their device. That can't be easy/cheap.
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