Analogue multitracking

[notbuck]

In my basement sits about 75 old multitrack cassette tapes created by a fostex 28h 4 track recorder. Since the creation of these jems (mostly drunken jam sessions with my buddies) the recorder died along with any way to reliably play the tapes back.

I'd love to have access to these old recordings, if only to deromanticize them.

Anyone who knows anything about how these things work knows that I can't just play them back on a regular tape deck. I also know that there can be head alignment issues from one manufacturer to another.

Does anybody have any suggestions as to how I can get these recordings back?

[Jasaoke]

Playing them back on a regular tape deck "should" only let you hear tracks 1 & 2 (left and right respectively), and then flipping the tape "should" let you hear tracks 3 & 4 in reverse. Even the most basic computer-based editing software (like Audacity) will let you reverse any track (or pair of tracks). So I suppose you could rout the left and right outputs from a cassette player into your computer, record tracks 1 & 2, then flip the tape and record reverse 3 & 4. Thenre- reverse 3 & 4, and you could then time-align those tracks by zooming in in a waveform editing view. I would expect moderate to severe audio degradation, being that they've been in a basement.

[notbuck]

I've considered that, and here's why I haven't tried it yet.

Doing what you described requires playing the tape twice. Once in one direction, and once in the other direction. The tape will not play the exact same length of time both times it's played. Physical variations in the playback may cause it to play 30 min in one direction and 30 min and 45 sec in the other direction. Without clear beginning and ending points, adjusting for the temporal distortion would be pretty tough.

Also, tapes don't roll at a constant speed. The first half of the tape actually travels slower than the last half. As tape piles up on the reel it's pulled across the heads more quickly at the end. So flipping the tape and playing it in reverse plays the last section too slowly to match up with the tape going the other way.

Does that make sense?

I know the sound quality is going to be compromised, but I'd be happy just to hear something again.

[HurricaneBob]

Sounds like a job for these guys, they are excellent with tape particles.
I got nuthin....good luck.

[CMOR]

Sounds like a job for these guys, they are excellent with tape particles.
I got nuthin....good luck.

Priceless...

Buck, if I remember correctly, isn't the playback of those tapes on a standard player also down to 1/3 of the original tempo? I think I have some of your tapes too...Potz n' Boxes, my friend, Potz n' Boxes.

[notbuck]

If only I could hear pots and boxes again!

[Ron]

I've considered that, and here's why I haven't tried it yet.

Also, tapes don't roll at a constant speed. The first half of the tape actually travels slower than the last half. As tape piles up on the reel it's pulled across the heads more quickly at the end. So flipping the tape and playing it in reverse plays the last section too slowly to match up with the tape going the other way.

Does that make sense?

I know the sound quality is going to be compromised, but I'd be happy just to hear something again.

It could definitely be done if you're willing to put some time into it.
Tapes do roll at a constant speed. The reel just takes up the slack, it doesn't control the speed. There is a capstan (spindle) and pinch roller (rubber wheel) that control the actual tape speed.

You may run into head alignment issues, but a small screwdriver can be used to easily adjust the head by ear for each pass.

The reason that one side of your tape plays "longer" than the other is only because the leader on one end of the tape is longer than the other. You have to physically wind the tape to the point where the leader end aligns with the tape head before you start each recording. It is impossible for the same piece of magnetic tape to be physically longer on one side than the other.

Both of the recording passes can be loaded into a digital audio editor, reverse the backwards pass and adjust its start point until they line up.

[notbuck]

Thanks for your response. This has turned into kind of a thought experiment for me now.

Ok I see what you're saying about the amount of tape on the reels not affecting the speed, and now that you put it that way I recall that when the uptake reel is nearly empty it spins faster than when it's nearly full.

What I mean when I suggest that one side of the tape may play longer than the other side has more to do with physical things that happen in the analogue world that don't happen with digital. Any slight variation in drag or voltage inconsistency in the drive motor during the second playback would change the length of playback. A variation of only 0.3% would result in a 5 second difference in a 30min playback.

Of course this is all in my head, and I have no idea how how precise these motors are.

Plus, the more I think about it the less i suspect it matters. Even if I am right about the second playback speed, I still have to compress a 30 min track down to a 10 min track to account for the high speed recording.

So, if I did my best to line up the tracks while they were still 30 min long, the minute differences might be imperceptible after returning the tracks to the correct length.

This whole thing would be a lot easier if there was a way to make an audible mark on all 4 tracks at the beginning and end of the tape.

Thanks by the way for reading this and taking time to discuss it with me.

[Jasaoke]

If you record the leader strip in both directions, you should be able to see the difference between leader and tape in a waveform editor. Your tape hiss should be visible to some extend. Or, you could time the leader, and record a constant signal (like white noise) for the duration of the leader plus 1 second in the forward direction, then record the same type signal after the reverse side has gone 'silent'. (I'm assuming that the recorded material starts a bit after the leader) That should give you a nice, clear squarish wavefront for time alignment. I'm very interested to hear if & how it works out.

[floodcitybrass]

Also, tapes don't roll at a constant speed. The first half of the tape actually travels slower than the last half. As tape piles up on the reel it's pulled across the heads more quickly at the end. So flipping the tape and playing it in reverse plays the last section too slowly to match up with the tape going the other way.

Not true. The tape moves across the head at a constant linear speed.

The two wheels can have different rotational velocities but that has nothing with its playback speed.

[notbuck]

yeah I was wrong on that. I got carried away thinking about all the ways it would be too hard to try.

[tornandfrayed]

If you have 75 tapes, that sounds like a lot of time spent no matter what. Might want to just checkout a 4 track tape deck and see if it works. They are cheap..

http://www.ebay.com/sch/Recorders-/1519 ... ks=4&rt=nc#

[notbuck]

Yep, I found another Fostex x28h on ebay since I started this thread. So problem solved. Assuming this seller is legit. Ithink that is gonna be the best way to go.

[onetooloud]

If your still looking at a 4 track I have a yamaha with low hours on it.

[MistValkyrie]

maybe you could convert them to a different format althogether? I know there are ways (and companies) that will convert video tape to DVD, it's pretty quick and painless from what I've been told. I would imagine companies would offer services for audio tapes as well, it's not really that different in the long run. Good luck with it, though! I really hope you get them back.