8 track cartridge looping gaps in audio

[vapidleopard]

I have a question about 8 track looping (though this probably applies to cassettes too).
I've basically made my own short loops (mostly 3-6 seconds).
I'm using by an Akai CR-81d recorder.
I keep getting a short gap in audio when I play back a loop I recorded. At first I thought this was because of the erase head ie the distance between the erase head and the record head, meaning the erase head is blanking a section ready to be recorded onto and when I press stop I'm left with that gap. So I tried to add a switch to cut out the erase head from the circuit but I still get a gap in audio.
Any ideas? Is it just bad splicing on my part?
I'm just wondering how you get a clean loop. I'd prefer to be able to record and loop live, rather than be chopping pre-recorded audio into loops.

I've tried so many things: stopping quickly when recording, switching out the erase head, yanking out the cart whilst recording, holding in play and record and just switching straight to play when I'm done recording. Everytime I still get that little gap in audio.

[TIMTAPE]

Pardon me if it's stating the obvious but did you put the splicing tape on the non magnetic side of the tape, ie: on the inside of the tape as viewed from the outside of the cartridge?

[vapidleopard]

Yes, I did. It's on the inside.

[jamesperrett]

Later multi-track tape machines used to have delays on the record/erase switching in order to allow gapless drop-ins and outs. I suspect that you will need to implement something like this in order to give you seamless looping.

[vapidleopard]

I didn't know this, thanks. Do you know of any particular machines that are enabled like this? Might be easier for me to look at purchasing one of them than attempt a modification to my Akai. Largely because I wouldn't know how to do this.

[Grubhead]

Eight track tapes have a small metal section that can NOT be recorded on. This is a foil sensor that causes the head to switch to the next track. Every time it passes the sensor it makes an electrical circuit which engages the solenoid to move from track 1 to track 2 and then track 3 and finally track 4, before returning to track 1. This thus ensures continuous playback.
Of course this of course doesn't make them ideal for endless recording. But without the foil the tape would be stuck on track one all the time, unless someone pushed the manual track button.

[vapidleopard]

I'm making tiny loops of just a few seconds and not using the foil sensors at all.

[ITAM805]

Usually one would record the piece first then do the splice, if done carefully there shouldn't be gaps or clicks, the later can be avoided by an angled splice.

May I ask what you are doing with these short loops?.

[crackle]

Record the audio then cut and splice into a loop, use an angled splice as mentioned above.

Mike

[TIMTAPE]

The angled splice will not be so good for narrow track, stereo tape like 8 track cartridge. On such a narrow track, the angle will have much reduced effect, and the two stereo tracks' being spaced some distance from each other, one track's edit will be ahead of the other in time. Also, a slow tape speed of 3.75ips is well short of ideal for splice editing of programme. You lose the timing precision.

Also the combination of slow tape speed and very narrow tracks has a high risk of tape dropout at or around the splice point - which may well be the problem complained about here. Back in the day professionals used wide tracks at fast tape speed to give themselves a fighting chance of noise free and dropout free splices. They also used the thicker Standard Play tape which was more robust and more able to withstand handling and physical splicing.

[ben]

I'd say its a momentary loss of good tape-head contact at the join. Bear in mind there is no backtension in the format, and without the spool of tape providing even minimal drag it's no wonder there are dropouts.

[vapidleopard]

Originally Posted by ITAM805

May I ask what you are doing with these short loops?.

I'm trying to avoid pre-recorded then splicing as I'd like to be able to loop live.
I make electronic music and use tape loops to loop short sections of audio to bring into the mix. Much like you would with a loop pedal, though I prefer the sound of tape.

[vapidleopard]

Originally Posted by ben

I'd say its a momentary loss of good tape-head contact at the join. Bear in mind there is no backtension in the format, and without the spool of tape providing even minimal drag it's no wonder there are dropouts.

Hmm, possible. Some of my tape loops use the central spindle, with the tape just wrapped around it once.
My shortest one is 3 seconds and that just goes around the outer spindles only, missing out the centre spindle.
Audio drops out for both.
Splice is 45 degree angle and looks to be a pretty clean splice.

I'm still leaning towards it being an erase head issue.
I would have thought a splice gap would be a tiny drop in audio but this seems longer. Also, just before the gap there's a slight pitching down of the audio, as if the gapping is gradual.

[llama]

I'd say a NAB cart machine (radio jingle machine) would be a much better starting point - 7.5 ips, 1/2 or 1/3 track, easily-opened carts, fully remotable.
Graham

[ITAM805]

and use tape loops to loop short sections of audio to bring into the mix

ok thanks, I love that sort of thing !

I'm sure you've checked this but does the drop out occur at the splice? A chinagraph pencil mark on the splice will highlight if the joint is timed with the drop out. If not then is sounds like an erase head issue as you suggested or maybe a bias osc over-run when you hit stop (I just made that up )

[Brigham]

It's GOT to be the Erase head.
Perhaps it has become permanently magnetized. Try screening it mechanically from the tape, or making the tape run past without touching it.
(I'm assuming that you haven't confused the erase head with the track changer, and are switching-out the wrong thing!)

[vapidleopard]

Originally Posted by llama

I'd say a NAB cart machine (radio jingle machine) would be a much better starting point - 7.5 ips, 1/2 or 1/3 track, easily-opened carts, fully remotable.
Graham

My dad gave me a load of NAB carts last year, after an upgrade at the Hospital Radio studio he works for.
I naively thought they would work in my 8 track before I investigated further. I must have around 20-30 carts of various lengths. The recorders don't seem to be widely available though (unless there's a variety of names they go under). Also, I'm guessing with it being for studio and not home use they will be quite expensive.

[vapidleopard]

Originally Posted by Brigham

It's GOT to be the Erase head.
Perhaps it has become permanently magnetized. Try screening it mechanically from the tape, or making the tape run past without touching it.
(I'm assuming that you haven't confused the erase head with the track changer, and are switching-out the wrong thing!)

I tried covering up the section of tape where the erase head touches but it doesn't record anything then.
I got the erase head switched out but it introduces pops into the mix. It was definitely the erase as I was getting sound on sound.

[vapidleopard]

Originally Posted by ITAM805

I'm sure you've checked this but does the drop out occur at the splice? A chinagraph pencil mark on the splice will highlight if the joint is timed with the drop out. If not then is sounds like an erase head issue as you suggested or maybe a bias osc over-run when you hit stop

The drop seems to be at the stopping point. Though I ought to try the above method with a chinagraph, to test the splice.

[cheerfulcharlie]

You know probably that you can create tape loops with a cassette?
- you just need to get some answer machine cassette shells
(the original tape in them is probably not good enough?)