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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 6th Dec 2020, 4:04 pm   #1
Michael Kay
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Default Ever so slight 'stuttering' sound on used tapes, but never on new ones

Hello,

I recently bought 6 brand new old stock Maxell UD 35-90 tapes, all still factory sealed in their original boxes. I then recorded various CDs onto them at 3.75 ips on the Akai 4000DB I have had for the past 12 months (which I removed from its case and cleaned all the switches and pots inside, including the essential SW1 switch, with isopropyl alcohol on buying, having downloaded the service manual and checked out comments on here. This eliminated all the crackles and occasional channel dropouts, and since then it has worked flawlessly).

All the recordings made on this brand new tape are perfect and play back flawlessly.

So I bought some used tapes, same type, and from different people on eBay. Recordings made on many of those tapes have very short, but fairly frequent 'stutter' sounds on them here and there. Not all the way through and I am being fussy. It's as if the tape's contact with the head isn't perfectly constant and smooth. It looks fine to watch recording though. Some, but not all, of these tapes have slight scratches on them running parallel with the edge. These are only light but persist thought out the whole tape. Damage I assume from a previous tape recorder.

I clean the heads and guides every time I make a recording and again between recording each side and again before playing anything back. The heads are in good condition as it is capstan and pinch roller (no indentations or marks). I also demagnetise the heads frequently.

Can anyone suggest what is causing this stutter sound please - it is very brief but I don't think they are dropouts as neither channel dims or disappears, even briefly. It is like a flutter/stutter to the sound.

I would suspect my machine but for the fact that it hasn't done it once on any of the brand new tapes.

Am I missing something?

Regards,

Michael
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Old 6th Dec 2020, 4:08 pm   #2
paulsherwin
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Default Re: Ever so slight 'stuttering' sound on used tapes, but never on new ones

It does sound as if the tapes have been damaged. Look at the surface closely with a magnifying glass. Can you see kinks or missing oxide?
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Old 6th Dec 2020, 4:15 pm   #3
Michael Kay
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Default Re: Ever so slight 'stuttering' sound on used tapes, but never on new ones

Hello,
Thanks for the reply. I am recording at this moment so can't stop the tape to check, but shining a torch on the tape and looking at it with a magnifying glass as it passes the heads (on the side in contact with the heads of course), I see very fine scratches parallel to the edge, but placed in different places on the tape rather than a 'groove' type scratch. That's just on this one, which isn't too bad actually.
Regards,
Michael

Last edited by Michael Kay; 6th Dec 2020 at 4:40 pm.
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Old 6th Dec 2020, 5:55 pm   #4
stevehertz
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Default Re: Ever so slight 'stuttering' sound on used tapes, but never on new ones

Before recording on the used tapes, try fast winding them from beginning to end and back again. They may be 'snagging' here and there as a result of them having become lightly 'bonded' layer to layer for many years. Once parted they should be ok unless left for a long period again.
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Old 6th Dec 2020, 6:36 pm   #5
Michael Kay
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Default Re: Ever so slight 'stuttering' sound on used tapes, but never on new ones

Thanks - I do play them first in case the recording on them has any interest, and save it if so. So they have all been through that process then. There is no sign of any sticky - when I watch the tape leaving the left reel, it does so cleanly without ever sticking momentarily to the surface it was in contact with. But thanks again.
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Old 6th Dec 2020, 8:39 pm   #6
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Default Re: Ever so slight 'stuttering' sound on used tapes, but never on new ones

The Maxell tapes were very good tapes so will tend to show up others. If it's dropout it's subjectively worse at slower speeds, with narrower tracks and on the thicker based tapes, eg: standard play, than long or double play as the stiffer tape doesn't conform to the head face as easily. Obviously dust and dirt on the tape surface makes things worse. Tapes can be cleaned. I had a particularly bad case of dropout on an old existing recording but cleaning didn't improve the dropout. I guessed the initial recording was the problem. An underbiased recording will dropout more. Slight overbias means that a small gap between tape and head reduces that overbias, increasing signal so dropouts are somewhat compensated for. Obviously dropouts tend to be worse at the ends of the tape due to physical tape damage and dirt.

Over the years with the use of slower speeds and narrower tracks manufacturers improved the smoothness and consistency of the oxide layer. It became more mirror shiny whereas previously it was a matt finish. In manufacture I believe they looped the tape back on itself so that no abrasive was needed. It polished itself.
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