Tape Splicing Thoughts

[TIMTAPE]

Paul mentioned that even the best splicing tape eventually fails. Sometimes old splice adhesive simply dries out and the splice just falls apart cleanly.

Other times some of the adhesive (especially if ordinary sticky tape was used) migrates to adjacent tape winds, gluing the winds together. It's not even safe to play the tape for fear the oxide layer will be torn off the backing layer. I've had to resort to playing the tape at very slow speed, looking out for signs of a splice coming up so I can stop the tape before the adjacent winds unwind from it. Then I had to apply solvent to dissolve or at least soften the adhesive so the tape could be safely unwound to reveal the original splice. Reels with opaque flanges which obscure the tape pack edges are particularly difficult as you're working blind. Very slow, careful work needed if you want to preserve the original recorded audio around those areas.

Sometimes the adhesive hasnt spread enough to cause this problem but still there's some adhesive now stuck to the recorded oxide so it has to be carefully cleaned off to avoid audio dropouts at those points.

[Simondm]

Anyone who worked in broadcast audio in the 1970s-1990s probably made many splices in the course of their career. I probably spent working years doing nothing but tape editing (for content), 8 hour days. Here's a few quick thoughts:

Tape gauge and speed: Cut-editing was universally done on 1/4" tape, not 1/8" (cassette) or larger, multitrack formats. Most speech editing was done at 7.5 IPS, and in my experience directly on location-recorded tapes, unless it was a studio recording at 15 IPS. It was considered wasteful to work on a copy, generally, although de rigur if working on something very precious (e.g. an interview with royalty). Anything recorded at slower speeds would be copied up to a higher speed for editing though, as it's too slow and fiddly to mark up edits at 3.75 IPS. Music editing was at 15IPS. Nagra SN tapes were transferred before editing.

Splice angle: From the late 1970s onwards, as stereo became commonplace in radio, The blocks fitted to BBC machines had three angles: 90, 45 and 60 degrees. 90 was almost never used. 45 was OK for mono tapes, and 60 was the most used on stereo machines.
Reasons for choosing specific angles:

• 45 and 60 give you a magnetic crossfade (obviously 60 is faster).
• They also ease the splice past the heads (the sticky tape makes the tape stiffer, so contact can be an issue).
• There are several issues with using 90: it can cause a physical jump (dropout), if there is any low-frequency content on the tape, it almost always introduces a click, as the LF content changes suddenly at the join. This effect also happens with 60 and 45, but isn't so severe (a muted thump). A magnetized razor blade will also cause a click.
• The unwanted effect of an angled splice is the swing of the stereo image. This is a right PITA in drama and music editing, and the main reason why 60 was the preferred angle. Mono recordings would be made on stereo machines (in Bristol we lost our last mono machines by around 1981), and unless the tracks are paralelled on playback, the image-swing effect persists, even with mono material. Furthermore, tape machines for TV use were twin-track, not stereo (the twin-track inter-channel gap is wider, to reduce crosstalk). This exaggerates the image-swing effect. This image-swing (i.e. timing) issue is one of several reasons why larger format tapes (multitrack) were not edited, apart from joining leaders, although I believe it was a music industry practice).

Tricks:

• To avoid an image swing (last resort), you might make chevron edits: cut at 60 usually, but only to the middle of the tape, then flip it over carefuly in the edit block, and cut the second track oxide-up (normally all editing was oxide-down, so you can see the marks on the back of the tape). This works really well, but it's fiddly and slow.
• I've seen really experienced editors stretch tape physically, to create a downward inflexion at the end of a word/sentence - copy first! I've tried it but only with limited success.

Other methods:

• Generally, BBC practice was cut editing, but other broadcasters (notably RTE in Duiblin) mandated dub-editing, to save tape costs. This is very slow, as the shortest possible time to edit an item will be its running time + each edit setup.
• Studer models (at least the A80 and B67, and probably later ones) could have their record circuitry timed, so that erase and bias currents came up at the same point on the tape, when record was turned on (I don't have experience of Telefunken, but I'm fairly certain Leevers Rich couldn't do this, and BTR2/RD4/4s certainly couldn't). I don't think checking this timing was part of BBC maintenance procedures (Ted?), but RTE's A80s were carefully tweaked. IMHO, their style of dub-editing, with its dependency on exact timing, required far more skill than our razor blades!
• On A80s there was also a record-inhibit tape guide, that could be pushed out of the headblock from the back, which returned fast under spring pressure when a buttin on top was pressed. This enabled a mechanical dub-edit (start the machine in record with the record-inhibit guide enabled, then push the button at the right moment).
• Earlier Studers (and optionally A80s) had pop-up editing scissors (after the capstan), but they were very sensibly disabled/removed on the BBC machines I used.
• A80s and some later models also had a clip-on edit-marker that worked a bit like a rubber-stamp pad. Tried and rejected by most editors, as every mark looked identical - we much preferred scribbling meaningfully on the tape with a Chinagraph!
• 16mm Sepmag* audio tracks (film soundtrack) were also physically edited. 16mm/25fps travels at roughly 7.5 IPS, and in later years had a Mylar base (originally Acetate), but the track widths are greater - both a blessing and a curse. A standard Italian editing block has two guillotines - 90 for picture, and 60 for Sepmag. Most of the time edits were done with the guillotine, but occasionally a diamond punch was used to make a physical hole in the soundtrack, either to remove a click, or ease the start or end of a piece of track. Obviously audio editing in this case was limited to frame boundaries, and 1/25 sec isn't sufficiently fine resolution for many editing tasks, so voiceovers, etc. might be edited on 1/4" tape and re-transferred to sepmag for dubbing.

Hope the above is of some interest...

*"Sepmag" is the common term for "separate magnetic soundtrack" in old-style film. "Commag" is "combined magnetic" (film with mag stripes at its edges). and "com-opt" means "combined optical", as used in cinema distribution for decades.

[af024]

Many thanks for everyone's thoughts - very interesting. Please keep them coming. In the meantine, I accidentally stumbled upon this:-
https://www.youtube.com/watch?v=PZVaK2TKgFA
Some of you may have seen it before, but you'd have to be a brave person to edit video tape (by cutting!) back then!

[vidjoman]

In the modern world it’s not necessary to cut a tape to make an edit. Just copy the original onto a computer, edit as required, then copy the result to wherever you want it, back to tape, CD, or just leave it on your computer. If the tape is damaged then you’ll have to make a joint to cut out the bad part.

[dave walsh]

A very interesting thread for anyone still using tape but "old splice" makes me think of aftershave! There used to be "Where do we get splicing tape?" threads at one time and it seemed to be quite costly. I've mentioned before that I use 1" micropore medical tape, strong but using a very low level adhesive, designed for sensitive skins and very secure in use on tape. Cheap at any Pharmacy! There were doubts expressed but I've never had any problems, although my splices are mainly repair jobs just so the tape can play. I don't think I've had a "medical" splice that failed.

I've never really made up program material by splicing sections together [as the professionals do/did]. Even as a teenager I was able to use a friends deck to 'dub' from the source so any splicing was re a break or adding leader tape.
I seem to have got away without ever damaging VHS video heads Michael [p12] but I clean the heads/guides regularly and there's no shocking "sellotape" sticky deposit effect to ruin things. I've seen video tapes that have parcel packing tape or even elastoplast in place [just about] now that does dry up. In the early nineties I was thinking of doing a media studies degree and went on an introductory day out. They had us splicing with blocks and razors but I had to demonstrate that I could do it "freehand" with scissors [even cassette tape] when the [sceptical] Instructor didn't believe me! He asked why and I said "needs must". A block was quite expensive in the sixties but splicing tape wasn't.

Dave W

[Restoration73]

As stated 45 and 60 are best when the tape is recorded. 90 is stronger and best for
leader and stop foils.
I agree with #21, if the tape is stored tails out, rewind slowly to start bypassing the heads and guides - you may need to defeat an optical sensor.
Examine any defective splices and repair. If possible use a deck without pressure pads.
Ensure razor blades are demagnetised.

[red16v]

Originally Posted by af024

Many thanks for everyone's thoughts - very interesting. Please keep them coming. In the meantine, I accidentally stumbled upon this:-
https://www.youtube.com/watch?v=PZVaK2TKgFA
Some of you may have seen it before, but you'd have to be a brave person to edit video tape (by cutting!) back then!

The video shows a ‘Smiths’ splicer block, but others were available. Our company used a similar product made by ‘EMT’ which did not require the tape to be developed.

http://www.vtoldboys.com/emt01.htm

I rescued one of our splicer blocks just before it was to be skipped and donated it to BECG so hopefully it will eventually be put on permanent display at their new premises. Cut editing was on its way out when I worked in VT, at the start of my career we’re had moved on to ‘cue tone’ editing which is the technique shown from about 9.00 onwards. Very happy days.

[af024]

Wow! So pleased you rescued that. What a great thing.