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Processing tape transfers which have speed issues

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Processing tape transfers which have speed issues

Postby Seapy » Tue May 19, 2020 8:56 pm

Hello, I am new here and am not fully familiar with sound processing technical terms.

I have tried searching but not knowing what to call it I haven't had much success with my searches, I ended up here, you look a friendly bunch so perhaps you can help me please...

in the 1960's my father recorded music onto a Grundig reel to reel tape recorder. I have about a dozen 5" reels of tape which I am trying to digitise into my Mac, using 'Felt Tip Sound Studio' I used an old Sanyo tape player to play the tapes into the computer.

At first all went well, so I went ahead and digitised all the tapes. I then started processing them adjusting the sound levels and and splitting the tunes etc. I started to notice towards the end of each 'side' of each tape the sound gradually becomes noticeably slurrrred, for about the second half of each side. I tried digitising them again but came to the conclusion that the tape drive was slipping progressively after about half way, I am assuming because the mechanical advantage reduces as the feeding reel diameter effectively reduces, while the take up spool effectively grows. I have considered cutting the tapes in half but suspect that isn't a good idea.

Discussing this with a friend he suggested shortening the duration of the sound clips, compressing them, thereby getting rid of the sluuurrrr.

Is this the best way to deal with this or do I need to go buy a better tape recorder and do it all over again?

Or... Is there some other way of fixing this?

I would appreciate any suggestions or help with this, I have been trying, on and off to sort this for about two years. I want to put it to bed.

Many thanks,

Robert
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Re: Processing tape transfers which have speed issues

Postby James Perrett » Tue May 19, 2020 9:20 pm

The first thing to check - does the Sanyo machine have a capstan and pinch roller? (If you don't know what they are - a capstan is usually a round piece of metal driven by a motor and the pinch roller is a rubber covered wheel that pushes the tape onto the capstan). In most tape recorders the capstan and pinch roller pull the tape past the heads at a constant speed but in some cheaper recorders they simply turned the take-up reel at a constant speed so that the tape speed changes depending on which bit of the tape you are playing. The Grundig will almost certainly have used a capstan and pinch roller (unless it was a dictation machine) so the speed of the recording should be constant which means that it needs to be played on a machine with a capstan and pinch roller.

If the Sanyo machine has a capstan and pinch roller then the next thing I'd check is whether the pinch roller is still slightly squashy or whether it has gone hard and shiny. If it has gone hard then it really needs to be replaced although some people have had success with roughening them up with sandpaper or applying rubber rejuvenator to them. The other thing to check is that any belts that drive the capstan are still tight - if they've not been replaced in the last 30 years then they probably need replacing.

Other things to check are that the tape path is scrupulously clean and that the back tension from the supply reel isn't too high.

Of course it is possible to correct the speed change by speeding up the playback in the computer but I've never even heard of the software that you are using so I've no idea whether it can do this. You can download a trial of Reaper for the Mac which will definitely let you adjust the speed - my suggestion would be to use pitch envelopes to do this.
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Re: Processing tape transfers which have speed issues

Postby Tim Gillett » Tue May 19, 2020 10:28 pm

Hi Robert, the tape is probably fine but needs to be played back on a good machine in good condition. Like everything the machines deteriorate and haven't been available new for many years. Experts use used machines but in top condition. My machines are over 45 years old. To do the work successfully yourself, as a minimum you will also need a good machine in good working condition. Failing that, for just one or two tapes it might be better to pay an expert to do it for you. I hope this helps. Tim.
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Re: Processing tape transfers which have speed issues

Postby Dub til you drop » Wed May 20, 2020 4:58 pm

Seapy wrote:Discussing this with a friend he suggested shortening the duration of the sound clips, compressing them, thereby getting rid of the sluuurrrr.

Is this the best way to deal with this or do I need to go buy a better tape recorder and do it all over again?

The first rule of audio is "fix the problem at source, before you start getting fancy". So yes, first off you should try playing back the tape on a better machine. Is there not anyone on here with a tape m/c who'll help? I sold my lovely B77HS last year, so I can't I'm afraid.

There is the possibility that your tapes have become sticky (most of my lovely old masters have and I looked after them carefully). Aging causes the backing of the tape to become gummy. As the tape comes off the feed spool it sticks for a fraction of a second, before coming free, causing speed variations.

Or... Is there some other way of fixing this?

Oh yes, there are number of tricks we can perform. :bouncy:

My first though would be to digitise it and run it through "Beat Detective" on a DAW (Digital Audio Workstation). This is a software routine which analyses the rhythm and works out the tempo. You can then pull a varying tempo back into a fixed one. Buttttt, it'll never be perfect, and could possibly sound downright nasty.

The best bet is to run the tape at the right speed on a stable machine, and get it digitised as soon as possible. Old tapes deteriorate over time
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Re: Processing tape transfers which have speed issues

Postby Seapy » Sun May 24, 2020 10:23 am

Thank you very much for all your replies.

I have not been ignoring you, I have been away from home helping my daughter during this awful pandemic and not had access to a computer. Replying to posts with more than a couple of words is not easy from an iPhone...

I accept the best way to get good sound is to employ good tools and get it right at capture, just like any medium, photography is one of my activities, a good lens, sensor and technique are essential to capture high quality images. Sound is no different. You can't make a silk purse out of a sows lug!

The tape recorder does have a steel and rubber pinch wheel, I have cleaned both parts with IPA and tried to slightly roughen the rubber part with very fine abrasive paper but it still slips, the internal belts are not good and the slipping clutch on the take up spool slips too much, while the drag brake on the feed spool drags too much. Adjusting the slip and drag is a dark art which I haven't mastered. At one stage when belts broke I would waylay the postman and cadge long rubber bands from him! LOL The postman's rubber bands actually worked quite well but only lasted for one side of a tape...

The software 'Felt tip Sound Studio', https://felttip.com/ss/ I have used over many years on my Macs, I have found it excellent for the limited forays I have made into sound recording. Mainly school concerts and the like. I have used Macs since 1988, I still have my original SE30.

I don't believe the tapes are sticky, but may be very slightly?

I think there are ten, five and a quarter inch tapes. There is an eBay seller about 60 miles from me who reconditions reel to reel recorders and sells them but I cant seem to tie him down, he says he will contact me when he has a decent machine to do my job but he never does, I have given up on that avenue.

That was why I bought this Sanyo recorder at a car boot sale for a tenner. I would say the first half of each tape side is acceptable (hence my silly idea of cutting the tapes in half...). They are't perfect to start with having been recorded in the 1950's by my father when he had TB, he was bed bound in a sanatorium for over a year and passed the time constructing a radio and recording music for his own amusement, he used the bed frame for the arial and had to lie very still else there were crackles in the recordings.

I will have a look at the pitch adjustment in Felt tip Sound Studio and experiment. It probably only needs a small adjustment, the amplitude is there and the waveform is reasonably well defined, it's the capture speed which is wrong.

If that fails I would be happy to pay for somebody to simply to transfer the sound using a decent tape deck, to a memory stick so I could split the tunes and adjust the sounds myself. The levels do vary from tape to tape and between tunes, some aren't too bad but some tunes need individual treatment. I have already spent a lot of time on this and don't really want to give up now. I don't have any experience fixing pitch issues with sound software. I guess this is an opportunity to put that right.

I have a high spec Mac Pro 5.1 which is more than capable of the task and I enjoy processing and cataloguing. Eventually I want to be able to play this music quietly, in the background, not to 'listen' to it but to break the silence in my home, which is currently deafening.

Robert CP
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Re: Processing tape transfers which have speed issues

Postby Kwackman » Sun May 24, 2020 2:04 pm

Seapy wrote:I would be happy to pay for somebody to simply to transfer the sound using a decent tape deck, to a memory stick so I could split the tunes and adjust the sounds myself.

Someone like James Perrett (see earlier in the thread) would be a very good bet for this type of thing. Assuming you're in the UK?
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Re: Processing tape transfers which have speed issues

Postby James Perrett » Sun May 24, 2020 2:35 pm

Seapy wrote:The tape recorder does have a steel and rubber pinch wheel, I have cleaned both parts with IPA and tried to slightly roughen the rubber part with very fine abrasive paper but it still slips, the internal belts are not good and the slipping clutch on the take up spool slips too much, while the drag brake on the feed spool drags too much. Adjusting the slip and drag is a dark art which I haven't mastered. At one stage when belts broke I would waylay the postman and cadge long rubber bands from him! LOL The postman's rubber bands actually worked quite well but only lasted for one side of a tape...

It sounds like a set of new belts and a bit of adjustment would probably help - although, like you, I find adjusting slipping clutches to be really difficult and frustrating which is why all the machines I've kept have been 3 motor machines with separate motors for the reels which I find much easier to set up. The other thing that might help is to find a spool with a large centre although these mostly came in 7" sizes like the one at

https://www.analogtapes.com/product/1-4 ... -large-hub

If you decide to persevere with the recordings that you have then the software that you have may, in theory, be able to adjust the speed but, if it is anything like similar software that i've used, it won't be easy which is why I'd suggest looking for something that supports pitch control from the timeline. There's an article about this sort of thing at

https://www.soundonsound.com/techniques ... cts-reaper
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Re: Processing tape transfers which have speed issues

Postby Seapy » Sun May 24, 2020 9:16 pm

James Perrett wrote:
Seapy wrote:If you decide to persevere with the recordings that you have then the software that you have may, in theory, be able to adjust the speed but,

Thank you James, for a really helpful post, I am determined to do this myself if I can... I have already experimented with one track in Sound Studio, selecting a tune at a time from about half way through the tape, when the slight sluurrr becomes apparent. I applied about 3% speed increase, 6% on the next tune, and so on, on a couple of tunes I didn't increase on the previous setting, perhaps I should have gone for 2.5%, there are about 17 to 20 tunes per tape side (in the region of 400 tunes). I will experiment as I go, but it appears, or sounds... MUCH better. Brighter and much more clearly defined sound, I have linked the pitch and tempo, on the basis that I am wanting to correct a time error, which I am assuming applies equally to pitch and tempo?

I am only doing this for myself, I was intending to have somebody do the actual tape transfer which took quite a while for all ten tapes, both sides, it took a while get the recording levels right, which varied quite a bit from tape to tape.

Quite honestly I am amazed how well defined the waveforms are, after at least 60 years, the tapes were played on a regular daily basis for at least 17 years, until my father died. I am sure a professional would cringe at the noise but for me they are more like a painting than a photograph, perhaps lacking detail and fine tone but retaining period character.

I will have a look at Reaper, I could set up a linear slope to increase tempo and pitch from about 1/3 of the tape. Looks very easy in the video you kindly pointed to.
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Re: Processing tape transfers which have speed issues

Postby James Perrett » Sun May 24, 2020 11:01 pm

Seapy wrote:Quite honestly I am amazed how well defined the waveforms are, after at least 60 years, the tapes were played on a regular daily basis for at least 17 years, until my father died. I am sure a professional would cringe at the noise but for me they are more like a painting than a photograph, perhaps lacking detail and fine tone but retaining period character.

Most domestic tapes from the 1960's onwards survive very well with virtually no degradation. It is usually the professional tapes that cause the problems. Izotope RX (and probably Cedar) can do amazing things with reducing noise these days.
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Re: Processing tape transfers which have speed issues

Postby Tim Gillett » Mon May 25, 2020 3:08 am

Hi seapy. It seems unlikely varispeed after the fact will fix this. AFAIK Ceremony Capstan is the most likely tool to succeed but it has to be music and with reasonable quality sound in the first place. Even then its not necessarily plain sailing. But this is going about it back to front. The problem is not the tapes but your playback. The problem is being created right before your eyes in real time. So best address the known problem directly, ie: play the many tapes back properly. Have you tried the UK Vintage Radio forum? Members are always repairing tape machines. Maybe for a nominal sum one of them will loan you a good working machine to transfer your tapes, and offer you assistance. This is not a digital problem but analog playback.
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Re: Processing tape transfers which have speed issues

Postby zenguitar » Mon May 25, 2020 3:27 am

This is a topic where Tim and James have a lot of 1st hand experience. You really should listen to what they are saying.

Andy :beamup:
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Re: Processing tape transfers which have speed issues

Postby BigRedX » Fri May 29, 2020 2:00 pm

I had exactly this problem with reel-to-reel tape recordings made by my first band back in the 70s and early 80s which needed to be digitised for a retrospective CD release in the early 2000s.

After trying a couple of domestic recorders that various friends still had, and which produced exactly the results you mentioned - the closer the tape got to the end of the reel the more erratic the speed of playback - I admitted defeat, and bought a second-hand Studer 1/4" machine off eBay (ex-BBC local radio IIRC) for about £100. This was able to play all my tapes bar one flawlessly.

The exception was one where the glue had seeped out of the edits and was causing the tape to stick together. In that case I had to manually separate out the individual bits of tape, clean the glue off them (hoping I wasn't also removing the oxide layer) and then wind each length of tape back onto a reel for playback. Luckily I did have a cassette copy of this recording as a back up, had anything gone wrong.

Once the tracks had been digitised and the CD released, I was even able to sell the Studer on for a slight profit!
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Re: Processing tape transfers which have speed issues

Postby ken long » Fri May 29, 2020 2:50 pm

BigRedX wrote:The exception was one where the glue had seeped out of the edits and was causing the tape to stick together. In that case I had to manually separate out the individual bits of tape, clean the glue off them (hoping I wasn't also removing the oxide layer) and then wind each length of tape back onto a reel for playback.

Lighter fluid is great for this.
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Re: Processing tape transfers which have speed issues

Postby ken long » Fri May 29, 2020 2:57 pm

Seapy wrote:I don't believe the tapes are sticky, but may be very slightly?

They may also have lost their lubricant which would cause them to stick. This is different from sticky shed where you would need to bake the tape and as James points out, is more common on pro tape. To re-lube, you can apply isopropyl alcohol on the tape with a cotton bud as it unwinds off the spool. This should lubricate it long enough to pass through the transport and evaporate quickly enough before it reaches the playback head.
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Re: Processing tape transfers which have speed issues

Postby Tim Gillett » Fri May 29, 2020 3:10 pm

In Marie O'Connell's setup the isopropanol is wiped off just after it has run over the repro head and just before the capstan. The wiping tool is actually small sections of car windscreen wiper blades.
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