3M Tape Viewer - see the sound on a tape
In this video I’m demonstrating a really intriguing little gadget that enables you to see the recorded pattern on a tape.
Despite being quite a short and seemingly simple video it still somehow took me the best part of a week to put it all together.
I hope you find this one as fascinating as I do.
Comments (58)
This is similar but I don't know if it is sensitive enough to read magnetic tapes. Search Amazon for: "CMS Magnetics 4" x 6" Green Magnetic Viewing Film", about $9 USD.
Yes it’s a lot less sensitive. It looks at broad field patterns - it can’t see a tape.
It's a shame it couldn't pick up the video tracks on a VHS, and I assume it would be a similar story with 8mm/Hi8, otherwise I would have been tempted to buy a (new) one to see if it could shed any light on a years-old mystery (a Hi8 tape I suspect recorded with the wrong alignment, but it'd be nice to get a hint as to whether the information is anywhere near intelligible...I even wondered if things went so skewiff that the tracks hadn't even managed to stay within the edges of the tape, if that's even possible). Great video, as always.
How cool is that! I've used the magnetic viewing film for years but this is in a whole different league.. Gotta get me one of those ;-)
This type of content is why I absolutely love your channel. It’s refreshing retro stuff :)
Always been a fan of old commercials / adverts. Any chance we can get the all the audio from the actor's reel?
Yes - I’ll be releasing it. Not too sure in what format yet.
A similar item is often included with STEM toy kits, but it's just a sheet of plastic. The display method is possibly along the lines of e-ink but in this case m-ink. The sensitivity is too weak for viewing recorded tape but it does display the field lines of regular magnets well enough,very much like the usual iron filings on paper.
On this side of the Atlantic, we had a version of Wooly WIlly called "Etch-A-Sketch", here suitably miniaturized. And very ingenious ... and cool.
When I started working in engineering at HTV (now ITV Wales) in 1979 the videotape department had some supersized versions of this to view 2" reel to reel tape for video editing. There was no electronic editing back in the day so editing had to be done by razor blade and tape. The viewer enabled the editor to see the synch pulses on each frame and place the edit so it wouldn't cause a frame roll. That was out of date tech even when I joined.
I saw the video description and thought, "what an odd little device." Then I watched and realized that I have dozens of tapes that came with different decks, and I have no idea whether they're 2 track, 4 track, etc. Many will be old 2 track nono. I guess it could be useful.
It saved me threading the Actors Reel on my two track machine (which isn’t usually set up) - and even then I might have convinced myself it was in stereo if I hadn’t seen the signal.
Fascinating to learn that there was some initial distrust of data recording on magnetic tapes in the early transition from paper cards and tape. Worth waiting 4 years for such a gadget.
I found that interesting too - the requirement to have a human double check the computer data. It seems that attitude must have faded away quickly for them to drop that purpose for the device just a few years later.
Wow - that is a BRILLIANT device - the sort of thing you used to see advertised alongside X-Ray Specs but this actually works! It is so great to see something that enables the invisible to become visible AND that I can understand how it works. I was going to ask about Floppy Disks, but I see that many got there before me. I suppose magnetic tape computer back-ups like TK-50s would also not show anything. Great video, Mat!!
edit: Kane waaaay beat me to it : ) I wonder if magnetic viewing film would work as well? https://www.amazon.com/s?k=magnetic+viewing+film&ref=nb_sb_noss_2 Only know of it because of AvE but been meaning to pick some up for awhile now
That was very cool to see, never heard of it before
I've used magnetic developer 30 years ago to show the the variable bitrate in C64 disks. Mag. developer is ultrafine iron filings in a thin alcoholic liquid. Shake the bottle, then pour a small amount on the media. Being directly on the media it's much more sensitive, and can display smaller transitions. One would have to be very careful to remove all traces of the filings, however before attempting to load tape/disks in a drive, though so I'd tend to look at Mag. developer as being destructive.
$400 in today's money! It seems like a minor labor saving device than a true instrument. How could you verify alignment with it?
Oh, and dont forget Kyread magnetic developer, a dolution you put directly on the tape. It will visualize digital data, but its destructive. https://www.magneticdeveloper.com/
I suspect the high resolution mag field viewer at this link might work, and is only $15 Us
What a fascinating piece of kit. So well crafted too. No wonder it took 4 years to find one. I suspect in time that fluid breaks down. You did a great job of demonstrating it too. I loved the 3M logo touch when placed back in the box.
That is fascinating, I've never heard of anything like this. Just think of when people stumble upon these videos 100 years from now how much more fascinating it's going to be to them.
I wonder if this works the same way as the liquid that editors would put on videotape when physically cutting them during editing.
Fascinating Mat + woolly Willie, far too many years since I’ve seen one of those. Champion! I’m now curious about how those striations equate to the voltage changes that create complex audio signals. Do you think there might be digital vs analogue in the comments?
I’m not sure what will be in the comments - recently the comments on youtube have been difficult to read. I’m aiming to stay away in future as I‘m sure reading through them isn’t conducive to good mental health.
Fantastic little gadget. Only recently, I found some old reel-to-reel tapes that are unmarked. This would help me see if there's anything recorded on them! Or maybe I'll just get a player up and running... 🤔 Edit: Just remembered! What about those wire recordings you did a video on some years back? Would be cool to see how they'd register on this device.
Perhaps I should do a follow up covering every suggestion of things to put it on.
That is SOOOOOOOOOOOOOOOO cool!!!!!!!!!!
You could have made a Moans sketch to pad the running time out to just over 10 minutes, Mat. Lost opportunity for a mid-reel ad there. ;) On a serious note, that is a neat looking little gadget. The closest I've seen to one of those is a Commodore 64 diagnostic cartridge, where one of the functions is a real-time visual representation of what's on the tape. It's used for adjusting the azimuth on the datasette. Very cool.
My best performing video in the last few years was under seven mins - hopefully the shorter playtime on this video will be an asset.
I never knew the left-right pairs on the compact cassette were separated like that. I wonder if the tapes used on home studio 4-track decks laid the tracks out similarly or were they more evenly spaced like the 1/4 inch tape.
I don’t know - but I understand better now how a machine like the Tascam 133 had space on the tape to lay down a cue track without affecting the audio.
PHENOMENALLY interesting - thanks for sharing! Reminds me of those analysed readouts of DNA. And you got Wooly Willy in too - top notch! And I have to say, that 3M logo in the ferrofluid is such a ridiculously cool touch.
Interesting little device! I’m curious, what’s the white round section in the wooden case?
That’s the viewing pad. The originals have all perished and crumbled to dust, so I’ve put down a circular piece of self adhesive backed felt to fill the empty space.
What a fantastic little item and it's great to see something old from 3M as most of their products throughout the years seem to be consumables.
What about the linear audio track on the VHS tape? Shouldn't that show up along the edge of the tape? Or did they abandon that at some point? There were also stereo linear track-encoded tapes which should have the same results as on the compact cassette.
I don’t know - it was a tape with the Tech 93 segment on it - recorded by me to the tape over composite and RCA L&R, the VHS recorder is a HiFi machine - I made sure the part I put the viewer down on was mid-segment.
Wow! I was surprised at how "digital" looking the analog cassette traces were. OTOH, I have no idea what I was expecting. :-) Thanks!
I would expect there's a threshold effect where the magnetization isn't strong enough to move the filings at all, and then as the field increases they abruptly start clumping, so the viewer makes the field strength look more off-and-on than it actually is.
I love this! I wish I could find one for sale.
Yet another instantly captivating thing I've never heard of, well worth the years long wait to get one. Such a nice box it has, too. Now I wanna try a sheet of magnetic viewing film on some tapes, I've never thought to try. Only ever looked at magnets on phones and laptops and such, I wonder if tape tracks would even show up.
I remember these viewers coming out in the 1970s when I ran a company called Teletape. They cost £30 and seemed like a lot of money so I never bought any.
Jeremy - you can't just write "I used to run a company called Teletape" and run. What was the company's remit?
The only name I recognise on that Actors' Demo Tape is Marvin Kaplan - he was the voice of Choo-Choo on Top Cat.
For me Richard Basehart and Tom Bosley were the big standouts.
I'm sure you're not surprised at all to hear me say I've been wondering what a DCC tape would look like under one of these. And I'm not surprised about the result either :-) Each DCC track records a data stream at 96kHz so the magnetic particles are really tiny (the tape is identical to video tape) and therefore the magnetic field is just too low. Though now I know there's a modern version of the viewer, it makes me wonder if that would show anything, being newer and using more modern materials. It's a bit of a bummer that it doesn't work for DCC because it would be really useful for that: If you hear nothing when playing a DCC cassette, it's impossible to tell whether the tape is blank, or there's silence recorded on the tape, or the heads are dirty.
Very interesting. I like the craftsmanship of it, with the etching around it and the wooden box to store it with the magnet. I'm sure the new one probably have none of that nice fit and finish. Glad to see Wooly Willie made it across the pond. I loved that thing as a kid. Although I'm surprised it wasn't renamed for the UK market. That actor audition reel was awesome too. I could listen to that all day.
It’s a very pleasing object to hold - like a nice rounded pebble with a good weight. I’m planning on posting the actor reel here on Patron - perhaps in a few instalments.
That is so cool I wondered if something like that existed.. thanks!
I haven't seen one of those in years. We used them to troubleshoot write head alignment issues for Reel to Reel Mag Tape units for Mainframes. But seriously Mat, we need to know, did you already have the Wooly Willie toy laying around the house, or did you go out to buy one?
I had to buy the Wooly Willie - it’s all part of the service.
Cool toy, would have loved to see the tracks on the VHS-tape, but apparently, they are too weak... Is anything visible on a floppy disk?
I haven’t tested it - but I doubt anything would be visible if it can’t see a DCC.
This is fascinating!
I wonder if magnet field paper would also work. £5 on Amazon for a 50mm x 50mm square.
I wasn’t aware of that - I’m imagining it’s got a far lower ‘resolution’ though. I’m really at the edges of what can be shot with my macro lens.