8mm Forum: Magnetic vs Optical

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Posted by Brad Kimball (Member # 5) on February 16, 2018, 07:27 PM:

Which is better?

Posted by Clinton Hunt (Member # 2072) on February 16, 2018, 07:37 PM:

I have an Elmo magnetic/optical projector but only have the 1 optical print,a Grizzly Adams 3 x 600ft edition.
I can't really tell which is better as I listen through the projectors in-built speaker.The beauty of optical is it can't be erased by mistake whereas i have a couple of magnetic that have been partially erased!
I will one day get more optical films and see [Smile]

I will read this post with interest [Smile]

Posted by Paul Adsett (Member # 25) on February 16, 2018, 07:48 PM:

Optical sound is greatly inferior to magnetic sound. The frequency response of 8mm magnetic sound is far better than 16mm optical sound. And you can have high fidelity stero sound on super 8mm twin magnetic tracks.
On the other hand, optical sound has no magnetic heads to wear out.

Posted by Brad Kimball (Member # 5) on February 16, 2018, 09:09 PM:

Curious as to why 8mm wasn’t manufactured for the home movie market with the more economical choice of optical tracks and 16/35/70 made with the more superior sounding magnetic soundtracks.

Posted by Paul Adsett (Member # 25) on February 16, 2018, 11:47 PM:

Magnetic stripe is more expensive than an optical track, but in the early days of 8mm sound it was the only way to get acceptable sound quality. When CinemaScope came out in 1953 the 35 mm prints all had multiple magnetic sound tracks for surround sound. But at the high speed of 35mm projection, the tracks and the sound heads wore out very quickly and it proved too expensive for the studios and the theaters so they reverted back to optical tracks.

Posted by Tom Photiou (Member # 130) on February 17, 2018, 02:06 AM:

We have had a number of films with optical sound and now we have none. We sold the lot. We always put the sound via a good pioneer amp and the reason for having none now is two fold,
1/the feature films were edited for a general audience and for me, making cuts to crocodile Dundee was just ridiculous so that ended buying any more.
2/ the optical sound is definatly much more inferior to magnetic sound,you get hiss,pops and bumps on the sound which are pretty awful even through an amp, & no there was nothing wrong with the projector, this was checked and a dealer at the time told us this is quite normal with optical and some films are worse than others.
On here i put up an article on optical films and how they came about etc which, if you can find it, it is quite interesting by Derek Simmonds. He explains why 8mm optical sound is so hissy and can have pops and bumps due to the fact the manufacturees didnt bother with a final proccess of polishing like they do with 16mm. Dereck thought that for some reason they just didnt think 8mm was worth the extra proccess for the airline prints.

Posted by Maurice Leakey (Member # 916) on February 17, 2018, 02:20 AM:

Here is that posting, Tom.
http://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011749# 000000

Posted by Brian Fretwell (Member # 4302) on February 17, 2018, 04:12 AM:

I would say that as magnetic sound projectors were originally made for making home movies with sound, not package films. Therefore the market for releases started with a base of magnetic sound projector owners to sell to, so magnetic sound was the only viable option.

Posted by David Roberts (Member # 197) on February 17, 2018, 04:30 AM:

When I had an st1200,i had just one optical print,ex airline and only 200 ft.
I was surprised how good the sound was,though not as good as magnetic. The other surprise was how sharp the picture was,and I wonder if having no magnetic stripe means the film is flatter in the gate.
Also,there being no oxide particles to clean away from the film path was another advantage. I find that with many of my films,the brown oxide left behind is an issue,and wonder at what stage,this may effect the sound quality,ie will the track wear out ?

Posted by David Hardy (Member # 4628) on February 17, 2018, 06:50 AM:

It makes very little sense to talk about magnetic sound sources be they on magnetic tape or film stripe having a frequency response as such.

The reason being that magnetic film or tape does not have a frequency response as such.

Magnetic tape has a "wave-length" response. This is because frequency response can only be expressed when the film or tape speed has been taken into consideration.

You also have to factor in other things such as the quality of the tape composition and the signal to noise ratio to get any meaningful measurements when trying to quote a frequency response for magnetic tape or stripe. Also the width of the tape and head gaps play an important role.

However let me state quite plainly that no 8mm stripe projector is capable of giving a True High Fidelity sound response due to the overall width limitations of the magnetic stripes on both the main and balance tracks and other factors such as the internal electronics.

Optical sound be it variable area or variable density is only frequency limited due to the widths of the scanning of the light on the tracks and the filmstocks. So the wider the track the greater the measured frequency response.

Here is ROUGH guide to some source frequency responses.

CD ... 20-20,000 HZ

1/4 INCH TAPE ... 30 - 16,000 HZ @ 7 1/2 ips SPEED ???

35MM FILM MONO OPTICAL ... 45 - 8,000 HZ

35MM DOLBY A OPTICAL ... 30 - 12,000 HZ

16MM OPTICAL ... 100 - 6,000 HZ

16MM MAGNETIC ... 30 - 12,500 HZ

8MM STANDARD OPTICAL ... ? - 4,500 HZ

8MM SUPER OPTICAL ... 40- 6,500 HZ @ 24FPS ( Fumeo 9119 )

8MM STANDARD MAGNETIC ... 75 - 5,500 HZ @ 16fps
75 - 8,800 HZ @ 24fps ( Eumig Mark S )

8MM SUPER MAGNETIC ... 50 - 13,500 HZ @ 24fps ( Elmo GS1200 )

However I question the figure quote for the Elmo GS 1200 and think they might be a bit exaggerated by the manufacturer.

[ February 17, 2018, 08:01 AM: Message edited by: David Hardy ]

Posted by Brian Fretwell (Member # 4302) on February 17, 2018, 09:20 AM:

They may be quoting the highest frequency they get any output, when usually the response is measured to the -3dB (half level) point.

Posted by Tom Photiou (Member # 130) on February 17, 2018, 09:21 AM:

Thank you for the link Maurice. For anyone looking in here that is a very good read.
David that is some good information there.
As a newish user of 16mm i must say,(only my opinion),i think the sound is better bearing in mind we curruntly only use the speakers built into the front cover, its obviously placed in the front centre of the screen but what comes out of them is stunning when you consider how old this technolgy is. Our 8mm magnetic sound is excellent but we put that via a good pioneer stereo amp. If i was comparing the two 8 and 16mm using only an extension speaker the 16 wins hands down.
As far as 8mm optical Vs magnetic is concerned i believe magnetic is without a doubt the winner by far.

All those numbers and figures dont mean too much to me, my ears tell me which is best [Big Grin]

Posted by Osi Osgood (Member # 424) on February 17, 2018, 11:50 AM:

The earlier super 8 optical prints could really vary in sound quality and as the actual optical track faded (sometimes the optical track would fade while the image would stay very colorful!?!), the pops and hisses got a lot more loud.

A lot of it goes into the care that went into the production of these optical features. other earlier prints like my "Boy Named Charlie Brown" and "Snoopy come Home" have very good optical sound playback and most of the sound issues with super 8 optical sound were pretty much solved by the 80's by everyone.

A lot depends on the projector used as well. I have had the good pleasure as of late to hear the optical sound playback on the ELMO GS1200 (I believe that's the model), and it definitely sounds better than other optical sound super 8 projectors.

My only real problem with magnetic sound is that, though you can record in stereo, I have as of yet to hear a stereo soundtrack that doesn't go back and forth in clarity with the sound and that has a lot to do with the very "variable" nature of the balance track more than anything else. It really takes me out of the moment with the stereo playback, as I tend to get "anal" with my viewing experience and hate distractions.

... so, I pretty much rule out bothering with stereo playback (even with my films that have a stereo soundtrack), as i really don't expect hi-fidelity with the sound, but certainly good enuf for that vintage "mono" sound I grew up with. [Smile]

Posted by Alan Rik (Member # 73) on February 17, 2018, 01:10 PM:

What made me a believer is when I heard "Fantasia" at Mr. Wiltons house hooked up to a GS1200 and through his sound system. I thought he was syncing it with the DVD sound. But no..he told me it was the sound recorded onto the mag stripes.
Now everyone has their own definition of High Fidelity. Was it Audiophile sound? No of course not. But compared to every 16mm Optical I have heard the sound was glorious and magnificent. To me it would be considered High Fidelity.
The main problem is that you can't get this great sound all the time. As we know stripe varies considerably and also machine it was recorded on, etc.
I am pretty particular when it comes to sound and if it sounds like the balance track is going in and out or whatnot then I will switch the print to Mono and listen to it that way.
I do think that 16mm Optical, while potentially not as great sounding as a well recorded Super 8 mag track, on the whole seems to have much better sound with their optical compared to Super 8 optical. Much clearer and fuller sounding to my ears.

Posted by Paul Adsett (Member # 25) on February 17, 2018, 01:13 PM:

Here is the actual frequency response of the Eumig 926GL Stereo. Eumig supplied an individual test curve for every sound projector they sold in the 800 and 900 series. This is the main track response at 18 fps for the 938 ser no. 8279736. As you can see it is pretty flat all the way from about 65hz up to almost 10khz. The Eumig specification for the 938 stereo quotes 40-11khz at 18 fps. At 24 fps the high end goes up to about 12khz. This would appear to hands down beat 16mm optical:

Posted by David Hardy (Member # 4628) on February 17, 2018, 02:26 PM:

That all very well and good Paul on paper graphs. However it means very little in practice as to the perceived and audible sound quality.

Granted there will be less top end and bottom end when compared to 16mm optical sound.

However in order to actually hear the measured f.r. you need an amp and speakers and a recorded soundtrack to take full advantage. Also the S/n ratio has to be very good too.

These measurements are a good indicator of what the machine may be capable of when recording your own soundtracks at 18fps of even 24fps.

It tends to negate itself when playing back pre-recorded package movies that have been sourced from maybe a 16mm Optical or Mag full coat track which may just be only in the 100hz - 6,000hz region or if you are really lucky 30-12,500hz.

Even worse if the sound was sourced and transfered from a 35mm commercial print which may have only been in the 45hz - 8,000hz region.

You also have to add to that the size of the listening room your equipment is in to gain the full benefit of the f.r. all things being equal.

For example in order to actually hear a say a 50hz tone your room has to be a minimum length of around 17 feet. If its not it is cancelled out due to the standing waves of the room wavelengths.

It gets even worse if you want to reproduce that magical low bass of say 20hz. Your room would have to be at least 50 foot long.

Things gets even more complicated with the other frequencies at the top end and midrange.

The room boundaries of width and height create there own problems too.

Then there is the also the room absorption to take into account. Some of those lovely flat line and extreme tops and and lows and mids just vanish into nothing when the room furnishings , reverberations , get to work with there sabin units.

So you see frequency measurements on graphs are one thing and all well and good but what you actually hear in practice is quite another.

Then of course there are the limitations of your own hearing as you age and all this techy stuff is not really worth getting excited or even bothering about.

As for me I am more than happy with Optical Mono as it works for me in all the really important frequency ranges for me.

They are those of the human voices .

MALE ... 85HZ - 180HZ
FEMALE ...165HZ - 255HZ
EVERYDAY SOUNDS ... 250HZ - 6000HZ.

All nice and MELLOW and never bass boomy or treble toppy or piercing. I just love it

I bother with all the rest in my Audiophile Hi Fi System which is at another level altogether...and for Music only!

Alan Rik , Osi and Tom ...you are all spot on !
[Smile]

Posted by Paul Adsett (Member # 25) on February 17, 2018, 03:19 PM:

You are absolutely right about the human ear David, and at my age it is probably the limiting factor of any equipment that I have. About a month ago I had my first hearing test audiogram, and I was shocked to see how attenuated everything above 10khz was! [Frown]

Posted by David Hardy (Member # 4628) on February 17, 2018, 03:34 PM:

Paul I sympathise with you on that one.
I was at an audiologist a couple of years ago and it was found I could hear nothing above 13Khz these days.

He said it was very good for a man of my age then 62 years old.
Who knows it may be even less now I am 64 years old.

No real point in even really worrying about Hi-Fi sound at those frequencies and beyond at all now.

[Wink]

Posted by Paul Adsett (Member # 25) on February 17, 2018, 11:53 PM:

Here is an super 8mm optical sound clip, showing the acoustic modulation:
https://www.youtube.com/watch?v=mpIejsWnPRY

Posted by David Hardy (Member # 4628) on February 18, 2018, 04:34 AM:

Paul thanks for sharing that one.
Its a shame about the dirty and scratched soundtrack though. [Smile]

Posted by Brian Fretwell (Member # 4302) on February 18, 2018, 05:01 AM:

I would think the frequency ranges you gave for human voices were a bit out, the harmonics that make them intelligible go much higher than what you had. Remember telephone landlines have always been equalised for a response of 300 - 3,00hz. The bottom 300hz were often split off on trunk lines for telex messages at 50 Baud (or bits/sec) needing a fundamental 25hz and odd harmonics up to 250hz.

Posted by Tom Photiou (Member # 130) on February 18, 2018, 06:57 AM:

All very good stuff, but here is how i determine good sound
8mm magnetic via my amp superb,some films better than others.

Super 8 optical. Im my opinion, even via my amp compared to magnetic, crap to good. In a word, average. Hisses and pops.

16mm optical, always excellent, via my amp as good or better than 8mm magnetic.

There you go, sound for cine in a lay mans terms. Hope this helps for anyone confused by graphs and numbers. I trust my ears much more [Big Grin]

Posted by David Ollerearnshaw (Member # 3296) on February 18, 2018, 03:45 PM:

Mine are average sound and some are so quiet recorded that the volume turned up just adds too much Hissssss.

Posted by Mark Mander (Member # 340) on February 18, 2018, 04:30 PM:

I have a few optical super 8 prints and the sound on them are pretty good,I've had a few bad ones too over the years,Rising Damp is a well known print for terrible optical sound and The Fourth Protocol which being a later print was terrible,16mm optical is by far better all round and I've very rarely experienced sound problems. Now magnetic sound rerecorded into stereo on my GS1200 gives outstanding results and will blow optical both super 8 and 16mm out the water,standard originally recorded magnetic prints are hit and miss and do vary on prints and also machines,if I had to choose it would be magnetic every time,Mark

Posted by David Hardy (Member # 4628) on February 18, 2018, 04:32 PM:

Brian you are correct there.

However I only averaged things out for normal quiet speech.

I did not take such variables as singing or shouting into account.

A MALE voice can reach as far as around 3,250 HZ.
A FEMALE voice up to 4,000 HZ.

However I still prefer the film sound of 16mm and 35mm Optical for my lugholes at home .

Posted by Osi Osgood (Member # 424) on February 20, 2018, 12:01 PM:

Nice sharing that clip, Paul (from the film "Izzy and Moe" (and thank you Dino Everette for sharing that youtube video in the first place!) ...

However, the sound on that clip was from an old 30's recording in the first place and not indicative of good 80's optical sound playback.

I could never afford to invest in 16MM but I'm sure that what has been said of the larger the track the better the fidelity is true.

Posted by Paul Adsett (Member # 25) on February 20, 2018, 12:14 PM:

Anybody here using a stereo equalizer to improve super 8mm mag sound playback?

Posted by Osi Osgood (Member # 424) on February 20, 2018, 12:18 PM:

I have in the past. I have an old, (but bought amazingly in mint condition in it's original box at the thrift store), Realistic/Radio shack brand Dolby processor, which allows switching back and forth between Dolby, stereo and as well as Mono, and it certainly does help hape a decent audio output that totally rocks those old school speakers of mine!

I do SOOO ENVY you're stereo 938, Paul!!! [Big Grin]

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