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Author
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Topic: Listening to film soundtracks via headphones
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted July 17, 2017 12:31 PM
You run into some interesting factors:
For example, especially with Super-8 you get often chatter from the lower loop being too short. It's really always there, it's just that the sound of the machine operating is very similar and when you can hear that it makes it easier for your brain to tune the chatter out. When you hear the audio track without it, it's much more apparent.
On my setup there's a phone jack on the mixer. It works very well, but since my hum filter is after the mixer, using the headphones there brings up the projector hum in all it's majesty.
I really should use the headphone jack on the Amp, but it's about 30 feet away from the screen! My wife is really good about all this, but if she did impose a cable limit, I'd probably be there already!
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All I ask is a wide screen and a projector to light her by...
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Rob Young.
Phenomenal Film Handler
Posts: 1633
From: Cheshire, U.K.
Registered: Dec 2003
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posted July 17, 2017 06:05 PM
Ugh..I'd made myself a promise not to contribute anymore, but...
Quote,
"with Super-8 you get often chatter from the lower loop being too short. It's really always there"
No, it really isn't, say using a Beaulieu.
If it was, you could never realistically use a super 8 projector in a separate booth with an auditorium sound system...and why would the lower loop be too short anyway...
Quote,
"the headphones there brings up the projector hum in all it's majesty"
Whilst I appreciate that some super projectors introduce hum more than others, even an Elmo ST-1200HD with a clean mains feed can have any significant hum removed from mag sound reproduction by use of a 50Hz bass cut, maybe someway into 150Hz.
You'll never get digital quality, but getting good, tight bass response is very possible.
Using headphones, will however, depending upon the quality of said headphones, make you more aware of high frequency drop-outs and inconsistencies between magnetic stereo tracks, which your room acoustics will often absorb and drown.
Again, balancing the playback in a given room to acoustically mask imperfections at either end of the response is perfectly acceptable, although your headphones may reveal all.
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted July 17, 2017 09:33 PM
quote:
Quote,
"with Super-8 you get often chatter from the lower loop being too short. It's really always there"
No, it really isn't, say using a Beaulieu.
If it was, you could never realistically use a super 8 projector in a separate booth with an auditorium sound system...and why would the lower loop be too short anyway...
So you are trying to refute a statement containing the word "often" in it by stating an exception? Doesn't the word "often" tell the reader that they should expect exceptions? "Often" is not "Always".
-No Touché, not even Oneché!
I guess its fair to say any analog sound on film system is somewhat subject to chatter because you have the pulsating film motion at the gate yet the smooth motion at the head(s). You can be absolutely chatter free when the mechanism to smooth the motion through the gate reaches perfection (good luck). Super-8 has an 18 frame separation between picture and sound: the shortest in the business. Regular-8 for example has something like 54 frames. This means super 8 has a lower loop of only about 3 inches: not a lot of room to smooth things out. It makes it harder to put the pinch roller between the loop and the head for one thing, so most S8 machines don't have it there. Even the ones that do have it can't be perfect.
As I said: It's always there. Most of the time you can't even hear it, but if you hung a 'scope on the signal I bet you could measure it, -even say using a Beaulieu.
quote:
Quote,
"the headphones there brings up the projector hum in all it's majesty"
Whilst I appreciate that some super projectors introduce hum more than others, even an Elmo ST-1200HD with a clean mains feed can have any significant hum removed from mag sound reproduction by use of a 50Hz bass cut, maybe someway into 150Hz.
If you read my post carefully here. What I'm saying is that I would expect better sound trough the phones if I moved them from the mixer to my Amp...but why is this?
Simple: The connection scheme is like this: Projector-mixer-hum filter-Amplifier. The hum filter is an active 60 Hz. notch filter. On the mixer side I am hearing the output raw. On the amp side it's cleaned up: much nicer. I use it almost all the time (even more than "often"), so when I hear the signal raw from the machine it sounds pretty bad.
A lot of this is about what happens when you hang any better speaker on a signal, you hear more of the good stuff, and more of the bad stuff too. Love them or hate them: the little internal speakers hide a multitude of evils.
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All I ask is a wide screen and a projector to light her by...
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Rob Young.
Phenomenal Film Handler
Posts: 1633
From: Cheshire, U.K.
Registered: Dec 2003
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posted July 18, 2017 02:29 PM
Quote;
"I guess its fair to say any analog sound on film system is somewhat subject to chatter because you have the pulsating film motion at the gate yet the smooth motion at the head(s). You can be absolutely chatter free when the mechanism to smooth the motion through the gate reaches perfection (good luck)."
What about all of those engineers for over 100 years who tried and, as you must obviously think failed, to do so with projected film...
Steve, look, no sword points are trying to be scored here, niether whole or half arsed.
To me, you implied that chatter was an inherent problem with super 8 sound and whilst I acknowledge that it can certainly be an issue (together with wow), I disagree.
That may be your experience, but please don't pass it off as a general issue.
If I misunderstand in some way then (yet again) I apologies.
I always think that new, younger people may visit our forum here and wouldn't like to think that they read such comments and then think, "So, super 8 sound generally chatters then..."
Because it shouldn't and realistically doesn't with a decent set-up.
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Steve Klare
Film Guy
Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003
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posted July 18, 2017 03:37 PM
I know all about Engineers: I'm one of them.
I work on a machine that develops high intensity X-rays by wiggling an electron beam. The steadier the beam, the finer and more controllable the X-rays coming out, the higher resolution the image.
All sorts of work was done to reduce jitter: ultra high precision power supplies on the beam magnets, a minimum of 3 feet of concrete on all sides around the beam tunnel. The equipment racks are all on seismic mounts to isolate the cooling fans from the concrete floor underneath.
Did we reach zero jitter?...No.
It's down to the point where (for example) there is this highway like a mile away and every time a truck hits an expansion joint some seconds later the beam twitches a couple of microns.
It doesn't mean we failed: we still met the spec the rest of the system needed to function up to expectations, and we even kept the budget.
So no, I don't think the AV engineers failed either (obviously or otherwise). They did the best they could and made something that met all the requirements as best as possible given the limits they worked within.
Engineering is humbling that way: never perfect, hopefully good enough. (It's very human!)
I think it's fair to say Super-8 is more vulnerable to suffer chatter than the other gauges. I wouldn't (and didn't) go so far as to say it's constant, since if it was I would find a different format. I enjoy sound too much for that.
It still remains that even if it was on the high side of inaudible with the projector sound masking it and you eliminate the projector sound by clamping a set of phones on your head, it may break the surface: that's all I was trying to say.
It's kind of like this: when I'm running with the notch filter I'm tempted to say at normal volume levels there is no hum, but this isn't really true. The hum is always there, it's just too low to easily hear. If I put an ear near a speaker I can hear it, if I crank the volume up as I would for a low track, it becomes audible, but still low.
Much the same: there is always some 24 FPS chatter going on in the signal. The typical projector sound system rolls off in the 50Hz neighborhood, so if anything what comes through is the harmonics. The problem is it's not as far down in the mud as it really should be. It doesn't take a great deal for it to come to the surface.
I think the 18 Frame separation was in recognition of Super-8's role as a medium for sound home movies. If they kept the 54 frame separation it would have given two or three seconds of weird sound at a splice. They compromised it down to one second, and became more vulnerable to audible chatter in the bargain.
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All I ask is a wide screen and a projector to light her by...
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted July 20, 2017 12:27 PM
Another factor has crossed my mind- optical sound. Presumably super 8 optical prints have the optical sound advanced the standard 24 frames. That means there is no room for the magnetic head at that 24 frames position. So the mag head has to go somewhere else, and no doubt the 18 frames position (for 18fps home movie film) now makes sense. Except its really too close to the claw for totally isolating the film jerk.
The discussion on the super 8 cartridge just makes one realize what a rotten design it was, and how the Fuji single 8 design was the logical engineering approach.
Steve, every military contract that I worked on started with an Interface Control Drawing, specifying the exact shape and volume, and other things like connector positions, that you had to design the device to fit. In some ways it helped as it rapidly helped to eliminate multiple options and finalize the design.
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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
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