Film-Tech Forum ARCHIVE: 16mm Sound problem

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Posted by Ed Johnson (Member # 94) on 10-13-1999, 04:58 PM:

Hi-

I recently became involved with a film organization at the college I'm currently attending. Although I've had a good deal of experience working projection at a 15-plex, I've never had the pleasure of working with 16mm prints before.

The problem I'm having is that the sound quality is horrible. We're using a relatively old Eiki Xenon projector. The only sound out put is a 1/4" plug labled 8ohms. This plug was originally designed to power a speaker, not to be used as a line output. I'm trying to connect this to a RCA type input on the PA for the audtiorium. Do I need to run the signal through anything between these to ports? I don't know what the impedance of a line input is.

Currently the sound is slightly distorted and lacks definition making it hard to hear dialogue over background music.

Any advice would be greatly appreciated!

BTW, the image is great. Strangely enough this little Eiki projector projects a rock steady picture...

------------------
Ed Johnson
Lawrence University
Appleton, WI

Posted by Randy Stankey (Member # 64) on 10-13-1999, 05:16 PM:

Once in a great while we have to run 16mm here at the college. We run the sound output right into the mixing board for the auditoriums 'regular' sound system. (As oppoesd to the 'movie' sound system.)

We have to start by adjusting the volume and tone controls on the projector itself then adjusting the EQ on the sound board and setting the trim and gain.

Set the "tone" controls on the projector to the mid-position and the volume in the lower 1/3 of its range. Then 'trim' and EQ from the board. If it isn't good, adjust the tone and volume on the projector then re-EQ the board. It usually takes us 2 or 3 tries but we can get 'decent' sound eventually.

I can't imagine the sound from these little projectors would be really good but they are acceptable for small audiences. It takes a little tinkering to get them to sound good for an auditorium-sized audience.

I'm no sound engineer but if I work at it, I can get passable sound this way.

Posted by Scott Norwood (Member # 30) on 10-13-1999, 06:49 PM:

I'm not sure what model Eiki you have (we had EX-6100s at my college...nice picture and sound quality, only fair quality of construction), but most of the xenon projectors do have a line output.

The portable Eikis that don't have a socket labelled "line out" do have a "hidden" line output: use a stereo 1/4" phone plug and take the output from the center ring and the tip; this should give you line-level output that can be connected to a line-level input on a mixing board or whatnot.

You could also rig something up to take the output directly from the solar cell and run it through a solar cell preamp or mike preamp on the mixing board, thus bypassing all of the (usually not-so-great) sound electronics in the projector itself.

Also make sure that your solar cells and slit optics are aligned properly. I have a 16mm "Jiffy Test" film that I'll loan you if you want to check this out.

At my college, we had the EX-6100s' line outputs feeding directly into a mixing board. We set up the levels to be more-or-less equal (by ear) and set the EQ to be pretty much flat. Sound changeover was controlled within the projectors themselves. It sounded pretty good, since we were using decent (not great) JBL speakers and decent Crown amps. The EX-6100 is one of the nicest-sounding 16mm projectors that I've ever used...not that this is saying much, but 16mm optical tracks really don't sound all that bad when they're well-recorded and played back on good equipment.

Posted by Rick Long (Member # 213) on 10-13-1999, 07:42 PM:

Never knew about that hidden line output on the Eikis. Neat tip (pardon the pun), Scott. Thanks.

Posted by Brad Miller (Member # 2) on 10-13-1999, 08:07 PM:

Yes, why wasn't that bit of information in the manual when I needed it back in college???

Anyway, we always just used the technique Randy mentioned above and got quite good results from it. I'd start with your input setting on the mixer at a standard level (typically 7-8) and adjust the volume on the projector so the loudest parts of the film just hit into the red on your meters. From there, use your master gain outputs on the mixer for a volume control.

If the sound is still bad, you need to adjust those optics. 16mm is fairly easy to do, especially since it's mono. I've done it by ear before and gotten pretty darned close.

By the way, I think the Eiki line is the best in 16mm. Those things just keep running and running. My only complaint is the lens barrel/focusing assembly. It leaves a bit to be desired. Other than that...ROCK STEADY PICTURES and an automatic loop restorer (for those masking tape splices) to boot! Forget film inspections, those machines would run anything.

Posted by Ken Layton (Member # 133) on 10-13-1999, 08:33 PM:

All Eiki's have the output of the solar cell going to a 1/8" miniature plug to the amplifier. I've seen alot of other people simply get a patch cord and plug the output of the solar cell into an "aux" or "mic" input on mixer or external public adrress amplifier with good results. But just don't yard out the Eiki's amplifier altogether as it also contains the exciter lamp power supply circuitry.

Posted by Ed Johnson (Member # 94) on 10-13-1999, 09:47 PM:

Thanks for all your advice- I'm going to go fiddle with the projector for a couple hours tommorow.

One other question- The splicer that they have here is a really cheap looking Kodak deal (I don't remember the model name) that does both 16mm and super 8. What I thought was strange was that the the cutting blade is not straight. Instead its cuts on part of the film with an indent and the other with a protrusion so that they fit together. This causes you to lose a frame from both and looks crappy. Why would you want to do this instead of a normal cut on the frameline?

Thanks again for all your help... This is a far cry from the Ernemann 15's I'm used to!

Posted by Scott Norwood (Member # 30) on 10-13-1999, 11:08 PM:

That splicer would be a Kodak "presstape" model. They're pretty cheesy and require special (and expensive) tape. The only good thing about them is that they don't cost much. The curved cut is supposed to run more smoothly through some projectors.

You need to get a "guillotine" splicer. The 16mm splicer is just like the 35mm model. They show up occasionally for under $100 used. I got one in top condition for $50 a couple of years ago, with both straight and diagonal cut blades. You only need the straight-cut model for repairs to release prints.

I think that Neumade makes a 16mm splicer that's like their 35mm splicers (which are great), but I've never seen one.

If you're running acetate-base prints (unlikely if you're getting relatively recent prints from the rental companies), then you can use a cement splicer. I like the Bolex cement splicer, but the Maier-Hancock hot splicer is the top of the line cement splicer...get the 16/35 version and not the 8/16 version, if possible.

Posted by Brad Miller (Member # 2) on 10-13-1999, 11:52 PM:

The Neumade 16mm splicer is a "wrap-around" where you only need to pull the tape across and "punch" it once. It leaves a stretch of pre-punched tape that you simply wrap around to the other side. They made excellent splices!

Posted by Steve Guttag (Member # 268) on 10-16-1999, 05:24 PM:

Wow Scott...I never knew about the "hidden" line-out on an Eiki.

For those that don't however, Pro-Co has what they call the AV-1. It takes "speaker out" from a 1/4" input and drops it to either "line-out" or "mic-out". One nice thing it does is put a low impedance load on the projector's amplifier. Most 16mm amps do NOT like feeding high-impedance inputs. Its always a good idea to put at least 8 or 16-Ohm resistors across the ouput when padding them down.

One of the reasons for the steady pictures on many 16mm projectors is that they use "claw" type pull downs. If they are two-tooth claws like Elmo's then they run shrunken film better too.

Steve

Posted by System Notices (Member # 2357) on 09-09-2009, 06:03 PM:

It has been 3616 days since the last post.

Posted by Laura Jean Kahl (Member # 5234) on 09-09-2009, 06:03 PM:

ok, even though this thread is pretty old, i've got an eiki 6100 sound problem.

intermittently the sound spikes and then drops out. when this problems happens it won't stop until you stop the show. sound builds louder and louder (becoming unbearably loud) then cuts down to nothing. then it starts all over again.

it's difficult to troubleshoot because the problem seems to happen randomly. of course every time i run tests nothing happens, but as soon as we bring in a visiting filmmaker with his films i'm embarrassed as all get out because the sound in freaking out in the theater.

the sound runs from 1/4" line out into a mackie mixer then into the rack through xlr.

my guess is a problem with a pre-amp in the pedestal. but again it's hard to diagnose because the problem seems so random. has anyone heard of this before? anyone have any feedback for me? i feel pretty up the creek right now.

Posted by Gordon McLeod (Member # 33) on 09-09-2009, 06:08 PM:

my suspicion is it is the eiki rpeamp
try connecting the cell directly to a LoZ mike input of the mackie mixer (make sure you disconnect the existing eiki preamp first

Posted by Laura Jean Kahl (Member # 5234) on 09-09-2009, 07:11 PM:

thanks gordon.
we have a visiting filmmaker coming in on the 20th with 4 16mm films to screen, so i'm scrambling for a solution. i've got a pgh friend who specializes in home built electronics coming in to help me troubleshoot friday. we will try this.

Posted by Tom Sauter (Member # 616) on 09-10-2009, 06:31 AM:

The audio board was never this projector's strong suit (neither was anything else). Its a pretty simple operation, you can follow the wire right out of the soundhead behind the slit lens and cut it off. If you open the non-operating side cover of the projector the wires are all very accessible. All of the audio circuitry is contained in the pedestal, so nipping it anywhere before there will work.

Use caution when working on this projector, there are EXPOSED HIGH CURRENT DC LINES entering the lamphouse.

Posted by Bill Enos (Member # 440) on 09-10-2009, 07:19 PM:

I've never heard anything good about Eiki preamps. After wasting a lot of time trying to get satisfactory results we finally routed to cell to an external preamp.

Posted by Laura Jean Kahl (Member # 5234) on 09-15-2009, 03:00 PM:

alright guys. after some soldering i successfully bypassed the preamp, so sound is directly in the mackie. have to use quite a bit of gain from there, but it sounds good.

now time will be the test to determine if it was indeed the preamp causing the spiking then the cutting out, or some other onerous working of electricity.

thanks!

Posted by Gordon McLeod (Member # 33) on 09-15-2009, 05:37 PM:

you may want to check just how well regulated your excitor lamp powersupply is
a voltage increase there will increase the gain

Posted by Jarret Chessell (Member # 5077) on 09-15-2009, 10:49 PM:

might be an excellent time to replace your exciter lamp. For the sake of balance anyways.

Posted by System Notices (Member # 2357) on 11-23-2017, 02:17 PM:

It has been 2990 days since the last post.

Posted by Abraham Robinson (Member # 10230) on 11-23-2017, 02:17 PM:

can someone explain what is meant in the earlier post by:

"For those that don't however, Pro-Co has what they call the AV-1. It takes "speaker out" from a 1/4" input and drops it to either "line-out" or "mic-out". One nice thing it does is put a low impedance load on the projector's amplifier. Most 16mm amps do NOT like feeding high-impedance inputs. Its always a good idea to put at least 8 or 16-Ohm resistors across the ouput when padding them down."

I understand the difference between the Speaker, Line, or Mic level outs, but am confused by the hi/lo impedance part.

I am looking at DI boxes for portable 16mm projection; is the 'Pro-Co Av-1' ' s low impedance load different, than say the Radial Engineering AV-1 box? or a much cheaper option than something like a 'Behringer ULTRA-DI DI20' ?

I am leaning towards buying the Radial box, as it is a bit more versatile, but I definitely need something that can do as described earlier by the Pro-Co, does the Radial do this too? or is that something unique about the Pro-Co's DI?

Posted by Gary A. Hoselton (Member # 3447) on 11-29-2017, 10:21 PM:

If mfr doesn't spec what their low impedance load is, then you'll have to measure it with an ohmmeter, hoping to find 8 to 16 ohms. The main thing is to always load the projector amplifier's output with an 8 to 16 ohm resistor rated at 10-15 watts, wirewound is fine, even if volume is down to zero and you are just using the exciter lamp power supply. The resistor costs a dollar or two; amplifier repair can be quite expensive.

Posted by Frank Angel (Member # 248) on 12-05-2017, 04:51 PM:

quote:
I think the Eiki line is the best in 16mm. Those things just keep running and running. My only complaint is the lens barrel/focusing assembly. It leaves a bit to be desired.

Boy, no kidding. I just got involved in a Film Department that as a dozen or so Eiki (and those same Eikis that B&H slapped there name on -- the 3585), and ALL of them have that rubber sleeve on the focusing knob shaft that has deteriorated into this glob of melted orange goo. When you were working with them Brad, they probably were just softening up -- given an additional decade or two and they're now just a oozing mess. And of course that is useless for moving the lens back and forth, so an otherwise perfectly good working projector that needs only a bit of cleaning and lubrication to work perfectly, more or less becomes an interesting looking door stop.

Does anyone know if there is a work-around fix other than getting an exact replacement part should someone even have such a part, it probably would be in the same useless state as those in the projectors. It was certainly a terrible design to begin with.

If I can't find something that will make a good substitute, I am thinking of just drilling into the lens holder unit and tapping it so I can use a set screw in it. This will at least allow you to manually move the lens and then when you get the image focused, lock it in place with the set screw.

Anyone ever found DIY remedy for this problem?

Posted by Steve Guttag (Member # 268) on 12-05-2017, 05:19 PM:

I had success using roundthane (you know, belting material for take up reels). You have to size it though, it won't be right out of the box/roll. I recall mounting the knob on a drill press with the tubing on it and then sanding the roundthane down until it was the desired size. It has been a LONG time since I had to do one though.

Posted by Scott Norwood (Member # 30) on 12-05-2017, 05:23 PM:

The usual fix for the Eiki focus knob problem is to remove the focus knob, scrape off the goo, and put on a bit of windshield washer tubing in its place, which is basically Steve's method. The tubing comes in two diameters and I don't remember which is correct. Or just order a focus knob (I believe that all Eikis use the same one).

Posted by Frank Angel (Member # 248) on 12-05-2017, 07:19 PM:

Yah, had the same idea -- took the outer jacket of audio cable and tried that, but it wasn't quite the right size. Tried shrink wrap, but once shrunk, it wouldn't protrude out of the slot to engage the lens -- it seems to really need rubber -- hense, your windshield wiper tubing, Scott. Sanding down roundthane...Steve, you are one tenacious tech!

Ah...Larry Urbanski just emailed me and said to use the silicone tubing that they use in fish tanks. Definitely will try that. He says he's had success with it. Still am going to do a set screw in addition to make sure once it is in focus, it stays in focus; I'll get a set screw with a knurled head on it so it can be tightened by hand with no need for a screwdriver.

Posted by Bill Brandenstein (Member # 7758) on 12-05-2017, 09:20 PM:

Frank, I did one similar to Larry's solution - silicone tubing, but it was fuel line from a hobby store. (Probably the same stuff.) It was actually too large by a minuscule amount, but by bunching it up slightly on that tiny shaft, it's functioned perfectly for years now.

Cost almost nothing.

Posted by Lindsay Morris (Member # 1430) on 12-06-2017, 01:30 AM:

What we in Aust often use is the very easy to source reticulation tubing which one uses to take off small sprinklers or sprays from the 13mm or 19mm poly retic lines.

The stuff is exactly the right size to slip over the spindle of the focus knob AND IF you purchase the SOFT version of that tubing the OD is exactly spot on to grip the lens threads & the focus works well. NEVER moves with vibration.
Sometimes the ID is a tad large for a snug fit on the shaft but a dob of contact adhesive on the spindle as you push the tube on goes off nice & firm & stops the spindle slipping inside the tubing.
BE aware that there is a couple of styles of this small gauge tubing. One type is quite stiff & almost semi rigid but the right ID & OD and the other is a swine as it is under size on both ID & OD and IF you manage to get it onto the focus knob spindle it simply will NOT grip the thread of the lens barrel.

It is a fair cow to actually get the small sprays & drippers that are meant to be inserted in this stuff actually go in without a lot of mucking around often breaking the sprays or drippers. [Mad]

So far have done dozens of Eikis with this stuff & never had a comeback and have used it on RT, NT & SSL models as well as the Xenon 4000P unit. It is the same barrel design on all.

Posted by Colin Brant (Member # 10162) on 12-14-2017, 01:10 AM:

This thread has a lot of great info in it, just wish it was broken up by topic and that I had found it sooner! I've had to learn a lot of this the hard way...

Question #1: does anyone have a preferred high-quality preamp for replacing the standard Eiki one? I've been looking into doing this for both my Eiki SSL-0 and EX3000.

Question #2: is there a way to apply an "Academy Cure" to 16mm mono optical soundtracks? I can approximate it using a 32 band graphic EQ but I believe the actual spec requires -18db parameters. Curious if it can be done with either the Dolby CP750 or 650? Anyone ever tried this?

Eiki Focus Mechanism: I like using heat shrink tubing (the kind w/ adhesive) and a heat gun. I believe the 1/4" diameter stuff works with two layers and should last a lifetime. The second layer requires stretching with a pair of needle nose pliers and you just slide it over the first layer before it resumes its normal size. But Larry Urbanksi is a great resource and I'd trust any advice he or his wife gives.

Posted by Bill Brandenstein (Member # 7758) on 12-15-2017, 04:50 PM:

#2 - I'm not an expert in the process of mastering audio to 16mm negative, but I'm pretty sure there is no Academy X-curve on 16mm. Most 16mm titles of any vintage can't afford to lose any of the precious little high frequency content present.

Posted by Steve Guttag (Member # 268) on 12-16-2017, 09:37 AM:

Some misconceptions here. There is no Academy curve, per-say. The filter was derived based on measurements of the end result of the normal record/playback process pre-EQ era. That is, speakers played back flat (Altec A4s, typically) in a pre-1970 theatre (large barn, typically). The Academy filter was added by Dolby to mimick the "typical" response of an old theatre since once a CP100/CP50 were installed, one EQed the room to a more flat response. Mono movies, with pre-emphasis would sound bright/sibilant. Furthermore, the noise of the track would seem increased since the high-end was no longer being "naturally" attenuated by the playback equipment/room.

16mm never had the same presumption of playback. Most 16mm projectors made had their own preamp/amplifier built in and by and large were played back on smallish speakers but in also relatively small rooms. The theatrical aspect of the format was not predominate at all. Furthermore, the speed of film and comparatively smaller area for the soundtrack also limits its potential frequency response, noise and dynamic range. If that wasn't enough, 16mm was often duped, further degrading the picture and sound.

There really isn't a "right" response for it. It is something that often has to be adjusted on a film-by-film basis for what sounds best, which is subjective.

Now there are SMPTE documents (now mostly marked "stable" regarding 16mm record/playback response but those relate to making the equipment as "flat" as possible and what the frequency range should be without regard to the room it is played in.

To tune it, I would forget about ⅓ octave graphic EQ (it would add more problems than it would fix...ever look at the actual response when one tries to use multiple frequenciy to shape a response? It isn't pretty). Start with just simple tone controls. I would put the bass frequency at 100Hz and the Treble at 2KHz. You might add a low-pass at 8KHz (there nothing above that but noise).

Another thing that can improve 16mm is a dynamic range expander with 10-20% expansion. It can clean up a track and undo what had to be done to get the audio to "fit" on the 16mm optical track. Having a full blown drag and drop DSP would be quite beneficial here. Another thing that I've had decent results with is actually a Kintek processor (separates or a KT-700, nothing later). Kintek's optical preamp was decent enough for 16mm and the system has the dynamic range expander built in.

As for 16mm optical preamps, I found that Elmo really had the best. The later Kinoton preamps (circa 1993 and later) also seemed to be decent. Most 35mm preamps don't mate up well. Yes, they work but the slit loss is all wrong and it never seems to sound good to me. Most any microphone preamp will work but remember that you have a DC offset introduced by the cell so the preamp has to be able to deal with that. Cells like to be loaded down (act like current sources) so don't be afraid to put a ressistor across the cell if the preamp doesn't load it enough for a flat response. You'll lose output level but gain a better response.

Posted by Bill Brandenstein (Member # 7758) on 12-18-2017, 08:15 PM:

That's wonderfully helpful. Thank you for those details, Steve. It makes perfect sense that the "X-curve" was a POST-mastering, presentation-related invention.

And yes, the studio originals in my small 16mm features collection are all over the map so far as the spectrum of the audio goes, so I agree that those tone controls are often best tailored to each title. Some are amazing, some are dull, some are thumpy or distorted, and a couple of Fox newsreels from the 40s have amazing frequency content from 40 Hz to about 8 or 9 Khz. They probably didn't even know it back in the day.

Posted by Steve Guttag (Member # 268) on 12-18-2017, 08:23 PM:

The "X" curve is technically the wide-band response (Dolby Stereo and the like) "N" curve is the band limited response that is associated with monaural.

Posted by Colin Brant (Member # 10162) on 03-13-2018, 08:12 PM:

Thanks for the information Steve (and sorry for the long delay). I would like to try finding a well-suited mic preamp and expander to pair with an Eiki EX3000. My thought is to disconnect and/or remove the preamp and power amp and install a new third party preamp on the side of the projector body. Though I think I remember hearing the amp supplies power to the exciter lamp so that could be tricky...

Based on your post, it seems like getting a well-suited mic preamp is the most critical aspect here, right? (Other than the condition and fidelity of the film print of course.) Not sure I understand your point about the DC offset. Is this something I should look for in the specs of a preamp or would I just want to solder in a resistor between the optical reader and the 3rd party preamp? I am looking at this Rolls MP13 box (though it would be great if I could find something with built-in EQ and even Low Pass, I mostly find High Pass on the mic preamps that I"m seeing).

Rolls MP13
https://www.bhphotovideo.com/c/product/155445-REG/Rolls_MP13_MP13_Mini_Microphone_Preamp.html?ap=y&c3api=1876%2C%7Bcreative%7D%2C%7Bkeyword%7D&gclid=Cj0KCQjw7Z3VBRC-ARIsAEQifZTcHdieIdNj53ESSK0IEFEiFwPWPYH7r4A-vHp9a2YgUdvuhlNYO-gaAmbaEALw_wcB

And I am also seeing decent reviews on the Dbx 1BX DR expander, but since it is for stereo I'm not sure it makes sense for my 16mm application. Seems like most new expanders are actually software plugins? I'd like something rack-mountable.

dbx 1bx
https://www.ebay.com/p/dbx-1bx-Series-III-1-Band-Dynamic-Range-Expander-With-Impact-Restoration/1508179232?iid=132529824961&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D49917%26meid%3D2efc6f4aa46a4caca2eb40732120c60c%26pid%3D100011%26rk%3 D6%26rkt%3D12%26sd%3D281821534227%26itm%3D132529824961&_trksid=p2047675.c100011.m1850

Thanks for any continued interest or support!

Posted by Gordon McLeod (Member # 33) on 03-14-2018, 08:16 AM:

The solar cell is a DC device and as such if just white light is shinning on it it will out put DC
that can bother some preamps Transformer coupled are usually the best
The expander works great on 16mm to open up the dynamics a bit I used a Kintek KT700 for many years on a 16mm setup

Posted by John Newsom (Member # 6656) on 10-13-2018, 10:07 PM:

In reading most of the posts about getting good sound from Eiki projectors, I'm not clear about the "hidden" line out using a stereo phono plug and taking the output from the center ring and the tip. Does this risk damage to the projector's amplifier by not putting a load on it? If so, how can this be averted. I have two NT-0 projectors. This may have been addressed in discussing another Eiki model. I am wanting to take a line level signal from my two projectors to my sound system amplifier using an input switch.