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bolex ebm sync sound


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#1 diego vazquez

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Posted 06 June 2007 - 05:54 AM

hi there, i bought a bolex ebm already converted to super 16 with 2 400ft mags and a mm motor for the magazines plus a tobin txm 24 crystal sync unit.

the first thing we ever shot with it was a 3 minute short film and because i was new to this we shot it with 100ft rolls (and this was before i recieved the tobin crystal sync unit)
we shot it using ten 100ft rolls we ended with around 30 mins of footage at 24fps
we then tranfered with a spirit telecine to HD SR tapes at 24fps ending up with our bestlight rushes in HD at 24fps, then with flame we captured all the rushes from hd, keeping the timecode intact, and converted to lowres quiktimes at 24fps, once i had a 30 min quicktime, before even bringing into final cut pro, i went straight to pro tools and captured the dat recordings from the set, and i lined up all the clap points of the clapper board, they all worked perfectly fine from clap, till you hear the switch of the camera switching it off and it was perfectly synced. then brought the 30 mins quicktime with sound attached to it into final cut pro and was ready to edit.
Now obviously due to the camera noise the soundtrack of my offline edit was just a guide track, so with a finished offline with a guide track containing the camera noise all through the film, i then called the actors back and we did the adr, it worked fine, and then edited the wild track and some foley, then exported my edl and reconformed in flame from the original HD tape, then graded of the HD 10bit 4:4:4 tape in flame. ENDING up with a HD master raedy for print.

the result was remarkable (at least for me)
so the point is that with 100ft rolls and WITHOUT a tobin txm24 the sound synced PERFECTLY.

we then recieved the tobin txm and thinking that it was just to make sure it ALWAYS synced, we went ahead and shot another short film, this time we also bought 400ft rolls and the used the tobin crystal unit.

after the shoot and telcine, (with the exact same process) when i was again in protools trying to sync the sound. it didnt work at all, so i freaked out and later noticed that the speed of the film was weird suddenly the actors would blink too fast and sometimes to slow.

so after a painstaking process of syncing 40 mins of footage with all looking weird.
it took me 2 days of my weekend of timestretching the sound like crazy with no predictable patterns just randomly timestretching and pitch shifting. at the end when i had my rushes quicktime with guide track attached to it and started editing, the motion of it was so weird that i found myself with 20 mins of footage completely useless, which for some reason happened to be the first five minutes of each one of the four 400ft rolls.

so i was devastated and stopped trusting my bolex, my 400ft mags, my MM motor and my tobin txm 24 unit, they were so unreliable,

i'm way better of using the bolex with no 400ft mags, and with no sync unit.


if you intrested in watching the first short we did, it was properly DI'ed so its a shame to watch with internet quality. here's the link.
http://www.filmaka.c...99-9D3A61011327

ANY OPINIONS?

thanks
regards
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#2 Nick Mulder

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Posted 06 June 2007 - 07:43 AM

ANY OPINIONS?

thanks
regards


Haven't watched your film but own an EL which is also 'electronically' regulated - whatever that means exactly I'm not sure - anyhoo's I've scoped my speeds and found that they are all pretty steady, problem is that although they are steady (they dont change) they are all off the rated speed +/- a few percent this way or that ... Your EBM must be luckly and right on 24fps ... I know I can open up my EL and access some trim-pots to try and change my speeds but I have a xtal sync unit for it... so havent done so yet ...

The 400' mag puts some extra loads on the electronics in terms of voltage requirements this maybe slowing down your EBM slightly - mind you if you were using the sync unit at the time the voltage/current offset should have been accounted for - unsure what happened there
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#3 Marty Hamrick

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Posted 06 June 2007 - 10:10 AM

The 400' mag puts some extra loads on the electronics in terms of voltage requirements this maybe slowing down your EBM slightly - mind you if you were using the sync unit at the time the voltage/current offset should have been accounted for - unsure what happened there

Had the same problem with my EBM a few years ago.Never bothered using it again for sync,I was told it would require an expensive trip to the shop.I ended up selling the camera anyway,got tired of dealing with camera noise.

Love your film!Excellent work!
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#4 diego vazquez

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Posted 07 June 2007 - 02:27 AM

hey nick thanks for reply, so you mean that the offset should have been accounted for , as in the red LED in the sync unit should have warned me? cus it didnt thats wahy we thought it was fine, but yesterday i took the camera out and i discovered something. i first ran it at 24 fps (without the sync unit) then at 25 fps and kept switching between, and eventhought it is very slight, i was noticing the change of pitch of the noise produced by the motor... it is very slight but noticable, its almost like one interval up at 25 and one down at 24. then i switched it off, plugged the crystal unit, and switched the speed of the camera to SYNC mode, and when its in this mode, you change the speed from 24 to 25 with the crystal unit right? so i did that and there was no speed change what so ever. at 24 it sounded exactly the same as when in 25, so it looks like my tobin txm24 is f$@£ed. GOD it was so expensive.

oh well. it sucks not being able to shoot with sound sync with 400ft rolls. i was really willing to keep doing adr. but i need a guide track that syncs. without it the bolex is useless, cus 100ft rolls suck for dialogue.
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#5 Tim Terner

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Posted 07 June 2007 - 03:05 AM

Beautifully filmed short Diego. I'd be interested to know how much the telecine was for the ten 100ft rolls
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#6 diego vazquez

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Posted 07 June 2007 - 04:36 AM

Beautifully filmed short Diego. I'd be interested to know how much the telecine was for the ten 100ft rolls


thanks man although my friend vaclav cizkovsky shot it, he's a dope photographer.

the tk was a favour by the guys downstairs at telecine, my hard work at a post house gives me the right of telecine use.
hehe, my way to go...

although development was expensive, in london you calculate the same price for development as for stock. i dont know about other countries.
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#7 Nick Mulder

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Posted 11 June 2007 - 03:12 AM

so it looks like my tobin txm24 is f$@£ed. GOD it was so expensive.


Sorry bout the delay. I haven't seen a unit up close, but many parts in Tobin units are replaceable and can be found at the local electronics store or online ...

Do you know your way around a multimeter or scope ?
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#8 diego vazquez

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Posted 11 June 2007 - 05:33 AM

Do you know your way around a multimeter or scope ?


not really whats this about?
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#9 Nick Mulder

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Posted 11 June 2007 - 07:18 AM

not really whats this about?

Well, if you did I was just going to give you some motivation and good vibes about attempting to rule out a few possible faults with the electronics (that might be easily fixed/replaced) - too hard for me to explain though without the unit here with me to fiddle with ...
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#10 Clive Tobin

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Posted 11 June 2007 - 09:17 PM

...plugged the crystal unit, and switched the speed of the camera to SYNC mode, and when its in this mode, you change the speed from 24 to 25 with the crystal unit right? so i did that and there was no speed change what so ever. at 24 it sounded exactly the same as when in 25, so it looks like my tobin txm24 is f$@£ed. ...

It is unheard of for one of our TXM-24 units to fail. I don't recall ever having to repair the circuit in one.

Important: Are you plugging the TXM-24 *DIRECTLY* into the camera body per the instructions, and not just into the handgrip? The handgrip is not wired for crystal.

Otherwise: Most likely the crystal-related input transistor in the camera has gone sour (shorted or open) so the camera is just running at 22 or 27 FPS and the TXM-24 has no control of the speed. It is quite common for the Bolex transistors to go bad, they are sometimes bad even in a brand new camera. In this case the Sync Alarm light will be flashing or lighted. If not, perhaps the cable is bad and the unit is not getting power.

The TXM-24 has a self-test mode where you leave it plugged in, but switch out of the SYNC position and try various camera speeds; the sync alarm should flash or light in most of them, though it might not light at 24 or 25 if the camera's built in speed governor is set very accurately. If not, the cable or socket is bad and the unit is not getting power. It will not harm the crystal unit to be run in this way.

Possibly the TXM-24 has a bad speed switch but I've never run into that.
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#11 diego vazquez

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Posted 12 June 2007 - 05:09 AM

Most likely the crystal-related input transistor in the camera has gone sour (shorted or open) so the camera is just running at 22 or 27 FPS and the TXM-24 has no control of the speed. It is quite common for the Bolex transistors to go bad, they are sometimes bad even in a brand new camera. In this case the Sync Alarm light will be flashing or lighted. If not, perhaps the cable is bad and the unit is not getting power.



thank you for your message sir. i think this is my case... it flashes red.... i just checked. and when i'm in sync mode on the bolex an with the txm-24, and i switch between 24 and 25fps i dont hear any speed change. without the txm-24, by changing the speed with the bolex's knob. i do hear the speed change between 24 and 25?

do you think i can fix this myself?

thanks, regards, my respect for your 16mm home telecine. respect
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#12 Clive Tobin

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Posted 13 June 2007 - 08:38 PM

...do you think i can fix this myself?
thanks, regards, my respect for your 16mm home telecine. respect...

If you mean the transistor is bad, this would be an easy fix, except that I think you have to completely dismantle the camera to get to the circuit board.

Not that it is any consolation, but these European BC-number transistors are bad news anywhere. I used to have the misfortune of being the one trying to keep a Rank Cintel working, and one of these lousy transistors (BC71 maybe?) would fail about every week. That was even after taking off the front bottom panel so the boards didn't overheat, as secretly and unofficially advised by the Rank sales rep. I started replacing all of them with popular reliable types like 2N3904.
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