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Topic: 35mm mag dubber suggestions

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 02-28-2001 03:04 PM

Hey everyone, I haven't posted in what feels like forever. Just content to read, lately.

Anyway, I am looking into replacing my 35mm dubber and wanted to know what other people think are the best dubbers out there. I would like to look at at least 3, so the more suggestions the better.

If you are wondering why I need a 35mm dubber, its because I work at a 15/70 installation, and I think that having a 35mm dubber is still important for all 15/70 theatres. Seeing as most of the older films aren't avaliable in my digital format.

So, come one come all, and tell me your tales of your favorite mag dubbers.

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 02-28-2001 03:38 PM

I prefer MTM (now Rangertone) for portable use but for a fixed installation either a WRE or a Magnatech would be best. I much prefer the DC servo drive system on the MTM over the Stepper drive of the Magnatech as it runs noisless and has much lower flutter spec. At any rate you could buy a Magnatech or WRE dubber refurbished. No need to piss away money on a new one. Its a take your pick market as most dubbers are being replaced by digital dubbers now so you'll have a big choice. For heads, Teccon, the best, is long out of buisness. Its a shame that the designs and assets were not sold off so the company could continue. There is a company on the west coast that manufactures heads that are rebuildable and this may be the best way to go. As far as preamps the WRE can't be beat.
WRE is located in St Louis, and Magnatech comes from International Cinema in Florida.
Mark @ GTS

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 02-28-2001 07:23 PM

Almost all the large format theatres use MagnaTech. They are relatively inexpensive and recently the National Film Board of Canada was selling them off for around 200.00
I own 3 of them for rentals but My MTM's are a far better machine
A note of caution in that the MTM realy doesn't like the weight of 4000' rolls of tape
I buy my replacement heads from electromag
Most of the parts in the CP dubber are probably replaceable elsewhere

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-01-2001 10:59 AM

After some thought (ie a bottle of wine

) here are a few other thoughts
1 What type of shaftencoder is in the projector?
MTM and Magnatech use different pulse rates and would probably require a belt change which will require changes in your TimeCode generator
MTM is usually 48 or 24 pulses per frame and Magnatech is 10
I don't know what the westrex/cp dubber used
Also the takeup load can be a issue. Most dubbers are reely designed for 400-1000' rolls. Magnatech offers hightorque takeup option.
What type of Magpreamps do you have. Most Imax theatres now use the inovonics preamps that have 4 presets for 0, -3 -6 -9 db and HF curves for the range up to 385nwb

If budget isn't a consideration the SONDOR dubbers from Switzerland and the best

There is a used RCA dubber on EBAY right now

What has failed in the CP unit? Dubbers arn't rocket science and usually most engineers can fix them

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 03-01-2001 11:35 AM

Gordon,

I am not sure about the preamps, the only name I can find on them is 'CineMag.' Does that ring a bell?

One problem is that there is a flat spot on one of the rollers. It's the one just before the head, not counting the lift. If it has a name I don't know it. It is hindering the film from traveling at a constant speed across the head, and we get a warble. My system supplier hasn't found a replacement, and with our service contract we have to go to them for everything. They are coming out next week, and should be bringing a new one hopefully.

The second problem is with the lower tension arm. When the mag is playing it is almost all the way tight. Almost of the point of damaging the film. I don't know of an adjustment, and neither does my supplier. Could be a bad motor I guess, but the control board is OK.

As you can probably tell I don't know much about dubbers, and without a manual haven't been able to learn much. ANY info would be greatly appreciated.

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-01-2001 11:43 AM

Cinemag is a company I have never been able to get any info on. There is a rumour that they are an ofshoot of Jensen.
The roller is you speakof is part of the Davis tight loop stabalizer. I have never heard of one getting a flatspot except when it ran foran extended period not turning due to a seized bearing.
A good tool and die shop could grind anew one for you. The weight and mass are important.
There is also usually a black knob above it that centers the damper.
The takeup is servo controled and should have a torque adjustment on it(small pot).
Are you useing a floating hub reel for the takeup?

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 03-01-2001 11:56 AM

Yup, you got that one right. The bearings on the the roller siezed up and one point. It was quite sometime before they were replaced, and unfortunately we had to run mag for a one trailer, but it was enough to cause the flat spot. I ended up getting tired of waiting and just went to a local bering shop.

Now they are wishing they had let me take the trailer off. heheheh

I don't have a floating hub for the take-up, but haven't had a problem till now. Makes sense to use a floater, don't know why I didn't think about it. Would you say that it is worth the cost to get a floater?

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-01-2001 12:50 PM

I use a floater on anything over 45min as the load of the solid reel is just to much

Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 03-01-2001 04:33 PM

Don't mag dubbers have torque motors that maintain constant tension throughout the length of the reel? If so, why do you need floating-hub reels? The IMAX installations that I've seen usually use fixed-hub reels with 1/2" shafts that hold about 4000' of film (or thereabout...they're smaller than regular 6000' reels, I think).

I'm genuinely curious about this. The only other place where I've seen mag dubbers up close is a few 16mm mix facilities that usually use 2000' split reels and can't fit anything larger.

What type of mag stock do the IMAX people use? I'm familiar with 3M (no longer available), FPC (a Kodak company), MPC (who are these people?), and that grey stuff (Zonal?) that's no longer available. Is it acetate-base or polyester-base?

Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000

posted 03-02-2001 01:37 AM

Dave,
Your dubber is a custom design from Westrex and is specially designed to accept 6000ft reels with or without floating hubs. It should have Teccon heads and preamps adjusted to the 385nW standard. You have Dolby "A" and "SR" noise reduction and you should have some set-up mag films there to adjust the system.

Your dubber uses the industry standard 960 Hz tach signal (from the 1570 projector). 24 fps x 10 ppf x quadrature = 960 Hz.

>>> Phil

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-02-2001 10:51 AM

Scott most of the tape is FPC with some RacalZonal still kicking around
With some of the longer Films we are seeing 5000' rolls
The problem he describes is related to the torque of the motor and the adjustment of the servo
I wouldn't be suprised if the servo amplifier isn't flacky I have seen that on many MTM units

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 03-02-2001 02:28 PM

Hey Phil how you doin? Don't know if you remember but we met a little over a year ago when you were out here in KC. I am hoping the Roger will be able to teach me some things while he is out here this weekend. Thanx for the info, I didn't know that about the preamps and the tach pulse. We were never given any mag test films though, not that I would have any use for them. I have never been shown how to setup a mag system, never had a reason I guess. I'd like to learn though.

Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000

posted 03-03-2001 01:59 AM

Of course I remember you, Dave! I hope all is going well with you.

I talked with Roger and told him and Gil to make sure all is OK at your site.

Hound Gil...and learn. He's a great mechanical tech.

>>> Phil

Phil Hill
I love my cootie bug

Posts: 7595
From: Hollywood, CA USA
Registered: Mar 2000

posted 03-03-2001 02:01 AM

Gord,
I tried to reply to your email but was rudely sent this message:

The original message was received at Fri, 2 Mar 2001 23:49:17 -0800 (PST)
from pool0427.cvx19-bradley.dialup.earthlink.net [209.179.245.172]

----- The following addresses had permanent fatal errors -----
<gmcleod@idirect.com>

----- Transcript of session follows -----
... while talking to ld.mx.idirect.com.:
>>> MAIL From:<mr70mm@earthlink.net>
<<< 550 We do not accept SPAM.Go AWAY.
554 <gmcleod@idirect.com>... Service unavailable

My reply was:

Hi Gordon,
Give me a few days after I get back from Showest and I'll look in our
library and see what I have.

Thanks,

>>> Phil

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 03-03-2001 02:38 PM

Sorry Phil
you are the 3rd person this year that has happened to and I can't figureit out since I don't have anyfilters set in my email reader eudora
I have again sent it to the good folks at my ISP who probably will file it
anyone have anyideas what happened

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