This is topic 35mm mag dubber suggestions in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Dave Cutler (Member # 515) on 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.
Posted by Mark Gulbrandsen (Member # 72) on 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
Posted by Gordon McLeod (Member # 33) on 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
Posted by Gordon McLeod (Member # 33) on 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 385nwbIf 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
Posted by Dave Cutler (Member # 515) on 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.
Posted by Gordon McLeod (Member # 33) on 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?
Posted by Dave Cutler (Member # 515) on 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?
Posted by Gordon McLeod (Member # 33) on 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
Posted by Scott Norwood (Member # 30) on 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?
Posted by Phil Hill (Member # 371) on 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
Posted by Gordon McLeod (Member # 33) on 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
Posted by Dave Cutler (Member # 515) on 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.
Posted by Phil Hill (Member # 371) on 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
Posted by Phil Hill (Member # 371) on 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
Posted by Gordon McLeod (Member # 33) on 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