We run Simplex XL & 35 projectors, XL soundheads (SH-1007 i think) component engineering analog ony reverse scans, Smart Mod2 B-Dit, Beheringer Compressor/Limitors and then a FM modulator.

Any Ideas?

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With traditional cyan+magenta+silver analog soundtracks, the optimum printing point is slightly different for red LED and "white light" readers, so one may hear slightly more distortion on the reader that the lab did not optimize for. "High Magenta" (magenta+silver) tracks are more compatible with both readers.
http://www.kodak.com/US/en/motion/support/dyetrack.shtml

Current surveys show that a majority of theatres now use red LED readers, but there is still a high percentage of "white light" readers. "High Magenta" tracks are an interim step until enough theatres use red LED readers to allow the use of cyan dye tracks.

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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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I don't recall what, if anything, was done to cope with this for the Smart processors. It's been ages since I serviced the MOD IIB's.

We turned the HF Gain all the way down for the Dolby units. Is there such a thing on the Smarts?

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Then there is the SMART NR circuit that is most likely mistracking to show off the problem (you will have the same problem with the Dolby CAT 222SR/A which is used in the CP-45 and lesser CP-65s).

As to the hums...that is poor grounding issues, pure and simple. I've installed CE's 20, 30 and 40 series units and you could put your head in a speaker with wide open gain and not get a hum out of it.

Steve

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So I am left scratching my head as to what the problem is. But several things began to point me in the right direction. 1) A feature reel used as a test seemed to play fine in analogue without the noticeably sibilance. 2) The clients where reporting that the same advert played at another preview house sounded fine. So we duly took the advert to this preview house, where we did indeed find the problem was not noticeable, we also took it to a third theatre, equipped with Sondor's also, and lo and behold the problem was there.

The second preview house was a very dry room and for a while I thought this could be a factor, but then this would not explain why Digital was fine in the theatre I was investigating. Eventually the pieces began to fall into place. After a few discussions with the Chief Engineer and a phone call to Dolby we discovered the problem mentioned in previous posts about the cross-mod effects of silver sound tracks on red light readers.

The adverts were being printed at one of the smaller processing houses near London and despite a lot of pressure from Dolby had not yet converted over to High Magenta, something all of the major film printers had done, which is why the feature test reel sounded fine, but the advert was sibilant. And, of course, the second preview theatre was still running with tungsten lamps, so no problem with silver prints.

So at the end of the day both the production company that owned the preview theatre and their clients discovered that they should be insisting on magenta prints in order for the products to sound as good as possible in cinemas.

Since then we have discovered that problem is more noticeable eon the latter processors (i.e. the CP500, CP45 and CP650), but does not seem to be a problem on CP-65’s a lower. This may have something to do with sound processing in the digital rather than analogue domain.

So what is the remedy for running older prints (all new prints should be hi-magenta), well the only one I have heard suggested so far would be to mount an older Dolby analogue pre-amp in an interface box so that it could be switched into the system to run older prints. I don’t believe this has been tested yet so I have no idea if would actually work. Of course it would require using non-sync input or the like to work, and switches in the cell lines (not a good option), but it may be an option where places run older prints.

The fact that the problem had not been widely publicized is interesting. A compromise was obviously decided upon in favor of newer prints and of course it is now too late to go back.

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Martin Dean

The only other alternatives to the JAX light I know of are using reverse scan units, which give great results, have space for the digital reverse scan, but cost more, or use a laser replacement. Lasers are a pig to line up (for the engineer) but work well with existing cells with no need of any extra pre-amps, can often use the existing exciter supply (if it is regulated), give good results and cost less than reverse scan. The only caveat with lasers is that the optic assembly has to be in good condition. But even the cost of a new optic is factored in it is still cheaper than reverse scan.

Interestingly the response from the lasers can in fact be too good. I have installed several on systems consisting of Westar 2001’s with CP-45’s, along with new optics and discovered even when the slit loss is fully rolled off that there was still a light peak at the HF end (only 1dB or so, so not critical). The theatre did complain of the occasional sibilant film, but I latter put this down to the cross-mod distortion effects of red-light readers with silver soundtracks.

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Martin Dean

Steve

And you were also asking weather it was conventional film or the high-megenta. I havn't checked yet but i would asume high-magenta. The films playing right now are "xXx" "spy kids 2" "Blue Crush" so they are all new releases if that helps. I'll be sure to check tonight though

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