35mm Sprocket Hole Buzz

[Paul Finn]

Two Norelco AA projectors upgraded with Kinoton Reverse-Scan Sound Device (analog/digital. Dolby CP200 processor."There Will Be Blood" 35mm film print in very good condition with no obvisous visible defects. DD mostly runs at 7 or FAIL throughout. Part way through in some of the reels running the analog soundtrack, a 96Hz sprocket hole buzz appears in the right channel at about the Dolby level for 5-10 minutes. Same results with same reels on either projector. If I recalI, I believe we saw the same thing last year with some of the prints in the "Star Wars" series.

Has anyone here ever seen this happening or can suggest a reason? My only conclusion is it has to be the film? Luckily, DTS digital saved this presentatio(s).

Thank you, Paul Finn

[Ryan Gallagher]

We showed TWBB last year on 35mm. Wonder if it's the same print. We did not have any such audio artifacts with our copy. I'm not at work or I'd pull up our inspection report for the print number.

[Christos Gartaganis]

Most likely the reverse scan reader needs realignment. The best way to determine what is causing the issue is to run a film loop using the SMPTE buzz track test film. Additionally, inspect the rubber "O" rings on the film pressure roller with a magnifying glass for any surface defects and replace both if necessary.

[Leo Enticknap]

If the fault presents with multiple prints, it is probably the reader alignment. If it's with only one, likely the print. I do remember getting a few reels with misaligned tracks during my projectionist days, that effed up the SR matrix decoding and/or caused high error rates on SR-D tracks.

[Ryan Gallagher]

If the fault presents with multiple prints, it is probably the reader alignment. If it's with only one, likely the print. I do remember getting a few reels with misaligned tracks during my projectionist days, that effed up the SR matrix decoding and/or caused high error rates on SR-D tracks.

The real question is, back in the day, did they do a custom alignment to fix the crappy print? Or just kick them back and say try again? Or neither and let it ride?

[Mike Blakesley]

One of the most dreaded types of film damage was if the soundtrack area had sprocket scratches -- that would create an awful buzz sound. I had a film once where one whole reel had that damage. It was obnoxious as hell. Since we only had the print for a week, there was no point calling in for a replacement reel on Monday morning so we lived with it.

[Tj Hopland]

Were you able to inspect the specific areas of the print that had the issue? Were you able to run those reels on both projectors to see if they both did it?

If the distributor says the print has been to many sites with no other complaints I would say get your tech in with no time pressure to carefully go through the alignment. Being a combo reader this will take the some time and the full kit of test equipment and loops. I don't know these specific model but my guess is something has things shifted off center in the optical reader so when you get a print that is a little off in some way you are getting a reflection thing going on inside the lens tube that is getting picked up. This doesn't happen as often with just optical but with the combo reader you are trying to get 2 readers aligned on one film path.

[Mark Gulbrandsen]

If the fault presents with multiple prints, it is probably the reader alignment. If it's with only one, likely the print. I do remember getting a few reels with misaligned tracks during my projectionist days, that effed up the SR matrix decoding and/or caused high error rates on SR-D tracks.

This is exactly why we didn't use the Kinoton basement reader on the rebuilds I did at Claco. If you have to work on one pickup, then you mess up the other and so on, We converted the optical reader to the machined in place BACP for analog, and top mounted BACP for SRD, Sony, or what ever other readers were needed. DTS readers went in place of the mag penthouse on their own machined mount and you could swap in the 70m reader if needed, or reinstall the mag penthouse if ever needed. We did do one Kinoton basement reader on a rebuild for Bran Ferrin. However, that projector had literally every possible playback system on the projector. Anyway, over about 50 DP-70 rebuilds, we found the BACP route was the best overall choice.

[Ryan Gallagher]

We showed TWBB last year on 35mm. Wonder if it's the same print. We did not have any such audio artifacts with our copy. I'm not at work or I'd pull up our inspection report for the print number.

Past due follow up. Our print was ID No. 5666 when we showed that one.

[Tony Bandiera Jr]

This is exactly why we didn't use the Kinoton basement reader on the rebuilds I did at Claco. If you have to work on one pickup, then you mess up the other and so on, We converted the optical reader to the machined in place BACP for analog, and top mounted BACP for SRD, Sony, or what ever other readers were needed. DTS readers went in place of the mag penthouse on their own machined mount and you could swap in the 70m reader if needed, or reinstall the mag penthouse if ever needed. We did do one Kinoton basement reader on a rebuild for Bran Ferrin. However, that projector had literally every possible playback system on the projector. Anyway, over about 50 DP-70 rebuilds, we found the BACP route was the best overall choice.

Funny, since the Kinotons I serviced in my days (including the UCI HIB100 ones) NEVER had that overscan issue and even the combination readers on the ones other than at UCI (HIB 100) never gave me any trouble during alignment.

Sounds more like a tech training issue than any fault of the readers.

[Marcel Birgelen]

I'd say if you have DTS media and timecode on the film, I'd always run DTS as primary instead of SRD, but that's probably a personal preference.

But I agree with Tony here, the fact that SRD constantly fails and you have this apparent overscan issue (if there is no print damage or misprints then it can, IMHO only be an overscan issue) and you had a similar issue on a previous print points towards a calibration issue of the Reverse-Scan Sound Device. I myself have found those to be pretty reliable.

[Steve Guttag]

I don't know what Mark is babbling about working on one RSSD reader messes up another. They are separate readers. The LED bracket/head is quasi-independent in that you move the whole head to align the optical and then there is a sub-bracket to align the digital LED.

The Kinoton RSSD did allow for adjusting magnification (turn the lens, then physically move the reader in/out to check magnification. My success rate on Kinoton RSSD was 100%. Was the DP70 and DP75 versions a little suspect? Yeah, a little with their damper roller. It was clear that they were a conversion of what they made for the production projectors of the time rather than a ground-up design specific to those models. They did work though.

My favorite basement readers remain Component Engineering. They too had a 100% success rate, for me (analog and digital). I also liked their 30 and 40 series LED power supplies best.