Film-Tech Forum ARCHIVE: Shrill Mono

This is topic Shrill Mono in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Martin McCaffery (Member # 37) on 08-17-2010, 04:31 PM:

We have Dolby 650 with Kelmar basement red readers. The digital sounds fine.

We've been getting into playing more classic films lately. Not frequently enough for me to get too worked up about it, but now it is starting to bug me. I've been attributing the problems to old 1950's and 60's tracks, but now we have a very good print of Animal House and still have problems.

The sound is very shrill, too much sibilance in the voices, and with some voices, mid-range dropout like the crossover is not working.

The drop out is particularly bad in Dolby A and SR. Plain Mono covers the dropout better, but still shrill.

Haven't broken out the oscilliscope yet, but wondering where I should start trouble shooting this, and is it likely an easy fix?

Posted by Mitchell Dvoskin (Member # 751) on 08-17-2010, 04:45 PM:

Any film made prior to 1977 should be played mono (no Dolby) unless the film was restored with a Dolby track, and is marked as such on the leader. Don't go by the shipping container label.

Any film made from 1977 to maybe 1996 would be Dolby SR if the leader is marked SR or SRD, Dolby A if it is marked Dolby Stereo, or mono otherwise.

Most of those old films from the pre-dolby era had very good sounding mono tracks, although they lacked (by design) deep lows and highs above 15K. If you are lacking mid-range, you have some issue that needs to be corrected.

My suspicion is that your photocell's azimuth is out of alignment due the sibilance issue, but the lack of mid-range is probably an equalization problem.

Animal House was MONO, and should be played back mono.

Posted by Marin Zorica (Member # 1716) on 08-17-2010, 05:17 PM:

There are also some EQ issues how is being recorded back than, mostly academy curve was used, but also some other type of emphasis were added to it (to improve S/N ratio). Also if you use red reader than you probably have issues with intermodulation (search in forum for it, it's beed discussed all ready), old prints (non cxan) should be played best with exciter lamp, or IR led in reverse scan readers.

Normally, it can be problem with A chain, but since you mentioned problem only with old prints, I thought you did check sound with newer prints in SR?

Posted by Victor Liorentas (Member # 5272) on 08-17-2010, 06:52 PM:

I have the same issues with mono movies except on occasion when i am surprised by a great sounding mono track like Jaws in IB Tech but not Eastman SP.
I put it down to lack of exciter lamps and tube amplification.

Posted by Louis Bornwasser (Member # 3063) on 08-17-2010, 07:01 PM:

Prior to Dolby, mono used a roll off: down 5 db at 5k. Probably 10 db at 7.5 k. Film was mixed that way, so you can't get it back with eq. Louis

Posted by Martin McCaffery (Member # 37) on 08-17-2010, 08:06 PM:

Let me clarify about Dolby A and SR, just tested the Mono print going on those channels to see if it would be an improvement and it wasn't. Wasn't running the films that way.

It does sound like the Academy Curve roll off. I want to stick a pillow in the horn;> Anyone figured out a work around?

I wlll give the azimuth a check, though we did readjust last December.

I recall the exciter discussion. At least until we show old films more than once a quarter I'm not messing with that;>

Posted by Mitchell Dvoskin (Member # 751) on 08-24-2010, 11:55 AM:

Your sound processor should be doing the "Academy" equalization for mono prints, when running in mono mode.

Posted by Gordon McLeod (Member # 33) on 08-24-2010, 11:07 PM:

I beleive there is a mono eq in the processor to control the amount of hf