Film-Tech Forum ARCHIVE: Getting Good Mono

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

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Posted by Martin McCaffery (Member # 37) on 05-11-2011, 10:58 AM:

I've complained before about older, pre-digital mono prints sounding shrill when we show them. We don't do many, but are doing more. Even the recent Sing Along Sound of Music, which had an SR track, sounded shrill in the dialog scenes (songs sounded fine).

Just to test if we are set up properly, I bought a 1956 sound check reel on ebay (ASTR-5). It is in great shape. It is one of those reels with music and dialog.

I gave it a coating of Film Guard and played it on both machines. It sounded great. No shrillness, even in the scene that was purposefully mixed high. And the scene with the lady singing operaesquely high sounded crystal clear, no distortion.

So, have I just been unlucky getting prints (really, really unlucky)? Or have the labs in the last 20 years changed recording standards? Or are the soundtracks on prints just as crappy as the picture reproduction? None of these prints are archive prints or newly restored, just the regular circulating copies.

Posted by Robert Minichino (Member # 3495) on 05-11-2011, 12:44 PM:

We play a lot of old mono films, and I haven't heard the same degree of harshness that you indicate. We're playing through Altec A2s with multicellular horns, so take that for what it's worth.

If there's a fault with the prints, it could be that poor soundtrack printing density control is causing excessive cross-modulation distortion. The negative and print densities need to be carefully controlled so that the cross-modulation caused by the high printing density is cancelled out by the negative density. If the lab doesn't have a cross-modulation reference to test against, they have to guess at the correct printing density, and they might be guessing wrong.

Posted by Mitchell Dvoskin (Member # 751) on 05-11-2011, 01:34 PM:

More information please:

Are you referring to "classic" films released in mono, or stereo films being played back in mono?

Red LED or White Exciter?
Mono pre-amp or Stereo Processor?

Recent "A" chain alignment?
Recent "B" chain alignment?

Posted by Martin McCaffery (Member # 37) on 05-11-2011, 01:48 PM:

Are you referring to "classic" films released in mono, or stereo films being played back in mono?

Red LED or White Exciter? Red

Mono pre-amp or Stereo Processor? CP650 set to mono

Recent "A" chain alignment?
Recent "B" chain alignment?

Both in the last 8 months.

Posted by Louis Bornwasser (Member # 3063) on 05-11-2011, 03:23 PM:

I believe that there is a screen for "MONO EQ" on the 650. Set by ear or set to Academy curve. louis

Posted by Ian Parfrey (Member # 5122) on 05-11-2011, 07:01 PM:

Martin.

Could you post some images of the soundtrack at various places and modulation levels? I'd venture to say that the optical sound recordists knew their business and an image or two of the track may help to confirm or reject this.

Posted by Phillip Grace (Member # 2262) on 05-12-2011, 07:25 AM:

I might have soething to offer here.
The CP650 has dedicated mono eq adjustment, but in our CP650's it does not behave as described in the set-up manual. According to the manual, HF boost increases as the indicator is moved to the right, (fine so far), and that the furthest right position enables an Academy Mono filter. In our case it doesn't happen, and that last position gives a colossal HF boost, with appalling results. We finished up setting the Mono EQ round about the middle of the scale, for generally acceptable results. We also have some addtional external EQ for extreme cases.
We see quite a range of Mono prints, from all over the world, and the variations in response seem to relate a bit to era of the material and place of origin to some extent - so I would put it down to variations in production methods at different times and locations.
There have been a few extensive discussions on FT over the years. Definitely worth the search.
It might be worthwhile to consider how uniform is the coverage of the mid and high frequency horn(s)across the auditorium. There could be zone(s) of more concentrated HF energy near the centre of the room for example.
AndI'll go away now!

Posted by Martin McCaffery (Member # 37) on 05-12-2011, 11:17 AM:

OK, according to my CP650 Installation Manual, section 7.6, I should use the left menu button until I get Mono Level Trim screen.

I've gone through it several times and I don't get that screen. There should also be a Mono EQ Adjust screen. Not finding that either. This is where the Academy filter should be, according to the manual.

What am I doing wrong? Has it been moved or renamed in recent software?

Ian: haven't been able to get a good photo yet

Posted by Tony Bandiera Jr (Member # 2365) on 05-12-2011, 01:16 PM:

Martin:

Try again, but make sure the DIP switch #6 under the flip panel is on...that is the "install" or service mode.

Failing that, get the software and your laptop out and do it using CP650 Setup.

(Even though CP650 Setup software is intended primarily for technician use, I feel it is a very good idea for ANY location with CP650's to have it so that they can save the processor's setup info in case a breakdown requires a swap out. One individual in the company should save all the processors' information, naming the files by location and screen number [ex. UCIrvine1] and burning those files to a cd-rom for future use.)

And before a certain person chimes in saying that won't work, I am aware that some settings (like A-chain levels) will change over time, at least you'll have a good baseline to operate from in an emergency until a tech can come in and fine-tune things again.

Posted by Martin McCaffery (Member # 37) on 05-12-2011, 03:11 PM:

Tony: Had the switch on when I tried before posting.
Out of town for a few days so will try the laptop when I get back.

Posted by Eric Robinson (Member # 2966) on 05-16-2011, 12:57 AM:

quote: Tony Bandiera Jr
I feel it is a very good idea for ANY location with CP650's to have it so that they can save the processor's setup info in case a breakdown requires a swap out.

Definitely a good thing to do! This has saved me many times.