Film-Tech Forum ARCHIVE: Cat 222 SR woes

This is topic Cat 222 SR woes in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Mike Olpin (Member # 1115) on 06-15-2009, 02:56 PM:

I've installed a Dolby CP-45 in a local theatre upgrading from mono. The levels are set, and the quality of the sound is excellent from the Non-Sync 1 (iPod), and external 6 ch input (BluRay).

When in SR, however, there is a lot of audible distortion from all 3 front channels. I don't know if it is present in the surrounds, as this theatre doesn't have any yet. The distortion sounds like clipping, but I cannot isolate it to any given frequency.

The distortion is not present in Dolby A-Type, Mono, or Bypass. In fact, it sounds quite good in A-type and mono.

I think a faulty 222 card might be to blame. Does anyone have any ideas to try?

They open on Friday with Star Trek, and while A-Type would be an improvement over their previous sound system, I'd like to be able to have them running on all cylinders this weekend.

CP-45
Kelmar DCPM reader
Ballantyne Pro 35
Crown i1000 amps (L/R) with unknown crossover module
QSC 1400a amp with UltraStereo crossover module (C)

Posted by Monte L Fullmer (Member # 2797) on 06-15-2009, 03:20 PM:

Hey Mike...Welcome to the "SR/A bad card group".

I have a CP55 where its CAT-222 card did the same thing - only hissing out of L/R in Dolby "A" and "SR" and have no N/S. It's clean in mono. Luckilly, I have an SR5 adapter attached along with a DA-20 for our CAT-700's to do its digital thing (in which I also had to attach an external Kelmar exciter power supply to it since its internal PS went kapooie to light up the bulb - my little mod works great!).

I swapped it out from another processor and I regained my N/S, along with saying "goodbye" to the hiss.

Dunno what to tell you afterwards .. maybe someone else can chime in on this condition, for I've got 18 CP55's that can easily do the same thing.

- good luck ... Monte

Posted by Scott Norwood (Member # 30) on 06-15-2009, 03:28 PM:

Obvious suggestion: can you swap the "SR"/A card with one from another theatre (there must be at least one house near you that has a CP500 or late-model CP65)? Everyone here (including me) complains about these cards, but they don't sound anywhere near as bad as you're describing.

Posted by Louis Bornwasser (Member # 3063) on 06-15-2009, 04:22 PM:

Don't let the naysayers sway you. Yes, there is such a thing as a defective 222sr/a card; they are horribly complex. You will be happy when you solve the problem.

I also think a short substitution is in order. (You may e-mail me.) Louis

Posted by Sam D. Chavez (Member # 1841) on 06-15-2009, 05:51 PM:

The 222 meter function is kind of funky so I would measure the preamp test points with Dolby tone test film running. It should read around 300 mVolts with the meter green LEDs lighted. If the card is defective the output level may not agree with the meters on the 222 and Louis is right, 222's are often bad.

In any case, set the level trim pots to around 300 mVolts and see how it sounds.

Another clue is that both trim pots should be set the same number of turns up from minimum to achieve this level. If one is turned up 5 turns for instance and the other 10, than either the reader is out of alignment or the 222 card is bad.

Posted by John Hawkinson (Member # 1135) on 06-15-2009, 07:36 PM:

Out of curiosity, is this tendancy to fail specific to Cat.222 SR/A cards, or does it also apply to Cat.222 A cards?

--jhawk

Posted by Louis Bornwasser (Member # 3063) on 06-15-2009, 09:22 PM:

You just can't believe how many parts "are in there!" Remove the cover and unplug the two boards. Be sure not to move anything or it will not plug back together. Louis

Posted by Pete Naples (Member # 761) on 06-16-2009, 12:54 AM:

And the two boards LOVE to become partially unplugged from each other, in my experience resulting in poor SR sound or loss of a channel in SR. A type is usually OK.

Posted by Gordon McLeod (Member # 33) on 06-16-2009, 08:45 PM:

also ensure that mono enhancment has been disabled before doing the level setting

Posted by Mike Olpin (Member # 1115) on 06-19-2009, 04:22 PM:

I'm happy to report that the issue has been resolved. Thanks everyone!
Dolby tone was a little, well actually a lot, off. I didn't think that was the case since a-type and mono were not overdriving.

Special thanks to Sam for the helpful advice about the test point needing to read 300mv.

Posted by John Hawkinson (Member # 1135) on 06-19-2009, 04:57 PM:

Wait...how do you know the Dolby Tone was off? Or do you mean the 222 LED meters were off?

--jhawk