Film-Tech Forum ARCHIVE: Strange sound problem Smart Mod II Processor

This is topic Strange sound problem Smart Mod II Processor in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Michael Gonzalez (Member # 593) on 09-02-2003, 01:06 PM:

Alright the situation is this; in the middle of a show the other day the center channel went really quiet. You could still hear the sound and voices however the volume was such that the rest of the channels (whos volume was unaffected) drowned out the dialogue. Now the problem isn't a amplifier because I switch the amplifiers and still have the same problem. Now in my experiance this means that the problem is with the center speaker (usually the JBL diaphram), however, that also cannot be the case because the sound is running through the center speaker in Backup and it sounds fine. I am at a loss and our tech is backed upped and cannot make it out here until Friday. Anyone out there have any ideas? Oh and just to be clear, the center channel problem is the same in Digital and Analog, it only seems to be working in backup.

Posted by Alan Haigh (Member # 1781) on 09-02-2003, 03:18 PM:

Ninety-five percent of problems are connectors, wiring and switches. check the connectors on the smart and the amp. If it's screw terminals, undo them and rescrew them. Re-seat the cards in the processor if you can. Have a look inside the connector at the amp end to see if you can see loose wires/shorts.

If the sound is quiet in the centre all the time, Try swapping Centre and Left at the amp end of the cable, and then at the processor end, This will tell you if it's the processor at fault or the cable/connectors.

Good luck

Posted by Trevor Bailey (Member # 75) on 09-02-2003, 03:31 PM:

I would start by powering off the Mod2 and reseating all the cards and the control unit cable on the back. If no improvement, swap the NR card with another house. If no improvement, return previous and swap the matrix card with another house. If no improvement, return previous and swap the center EQ card with another house (yes this will not be the correct EQ, but we are troubleshooting). If no improvement, return previous and swap the output card with another house. If none of this works, I have had bad bypass switches that caused strange things to happen. I would also double check the outputs from the Mod2 with a scope to determine if there was a level change from the processor. After that we're down to the amps. I would double check the output of the center channel amp. Not knowing what type, could the amp be going into thermal protect? What is the resistance measured on the speaker lines when removed from the amp? After that, I'd start looking at the a-chain...

Posted by Michael Gonzalez (Member # 593) on 09-02-2003, 04:00 PM:

I've already done most of what was posted including swapping some of the cards (but not all). Unless there is a problem with a wire that is not readily visable because otherwise they all look fine. I KNOW that the problem is not with an amp. I guess I will just leave it up to the tech. Thanks.

Posted by Gordon McLeod (Member # 33) on 09-02-2003, 08:03 PM:

Do you by chance have the DSP processor for the matrix card as they can sometimes boot up incorrectly and then they have a low centre channel
Try swapping the matrix card with another system
Also is the centre channel low in mono

Posted by Oscar Neundorfer (Member # 458) on 09-03-2003, 06:07 AM:

Michael,

Your topic title says the processor is a SMART MOD II. I just want to verify whether it is indeed a MOD II and not a MOD IIB or MOD IIC. BUT, based on your statement, "Oh and just to be clear, the center channel problem is the same in Digital and Analog, it only seems to be working in backup", I will assume this is a MOD IIC processor. This is because if you are using digital, it is most likely a MOD IIC (although it could be a MOD IIB).

Since the problem is also in Digital format, this rules out many possibilities, and basically leaves Output card, EQ card, or bypass switch problems. A motherboard problem could be at fault, but this is the least likely suspect at this point.

Do you play non-sync music, and if so, is center channel OK in music format?

Since you say that BACKUP is fine, this should rule out wiring, amps and speakers as you have suggested.

You said you swapped out some of the cards. Make sure you tried swapping the EQ and Output cards, and if that does no good, swap the Format card. Just make sure to put the cards back where they belong after you finish.

Call me at 1-800-457-6278, and I will try to help more.

Posted by Bill Mantz (Member # 754) on 09-03-2003, 07:24 AM:

I just had the same problem on Monday with my Mod IIc people kept on saying that it was too loud so I turned the volume down they complained again it was too loud then another complaint now its to soft after fixing problems on other projectors (lots of people lots of complaints) I finally was able to get down stairs to check the sound in the theater with the sound problem and found I could bearly hear the dialog so I boost the center channel output on the sound card had to do it three time until I was able to equalize the center channel with the left and right speakers. Well I guess I will be replacing a card one question I have is why dose the card affect the sound when it is in digital I thought the outputs on the DTS-6D are there to pass thru the processor when the DTS unit is in control and the outputs on the DTS would control all the channels levels.

Posted by Oscar Neundorfer (Member # 458) on 09-03-2003, 08:56 AM:

Bill,

The DTS signals do not just pass through the processor unaltered. The processor is still controlling the equalization and overall volume level in digital as well as in optical modes. If this were not so, you would have no overall volume control in digital and there would be no equalization applied to digitally sourced signals.

As to your sound level problem, it appears that you need to get your sound technician in to do a complete level setup to make sure you are at the correct house levels. Then the system needs to be monitored to make sure that the levels are staying as set up. If they are not, we need to determine what is wrong and take the appropriate action.

Posted by Barry Floyd (Member # 385) on 09-03-2003, 02:35 PM:

I've got a MODIIB-DIT, and I've yet to figure out how to increase the input level from the non-sync music, so it will be the same level as the SR sound format when I start the show. We had alot of people tell me they have to crank their car stereo up pretty load to hear the music, but when the movie starts, it blasts them out of the car.

Could it be our tech has the movie sound too loud, or the music levels too soft. We took the front panel off the processor and adjusted the tiny screws on the card where they are labeled MUSIC, but it resulted in no change in the sound level?

What else could we do?

Posted by Gordon McLeod (Member # 33) on 09-03-2003, 05:48 PM:

Non synce is two pots on the output card and also the small pot on the side of the format card as well

Posted by Michael Gonzalez (Member # 593) on 09-04-2003, 11:15 PM:

Sorry I had the past two days off but thanks for the replies. AND the winner is.... The Format Card. I swapped the card with one from one of my other houses and the sound was back to normal. Well at the very least I saved the tech a trip out here (and myself having to get up a 7:30 in the morning to meet him). There is nothing anyone can do until we order and receive a new card. Thanks again for the help.