Film-Tech Forum ARCHIVE: Yuck, static!

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » Yuck, static!

Author

Topic: Yuck, static!

Rob Brooks
Film Handler

Posts: 57
From: NY, U.S.A.
Registered: Oct 1999

posted 11-19-1999 10:10 PM

Does anyone have an opinion on this problem?
I'm using an ultra-stereo processor with just one amp. There is no digital sound. I got some radio shack speakers on the side of the theater. Every time there is audio in the theater, static is mixed in. There is no noise when the speaking stops, so I figure the excitor is aligned correctly. I think the static is mainly from the front speaker. I checked the speaker and it's not torn. The wire connection looks normal. Any ideas where the static is coming from?

------------------
Rob

| IP: Logged

John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 11-19-1999 11:38 PM

Did you mean "speaker" or "speakers"

Two guesses:

Bad speaker diaphram- such that it only distorts (in this case sounds like static) only at certain frequencies. I had this happen once. Especially possible if there are seperate woofer and tweeter. Easily checked by swapping speakers...

(Not too likely, but) bad transistor in amp for the same reasons. "They" taught us in school that a transistor could fail like this, but I've never seen it.

Same if there's an active crossover, but I somehow don't think there's one installed.

| IP: Logged

Scott Ribbens
Expert Film Handler

Posts: 118
From: Los Angeles
Registered: Oct 1999

posted 11-20-1999 04:02 AM

Could you supply us with a little more information?

Do you have a booth monitor?, If you do, do you hear the static in the booth monitor too? Is the booth monitor hooked up such that you can switch between listening to the processor and the amp output?

Have you tried switching the channels between the surround and the center channel?

Is this an Ultra Stereo JS 5/95?

Have you tried, with the power off of course, pulling the cards and then plugging them back in?

The sound is just static, it dosen't cut out at all, does it?

Have you tried running some film in mono, or bypass, to see if it goes away?

Did this problem just start today, with a "new", at least to you, print?

Are you going into, or coming out of the amp with any 1/4" phono jacks, or RCA plugs? If so the connection could be corroded.

Does the problem seem volume, or frequency dependent?

Anything else odd about your system? (Hook up ect).

------------------

Scott

| IP: Logged

Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 11-20-1999 05:32 AM

There's some good ideas above, but a very simple one might be a dirty pot. Try turning the gain inputs on the amplifier in question up and down a bit (make SURE to mark where they are to be returned to after this test). If the static comes with a vengeance during the turn of the gain control, there is your problem. It is quite common with older amps.

If nothing in this thread helps, please give us the make and model of everything in the rack as well as speakers and specifically what channels the static is coming from. Someone here will be able to help you!

| IP: Logged

Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 11-20-1999 10:24 AM

I'm betting on the "blown diaphragm" idea. If that turns out to be the problem, make sure that you find out what blew it before you install a replacement...otherwise, you might just blow another one if the amp is going bad. In the meantime, run the film in mono; good mono is much less offensive than bad stereo.

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 11-20-1999 02:35 PM

Try disconnecting the input of the amplifier from the processor and feed say a tape deck into the amp directly at a good high level
Listen for static if there it is either the amp of speaker. Try switching the speakers to opposite side of the amp
If it stays witht the speakers then that is where the fault lies if not it is with the amp

If it was not present feeding directly into the amp feed the tape deck into the nonsynce input and turn up the system and listen for the static
then unplug if there unplug one eq card at a time top see if it is the vvac fader or eq card

If it was not there it is either the NR card (not likly) the preamp or the cell and that test film and a scope would be required for

| IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.