Film-Tech Forum ARCHIVE: Bridging two audio sources together into one NS input...doable?

This is topic Bridging two audio sources together into one NS input...doable? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jackson Gilman (Member # 2142) on 12-11-2004, 07:08 PM:

This is embarrasing. Someone sabataged our booth a while back forcing us to run movies in that theater on a DVD player and LCD projector. Consequently, we're running the audio from the DVD into the NS input on the processor, leaving us with no input for the intermission music. I'm wondering if it is safe to bridge the cd player leads and the DVD player leads together onto the Non-Sync IN terminals...or would we need a small mixer to accomplish that.

Any comments most helpful (except mean ones.) [Big Grin]

-jackson

Posted by Michael Schaffer (Member # 1204) on 12-11-2004, 07:24 PM:

Basically yes, but you may run into problems with grounding (buzzing). It is always best if you tell us what equipment you have (in this case, specifically which sound processor), there should be far more elegant solutions like using the external digital inputs for the DVD source.

Posted by David Favel (Member # 1125) on 12-11-2004, 08:36 PM:

In my analougue house I have 2 non-syncs into a switching box with 1 outlet. (very simple) CP65

Digital houses have C.D. into non sync, DVD into 6 channel input CP650

Depends on equipment used

Posted by Nicholas Suchyta (Member # 2050) on 12-11-2004, 09:12 PM:

You can order or buy some Y cables. RatShak, i mean, Radio shack has them, you'll need to get 2 of them, they have one male connector and 2 female connectors, this is the cheapest way to do it without any interference. They're like $3 a piece. If they dont have them email me and i can get you them.

Posted by Chris Hipp (Member # 1788) on 12-12-2004, 02:21 AM:

I do just that on one of my houses with a basic AB switcher. works fine.

Posted by Carl Martin (Member # 1146) on 12-12-2004, 04:19 AM:

this is off topic i suppose, but i'm very curious what the story is behind this "sabotage". i assume it's not just vandalism, but a deliberate act to disable the equipment. competition? former employee? do tell.

carl

Posted by Brad Miller (Member # 2) on 12-12-2004, 04:20 AM:

I'm more curious as to know how they are getting DVD copies of the movies.

Posted by Chase Hanson (Member # 2779) on 12-12-2004, 04:45 AM:

AB switches are your friend.

Heck you can buy a simple two position switch and solder away if you feel so inclined (and it has the proper operating specifications)

Posted by Oscar Neundorfer (Member # 458) on 12-12-2004, 07:10 AM:

Jackson,

Do NOT bridge the outputs of two devices together with y connectors or any other way. While it might work, the outputs of most devices are not designed to work into the load impedance presented by the output of another device. Levels will be lowered and distortion may result.

Use an input selector switch of some kind such as can be found at Radio Shack.

Posted by John Hawkinson (Member # 1135) on 12-12-2004, 08:12 AM:

Full agreement with Oscar; earlier comments recommending you do this are inadvisable.

It is not safe to connect two outputs to a single input.
It is safe to connect a single output to two inputs, but that is not your situation.

It is even possible to damage equipment doing this, but invariably it will not sound as it should.

See Rane Technical Note #109: Why not Wye?.

--jhawk

Posted by Frank Angel (Member # 248) on 12-12-2004, 05:38 PM:

Then again, this theatre is subjecting its audience to a DVD quality image projected by an LCD quality projector.....why not introduce a little distortion in the sound to match the image degradation? I bet they don't reduce the ticket price....I bet they charge the same as if they were showing a real movie.

And does this theatre inform the public that they are paying top dollar for an inferior product? If they don't, I would think that would be considered fraud....selling a product without full disclosure and under false pretenses. Kind of like a merchant selling Gucci bags that were really made in Moldavia. Knock-off cinema.

And I am with Brad; where do they get DVDs of current theatrical releases? Inquisitive minds want to know.

Posted by Dean Kollet (Member # 1789) on 12-13-2004, 12:40 AM:

yeah....and how did this "Force" you to place just DVDs...call a tech or something... [Roll Eyes]

Posted by Ken Russell (Member # 2491) on 12-13-2004, 07:30 AM:

Why not just play the CD in the DVD player?

Posted by David Favel (Member # 1125) on 12-13-2004, 04:02 PM:

Perhaps the DVDs are pre show?

Posted by Dean Kollet (Member # 1789) on 12-14-2004, 03:22 PM:

quote: Jackson Gilman
Someone sabataged our booth a while back forcing us to run movies in that theater on a DVD player and LCD projector.

sounds like movies to me...

Posted by Thomas Procyk (Member # 1170) on 12-14-2004, 04:03 PM:

Yeah, this sounds fishy. How big is the screen? Auditorium size? I can't imagine an LCD projector filling a theater-size screen and looking acceptable. Even most pre-show projectors lack the contrast and saturation of film, or even 3-chip-DLP.

If you ARE a first run theater, shoot a few of those DVDs my way! [Wink]

=TMP=

Posted by Jean-Michel Grin (Member # 1360) on 12-14-2004, 04:29 PM:

Hi Everyone !

Just a Question, What kind Of sound Processor do You Use ? Certainly You don't use a Dolby CP500 or CP650. They have two non-sync Input.
In Our auditoriums equiped with CP 65, we use a simple mixing desk or an best one RANE CP52 zoner: they are verry easy to use by just turning a knob to select the source.
Alternatively if You use he dvd player for alternative content e.g. advertising, You could use te "magnetic input" of the CP65, but You will lose the matrix decoding of the Dolby.
The best is to switch to CP 650, but is a question of $$$$ :-D

In Our smalest theater, equiped with a CP65 we had to play a special feature recorded on digital betacam tape. the only solution was to disconect the cd player and connect the non-sync input of the Dolby to the sound output of the Beta player trought a isolating transformer to avoid ground loop hum...

Good luck ant apologyse for my weak English !