Film-Tech Forum ARCHIVE: Subs not working

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Posted by Dane Cash (Member # 2112) on 08-03-2008, 06:31 PM:

I have 2 auditoriums where the subs aren't working. The amp the subs run off of also run the center. The center is ran off Channel 1 and the Subs off Channel 2. I have Crown 460-CSL Amps.

On Auditorium 1 I can switch the input plugs on the back of the amp and what should come out of the sub comes out of the center but still nothing comes out of the sub. So the amp can't be bad because both channels work. All the wires are connected right and everything, I've already double checked. What else do I need to check. There is sub output on the booth monitor as well. Is it possible the input wire from the processor is bad?

On Auditorium 2 I can switch the input plugs but nothing happens. What should come out of the sub doesn't come out of the center. All the wires are connected right and everything. Could the amp be bad and how exactly can I check it? I know the wires are connected right because the sub was working up until about 2 days ago. While screening The Mummy I noticed the sub had stopped working.

I already did a search on this forum and didn't really find anything that would help. If there is something I missed it would be cool if I could be directed to it. My tech has been too busy to help me with this issue so I figured I'd come here since most of ya'll are techs.. heh... Any help would be appreciated. Thanks

Posted by Joe Redifer (Member # 3) on 08-03-2008, 07:15 PM:

Have you checked to see if your subwoofers are still there? People like to steal those. Or at the very least they like to steal the drivers and leave the cabinets behind.

Posted by Dane Cash (Member # 2112) on 08-03-2008, 07:26 PM:

lol Yeah they're still there.. I've actually taken the subs out of the boxes to make sure some wires haven't vibrated loose or something like that. People have actually stolen the cones and whatnot? That's crazy, It takes just a little bit of time to unscrew them from the boxes... or it did me.. lol ... But in all seriousness, yeah they are still there.

Posted by Troy Hilsman Powell (Member # 4326) on 08-03-2008, 07:39 PM:

Hey dane you said inputs which I am assuming line level so that tells me that the subs are self powered with there own amp in the sub box.Check power to sub amp.

Posted by Dane Cash (Member # 2112) on 08-03-2008, 07:43 PM:

It's setup like this... Wires from the processor plug into the input on the back of the amp... then the actual speaker wire is connected to the outputs on the back of the amp then straight to the sub cone.

Posted by Mark Gulbrandsen (Member # 72) on 08-03-2008, 10:14 PM:

Are the signal presence led's flashing on the subwoofer channel to indicate the amp channel is being fed with signal ? Also does the ODEP led stay on all the time. if so this is indicative of a shorted output transistoror two or three, never seen all of them fail yet... have repaired lilterally zillions of Crown CSL power amps! After first checking behind the screen to insure the presence of such beasts and that all guts are present then check the above....

Mark

Posted by Dane Cash (Member # 2112) on 08-04-2008, 05:58 PM:

These are older amps, they don't have any leds showing any activity. Only lights they have is showing the amp is powered on. I'm going to move the center to channel 2 and the subs to channel 1 and see if the center will still work on channel 2. Maybe I can narrow the problem down even more that way.

Posted by Brad Miller (Member # 2) on 08-04-2008, 06:12 PM:

How many flabillion is in a zillion?

Posted by Darryl Spicer (Member # 711) on 08-04-2008, 06:37 PM:

Take a multi-meter and check the ohms. Remove the speaker wires from the output of the amp for the subs and set your meter to read ohms. Now connect each lead to a wire. You should get a ohm reading if the speaker is connected. If not either the speaker wire is not connected or there is a problem with the connection point on the back of the sub (I have had to remove those before and wire straight to the speaker cone assembly connections).

Posted by Mark Gulbrandsen (Member # 72) on 08-04-2008, 08:46 PM:

quote: Brad Miller
How many flabillion is in a zillion?

At least I haven't made the gazillion mark... yet... it feels like it though.

Mark

Posted by Richard May (Member # 2627) on 08-05-2008, 09:46 AM:

For auditorium one you said you switched the inputs and sub comes out of center channel. That doesnt mean that the amp output is good for the sub channel. Move the center channel inputs and outputs over to the other channel to rule out the amp. Also, if it is an Ultra Stereo processor, I have had the format card go bad, which is where you set your sub level.

Posted by Dane Cash (Member # 2112) on 08-05-2008, 02:12 PM:

Yeah, you're right. I did that for Aud. 2 and ruled out the amp being bad. Now it's its in the wire somewhere or on the sub itself, which is my next task.. taking the sub out of the box and making sure everything is connected there.

Although on Aud 1, I touched the sub wires and got a little shock, so that should mean the sub is getting power from the outputs right?

Posted by Louis Bornwasser (Member # 3063) on 08-05-2008, 07:26 PM:

A 9 volt battery is useful for testing speakers remotely; just don't do it to the hf driver. Also useful to "phase" any speaker without harm. Louis

Posted by Monte L Fullmer (Member # 2797) on 08-06-2008, 03:16 AM:

quote: Louis Bornwasser
Also useful to "phase" any speaker without harm. Louis

.. I heard about this, but never knew how this worked with using a 9v battery.

Only thing I did with the battery trick was to 'ring' out the speaker wire runs from booth to speaker since we would hook up all the speakers then bump them each with the battery to find the correct run for termination.

We would scratch the HF wires with a 1.5v battery.

-Monte