Need setup advice: Denon 3808CI + Atlantic Tech. System 920 -- overpowering? - AVS Forum
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post #1 of 4 Old 06-22-2009, 11:53 PM - Thread Starter
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I have a Denon 3808CI receiver connected to a set of Atlantic Technology System 920 speakers in a 5.1 configuration. The system is set up in a small/medium-sized bedroom.

The problem: when watching movies at louder volume levels, the receiver will often shut off unexpectedly. Aggressive audio sections of movies played any louder than about -16.0dB seem to cause the shut down, so I'm forced to constantly adjust volume levels with my remote while watching a movie to prevent shut downs. Obviously this is distracting to me, and the presentation is ruined for viewers if I don't adjust the volume fast enough and the system shuts off.

The receiver manual indicates that shut downs are probably due to either overheating or because the impedance of the speakers is not correct for the receiver.

I'm guessing the system shuts down because the receiver is too powerful for these speakers, and at louder volumes (necessary to achieve a theater-quality presentation), the speakers are being driven beyond their ability and cause the receiver to shut down.

I'd like some specific advice on how I can adjust the settings on both the Denon receiver (model 3808CI) receiver AND the the Atlantic Tech. subwoofer (model 102 SB) to achieve the correct crossover frequency, to help ensure it isn't incorrect settings causing the shut down.

Is it possible that I have the crossover frequencies set incorrectly on either the speakers or the subwoofer? Based on these specific models, what *should* the frequencies be set at on BOTH devices?

I appreciate general advice (though I have only a layman's knowledge of watts, impedance, crossover frequency, etc.), but what I'm really looking for are specific directions like:

"On your Denon receiver, using these speakers, set the speakers to Small, and the crossover frequency should be exactly X."

"On your subwoofer, set the Crossover Frequency dial to X to match the receiver setting, set the Crossover toggle switch to [Normal or Bypass], set the Standby toggle to [On or Auto], and set the Bass Level knob to Y."

Or, if the answer is "The shutdowns have nothing to do with your crossover frequency. This receiver is going to overdrive these speakers at higher volume levels no matter WHAT your settings, and you simply need to buy higher-end speakers to handle the output from that receiver", that would be good to know as well. Suggestions for more appropriate speakers within a modest-to-fair budget are appreciated as well.

Here are the links to the relevant PDF manuals for the Denon receiver and the Atlantic Tech speakers and subwoofer:

AT Subwoofer 102 SB manual:
http://www.atlantictechnology.com/Up...2sb_manual.pdf

AT System 920 speakers manual:
http://www.atlantictechnology.com/Up...00_920_pis.pdf

Denon 3808CI manual:
http://www.usa.denon.com/AVR-3808CI-OM-E_404A.pdf

Thank you very much for your help!

-Robbie

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post #2 of 4 Old 06-23-2009, 11:26 AM
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Quote:
Originally Posted by rsinclair View Post

The problem: when watching movies at louder volume levels, the receiver will often shut off unexpectedly.

Could you tell us exactly what happens? Is it this symptom listed in your manual: "Power turns off suddenly and power indicator flashes red." If so, the problems and remedies listed in the Troubleshooting section of the manual for your receiver are probably correct. I don't think "overpowering" your speakers or having the crossover set wrong could be the causes. Having speakers with the wrong impedance does not seem to be your problem.

In addition to following the directions in your manual, you could try to narrow down your problem to one of your speakers or the connection to it by disconnecting each of your speakers, one at a time, and playing some loud music. If the problem goes away with one specific speaker disconnected and not the others, you may have localized the difficulty. If the problem remains regardless of which speaker you disconnect, or if it always goes away, that suggests your receiver is defective.

The most likely cause of your receiver going into protection mode, if that is what is happening, is a stray wire at one of the connections to the cables going to your speakers. So check all these connections carefully. Also, look at the instructions in your manual in the little box titled "Protection circuit".

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post #3 of 4 Old 06-23-2009, 11:50 AM - Thread Starter
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Greg, yes, that's the symptom as described in the manual "(power turns off suddenly and power indicator flashes red.")

I did check to make sure none of the speaker wires were interfering with one another or loose, but I can disconnect and reconnect them all again to make sure.

I'll check the "protection circuit" section of the manual, thanks.

-R

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post #4 of 4 Old 06-23-2009, 12:08 PM
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Did you run Audyssey for this setup? It has several items it looks for, and it may warn you of the problem. Besides, it sounds really good when it does its work! Even a single strand out of place can cause a shorting condition.
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