Trying to Solve a Subwoofer Mystery

[KellenVancouver]

Trying to solve a subwoofer mystery and hoping ASR members may know what's going on and can help illuminate where the fault lies. I tried to search for this in past posts and didn't find this particular issue, so if I missed it and this is a redundant post then my apologies in advance. Still working with the company on the problem so I'll forego brand name for now. Here's the issue:
Brought home a new subwoofer. It has a class D amp. I'm connecting it with a Mono Out from preamp to LFE In on subwoofer. We've resolved that the preamp Mono Out is not the problem, the cable is not the problem, and the LFE In is not the problem. Switched subwoofer standby from "auto" to "on" to ensure that is not the problem. Have resolved that the subwoofer is receiving signal from the preamp to the LFE In.
So here's the problem: signal is not getting from LFE In to the speaker. In other words, dead silence. That said, I found a way to make it work, and that is by unplugging the subwoofer from the wall outlet, waiting for it to drain power such that the green power light turns off (takes about 25 seconds), and then plugging the subwoofer back into the wall outlet. After power cycling the subwoofer that way it will successfully send signal to the speaker and thereafter works and sounds fine. However, once I turn the system off and signal ceases, the only way I can get the subwoofer back to working again is to go through another power cycle all over again. So I guess there is good news in that I've found this cumbersome way to make the subwoofer work and it sounds fine, but having to power cycle it every time I want to use the system is a real pain in the arse.
I never expected a subwoofer to be so frustrating. Any ideas what may be at fault with it? Thank you for any help/insights you may provide.

 

[alex-z]

That behaviour is normally only seen when using standby mode with too little pre-out voltage. Perhaps the amp has some internal standby mode which the switch does not control, which would be silly but easy to diagnose. Just give it more pre-amp voltage.

 

[abdo123]

That behaviour is normally only seen when using standby mode with too little pre-out voltage. Perhaps the amp has some internal standby mode which the switch does not control, which would be silly but easy to diagnose. Just give it more pre-amp voltage.

This is the worth the try, do the calibration of your AVR but with the gain of the subwoofer being much lower than what it is right now.

 

[KellenVancouver]

Thanks all for the helpful suggestions. No luck. Gave up and had to return it. Dang...

 

[spacevector]

What model was it?

Hope you find another functional one.

 

[gks333]

Yep, going with too low of pre-out level. I have had this happen to me several times over the years. Basically, the fix was to turn subwoofer volume down on the actual sub and turn up the SW level on the AVR to get it back to matching the levels of the mains due to the , now, decreased volume on actual subwoofer. Be sure to use an SPL meter on mains by themselves and subs by themselves before you do anything. Then mess with volume/SW levels in AVR.

 

[KellenVancouver]

Hi all. Just to close the loop, the problematic subwoofer was exchanged since the issues were not resolvable at the user level. Just luck of the draw that I ended up with a faulty unit. Have received the replacement subwoofer and very happy to report that it is working perfectly. Thank you again for all of your input shared above, much appreciated and hopefully your comments may benefit other users with similar issues.