Problem: Sub cuts in and out at high volume

[DJ Demonstr8]

I have a Polk Audio PSW125 (active 12” sub) connected to a Denon receiver (AVR-e300).

We recently moved and everything was fine before, but now when I listen to music at higher volume the sub quits during some of the lower notes. It will come back on briefly but will not stay on until the volume is lowered.

I did purchase a new sub cable because I needed a longer one and ran through the receiver’s calibration function for the new room.

For reference the volume scale goes from 0-98. Before I could listen between 75-80 (or even higher) without any issues. Now I am experiencing this problem when I get to the 65 range.

Is it possible that the new cable is faulty? Or could it be the crossover settings because of the calibration?

I appreciate any input because I’d like to see what I can try before taking it to a repair shop. Thanks!

 

[shadyJ]

It almost sounds like the sub might be going into thermal protection. Either that or you are clipping the input signal. It probably isn't due to the newer cable. The calibration may have caused the AVR to send a larger signal to the sub that is either overloading its input stage or running the sub so hard that it enters self-shutdown to avoid over-heating.

By the way, none of these parts are worth taking into a paid repair service, the repair is likely to cost more than just buying a new unit. I think the solution may end up being just needing to get a more powerful sub. One way to test if the input signal is clipping the sub inputs is to lower the LFE output in the AVR (maybe by 8 dB or so), then play something at a high volume on the AVR and see what happens. Alternatively, you could just raise the gain knob on the sub itself and rerun the calibration.

However, if the problem is the sub is going into thermal protection, you are going to need a bigger sub, since that one cant handle how hard you are pushing it.

 

[DJ Demonstr8]

It almost sounds like the sub might be going into thermal protection. Either that or you are clipping the input signal. It probably isn't due to the newer cable. The calibration may have caused the AVR to send a larger signal to the sub that is either overloading its input stage or running the sub so hard that it enters self-shutdown to avoid over-heating.

By the way, none of these parts are worth taking into a paid repair service, the repair is likely to cost more than just buying a new unit. I think the solution may end up being just needing to get a more powerful sub. One way to test if the input signal is clipping the sub inputs is to lower the LFE output in the AVR (maybe by 8 dB or so), then play something at a high volume on the AVR and see what happens. Alternatively, you could just raise the gain knob on the sub itself and rerun the calibration.

However, if the problem is the sub is going into thermal protection, you are going to need a bigger sub, since that one cant handle how hard you are pushing it.

Thanks for the response! I’ll give the clipping option a try. I don’t think it’s the temperature because the problem remains even after the power has been off overnight. Even today I was listening to music at a moderate level for an hour or so and the amp plate was cool to the touch afterwards.

But like you mentioned, it might be time for a new sub. I’ve been using it since 2011 haha.

 

[WaynePflughaupt]

Is your new listening room larger than your old one? If so, you’re probably pushing your sub harder, which would explain things.

Regards,
Wayne A. Pflughaupt

 

[lovinthehd]

Could also be an indication of the sub amp starting to go out. I had one that behaved similarly before the amp fully crapped out. Would be interesting to know differences in room placement between the two rooms (did you put the sub significantly further away in the new room as to why you needed a different cable?). Do you remember the sub level you set in the avr vs what you had the avr set it to?

 

[j_garcia]

Could also be an indication of the sub amp starting to go out. I had one that behaved similarly before the amp fully crapped out. Would be interesting to know differences in room placement between the two rooms (did you put the sub significantly further away in the new room as to why you needed a different cable?). Do you remember the sub level you set in the avr vs what you had the avr set it to?

Same here, it sounds like the caps in the amp may be beginning to fail. That's what mine did for a while before the amp went up in smoke. Replacement amp fixed the issue and it has been fine for years since. Agree that fixing that one won't be worth it though.

 

[DJ Demonstr8]

Just wanted to post an update.

I finally had an opportunity to do some testing (aka jamming out) after taking a look at the sub level on the receiver. It was at 0db, I lowered it to -5db and it’s a lot better than it was but it will still go out. The sub gain must’ve been set incorrectly during calibration for it to set to 0bd, not exactly sure. The room is roughly the same size, I had to buy a longer cable because it’s ran under the floor into the basement because of a fireplace. At the other location it was just ran under the baseboard.

Overall I’m satisfied with the result and will be shopping around for a new sub in the mean time. Leaning towards Klipsch but open to recommendations!

 

[lovinthehd]

Just wanted to post an update.

I finally had an opportunity to do some testing (aka jamming out) after taking a look at the sub level on the receiver. It was at 0db, I lowered it to -5db and it’s a lot better than it was but it will still go out. The sub gain must’ve been set incorrectly during calibration for it to set to 0bd, not exactly sure. The room is roughly the same size, I had to buy a longer cable because it’s ran under the floor into the basement because of a fireplace. At the other location it was just ran under the baseboard.

Overall I’m satisfied with the result and will be shopping around for a new sub in the mean time. Leaning towards Klipsch but open to recommendations!

How did you choose gain on the sub and sub level in the avr initially? Sub gain dials can be easily moved by accident, not so much for the avr's sub level....

 

[DJ Demonstr8]

How did you choose gain on the sub and sub level in the avr initially? Sub gain dials can be easily moved by accident, not so much for the avr's sub level....

Denon’s Audyssey setup calibrates everything with a microphone, you just plug it in and follow the prompts and it adjusts everything automatically based off of what it picks up. It says to set the sub to 50% which I thought it was, it probably wasn’t.

 

[lovinthehd]

Denon’s Audyssey setup calibrates everything with a microphone, you just plug it in and follow the prompts and it adjusts everything automatically based off of what it picks up. It says to set the sub to 50% which I thought it was, it probably wasn’t.

Yes, you can start with gain on the sub at 50% but it's just a starting point depending where Audyssey sets sub level after running it....might be worth simply re-running it (as should be done after moving things around anyways).

 

[DJ Demonstr8]

Yes, you can start with gain on the sub at 50% but it's just a starting point depending where Audyssey sets sub level after running it....might be worth simply re-running it (as should be done after moving things around anyways).

Before starting the calibration the system says “set the sub at 50%” as the starting point, and I thought I did, but maybe it was set lower causing calibration to set the subwoofer level to set to 0db.

I’ll probably run the calibration again when I’m able to get a moment of silence (did I mention I have kids haha). I’ll make notes of the levels before hand and compare them this time.

 

[lovinthehd]

Before starting the calibration the system says “set the sub at 50%” as the starting point, and I thought I did, but maybe it was set lower causing calibration to set the subwoofer level to set to 0db.

I’ll probably run the calibration again when I’m able to get a moment of silence (did I mention I have kids haha). I’ll make notes of the levels before hand and compare them this time.

FWIW on all my store-bought subs I've usually ended up with gain in the 1/3 range. I usually aim to set my subs into the negative sub level range so that even with boost I remain under the 0 sub level in the end. YMMV. Making note of settings isn't a bad idea (or if you have a model that can save the results to a computer file for reloading later).

 

[Alex2507]

I had a small ported sub cut in and out like that. It turned out that the printed circuit board had melted in a tricky spot where a repair was beyond my ability. I'm pretty happy it didn't catch fire.

I ended up wiring up an external amp and then did the same to broke sub's working twin ... and then EQ'ing ... after learning to use REW. It was horrible to do all that but pee-pee subs come at a cost.