subwoofer connection disables auto shutoff

[bldawley]

I have an Onkyo DS747 receiver with a Polk PSW120 active sub. I originally had the sub connected to the front speaker terminals but have now switched to the line level input. The receiver has one jack out for the sub so i've used the left channel of the sub to connect. Sub works great, except that now the sub never shuts off. I shutdown the receiver and the sub stays active. Is this typical for this type connection? When i used the front speaker teminals to power the sub, the auto shutoff on the sub worked.

 

[Adam]

In my experience, that is not a typical result for that type of connection. I've had two different receivers and two different subs connected like that, and the auto-off worked in both cases. In fact, my experience is that the subs will shut off whenever there are long pauses without bass while watching TV or a movie (with one remedy being to increase the output level on the receiver for the sub signal).

When you say that the sub never turns off, I'm guessing that it has an LED that is indicating that it is powered?

 

[bldawley]

Yes, the LED stays on constantly now; i gave it all night long but it was still on in the morning. i've noticed that if i disconnect the cable at the receiver end while power is on, i get a loud hum if i touch the end of the connector. i was wondering if both inputs at the sub had to be used, like with a y-cable.

 

[Adam]

i was wondering if both inputs at the sub had to be used, like with a y-cable.

I suggest checking the manual if you still have it (if not, I can try to track one down). It should say if connecting a cable to both inputs is recommended or necessary. Sometimes a y-cable can help if your auto-on isn't coming on, but this would be the first that I've heard of it helping the sub turn off.

 

[bldawley]

thanks. i have checked the manual for both the receiver and the sub; neither one mentions anything about this kind of problem. now i'm beginning to think that maybe i've just got a bad cable. i'll try another cable and see if there is any difference. thanks again.

 

[mtrycrafts]

I have an Onkyo DS747 receiver with a Polk PSW120 active sub. I originally had the sub connected to the front speaker terminals but have now switched to the line level input. The receiver has one jack out for the sub so i've used the left channel of the sub to connect. Sub works great, except that now the sub never shuts off. I shutdown the receiver and the sub stays active. Is this typical for this type connection? When i used the front speaker teminals to power the sub, the auto shutoff on the sub worked.

Try to use the right input on the sub to see what happens.
When you unplug the cable from the receiver and touch the center pin on it, of course it will hum, you are inputting a signal, believe it or not, from yoru body.

You may also want to decrease the control on the sub. There should be a level control on it, this one, and see what happens.

 

[bldawley]

OK. got it. Thanks for the input mtrycrafts. I lowered the frequency level and that seems to have done the trick. appreciate all the help.

 

[MDS]

OK. got it. Thanks for the input mtrycrafts. I lowered the frequency level and that seems to have done the trick. appreciate all the help.

You decreased the frequency? That is the crossover control. Mtrycrafts was suggesting you decrease the level (ie the volume control) and bumping up the subwoofer level in the receiver.

IIRC, the DS series did not allow you to set a xover and was fixed at 90 Hz. If you are using the sub out on the receiver, you want the frequency control on the sub set to its highest level. If you set the xover frequency on the sub lower than 90 Hz, you will be losing the frequencies between 90 Hz and whatever the sub is set at.

 

[bldawley]

I did try setting the sub's volume level lower; didn't seem to help. This sub's lowest xover frequency is 80; highest is 160. I also have the DS subwoofer level set to it's highest. I will try your suggestion and crank up the sub's xover to 160 and then lower the volume on the sub. I guess i figured that the receiver's fixed xover level was sufficient.

 

[bldawley]

MDS, just wanted to let you know that i was able to set the xover to about 120 and still keep a decent volume level. Couldn't get to max xover no matter what level the volume was set at. Thanks for the help.

 

[j_garcia]

Regardless of the volume level, you should be able to set the sub's x-over as high as you like and SHOULD if your system is configured properly. If your speakers are set to small and your subwoofer = yes in your receiver, once you set the sub's x-over above about 100Hz, it shouldn't be making a dramatic difference to the sub anymore as you go up from there.