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Subwoofer issues

post #1 of 21
Thread Starter 
Hi folks, I've been struggling with an issue for some time now and I'm totally out of ideas. I have a PSB HD8 sub hooked up to an NAD 748 receiver. It is hooked up with a sub cable to the LFE input of the sub. The sub is always turned on with the volume at about 55%. Sometimes, everything works fine, the sub comes on when it gets a signal and all is cool. Other times, the sub does not turn on at all. Turning it on/off doesn't help either. The only way to get it to turn on is by physically unplugging and plugging the cable back in (I know that's not a good idea, but that's where my troubleshooting got me). Even that sometimes requires doing it 2-3 times. After it turns on and works, I've also tried turning the receiver off and on... in which case the sub remains on, but no sound comes through until I unplug/plug the sub cable again. The problem is not the sub, because I've tried it with another sub and the problem persists.

Does anyone have any idea what it could be? Physically examining the sub cable, it seems fine, though I haven't gone out to buy a new cable yet. I'm wondering whether it could be the receiver. But want to eliminate all other issues first.

Thanks.
post #2 of 21
What is the LFE level set to in the AVR? It is set too low it maybe sending a signal that is too weak to wake up the sub. Set it to at least 0 dB and see what that gets you if it is negative right now. You can always compensate by turning the volume down on the sub.
post #3 of 21
Thread Starter 
It's always been set to at least 0.

The strange thing is that, even when the green light on the sub is on and I turn the AVR off/on, the sub remains turned on, but no sound comes out of it at first until I unplug/plug the sub cable. Does the green light on the sub being on mean that it should be working if there's any signal coming through, or can it still remain "inactive" with a green light?
post #4 of 21
Try turning the sub volume/gain down from 55% to about 25%.
post #5 of 21
Could be the amp, but before you get down and dirty on the amp try a new cable. Also, does the sub input connector on the sub and receiver seem to be 100% solid? No wiggling or back and forth and the cable is snug both sides?

butter and jelly please.
post #6 of 21
Thread Starter 
Ok... I tried a new cable this morning and that doesn't solve the issue. I turned the sub to +4 on the AVR and the volume down to about 40%, doesn't solve the issue. Switched subs again from a different room and same issue, so it's not the sub. The cable connection is solid for sure. Once the sub turns on, it plays well with no interruption, so the signal consistency seems fine. The issue is only getting it to start playing.
post #7 of 21
To help you, do the following:
1. Go into the OSD for loudspeaker settings
2. Go to subwoofer and select LFE + L/R or it may read LFE + Main
3. What source input is being used? Note that some sources have an LFE track and others do not. For sources without (such as FM) the DSP must create it.

Try the above steps, and post back.

Just my $0.02... wink.gif
post #8 of 21
The unit has "hysteresis" meaning it won't instantly turn off when sound goes away. It will delay that so that it doesn't get triggered with sound going quiet for a few seconds. So the unit staying on after you turn off the AVR is normal. It should however eventually time out and shut off. If it never does that, then the input detection circuit is damaged. That would also explain why it won't turn on. It is a simple circuit and getting it repaired should not be expensive.

Try the M Code test to make sure LFE is always on and the sub not coming on. If that is the case then it is probably broken smile.gif.

BTW, it should have a switch that puts the sub in always on mode. Try that when you are not getting sound and that should wake it up. I had an active speaker where that switch itself went bad (unlikely failure mode).
post #9 of 21
I don't mean to hijack the thread but my new S10.3 is doing exactly the same thing. I first hooked it up to my old Yamaha and blamed the receiver. I thought that my new Denon 2313 would solve the problem but it didn't. So, thank you for posting this here Sportstripe.
post #10 of 21
Thread Starter 
Quote:
Originally Posted by sheshechic View Post

I don't mean to hijack the thread but my new S10.3 is doing exactly the same thing. I first hooked it up to my old Yamaha and blamed the receiver. I thought that my new Denon 2313 would solve the problem but it didn't. So, thank you for posting this here Sportstripe.

The thing is, I have two of these subs. One works perfectly in one room, but sporadically in the other. When I swap them, vice versa. So it's definitely not the sub. Though, even the one that works well sometimes takes a minute or so to turn on. Nonetheless, it turns on every time. That one is hooked up to a Denon AVR-1912.
post #11 of 21
Thread Starter 
Quote:
Originally Posted by M Code View Post

To help you, do the following:
1. Go into the OSD for loudspeaker settings
2. Go to subwoofer and select LFE + L/R or it may read LFE + Main
3. What source input is being used? Note that some sources have an LFE track and others do not. For sources without (such as FM) the DSP must create it.
Try the above steps, and post back.
Just my $0.02... wink.gif

Ok, the NAD AVR doesn't explicitly show these options. However, by setting the front speakers to "small", it sets itself to an LFE + Main setting.
post #12 of 21
Quote:
Originally Posted by Sportstripe View Post

Ok, the NAD AVR doesn't explicitly show these options. However, by setting the front speakers to "small", it sets itself to an LFE + Main setting.

OK...
That setting forces full-time output from the Sub out jack.
Now what happens?
Does the sub play continously...rolleyes.gif
Yes??
No??

Just my $0.02.. wink.gif
post #13 of 21
Quote:
Originally Posted by Sportstripe View Post

The thing is, I have two of these subs. One works perfectly in one room, but sporadically in the other. When I swap them, vice versa. So it's definitely not the sub. Though, even the one that works well sometimes takes a minute or so to turn on. Nonetheless, it turns on every time. That one is hooked up to a Denon AVR-1912.

Darn.

Either way, this is a good troubleshooting thread. I'm hoping that someone will suggest something I haven't tried yet.
post #14 of 21
If you the sub works fine when using it with the other setup, then the problem is most likely with the sub cable or the Receiver. Process of elimination.

Try switching cables.

If that doesn't solve the problem, then move on to the speaker management settings in the Receiver. Perhaps the subwoofer works fine in the other room because you have different speaker management settings.


With the problem system, adjust the Receiver so that you are sure that it is getting a strong signal to the subwoofer.

- set all speaker size settings to "small"
- set bass below the crossover to go to the subwoofer only
- adjust the crossover to a higher setting (100Hz or above)
- set LFE to sub only (would only effect the bass when listening to Dolby/DTS surround sound tracks)
- play music with plenty of bass

Any music using bass guitar or drum emits frequencies below 100Hz and you should have no trouble hearing the bass coming from the sub. Get up close and listen. I say that because I tried helping a guy online who had a similar problem and the problem was with him and the Receiver settings. He had already returned a couple of subs and tried different cables before asking for help, and then failed to adjust the settings properly when advised to do so. It caused a lot of confusion. I'm not saying that this is the same problem, but then again, I don't know how much experience you have with audio systems.

There is still the possibility of a bad auto-power switch on the sub. However, from the way you describe it working okay on the other setup, it seems unlikely.
post #15 of 21
Quote:
Originally Posted by UndersAVS View Post

If you the sub works fine when using it with the other setup, then the problem is most likely with the sub cable or the Receiver. Process of elimination.
Try switching cables.

Read post #6 for the whole thread, he already tried another cable..

Just my $0.02.. wink.gif
post #16 of 21
uh huh. thanks.
post #17 of 21
Thread Starter 
Fiddled with the settings and seems to be working the last few times, though this issue has come and gone in the past. Will keep testing when I have more time, but I think the AVR is the problem.
post #18 of 21
Well sportstripe, that's good news. I'm not sure what "fiddling" with the settings means, but hopefully you meant that you adjusted the AV Receiver (AVR) settings as I suggested. Changing the AVR settings will ensure a strong bass signal is sent to the sub. As long as the sub continues to output bass with no hiccups, then you can be sure that the AVR and sub are both in good working order. Keep running it with this configuration for a while to be certain.

After you've done that. You might consider running the AVR's auto setup. But beware that it might reverse your settings and cause the same problem that you experienced in the past. I've noticed with the auto setup on both of the two Yamaha AVR's that I've used, all of the speakers are set to large and the subwoofer crossed over at about 60Hz. The subwoofer gets very little signal, particularly with music listening, when the system is setup in that configuration, and its easy to assume that it isn't powering up properly.
post #19 of 21
If the sub has two inputs, use a Y-connector to the RCA cable to the subs two inputs. This will increase the signal to the sub and help it stay awake. It may also net you a couple of extra db's in volume.
post #20 of 21
These are a few advantages (some real and some claimed) to using a Y adapter:
If you leave one of the RCA inputs open, dirt may get in there.
Using a Y adapter may add a few dbs to the subwoofers's output.
Some claim that the subwoofer works better at lower levels with the Y-cable.
The auto-off mode of some older subwoofers (e.g, Velodyne CH-12) may not come on at lower levels without the use of a Y-cable.
Some older subwoofers may actually need a Y cable because the left channel L may not default to mono signal.
Another benefit of using a Y-cable at the sub input jacks may be for reducing the amount of Radio Frequency (RF) and Electomagnetic (EM) interference, because you are not leaving the other input open and active. Subwoofers can be affected by annoying buzzes and hums.
Conclusion: Since Y adapters cost a few dollars and there is no significant risk involved, I would recommend using a Y adapter (2 male, 1 female) at the subwoofer's RCA input jacks. Make sure you use a good quality Y adapter that is shielded. Otherwise, you may hear hum and noises.

http://forum.blu-ray.com/showthread.php?t=95817
post #21 of 21
Quote:
Originally Posted by derrickdj1 View Post

These are a few advantages (some real and some claimed) to using a Y adapter:
If you leave one of the RCA inputs open, dirt may get in there.
Using a Y adapter may add a few dbs to the subwoofers's output.
Some claim that the subwoofer works better at lower levels with the Y-cable.
The auto-off mode of some older subwoofers (e.g, Velodyne CH-12) may not come on at lower levels without the use of a Y-cable.
Some older subwoofers may actually need a Y cable because the left channel L may not default to mono signal.
Another benefit of using a Y-cable at the sub input jacks may be for reducing the amount of Radio Frequency (RF) and Electomagnetic (EM) interference, because you are not leaving the other input open and active. Subwoofers can be affected by annoying buzzes and hums.
Conclusion: Since Y adapters cost a few dollars and there is no significant risk involved, I would recommend using a Y adapter (2 male, 1 female) at the subwoofer's RCA input jacks. Make sure you use a good quality Y adapter that is shielded. Otherwise, you may hear hum and noises.

http://forum.blu-ray.com/showthread.php?t=95817

Certain brand subwoofers such as JBL, Infinity have (2) RCA input jacks, however (1) RCA jack (marked MONO) and is a closed circuit type that parallels the L/R jacks so a Y adapter is not necessary only a single cable is required...

Just my $0.02.. wink.gif
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