Why aren't my subs turning on?

I have a pair of Von Schweikert VS-3/S subs. Auto-on appears to be the only option, but they do not turn on unless I manually turn them off and then on? They are being fed from the line level (called LFE) outputs of an SMS-1. One to each sub. Both were purchased used from diff owners; hard to believe that they both are independently defective in the same way. They both play when I run the auto-eq frequency sweep. I am sending same question to VS, but your thoughts would help. TIA.
Could it be something with the SMS-1? Would it be easy to verify it's functioning? (Make sure the subsonic filter is set the way you want.)
The LFE channel is not the same as bass. The LFE channel is used by DVDs for low frequency effects such as explosions, earthquakes, and airplane flyovers. Some preamps allow you to direct bass output to the LFE channel, so that all bass is redirected to it. If you could do this, then you would get a response when playing musical material out of your subs. Otherwise, you should send the right and left channels to the subs if the subs have a high-pass filter in them that you can use to roll off the high frequencies that are being fed them. Another alternative is to feed the left and right channels to an outboard crossover, that would allow you to feed only the low frequencies to the subs. Since frequencies below 100 Hz are non-directional, your subs' performance would improve if you fed both left and right channels to each sub and used a crossover frequency of 80 Hz for the subs.
You probably have to leave the power off/on switch in the ON position at all times in order for that feature to work.

They will turn off 15 minutes or so after you stop playing music. Once you start playing music again (as long as the switch is ON) they should turn on and begin playing. That's how most subs with auto-off/on usually work.
Plato- I am leaving the in the auto-on mode all the time, but they don't turn on when I start playing.

Jameswei- The SMS-1 does "work"; at least it goes through auto-eq or manual eq, emitting frequency sweep tones and teh eq can be adjusted.

All- the subs show a red light when plugged in, in the auto-on mode and in "stand-by" They are supposed to switch to green when activiated by a signal. That does not happen unless I manually turn them off and then turn them back on, while music is playing.

Swampwalker: Sounds like SMS-1 isn't providing enough signal to trigger the subs at initial turn-on (lower)volume settings. Do they trigger when the volume is raised much higher? I've had this issue with several subs, but deal with it with more "initial" volume.


Pz may be onto something. By nature, LFE is "low frequency effects" for discrete multi-channel encoded material. Until you actually play some material that has discretely encoded LFE information, your subwoofers may not turn on. This would seem to make sense considering you know they work when you auto-Eq, which you know needs to send a signal to the subwoofer.

An easy way to test this theory would be to put in a DVD and play a scene that has explosions or something like that. You could use the "lobby" scene from The Matrix or the "airplane crash" scene at the beginning of Mission Impossible-2 for instance.

If they still don't work, I would check all of your configurations and maybe contact the manufacturer of the SMS-1. If you find that the subs do work when LFE output is know to be present (explosions when playing DD 5.1 or DTS content), but they don't work for music, check your configuration and make sure the processor is supposed to output through the LFE port. It may be that your processor doesn't work that way and you may need to change your setup to power the subs off of the L&R pre-outs.

Pzuckerman- Perhaps I should have posted more detail. This is a music only system and the SMS-1 is an outboard x-over equalizer. My mains (Merlins) are recommended to be run full range and they get their signal from the main amp which is fed by the Merlin Bass Augmentation module, which in turn is fed by a pass through from the SMS-1. LFE is the label Velodyne uses on the SMS-1 for the equalized and crossed over, line level output. the SMS-1 gets its signal from the output of my volume controlled APL 3910 U-player. Se we have CDP to SMS-1 to sub (all line level) and CDP to SMS-1 (looped out aka pass through) to BAM to amp to main speakers.

RubenT- Understood. As you can see, I am powering the subs from the main L&R outs from my pre.
Looks like the signal to your sub is just too low to trigger it to turn on. You will probably need to leave it on when you will be using it, ie not in auto mode.
Geared4me- Unfortunately, that means going to each (I have a pair), reaching behind, shutting them off and then back on after about 30 sec. A real PITA. Hopefully VSA has a work around.

Does it sound correct after you manually force the subwoofers to turn on? If so, then it seems that the subwoofers are not working correctly or they are not receiving enough of a signal to turn them on.

What is the low pass frequency you have set up in the SMS-1? If it is really low, it is possible that the music you are playing does not have any content below that frequency. If that is the case, I think it is very possible that the subwoofer will not be receiving a signal from the SMS-1 and therefore it will not turn on until some content below that frequency is played.


Do you have the manual that came with the sub, because it sounds like it may be a problem of not having your settings correct.

When you are playing music you have a stereo line-level source hooked up to the line-level stereo RCA inputs and the switch is set to "Auto-On" with the Red LED (not "stand-by"). Also you have the crossover switch in the position to use the sub's internal crossover and not an external crossover, correct?

Those are my best ideas to check without having the manual for reference...
I will look for the nanual. I have the L and R pre-amp output (not stereo, the SMS-1 does not output stereo) going to the SMS-1 which IS an external x-over, so I have the internal crossover OFF. The switch is set to Auto-on with the red LED lit (which is stand-by, I think). It goes to green if I turn it off and on manually, and seems to play correctly after I do that. I turned the SMS-1 output (called volume) up to about 60% and still did not get it to turn on when the CD starts up, but it will come on when cycled off and then back to auto-on.
What happens if you set the SMS-1 output to 100%?
I've downloaded the manual and the subs are set up (at least I think they are) the way its recommended. Pre-amp level outputs to SMS-1, equalized output of SMS-1 to sub (there are three equalized (aka LFE) outputs to use so you can run 3 mono subs at once if you desire. No way to run stereo subs without 2 SMS-1s (I asked Velodyne). I will try the 100% output on the SMS-1 and turn the sub volume way down and see what happens.
OK, color me red!!! I just went back to swap right for left at the sub input in case it made any difference, picked up the sub end of the i/e and the other end was dangling loose!! I guess they won't work if they are not connected. Problem solved. Thanks to all who made an effort to assist one dumb-a$$ audiofool. Happy holidays, all.
First step of troubleshooting tree for many electronics issues: "Is it plugged in?".

Glad you got it going and don't have a sub issue......


I'm glad to hear it was something so simple. So, how do they sound now?
Only just begun dialing them in. Still trying to get over the embarrassment ;~)
Well, at least it was a cheap and simple fix.
The best and most satisfying solutions are the ones that are free!