Why aren't my subs turning on?

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.

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.

Frank

SW,

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.

TIC

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.