Hi everyone. I'm curious about how folks have their subs calibrated relative to the rest of their speakers. I've SPL matched my LFM-2 to the rest of my speakers using the 990 test tones and consequently found the bass a little lacking in movies.

The purist in me says leave it flat to stay as true as possible to what the director and sound engineer intended. The hedonist says to kick it up a few notches because... well, it just sounds better.

So, in your system, do you like your sub flat or hot for movies? For extra credit, how about music?

For movies, I've got it flat (especially with the SMS-1 in the mix). For music, I run the sub a couple dB cool.

I initially let my receiver set the level using it's auto setup. It set the sub at -4db so I guess the sub's gain was too high. I tweaked the LFE trim in the receiver to 0db, so relative to the receiver it is now 4db hot. I can adjust the level on the fly via the remote in case the bass level seems too low/high.

If it sounds good to you, set it where you like it!

This my theory when setting up subs. Use your ears to get it where you like it. If you need a reference level, the best sweep I've found is the subwoofer sweep on any THX certified disc. It sweeps down from 200hz to like 20hz (I think)and you can really hear if your subwoofer is set right by how clean the transfer is from your mains to your sub. You can also hear room nodes very nicely. Those are the parts where the volume goes up and down for no other apparent reason. Very educational for your system...

So, with a meter, you watch the spls as the sweep moves down. If the spls change as you pass the crossover frequency, you need to make a adjustment. Is this correct?

No meter needed. Just use your ears. If you hear a large volume change when the subs kick in, they're probably set too high. I suppose you could do it with a meter but your ears should work just fine.

Your just looking to get the smoothest sweep possible from end to end. Unless you have your room tuned, however, you're going to hear some bumps. Just try to make it as smooth as your current system allows.

The other "by ear" bass check for subwoofers is playing a CD containing either acoustic piano or acoustic bass. Listen closely to the bass lines and see if you can hear your crossover point as the bass line goes from higher to lower. Again, if the change to your subwoofers is too much, take a little level off of them. This also relates to what Gonk mentioned where his bass levels are different for movies and music. You're probably going to want more "boom" in your movies than in your music. It's really all about what makes you smile.

I tried Jason's suggestion to use the sub calibration in the THX optimizer. Sure enough, my "flat" calibration resulted in the sub being audibly quite a bit lower when doing the frequency sweep - by about 8dB.

Anyway, after the new adjustment...I listened to some bassy scenes in a couple different movies, and the bass is definitely no longer lacking - in fact, it may be a bit much for my taste. I suspect I'll have to compensate for music now too. We'll see. Thanks for the advice, Jason.

Anyway, this is interesting since it suggests that the 990's internal test tones are not so useful for sub calibration... seems like a sweep tone ala the THX optimizer would preferable to the pink noise approach...

This isn't terribly surprising. RTA's and level meters have a lot of trouble with bass frequencies. It requires a lot more processing for those devices to accurately gauge bass performance. For instance if you look at the Galaxy Audio meters , you will notice that the CM130 is half the price of the CM140. But the CM130 is only rated down to 125hz, where as the 140 is rated down to 31.5hz.

Also the human ear can easily be fooled while listening to pink noise going from speaker to speaker, and suddenly to the sub. So a sweep works better since you are continuously listening as the tone changes pitch.

Now since I don't own a 990, and am not familiar with its programming, I can't state whether or not Outlaw dedicated a bunch of processing to that feature to ensure truly accurate bass setup. But it is possible they did, and in that case mic placement and sub placement issues could have caused the mis-alignment in your system. Moving the mic or sub just a small amount (a foot or so) could cause it to end up in a peak or cancellation node within your room.

With regard to SPL meters what is the best value today? I have the Ratshack meter, which I have heard was bought by ATI, and recoginize the errors of my ways. I would like something that will be more accurate at levels down to 5 Hz.