An odd calibration issue. When my sub is set properly in Dolby Digital mode using either the built in test or something like Avia, it is very bass shy when listening to my CD player. The difference is very large--I feel like I need to trim the sub up 10db settings to get it to sound right with music. But at that level it's blasting with movies. This is the same whether I use bypass mode or "stereo" mode.

Anyone know why this is happening? Anything I can do to correct things?

For the record, I'm using analog outputs from my CD player, and I'd rather keep it that way (it's an expensive player, and in part I paid for the good quality DAC).

Thanks!

For the record, in case anyone else has this problem, I think I figured out what's going on. The crossover for my mains is set to 60hz. The crossover for my center and surrounds is 100hz. That means in movie mode the sub is playing freqencies from 60-100 hz--but in stereo mode it's only below 60hz.

I think because of room acoustics or a sub problem I have a lot of extra energy between 60 hz and 100 hz, and a bit of a null below that (at least, it seems that way from pink noise sweeps). So when I calibrate the sub so that it's not too loud from the 60-100 range, it doesn't really fill in the low frequencies that well.

The folks at Outlaw recommended I switch my center crossover and the mains to 80 hz. That way the sub is producing a bit more of the bass range in stereo mode. That does seem to help a bit so far.

Of course, my main issue is to try to fix the boominess in the upper bass. I'm not sure if I need a bass trap, or if there may be something wrong with my sub such that it doesn't reproduce ultra-low frequencies anymore (it's a decade old, and it's been moved 3 or 4 times).

Hope this helps someone!

its not likely that that sub is worn out... but it could have been damaged slightly during moving... it sounds more like room acoustics to me. i dont consider ultra-low as below 60hz :-).

if i had to choose, i would pick to put my mains at there response range and turn up the sub rather than, lose some range on the mains to slightly compensate for the sub...

Well, today I re-tested with test tones, and the situation is different what I assumed. After pink noise calibration (at 5 db above the rest of the channels), It seems have much higher response from 25-50 hz than at 60 and 80 hz (the crossover point). It's actually a little high and boomy in the 30-45 range. So I think what's actually happening is that movies have a lot of impact in low frequencies (30-50 hz) during test scenes, whereas typical music is punchier from 50-80hz, excactly where my response is fainter.

Unfortunately, for now I really have no placement options at all, and no ability to move the sub.

[Just thought I'd add this addendum. I called my subwoofer company (Definitive), and they suggested that I raise the 950 crossover across the board to 100hz. They were concerned that the internal crossover in the sub (set at 100, and not bypassable) might be conflicting with the crossover in the 950, creating a cascade effect.

The end result is a much flatter response at 60 and 80 hz (which makes sense), though still with a big dip at 80hz (which at this point I'm pretty sure is a standing wave). Now, music sounds pretty great with the sub set about 2-3 db high using pink noise, which is about right for movies, too.

One interesting thing, though--using the sub with my main speakers full range (bypass) does AWFUL things to the sound. There's a huge peak at 40hz, and a total suckout of frequencies at 50hz. There must be a phase difference at certain frequencies that both the sub and the mains reproduce. The mains by themselves in bypass sound great, though a little boomy (they're apparently creating some standing waves of their own).]

Hope this helps someone!

I think cg might of been onto something with room acoustics. The biggest bass issues anybody has are caused more by the room than anything else. I'll suggest two things that could help...

1) For a quick, and cheaper, start, you can try out the "Subdude", aka "GRAMMA", platform as made by Auralex. For $60, this wonder of wood and acoustical foam isolates your subwoofer from the floor, reducing room interaction and boominess. That's not just type, I own one and that's exactly what it did for me. I'm not saying it corrects all bass problems but it's certainly a start.

2) Look into getting, or making, some kind of bass traps for your room. This doesn't mean covering your room in egg crates or putting up a lot of curtains but actually investing in a full-range absorber of some type. For me, the best advice I've seen seems to be coming from Ethan Winer and his site:

www.realtraps.com

As an alternative, you can also find a ton of acoustical information on the Auralex website.

www.auralex.com

From your post, it sounds like you have some sort of test equipment. If you're serious enough to get something like that, investing in acoustical treatment should be a very small but very important step.

Good luck...

P.S. You're more likely to get replies if you list what equipment you're using.

Oh, sorry. Well, I'm just measuring test tones with my RS analyzer, just to get an idea of what the problems are. I'm using an Arcam Alpha 8 CD player, running into the 950, running into Rotel amps, then driving a pair of Vandersteen 1cs for the mains, and Gallo Nuclei (divas and micros) for the center and surround). Because of room placement problems, the Vandersteens apparently have their own full range bass issues when run alone, so I'm better off crossing them over high, anyway.

I'll look for that Auralex platform, thanks! This is only my listening room for the next year, so I think I may just have to suck it up for a while.

I had the same problem with music...I kept having to adjust the volume to get the bass response correct. When I plotted my frequency response, it looked like a roller coaster between 30Hz and 80Hz.

To fix the problem, I purchased a Behringer Feedback Destroyer Pro ($120) and used the parametric equalizer to flatten my response curve. My plot with the BFD in place...ruler flat from 25Hz to 80Hz.

The change has been amazing...the old Velodyne has NEVER sounded this good.