No Bass After Avia (1 Viewer)

[Mike Pgh]

I recently used the test tones in Avia + a Radio Shack SPL meter to tweak my 5.1 DD/DTS setup. It did a VERY good job of balancing all the main speakers and made me realize that I had the surround speakers WAY to high and the LF and RF speakers a little too low.

The sub setup was a different story. When I used the tones to balance the sub what resulted was absolutely no bass at all during movie playback. I knew I originally had too much bass in the system...sub volume turned all the way up, reciever bass management on +3dB. After Avia my settings were, sub volume on about 30%, receiver +2dB. With these settings, the balance was just about perfect according to the sound meter. I popped in Saving Private Ryan (DTS) and played the first beach scene which has tons of explosions and there was no bass to be had. I left the reciever settings where they were and started to turn up the sub volume until the house was a rockin' again. I ended up with a sub volume of about 75%...way above where Avia said it should be.

Anyone have similar experiences?

 

[Ron-P]

AVIA is a great guideline, but after I am done, I will usually make small adjustments to suit my ears and eyes.
Peace Out~

 

[Mike Pgh]

Thanks Ron. I did a search on the subject (doh! what a novel idea ) and found that it has been discussed at length. I also opened up another whole can of worms for myself on the reference level issue.

 

[Jack Gilvey]

Here's what might be happening:

The tough part about using pink-noise-type tones like those on Avia for calibration is that you are most likely reading the SPL of a room mode. Many (most?) rooms tend to have some bad ones around 40-45Hz, maybe as much as 12-15db of "boost",so you're actually reading the amplitude of that hump and adjusting it to 85db. This can cause the lower bass to be attenuated, obviously.

 

[ling_w]

You would probably have to adjust the sub level based on the level at the crossover freq. So get some disc that has some warble tone centered at the crossover freq, Measure the SPL for the main speaker, then set the sub at -3dB lower than the main. This is assuming you have the THX spec'd 2nd order high pass & 4th order L-R low pass.

 

[Jeremy Anderson]

Several things that might help:

1) Just a reminder (since I've seen people forget this before), but you must have all speakers set to small for the bass calibration on Avia to work properly. I know that's a really basic thing, but you'd be surprised how many people don't pay attention to that.

2) You might want to set your receiver's subwoofer level to about -5 and then adjust the level on the subwoofer itself during calibration (so that you aren't introducing any distortion or coloring of the sound from the receiver).

3) Use Avia's subwoofer phase tests. If your subwoofer is out of phase with your other speakers, your calibration will be all wrong since the sub and the speakers will be cancelling each other out in the crossover range. This will make for exaggerated low-end and almost no bass in the crossover range. A good way to double-check phase is to set the phase on one setting and then run the frequency sweep for the left main speaker while watching your SPL meter. Then, reverse the phase on the sub and play the same sweep. You want to leave the sub's phase on the setting that produces the least dip on the meter across your crossover range (which is likely around 80hz). It should be pretty obvious which setting is correct. Once you've found the proper phase setting, re-check the sub calibration.

4) Some receivers have an adjustment for LFE compensation for DTS. The options for this are usually 0db/+10db. The proper setting is +10db, since LFE on DTS tracks is encoded at -10db from the other channels. If your receiver doesn't have this setting, then it is most likely performing the proper boost (so no worries there).

Hope that helps!