Originally Posted by AltaHomeTheatre
Hi to all in this great thread. First time post although I have read the entire thread a couple of times over the last few months.
I have recently installed my first HT and am very happy with the results. I am very much a novice and thus my question may be insulting to some. I may also be posting this in the wrong forum, but you seem to cover a bit of everything here. The question concerns calibrating the subs through my D2.
First a little background: My HT is a dedicated room approximately 12x17. It is in a basement. Walls are doubled for sound insulation. Carpet is on the floor. My equipment consists of Anthem D2 and AVM50. Paradigm Reference speakers. 2 subwoofers (10" Paradigm Siesmic and 15" Klipsch).
My problem is what seems to be a lack of bass "within" the HT room. I hear others talk about bass shaking the entire room (even causing projector lens to shake), but I dont feel much in mine. I have used a sound meter to balance all the speakers to the same level (although I increased subs by a couple of Dbs). Previously, I had the Klipsch upstairs in a larger room powered by a Marantx SR6200 and I could feel the bass.
When a scene with a lot of bass (ie beginning of War of the Worlds) is played, I can turn up the bass enough to start to feel it (increasing bass level on D2 by +7Db from my balanced default setting). With this setting I can feel a bit of the bass. But what is odd, if I go upstairs - the walls, pictures, china, etc are vibrating like crazy. Therfore I know bass is coming out of those subs, but dont know why its not in the HT room. The subs are currently at the front of the HT, but I have experimented with moving them around.
I dont know what to try next. I dont have any room accoustics yet. There is only one leather chair currently in the room. I dont know if the two subs are cancelling each other out (although I get similar results with only one sub). I dont know if I have the D2 configured properly. I dont know if the subs are configured properly. I did go through the very helpful Bob Pariseaus post on configuring his Velodyne sub.
Any help or direction would be greatly appreciated. I think there must be some way of keeping the bass in the room without having to turn it up so high that the rest of my house is going to shake apart.
Thanks in advance
First make sure the crossover inside each sub is disabled. Turn it off or turn it to its highest frequency.
The most common reasons for feeling you don't have enough sub are:
* Insufficient size of subwoofer for the volume of the room that needs to be pressurized. Remember that any openings out of the room increase the work the sub has to do. Fix this by getting a bigger sub or more than one sub. I suspect this is not your problem based on what you are seeing/hearing outside the listening room.
* Room response canceling out critical frequency ranges in the bass area. Every room generates some standing pressure waves in the bass frequencies. When these cancel the audio coming from the sub, the sub has to fight with that cancellation. Fix this by repositioning your subs or putting up bass absorbing room treatments that block the reflections that produce the canceling pressure waves.
* Subs out of phase with each other or out of phase with the main speakers. Again the audio gets canceled out -- this time by direct conflict with audio coming from the other speaker.
The Anthem's internal test tones in the Room Response Filter menu can help you determine how bad your room effects are. Set up the basic level for your subs, and then use your SPL meter and the test tones on this page to see how SPL varies as the tone frequency ranges from the crossover to very low frequency. It is not unusual to find some pretty severe dips, and also some surprising peaks.
Repositioning the subs a little at a time, and room treatment, can help eliminate the dips. The Room Response Filter can help eliminate your most dramatic peak.
Take your time and work to get as flat a response as you can. Then readjust the basic speaker level for your sub and do some listening.
Phase problems in subwoofers are hard to detect by ear. The phase test tones in calibration DVDs can help make sure your sub is properly set for phase against the main speakers. What you are looking for is the phase setting that maximizes the higher end hiss of the bass frequency white noise put out as the test tone. The more of the high end of that low frequency white noise you can hear the less the audio from the mains is canceling the audio from the subs (which cancellation will, naturally, occur at the higher end of the base range -- near the crossover -- where both the mains and the sub are putting out sound).
With two subs, try disconnecting one and setting phase for the other against the mains. You can do this with the phase control in the Anthem or on the sub. Then disconnect that sub and reconnect the second sub and do it again. Note that the phase control in the Anthem applies to both sub outputs, so you can only use it to set one sub. The other sub has to be set with its own internal control. This is also a good time to see that the volume control on each of your two subs is set so that the two subs are contributing roughly the same amount to the bass test tone SPL output.
When each sub is, separately, in phase with the mains, then they must also be in phase with each other.
There are PC graphing programs available that will help you see what's happening to your room response in real time as you make adjustments. See the subwoofer forum here.