Axiom Home Page Forums General Discussion Home Theater Working with two different brand subwoofers

I am sure this is a topic that has been covered to some extent but it probably bear5s repeating. I presently have an old velodyne subwoofer. I plan on getting either the new 350 or HSU VTF 2 v 3. If I use both subs in my system how do I go about setting them up. For instance: Do I use the same crossover point. How do I adjust the loudness and figure out the phase settings? Also, how do I place them? Also, I know the HSu and Axiom are superior. Am I better off just using the one. I am in a fairly large basement with ceramic floors. However, my listening area is fairly small maybe 10 x 12, with my couch set against a back wall. The m60's are angled and about 8 feet from the listening position and about 6.5 feet apart. Thanks in advance for your suggestions.

I would use both on opposite walls and then calibrate them at the same time. Both should have the same crossover, as it is usually done through your receiver and the subs' filter is on bypass. This should be a good starting point, this is what I plan to do when I get my next sub.

I am sure others with more dual + sub experience will be along shortly and have more to say.

When I was running dual Hsu Vtf 2s I calibrated each separately @ -3 db from reference. Running both subs at once you gain the 3 db back.

What about phase?

I think phase has alot to do with the room dynamics and the exact spots of the subs.

I left the phase @ 0, this seemed to give the best output for my room.

Sure, Eddie, the same crossover that you set in your receiver would have to apply to both subs since they're both receiving the same signal from the sub out(bypass the sub's internal crossover if it has that option; if not, turn it to the highest setting to get it as far away from interfering with the receiver's crossover as possible). The crossover frequency is of far more significance to the speakers than the sub anyway.

Although the subs receive the same signals, different efficiency and room placement might lead to different sound levels. The subs should be calibrated separately and the levels balanced by using the level adjustment on the back of the subs.

The best placement to help minimize the effect of room modes would be at the midway point of the opposite side walls(or the front and back wall).

Different subs aren't the ideal arrangement, but you should certainly use both if they're available and see how you like the effect.

yes.



This is a generic suggestion because your room acoustics will be unique. But in a typical room I would first start with making sure once again that all your speakers are level balanced at 75db. Lower the subwoofer level at the receiver to -5 to minimize distortion and give you room to raise it. Next set up one sub A on the mid sidewall and adjust level so it is 70db on the rs metre and 0 deg phase. Turn off sub A Then set up the other sub B right beside it so it is colocated follow the same steps above. Now turn oon both subs. Measure combined output. It should be very close to 76db and the subs are working properly. Turn off both subs again.

Then put the other sub B on the opposite sidewall but just off perpendicular, so its not exactly across (the idea being to make it slightly asymetric since I've found its just a bit smoother off that perpendicular axis). Adjust level to 70db again at the new placement. Next set the phase in that sub to 180 deg so the woofers facing each other are moving out of phase. The idea is not to maximize output from reinforcing peaks but to smooth response so there is less volatility on your RS metre. Depending on your room 0 degrees may be smoother (not louder from reinforced peaks). Now turn on both subs and measure output. Depending on how far they are from each other the coupling effect will give you a combined output between 70bd to 76db. At 72.5db the subs output will be level with the speakers. Now adjust the subwoofer level on the receiver to taste, remembering that anything above 72.5 will be running the subs hot. Chill drinks and get the popcorn ready.

How about 3 or 4 subs, same idea?

I like the way you think, Randy. I can't wait to have 4 EP600s in my huge dedicated basement home theater.