[corock]

I just got my second PB13-ultra and I noticed the new one seems to have more output then the original which is only three months old. They are both corner loaded in the back of the living room facing each other. With both gains set at 10 o'clock the new one seemed to have more extension and be pushing more air. measurements with my spl meter confirmed the new one is 2-6 dbs louder. I took the measurements at my usual music listening level. I measured about a foot in front of the driver and the new one was at 120 dbs while the original was at about 114. I took measurements with the BFD filters on and also in bypass and the results were the same. I adjusted the gain on the original up, but by 2 o'clock on the dial it still wasn't caught up to the new one and I didn't want to push it any further. It is it usual for two identical subs to have such different outputs?

 

[Jon Liu]

Room acoustics plays a major factor in audible differences and could be the reason why you are getting such different readings for your output.

What you might want to try is swapping the two and see what results you get when you do that.

 

[corock]

I figured that is what I would have to do. I just wasn't looking forward to moving these beasts across the room. The tech guys at SVS also indicate its not unusual for two subs to have different input sensitivities. But I think I will switch positions to confirm wether its room acoustics or the sub sensitivities.

 

[snowmanick]

Differing input sensitivities possibly, but did you also experiment with the phase control?

 

[corock]

I haven't messed with phase control yet. I may experiment with that a little when I balance the gains. But Jack at SVS says I should be able to leave the phase controls at 0 because my subs are equadistant to the listening position in opposite corners.

 

[snowmanick]

Jack is a sharp cookie (and a of a nice guy as well) so he is most likely right.

Surprisingly, my two subs which are serving as end-tables next to my main sofa are exactly out of phase with each other. Room are quirky, sometimes you can find answers just by playing around, even if it doesn't make sense.

 

[corock]

I balanced the subs last night. The new one has the gain at half way between 10 and 11 o'clock and the original is just past 12. I did play with the phase control and found turning the original subs phase just a slight amount gave me 1-2 db reinforcement.