Originally Posted by mantaraydesign
My subs was making the rattling sounds from the 12" drivers. SVS told me one of the sub was connected incorrectly internally. I had to opened the sub apart and switched the Red and the Black cable. That was it.
But wasn't that a long time ago? I do remember you had that problem maybe what, 1 year ago or so? Not able to go above like -15 dB from ref on Undeworld: Awakening without distorting your dual Pluses if I remember correctly. I even checked on my own setup and made a movie of what the driver looked like above ref to compare
Here is a question I have about the PB-12 Plus. When you plug all 3 port holes (Sealed Mode), what is the lowest signal it can produce? In Sealed Mode, can the PB-12 Plus go down to 16 Hz or more?
Yes -- but it's more room-dependent. When the sub is sealed, the roll-off at low frequencies is shallower that for ported subs, with a slope of 12 dB/octave. Combine that with room gain, which can pick up what's left of the signal and you can have significant output lower than a ported sub, but probably not as much output.
On a ported sub, the port resonance adds lots of output around the tuning frequency. But below that frequency, the roll-off is twice as fast as for sealed sub, at 24 dB/octave. Furthermore, since the sub enclosure is in effect "open" at frequencies below tuning, the driver doesn't see any resistance from the enclosure -- the enclosure is then said to be "unloaded". To protect the driver against extreme excursions, a rumble filter is applied on the input. It's basically a high-pass filter with a cut-off a bit below tuning (e.g. 13 Hz for the 16 Hz tuning mode on the Plus and Ultra models). This filter further cuts the frequencies below tuning so that there's very little remaining below tuning.
Originally Posted by Bond 007
They're not assembled in the USA? SVS does not test them here before they ship them out?
I think they QC the subs in the US but checking for polarity may not be part of their tests. You'd have to hook them to a mic'ed rig to detect the polarity inversion -- it's not something you can hear, unless you're running dual subs with opposite polarities.