Originally Posted by chiliman
The search function here is maddening. Can someone point me to the ARC instructions for setting up with 2 subwoofers. Just set up 2 new SVS PB12+ to replace a single PB Ultra.
Bob...if you're out there...help....
Measure the distance from ARC mic position #1 to each sub. Use the average of those two distances as your Subwoofer distance setting. Put in normal distance settings for your other speakers.
Set "1 Sub" in your Speaker configuration, even though you have two. When using ARC you must set "1 Sub" if you have Subwoofers.
Zero out all the lines in Setup > Level Calibration. Use the internal test tones to set the Test Level line to yield 75dB SPL (the noise will be coming from Left Front). Go to either of the Subwoofer lines but leave that line at 0.
With only one sub turned on, adjust the volume knob on that sub to 72 (not 75) dB SPL.. Switch and do the same with just the other sub powered. When combined they will yield roughly 75dB SPL which is close enough for ARC to work with.
(All the lines in Level Calibration stay at 0 except for Test Level, which ARC will use.)
With one sub powered at a time, adjust the Phase and Polarity controls on that sub for best match with the Left Front speaker. You can use the FM tuner set to produce the hiss between stations (set Stereo audio surround mode so audio only goes to Left Front/Right Front/Sub). Adjust Polarity/Phase (controls ON THE SUB) for maximum bass in that hiss. See the Setup section of tutorial post links in the first post of this thread for more hints on this.
Repeat with just the other sub powered. When each Sub is in proper phase with the fronts then they are also in phase with each other.
All the preliminaries are now done.
Power up both subs and do an ARC Measurement pass as normal. Look at the red Measured curve for Subwoofer to see how well your two subs are operating together without producing peaks and dips. If there are still substantial problems you may need to shift one or both subs and redo the above preliminaries. The Quick Measure tool in the ARC Tools menu can be used with one sub powered at a time to get a feel for how shifting the sub alters its uncorrected output.
If the red Measured curve doesn't look too bad, and the green Calculated curve shows that ARC has produced results close to the Target curve then you are in good shape. As a final check, the volume trim ARC Uploads into Level Calibration when you do the Upload should be within a few dB either side of 0.