Originally Posted by Rythmik
, Here is my recommendation (based on importance and priority):
First, when roomEQ sets the left and right subwoofers to different gains due to very different room gains from two subs, it can make the unit with higher boost much easier to reach max output. You mention the difference is 10db. That is close to 3x in magnitude. I am not sure if that is still the case right now. If you don't think you will use up all the power headroom, then it is ok to keep results from the roomEQ. If you ever run into max output, then it is good to compromise a bit. You don't need to make yes/no choice. For instance you can do half of the boost. Instead of boosting 10db, you can do 5db boost. In other words, set the level down 5db after roomEQ by either manual override or turn down the volume setting on the back of the amp. If you do the latter, then next time you do roomEQ, you need to make sure you restore the volume setting to normal.
Second, we design the FV18/FV25 rumble filter to have 6db attenuation at 10hz. That cuts down the excursion by 50%. So it is alway good to turn that rumble filter ON if you know you will need all the headroom of FV18. It is a good compromise. If that is still not enough, we can also move the bass extension filter setting higher.
Thrid, the limiter can prevent the amplifier getting into clipping. In class-D amps, the clipping can sound like voice coil rubbing which is another annoying noise. We suggest keep limiter ON.
Originally Posted by basshead81
You can tell it's not the sub making the noise in that video. However in Gwsat's video it's clearly the sub making the noise. I think Brian Ding is correct...something to do with audyssey boosting 1 sub 10db, which tells me that placement is not ideal for that sub.
As a result of our tweaking over the weekend, both Limiters on my FV18s are set to ON. The Limiter was OFF on the right hand sub, which exhibited stress in the video while the opening of EoT
was playing. We also changed the settings of both subs so that they were running much less "hot" than the levels at which they had been set.
As Brian and Enrico have suggested, the Rumble Filter is now ON on both subs. I have also set the port tuning frequency at 12Hz. After our tweaking, the volume knob is now in the middle on both subs. Finally, there is now only 2.5dB difference in the levels and the SPL meter built into REW tells me that they are outputting equally. Finally, I am now convinced that the opening of EoT
is an outlier, which will setoff sympathetic vibrations in any multipurpose room, even if the subs' drivers are not under stress. In the past few days, I have played Hacksaw Ridge, Leon the Professional, Master and Commander,
and War of the Worlds.
None of their prodigious LFE stressed the FV18s. In fact listening to it was thrilling. The EoT
opening, though, still makes my windows, shutters, and a door rattle unpleasantly.