Saturday, August 11, 2018

Subwoofer back, and limiting adjusted

I finally got around to replacing the plate amplifier on my SVS PB13 Ultra subwoofer with a new one purchased earlier this year from SVS.  The original plate amp was from 2008 and was not under warranty, but I was happy to pay for this new unit, which looks excellent (and actually looks better made than the replacement for the other channel I got a couple years ago).

And it works great on the new dedicated circuit, and there is no hum or noise aided by the balanced connections from my Emotiva Stealth DAC.

Perhaps it's just because my ear has become more sensitive to bass distortion after 6 months of using the Acoustats with no subwoofer, or my subwoofer driver is ageing also, but I noticed after awhile that more limiting was needed to avoid serious bass distortion on some torture track recordings, such as Bass Connection.

I was already using a frequency selective limiter and the lowest frequencies (in the Behringer DEQ 2496 that serves as crossover and eq for the subwoofer channels).  I had set that up before. Actually I don't think I understand that and may need to re-read the documentation.  For now I set up a standard limiter function, somewhat more agressive than before.

After listening to torture track recordings over and over I adjusted all the limiter parameter for both the standard and frequency selective limiters.

I had figured the limiters in the subwoofer itself would be good enough, but they are clearly not, especially with the new amp (is it tuned correctly?  I did set the type correctly to "sealed") and dedicated circuit.

I am thinking now that pretty much all practical subwoofer systems intending to achieve bass below 30Hz need to include limiters if they are going to provide something like flat response, to deal with different kinds of recordings.

I believe previously I was very messed up about setting the bass level, sometimes setting very weak bass to allow my torture track recordings, then playing those recordings and causing ceiling cracks and turning it back down again.  Now I seem to achieve precisely the desired effect with limiting.  If I play at modest levels, the limiters have absolutely no effect.  Only at super loud levels do they kick in, and still sound fairly good when they do (because of my clever adjustments), just somewhat softer than the bass might otherwise be at those super loud levels (still loud enough).  And it was actually sounding quite distorted and horrible when those higher levels were being "reached."  I had just been ignoring that apparently, and enjoying the "BASS, Man."

Read on my RTA app at 1/6 octave resolution, my bass is as flat as it has ever been, very little room curve bulge, but slightly decreasing down to 20Hz.  And yet sounds plenty loud, but far more musical than ever before, notes rather than booms and rattles on the torture track recordings.

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