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.

Krell finally fixed by The Service Department

My Krell FPB 300 has been fixed, refurbed, and upgraded, and it is working perfectly for the first time ever, thanks to Steven at The Service Department in Connecticut.

I had sent my unit to the Krell factory on 3 previous occasions, and never did they get it this good.  There was always a significant thermal difference between the two channels, like one channel at 180F and the other at 140F, according to my IR measurement technique (which might not be accurate, but fairly repeatable).

Also, it always used to make a "clink" sound (what the service people call "ping," but mine were so loud, they really were clinks and not pings) frequently, like many times per hour.  After the latest repair/refurb/upgrade, it has hardly made any in a week, and they've been mostly soft.

I also credit myself for insisting on having repairs done to both channels, and for insisting on replacing every suspect part, including the relays and XLR jacks.

NOW, both channels track within a few degrees, reaching reasonable levels like 150F for moderate to loud playback, 140F for low levels, and up to 168F for really really loud and sustained.  Previously it had been going over 200F in one channel.  My belief is the Krell is designed to force the 2nd lowest plateau when the temp goes to 180F (it is designed to handle the heat) and shut off at 200F.

And it sounds even more transparent and dynamic, thanks to the refurbs such as replacing the power supply capacitors, which even the factory "capacitor service" did not do, and upgrading the front end to the 400cx design.

The program was changed previously (by the factory) and now my front end has been upgraded (perhaps these two changes anctually should have been done together???) so I basically do have a 400cx now, except for lacking the CAST input, which I would not be using anyway.

Now, more than ever, there may be a chance for a history making ABX in comparison with the Hafler 9300, which also sounds excellent and perhaps sweeter, but is even farther from the dynamics and transparency of the Krell now.