Got the SVS 20-39PC+, bottoming out? (1 Viewer)

[steve nn]

I seem to fair out OK to running +4 db hot. I can't handle reference though so this is at -15 to -10. Now that I run duel I never have any worry. One sub at reference running hot is still allot to ask imo. Placment and room will dictate to a certain degree.

 

[Edward J M]

Dustin:

I'm also running a bit hot (2-3 dB) for the sub, but my SPL meter IS accurate in the bass range - so it's a true 2-3 dB hot. I'm also running no ports plugged and a 20 Hz setting on the rumble filter, so that helps too.

Regardless, I MIGHT be able to push it to 6 dB under reference (that would be about 112 dB at the listening position), but I would never attempt it at actual reference.

With two subs (which would add another 6 dB of headroom under optimal conditions), yes - I could probably nail it at reference - barely. That would give a 118+ dB peak when the ball explodes.

Can your Tempest take it at full reference, or is 5 dB under your safe max?

I still consider it in very poor taste to master in a bass peak on an intro that will bottom even a properly calibrated Ultra (or just about any other single sub you can mention that is not equipped with a limiter of some sort) at reference level. It's simply TOO hot and catches listeners off guard. Bottoming a $1,000 sub even once has GOT to be disconcerting to most owners, even if it doesn't result in permanent damage.

Ed Mullen

 

[Dustin B]

I hadn't figured out how to store the max level in my RatShack meter when I did this before. I just ran it again with my digital meter set for the 100-120 range, C weighting, fast response. Level was at 5dB below reference. I have some roommode problems (hope to get a BFD by Christmas) so things might be a little out of whack.

With the speakers at 80dB on Avia the sub tone will wobble between 78-84dB (I assume because of roommodes). The Avia frequency sweep also shows the largest mode to be around 40hz (after I get a BFD I'll do a proper test with individual tones, till I can fix it I don't want to know the specifics). But I'm flat again under 35 and over 45 hertz (I think). Pausing after the ball explodes the max value displayed on the meter was 117dB. From Ron's graph, if I'm reading it right that peak value should be produced around the 30hz area.

I don't like taking my system to full reference becuase of my receiver (Onkyo 575). I'm afraid I'll clip it. If I ever find a job, I plan on buying a used Denon 4800. At that point I may attempt a few full reference runs.

Tom and Vince Maskeeper provide conflicting reports on the radio shack meter. Vince says that on a filtered wide band pink noise signal the meter is accurate (says he has calibrated with the Rat Shack, then checked that calibration with a calibrated professional mic and didn't have to change anything). In otherwords wide band pink noise calibration doesn't need a corection value. Only individual sine waves do.

Anyways, being unfair to a sub will depend on the sub. A bass reflex tuned to around 30hz with a good subsonic filter shouldn't blink an eye at it, they also won't play most of it (most commercial bass reflex designs). A SVS on the other hand isn't most commercial subs. Tuned to 20hz the max excursion will be reached around 30hz and only the really low stuff will be filtered (PC series, not CS series). The PC series have good subsonic filters to take care of over excursion below tuning (CS don't). So this intro seems talor made to bottom a 20-39. So the only solution is to back off or buy another one. Most commercial sealed subs won't hit max excursion until under 30hz and will have sub sonic filters that roll response of to prevent bottoming.

The other thing with my Tempest is I have 280W going to it. That is enough to make it go 1mm over Xmax at 27-28hz (but no where near Xmech, even below tuning because of the rumble filter). So my amp will clip before I bottom the Tempest.

 

[Wendell]

Well, I'm glad to know that the sub bottoming out was normal for that scene. We played the Intro again and it didn't bottom out -6db below refernce. On the pod race the sub totally rocks!

Thanks!