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Any warning signs before SVS bottoms? (1 Viewer)

AlanZ

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My wife and I are about 80%HT, and we don't listen quite at reference levels. When we first got our sub, before we calibrated everything, the bass was so powerful (Blade II)that it was creating pressure waves in the room that were messing up our hair! :) Anyway, since we listen at loud, but not obscene, levels, we're sometimes tempted to crank up the SVS PCi20-39 a little bit.....it's passed every test we've thrown at it, so I do have a lot of confidence in this member of our family.....but since I've never bottomed out a sub I'm wondering if there is some way to tell when you are getting close to its limits. Not that I wouldn't mind an excuse to get another (bigger!!) SVS, but I just assume get some more use out of this one for the time being. Any help is appreciated :)
 

keir

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i think the only thing to do is just put it at the level you want, then turn it down if it does bottom out. my 16-46 has never bottomed out, but i listen about 10-15 dB below ref level usually. i think my receiver clips before the svs distorts ;)
 

DerrikW

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I personally do not own an svs:frowning: , but from what I've been hearing on this forum, I will soon be getting one to replace my paradigm ps-1200, now just to decide which one to get:D . Now for your question, from what everybody has said on this forum, the easiest way to know that your svs is going to bottom out is to keep turning it up until the windows rattle, the walls shake and the house starts to slide off the foundation.:D
 

Edward J M

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The SVS design does not employ peak limiters like some other brand subs. YOU are the limiter in the equation.

And no, it will generally not give any indication it is approaching its excursion limits. The SVS stays clean and flat all the way to its high limits, and then you will hear a "clack" as the VC former strikes the backplate.

While no incident of bottoming is desirable, one time shouldn't hurt the woofer, and if this ever occurs you should carefully note the DVD, the time stamp, the sub level, and master volume level and take measures to prevent it from recurring.

While the 20-39PCi is no slouch, if you want to play bass heavy DVDs at/near true Reference Level (as determined with Avia or VE, etc.) with the sub running on the hot side, it generally will require dual Plus subs or the PB2+.

Regards,

Ed
 

steve nn

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When I ran a single 25-31 CS+ in my leaky 24' X 12' HT with 10'ceilings, I could bottom it out. It did take allot to do so. {more than enough} But now with duel and each calibrated -2 under which brings me in at a +4 sub calibration I can let her really rip if I desire. On the first Fly-By in (STAR WARS II) I just hit 118 db at -5. My meter put up quite a fit for I have never required it to work so hard or should I say to go so far up the scale? Duel or the PB2+ will give you the performance spike that your looking for.:)
 

AlanZ

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Thanks for the replies :) I love my PCi....but I feel that I could be doing someone a great service by perhaps offering it up for a fair sum. Think of all those out there who are dreaming of becoming a part of the SVS family that I could help by saving them a few bucks on a still relatively new sub.....of course, I am also thinking about a PC Plus or PB2 in the front corner of my living room.....but this isn't about me......if you don't believe me, just ask my wife....cause that's what I'll be doing for the next couple weeks :)
 

MikaelG

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May 20, 2002
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I just have a question to you guys who get these numbers with your meters; Do you acutally turn of all other speakers when you measure these peaks, or is the sound pressure of the other 5 (7?) speakers included?

My 16-46 PC+ only bottoms when I play a THX demo (it might be DTS or DD too, don't know, it's an mp3 so it could be anything), it's titled "Jurassic Lunch". At about the first 40 seconds you hear the footstomps of the dino, the woofer is pumping like crazy, it's some really lo freq stuff there. The footstomps in the original film (JP) are pretty lame in comparison with this, do the stomps in JP even go below 25 Hz? Don't feel like it... I'd guess these come close to 15-16 Hz, perhaps lower. When I play this mp3 at a loud volume I hear a clack here and there, the woofer is really pushing itself to its limits.
 

Edward J M

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I just have a question to you guys who get these numbers with your meters; Do you acutally turn of all other speakers when you measure these peaks, or is the sound pressure of the other 5 (7?) speakers included?
Hi Mikael:

I use c-weighted fast and leave all the speaks running. Ostensibly, the highest SPL by far will be generated by the subwoofer, since it has the greatest ability to move air and create sound pressure.

With that said, the surround speaks will contribute some SPL, especially if they are bass capable and you use an 80 Hz or lower crossover to the sub.

If you really want to get picky, the c-weighted scale drops off slowly below 30 Hz and drastically below 20 Hz. That drop-off, combined with the inherent error in the RS meter, will result in SPL readings that are on the low side for really deep bass passages. If you have the commonly available "RS Correction Factors", and a waterfall chart for the passage in question, you can apply the approximate correction factor to your peak SPL readings for the true SPL.

There is a waterfall chart floating around for JPIII, and if I recall correctly, the stomps during the dino fight seem to fall in the 20-30 Hz range with 25Hz being about where the peak amplitude occurs. I think "Jurassic Lunch" is deeper than JPIII, and possibly higher in amplitude - a real sub killer.

Regards,

Ed
 

MikaelG

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May 20, 2002
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Ed:

Ok, thanks.

If only I could find a program, able to display waterfall charts... I've found some at www.download.com but they're pretty primitive, nowhere near the waterfall charts up on the SVS homepage...
 

Mark Zimmer

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Jun 30, 1997
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I don't listen to DVD at reference levels very much, but I have run all of the torture-test discs at reference and I have yet to have my 16-46 bottom out even once. So I can't be of much help, but by the same token I don't think you need to be too worried either.
 

Seth_L

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SVS subwoofers will distort (Due to the BL curve) before they bottom out as will every other subwoofer. Whether you will hear the distortion is another matter.
 

Andrew Pratt

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My 16-46 PC+ only bottoms when I play a THX demo (it might be DTS or DD too, don't know, it's an mp3 so it could be anything), it's titled "Jurassic Lunch".
Jurassic Lunch has some very strong sub 10 hz bass in it so its not a very good real world indicator since it will bottom out nearly all ported subs that don't have a limiter on them.
 

Brian_DR

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Mar 19, 2003
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Jurassic Lunch has some very strong sub 10 Hz bass in it so its not a very good real world indicator since it will bottom out nearly all ported
subs that don't have a limiter on them.

On the other hand, it also depends on whether or not a rumble filter is in place. The purpose of rumble filter is to limit the excursion requirement below port resonance frequency. Most of commercial vented box run at 6th order extension, instead of 4th order.

Brian
 

Jaimin

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Aug 4, 2002
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Pardon my ignorance, but what causes a sub to bottom out? Is it lower frequency sounds, high listening levels, or a combination of both? Cause I have a PE Plate amp and I use it for my 2231 CS, and there is an option to install a rumble filter, but I don't know if its worth it to install.
 

Seth_L

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More power at a given frequency than the combined driver enclosure system can handle. This causes the driver to extend to the limits of it's travel (either suspension or magnetic). In ported applications this occurs below the tuning point of the system. In sealed applications if your amp is properly sized to the box and driver it will never bottom out.
 

MingL

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Mar 26, 2003
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Its a combination of low freq at high volumes that causes the sub to bottom out.

The lower the freq, the further the cone has to move to maintain the same listening level. Couple that with high volumes, sub bottoming out will happen.

Occasionally, my 16-46PC+ bottoms out on the Cavalcade THX trailer found on SW2:AOTC. Its at the instant that globe bursts into a thousand pieces.
 

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