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SVS: Love and Hate

Discussion in 'Speakers' started by Nick Breckon, May 15, 2004.

  1. terence

    terence Supporting Actor

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    WOW! Your space is big is mine, and then some with that opening. Sorry buddy you need an upgrade, like Vanilla Ice needs a hit song.
     
  2. SVS-Ron

    SVS-Ron Screenwriter

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    Nick,

    Like Steve said.

    Yes. That would do it. Put that control on 20Hz and make sure you run it for a bit with no port plugs in either (it ships with none installed but just in case... check).

    You can still overdrive a PC-Plus that's properly set up, but it's probably a good idea to get out your SPL meter and test disk and receck EVERYTHING. For now, since you clearly like loud SPLs, set the sub the same as your other speakers (as measured by the SPL meter, doing by ear doesn't count ;^).

    If a subsonic filter knob is off like it was (with its own detents), it's a piece of cake to accidentally change gain on a sub too.

    Ron
     
  3. Nick Breckon

    Nick Breckon Stunt Coordinator

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    Thanks a lot guys (especially the hard-working SVS guys) for taking the time. Apparently home theater has managed to make a moron of me yet again. SS filter set to 20hz has completely taken care of the bottoming issue. [​IMG]

    Of course, now the bass is not -quite- as impressive due to the lack of very low-frequency sound. [​IMG]

    Here's one last question while I've got my 15 minutes. Supposing I decided to block a port and set the SS filter to 16hz, I understand I'd be losing a few decibels. However, if I compensated with gain to account for that, I'm assuming I'd run into the same bottoming issues as before. Is this assumption correct?

    Terence - yeah, it's a big space to fill. Unfortunately we're not even using half of the space, but there's no other room in the house where the theater would fit. What are you using woofer-wise?
     
  4. terence

    terence Supporting Actor

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    I understand about your only choise room wise. I'm running dual 20-39PC+'s. Yesterday i just added another pair of Acoustic Research AR5's, i got lucky and found a store that had them tuck away in the back of their show room. [​IMG]
     
  5. SVS-Ron

    SVS-Ron Screenwriter

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    Nick,

    You haven't mentioned your SPL meter, or what sort of test tone you are using but those port plugs and subsonic filter are very much interactive (there are EQ tweaks engaged at the same time but we like to keep the discussion simple ;^). Just don't mismatch settings and you should be fine.

    One plug... with a 16Hz SS filter setting isn't that big a deal. But you should not "compensate" by turning up the sub, rather, calibrate with that meter as you normally would. Heck, you might even find the 12Hz setting is to your liking. Just don't run the 12Hz setting with no plugs! (rather the requisite two ;^)

    It's true you do lose some headroom CAPACITY above the tuning point with this sort of configuration but the PC+ is pretty capable, and you might not ever discover the limits when things are properly configured. IF you have a meter to keep things honest (do not trust your ears in other words) calibrate with the 20Hz mode and do some demos. Then, changing nothing else, try the 16Hz setting, calibrate, and do some more demos.

    Eventually try the 12Hz config but keep in mind this is very much a worst case setting on the sub and will indeed reduce headroom in the common 25ZHz and up region a good bit.

    Given good corner placement a PC+ is pretty much ruler flat (in a mid sized room) to around 15-16Hz even in the 20hz mode, so it's not like you should be missing much with the sub in that, its most efficient configuration.

    Now that you know about the subsonic settings and the port plugs (this is recapped in the manual here: http://www.svsubwoofers.com/manuals/PCPlusManual.pdf ) ... by all means experiment a bit! There is no doubt that tuning your sub lower puts more stress on a woofer but within reason that variable tuning can and should be used to get the extension you want.

    I think you will have a much better more accurate feel for the considerable limits of the PC+, and won't be bottoming out any more.

    Get down to some nuts on accurate calibration runs with the different tunes of your sub (with your favorite demos run only AFTER you calibrate each time) and I think you'll only use "Love" to describe your SVS.

    ... of course it's hard not to love twins ;^)

    Ron
     
  6. steve nn

    steve nn Screenwriter

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    ... of course it's hard not to love twins ;^)

    Who said that?[​IMG]
     
  7. RISUG

    RISUG Stunt Coordinator

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    Originally posted by Terence

    Really?! Cool. Send me an email with the details on that.

    I'm assuming you replaced a pair of AR17's with the AR5's for the surround?; if so was it the side or back pair?.
     
  8. Edward J M

    Edward J M Screenwriter

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    Phew! No wonder. This is called a "non-conventional" or "mismatched" tune setting.

    Not only does the 12 Hz setting lower the infrasonic high pass filter to probably around 9-10 Hz, it also provides EQ in the 12-18 Hz region. That 1-2 punch is what was bottoming your woofer.

    A vented subwoofer is quite susceptible to bottoming below the tune point. The tune point with all ports open is 20 Hz. The 20 Hz tune switch setting raises the high pass infrasonic filter setting to about 16-17 Hz, thereby helping to protect the woofer from bottoming by cutting out spurious infrasonic signal content.

    It is normal to lose some efficiency if you plug a port. Like Ron said, simply recalibrate, but the result will likely be increasing the sub level about 2 dB to obtain the same overall sub level as you had with the 20 Hz setting. The 20-39 PC+ already TROLLS in the stock tune; I never felt the need to tune it lower, and it definitely works the most efficiently (max power/output) in the stock tune, too - an important consideration in your size room. Give your ears a chance to readjust to the stock tune for a day or two before you make a decision to run in the 16 Hz tune.
     
  9. Ronneil Camara

    Ronneil Camara Stunt Coordinator

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    Hey guys,

    Thanks for the short explanation on sub bottoming out. I actually have here some screenshots of my small home theater. I also have a very close screenshot of my SVS 20-39 PCi panel.

    SVS gurus, I would like to know if my settings are ideal? I can't afford to buy the Radio Shack analog SPL now but I did use my receiver's YPAO automatic calibration. In my own ears, I can say that the performance is awesome!

    The link is at http://restricted.dyndns.org/ht.html

    Thanks.

    Neil
     
  10. Matt_Smi

    Matt_Smi Second Unit

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    Hey Ronneil nice setup you got going man [​IMG] Cant comment on your settings however...
     
  11. Nick Breckon

    Nick Breckon Stunt Coordinator

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    Haven't had the chance to run through some tuning port tests yet Ron, but I'll give it a go and see how she sounds. I'm using a Radioshack analog SPL. My major problem is that I've been told the DVE woofer tone is off by an argueable amount of decibels, so I have no real way to calibrate the sub to the rest of the speakers reliably (the receiver has no woofer test tone).

    I was using the final cannon shot on Master and Commander to test out my ears, and I'm finding a major difference between the 20hz SS filter setting and the 12hz. I'm assuming these blasts have a good amount of sub-20hz bass, and it's just not hitting me like it did with the setting at 12hz.. of course, I will take less oomph (if I have to) over worrying about it bottoming out, as a quick test showed the SVS filter to work perfectly.

    I'll try blocking one port and setting it down to 16hz tomorrow. I'm still a little hazy on one issue though, as far as the SS filter goes. Am I as protected from bottoming the sub out with all 3 ports open and the filter set to 20hz, as I am with 1 port closed and the filter set to 16hz? With the same gain/receiver settings, I should simply be losing an average of around 2-3db and gaining a few decibels in the 14-18hz range, right?

    Given that being correct, would adjusting the gain to compensate for the port being blocked give me the same bottoming issue as having the filter set to 16hz with no ports blocked?

    I hope that sounds more clear to you than it does to me. I think in the long term I'd probably benefit from grabbing another PC+ [​IMG] (I'm probably driving this single one much too hard), but as long as money doesn't grow on trees, I'm gonna need to find a job first. [​IMG]
     
  12. David Strand

    David Strand Agent

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    Hi Nick. I do not own an SVS personally (yet!), so I can't comment on how much peak output you will lose by tuning it for a lower frequency. I can however, assure you that you are protecting your sub in the same manner no matter which tuning you use, as long as you use the accompanying sub sonic filter setting.

    As the frequency being played through a speaker in a ported enclosure reaches the tuning frequency of the enclosure, the driver does not physically move as much, because the port is producing most of the sound at those frequencies. However, below the tuning frequency of the enclosure, the speaker will begin to physically move far more than it normally has to, which in turn causes the bottoming out. As long as you set the sub sonic filter to match with the tuning you use (1 port blocked, set it to 16Hz), you should be pretty safe as far as bottoming it out goes. (not to say you can't, but it will be FAR more difficult)
     
  13. Edward J M

    Edward J M Screenwriter

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    Dave's answer = [​IMG]

    While no one has run a waterfall yet on that cannon blast, the great majority of that signal content is above 20 Hz. There are probably some infrasonic decay components, but I doubt there is much strong content in the 10-15 Hz region. The PB2-Ultra in the stock 25 Hz tune flat shreds the room on those cannon blasts, and the infrasonic filter on that model starts kicking in around 20 Hz.

    The reason your PC+ was hitting you harder in the "3/12" mismatched tune is because the amp was applying too much EQ for the corresponding port configuration and boosting the response.

    Without question, the PC+ will dig deeper in the 16 Hz tune, but it will also work harder, the VC will run hotter, and you will lose some efficiency and impact. If you want to be slammed hard on those cannon blasts, the stock tune is the best way to achieve that.

    Definitely break out the SPL meter and recalibrate the entire system. You may find that a simple boost in the sub level in the stock "3/20" tune gives you the missing impact you were feeling in the mismatched "3/12" tune, and still protects the woofer from bottoming.
     
  14. MingL

    MingL Stunt Coordinator

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    I've got that DVD but not have the chance to watch it yet. Give me the time stamp and I'll run a waterfall of that canon blast.
     
  15. terence

    terence Supporting Actor

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    No problem.
     
  16. Edward J M

    Edward J M Screenwriter

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    Thanks, Ming - 13:31 - the last blast of the opening battle sequence.

    It's a whopper, that's for sure. I'm expecting most of it to be centered in the 25 Hz region, with some infrasonic components in the 15-20 Hz bandwidth.

    Don't know if he used the DTS or DD version. I used the DTS version for the PB2-Ultra review.

    Regards,

    Ed
     
  17. Brian Henchey

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    Interesting thread, especially the part about the eq boost with an SS filter. I am also running an asymmetric configuration--B4+ (one port blocked) with an SVS black box (SS filter set to 12hz). Does anyone know if the black box contains the same type of eq boost as the SS filter in the PC+'s?

    I've never bottomed out the sub, but just this weekend I re-BFD'd it to a much flatter curver (losing some headroom in the process). I didn't hear any strain on M&C (sounded great!), but now you've got me nervous.

    Brian
     
  18. Edward J M

    Edward J M Screenwriter

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    An owner over at Club Polk actually measured the voltage vs. frequency on the SVS01 Marchand Bass Box. The HPF settings were right on the bean, and the curves also showed a very small amount of EQ built into the lower settings, but nothing that would amount to more than about 1 dB, IIRC. If you want more details than that, email Tom V; he's got the specifics.

    Pretty hard to hurt a B4+, anyway; I wouldn't be nearly as concerned running a mismatched setting with the B4+ as compared to single driver sub.
     
  19. Tom Vodhanel

    Tom Vodhanel Screenwriter

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    Ed is correct. The Marchand unit was designed to work with our CS and CS+ models...which require very little EQing to be *flat* to their rated extension. Actually, they require no EQing at all to fit within the industry standard +/- 3dB window. But we added a very slight amount to the circuit design to keep the tolerances even tighter. We are remeasuring all SVS models with the latest LinearX setup right now...we should have some cool graphs up on the website soon!

    The Marchand unit has 15/20/25hz settings. Ideally, I'd say use the 20hz setting with one port blocked on the B4+...but as long as you don't hear the unit stressing in its current cofiguration...no worries..[​IMG]

    Tom V.
    SVS
     
  20. Sami Kallio

    Sami Kallio Screenwriter

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    Ronneil, the $50 that you spend on the SPL meter is not that much considering how much you have on your system. I thought calibrating by ear would be enough but I still decided to go ahead and buy a SPL meter (could have borrowed an $8000 one from work but though it would be better if I had one at home all the time). What a difference it made, I can tell you that. Will probably get better once I calibrate the cheap RadioShack meter with the pro quality meter.

    I first used the autotune from my H/K receiver. Not good, I got much better sound by ear. And the receiver didn't touch the sub at all. Go ahead and spend that $50 on SPL meter (and $20 on calibration disc if you don't already have one), you won't regret the relatively small investment.
     

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