SVS 25-31pc Plus. ?

Discussion in 'Speakers' started by steveGamble, May 24, 2006.

  1. steveGamble

    steveGamble Stunt Coordinator

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    I just recieved my 25-31pc Plus sub 5 days ago. To replace my 2year old Velodyne cht 10. I thought this would be a huge upgrade?
    I must be doing something wrong , I am still learning.
    My completely sealed, HT room 11.5 x 20 x 7.5 is 2 weeks away from being ready to move in.
    For now I'm testing stuff in my living room 12 x 16 x 15 foot ceiling open to upstairs hall, a kitchen a dining room, so pretty open area.
    But My 10" paper woofer Velodyne has similar upper bass impact, as the SVS ? down low The SVS is good, vibrating the bedroom doors, + my DLP screen is Rattling (have to call Samsung about that only 90 days old.)
    I have My reciever calibrated using the test tones, and a SPL meter , SVS sold me, at 00db on my Yamaha 140 watt/ch 7.1 I get 94db on all 8 Polk speakers. 100db on sub, gain to almost half. reciever sub out set to 100hz..the higher I go the better it sounds??
    I put Matrix to -15db. Lots of impressive down low bass, but upper mid bass , seems missing, and as I turn it up a little more, the sub distorts and clacks.
    I only played 2 full movies,,so maybe I'll play a bit more.

    Should I try to add a EQ to it ? to boost the upper bass.
    Maybe the sub has a problem?
    Maybe I just want too much, and need a dual woofer sub ?
    I didn't think I was bass crazy? I don't know now....

    thought I'd ask you guys. before I see about a upgrade.
    I must be doing something wrong, because evryone loves their SVS.
    I want a good thump, in the mid bass area.I just don't hear it, and I am afraid to damage the sub, as I try to turn it louder, when it starts to really distort.(clack)

    Thank you for you responses. :>)
     
  2. Geoff Gunnell

    Geoff Gunnell Stunt Coordinator

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    In your new theater room one 25-31+ may be all you need.

    In your current large air volume, a permanent solution would probably involve 4 12" drivers -- 2 pb12-NSD/2's -- as a minimum to power the room. The only way around this is to move the sub next to you so you can 'bask' in nearfield bass...
     
  3. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Hi Steve,

    Would you be able to send me a sketch of the room layout? If it is easier to fax me...my number is (330) 793-8183. Please include the room dimensions, any openings into the room, and the current speaker and seating positions. Thanks.

    The 25-31PC+ has a slight rise to its frequency response toward the lower frequencies. It is still within the industry standard +/- 3dB window from 25-80hz in 25hz mode...but if you subjectively prefer a little more "upper" bass(in relation to the lowest frequencies)...using the 20hz setting will help. In 20hz mode, the response ranges from 18-19hz to well over 100hz. And if you only consider the 25-80hz range...20hz mode provides a very tight +/-1.5dB tolerance.

    The cht10 is a good unit for the price…but it has been shown to have limited output
     
  4. John Garcia

    John Garcia Executive Producer

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    Often, when moving from a sub that has exaggerated upper midbass because it doesn't extend low is that "something is missing", when in fact what you are hearing is bass the way it was meant to be heard - accurately.

    IMO, this sub should not distort and clack in a room that size, it should be plenty. I've heard the 25-31PCi in a larger room than that and it had no problem, and I've heard the 20-39+ in a room slightly smaller than that and it had immense output (noticed that output at the bottom was greater than up top).

    Try a different movie....U-571, Master & Commander, War of the Worlds, etc...

    Now, room is also a factor and it could be that room modes in this particular room are working against you also, so you may need to experiment with placement.
     
  5. steveGamble

    steveGamble Stunt Coordinator

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    Thanks Geoff....
    Really ? room acoustics make that much difference ?
    I guess I'll have to try a temp set up for tomorrow.
    just worried...
    when I turn it up -25 to -15 depend on DVD. It really bottoms out Hard ! ...I better take it easy on the sub gain, and just take all this stuff down to the new room and give it a try? even for a day... I know when I walk in and close the fast my ears pop..
    I kinda like the sub to dominate the soundtrack, just a tiny bit.
    can't do it, she bottoms out too hard..
    Never had that problem with a sub of lesser power.
     
  6. steveGamble

    steveGamble Stunt Coordinator

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    Tom, If I try the 20 hz mode, I MUST put in the foam block, right ?
    you don't mean just switch the knob, and try.
     
  7. ChrisWiggles

    ChrisWiggles Producer

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    I really think this may just be a "getting used to real bass" issue. It really does sound like you are accustomed to grossly boomy midbass (a lot of people are) and it may take time to familiarize yourself with flat response.

    You should do a frequency sweep and see how flat the response is in your listening position, because room acoustics also can have a very significant affect here, and a sweep will give you a good idea if this is a culprit.
     
  8. TimJC

    TimJC Stunt Coordinator

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    Yep, Tom will tell you that you need to put the foam block in and flip the switch. Not putting the foam block in will put the driver at further risk of bottoming.

    My take on what is happening:

    You are hearing real true infrasonic bass, not thumping bumpy bass-like sounds.

    Good bass is smooth, clean, lifelike. The sub should perform in the same manner as any other speaker in accurately reproducing a range of sound.

    You have a very peaky frequency response in that room, with a very large peak in the 20-25hz area, which is at or below the lower limits of human hearing. This is a common type of room gain encountered with subs that go very low strongly. The problem is though that this is the most demanding frequency range for the driver of a 25-31PC+ to produce. When you calibrate your sub to +6db with the RS SPL meter, that is based only on a limited range of midbass frequencies contained in the subwoofer test tone. The sub may well actually be running 15-20db hot in the range of frequencies below the sub test tone. Since the sub is working way too hard to produce those lowest frequencies, it is bottoming out.

    The frequency response needs to be evened out somehow. At least try the following:
    - change the location of the sub in the room
    - change the listening position in relation to the location of the sub
    - tune it to 20 hz as described above
    - use the Avia warble tones to check/set the phase of the sub. An out of phase sub will be lacking in the upper range of bass near the crossover frequency. This will again tend to lead someone to want to run the sub hotter to make up the difference, but all that will do is put more demand on the driver to produce the lower frequencies which it is already overproducing ... it's a vicious cyle of sorts at that point.

    More advanced techniques of evening out the frequency response involve bass traps and an equalizer, but no need to go there just yet...

    Your ears are popping because the air pressure is changing rapidly in the room. This is because the sub is creating wavelengths over 25 ft long at fairly high amplitudes. As these waves bounce around the room and collide with each other, they sometimes sum and multiply, creating even higher pressures, and other times they negate and cancel each other out, causing a loss of perceived bass volume at certain frequencies.

    First thing you need to do is get the sub in the room where it is going to stay, then start over again.

    Good luck, and please post back with how it's going.


    Tim
    [​IMG]
     
  9. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Hi Steve,

    When you say...

    """I have My reciever calibrated using the test tones, and a SPL meter , SVS sold me, at 00db on my Yamaha 140 watt/ch 7.1 I get 94db on all 8 Polk speakers. 100db on sub, gain to almost half. reciever sub out set to 100hz."""


    This looks like you are using the receiver's built in test tone sequence for calibration---which should require you to set everything to 75dB(per the owner's manual). If *00* is giving you 94dB from the main speakers(which must be REALLY loud for this type of test tone)...then -19 on the volume setting should be about 75dB of output(assuming there isn't any significant compression going on here). If this is correct, then -15dB on the receiver would be 4dB over reference level...which is extremely loud. Am I misinterpreting something in your text here?

    Tom V.
    SVS
     
  10. John Garcia

    John Garcia Executive Producer

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    I was going to mention that also, that you are bottoming because you have the receiver at basically a ridiculous level AND you are running the sub hot. With my receiver ref cal at 75dB, -15 on my receiver is extremely loud - average listening levels are between -25 to -20. That sub is a beast, and if you are bottoming it out, you're really pushing it. I would recommend you avoid continually bottoming it also...not a good thing.
     
  11. steveGamble

    steveGamble Stunt Coordinator

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    Yes Tom you are correct.
    I know 75db , just seemed too low, so I bumped it a little.
    I suppose I am watching my movie too loud.
    That will be a hard habbit to break, as my hearing is NOT getting any better.
    The SPL meter would peak about 104db give or take, during the DVD Alien VS Preditor.
    Geeze that didn't seem rediculous, it sounded so awesome.
    I don't do this regularly, usually watch a show at -30 to -25 .
    But once in a while, mission impossible type DVD, I'll try 90 minutes of Loud movie watching,-18
    I didn't mention all speakers except sub are enhanced also with the EQ. built in to the receiver. pushing the 400hz and 1khz a little, bring out the dialog.
    I'll try to focus on sound quality over sheer volume, I am 38 years old, so time to mature...right ?
    I am adding a pair of Polk RTi 12's next week, (put my RTi 8's in the rear)with three 7" woofers and two 5 1/4" mids and a tweeter. These are suppose to have good Mid and upper bass, maybe this will help, with that punchy sound you get from a gun shot, race car engine, etc... sound.
    I'll give it a try. I needed an extra pair anyway for the 7.1
     
  12. Ron Temple

    Ron Temple Stunt Coordinator

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    If you're adding RTi12s to 8s in a 7.1 config, you might consider adding a separate 2/3 or 5 channel amp or you might be compromising your SQ rather than improving it. There's no way a receiver can power those hogs adequately at volume.
     
  13. douglas-b

    douglas-b Stunt Coordinator

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    If you don't like calibrating the system at 75db you should invest in a calibration disk like "Avia" or "Sound and Vision Home Theater Tune up". Then you could calibrate at the 85db mark. Not to mention if you had Avia you could easily set up your sub...gain, phase etc. I had no problems setting up my 20-39. I had to do some research on phase but after a few searches...that was no problem at all. I have a 6.1 setup so I use "SVHTT" tones for that and the sub tones with "Avia".
     
  14. Geoff Gunnell

    Geoff Gunnell Stunt Coordinator

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    In my experience high ceilings significantly affect bass response. Put another way, its hard to realize how much bass advantage we get from our 8' ceilings until they aren't there...[​IMG]

    In your new theater room the 25-31 will be fine. I've had cht-12's and a 20-39+ on my way to my current 2 Ultras in a cathedral ceilinged 2500 cubic feet...that has two large openings into about another 5500 cubic feet [​IMG]

    Right now you are in a room that's tough to power with any single 12" driver. Don't let that distract you from finishing your sealed dedicated theater. In that room you will clearly hear the difference between the cht-10 and the 25-31.

    If you want to continue to see what you can do in you big room:
    1. Use both subs. A correct solution in that area would involve subs in different locations but that involves a lot of tuning -- just keep the subs right next to one another or stacked.
    2. Try locating them right next to where you sit first. This is an often used solution if you can't afford to power an entire volume. While they are there, walk around the room and find the places where the bass is strong, weak, and even. In your seating position, locating the subs in these spots will result in bass that sounds strong, weak, or even.
    3. As you 'map' your room, you'll find spots where the bass often sounds good, and more importantly places where it often sounds bad. Try, try, try, not to sit in a place it sounds bad. You can surround yourself with equipment to little avail if you sit in a bad spot.

    Oh, and, uh, yeah, listen to Tom [​IMG]
     
  15. Blaine_M

    Blaine_M Second Unit

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    I agree Douglas, I personally wouldn't even bother with the test tones on the receiver, get the Avia disc and you'll have a much better representation of the signal path. I think a lot of the receiver test tones end up with people having the sub set way too high or way too low. Even some of the discs that have the THX Optimizer would be better than the receiver test tones. Your SVS will smash your old Velodyne. I've heard some Velodyne's that cost over $1500 that I would absolutely NOT trade my SVS PB-12 NSD/V for, which cost significantly less!
     
  16. steveGamble

    steveGamble Stunt Coordinator

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    Thanks very much guys, I shouldn't hit the panic button until I move into the new room with the 7.3" foot ceiling. 6.9" last 7 feet where second row seating is. Actually about 1300 cu, ft. to fill..

    Ron....on the RTi 12's , to replace my 8's...I will need a amp ? hmm.. The RTi 10's have 2 of those 7" woofers as well as 1 mid,,
    but,, I heard they are not much different sounding than the 8's.?
    so... I was going to splurge on the 12's...but now an amp. ok.. any recomendations,, good value for dollar, as well as good power, as it seems I listen to movies fairly loud ?
    and......anybody ever compare the 8's to the RTi 12's . Would be a good question. Do they produce some good mid+upper bass ?
    The 8's do not !

    and for now, I will place the 25-31+ on top of the Velodyne, just like on the little video SVS has.
    I have the Avia disc as well from SVS, I was just waiting to do an extensive calibration until after the move in, in a week or two. Video and Audio.
     
  17. dany

    dany Supporting Actor

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    Are you buying before you know what your doing and buying?
     
  18. steveGamble

    steveGamble Stunt Coordinator

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    Are you buying before you know what your doing and buying?


    --------------------------------------------------------------------------------


    Denon2805-Sony KV-30HS420-SonyDVPNC555ES
    B&W 603's & 601's SVS20-39pci Hughs TiVo


    I will buy whatever it takes to create my dream movie room.
    without going to extremes.
    If I'm not there already ?
    I need two more speakers to fill my 7.1 surround, instead of buying booksheve's for the rear, I thought...buy RTi 12's for the front, move my 8's to the rear, and create that really punchy, bassy, sound I like.. for a little more money ? The whole project cost enough, I want to make sure I get the wow factor for my movies .
     
  19. Geoff Gunnell

    Geoff Gunnell Stunt Coordinator

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    I'd wait on an amp until you get the room going, but I like (and own) both the Rotel RMB-1095 and the Emotiva MPS-1. I slightly favor the sound of the Rotel, possibly because I am using speakers (Onix Ref3's) that have extended (40kHz) high frequency response, and the Rotels are voiced with B&W speakers which also have extended high frequency response.

    I think the biggest challenge you will have in the room you describe is getting even sound quality to both seating rows. You will probably need to put some absorptive materials in the back half of the room to cut down on reflective sound and improve vocal (center channel) intelligibility. You probably will have to try different locations for your surrounds (dipoles I hope) to get the best mix in both rows... [​IMG]
     
  20. steveGamble

    steveGamble Stunt Coordinator

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    No dipoles.. If I do that, I'll be keeping the 8's up front. and..
    I'll wait on the amp, as you say. maybe RTi 12's too much for balance with rest of system, as you mention. I will read some reviews of the RTi 10's
    I'd like to buy a pr. polks with more bottom end sound than my 8's...
    The seating is pretty centered in the room. 65 / 35 split. But my wife and I sit in the front, the extra seating is only for when family comes to visit.
    I'm focusing on front row seating, when calibrating, using Avia.
    anyone experience RTi floor speakers ?
    and combining SVS 25 31+ with a cht 10 ? think that can create a little more output ?
    I'd put them side by side, or stacked. ..I have to go buy a cable so I can try.
     

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