25-31 PC-Plus Review

Discussion in 'Archived Threads 2001-2004' started by Russ_T, Mar 5, 2003.

  1. Russ_T

    Russ_T Auditioning

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    Inspection

    My new 25-31 PC-Plus arrived in excellent condition, the box looked brand new with no dents, dings, or other signs of UPS tomfoolery. Must be my lucky day! [​IMG] I opened the package to find a subwoofer nicely wrapped in clear plastic with foam inserts surrounding it to shield any blows from the outside world.

    Upon removing the sub from it's protective surroundings, my first impression was very Keanu-esque...."Whoa". The 25-31 is the smallest in the line of powered cylinders, but the website does not do justice to the sense of mass this thing exudes! It measured a hair under 17 inches in diameter and almost 33 inches high from floor to grill. The unit is VERY solidly built--the cylinder is rock-solid and exhibited no give when given a bear hug as I hauled it down to my basement. I also want to mention that I was fortunate enough to receive a B-stock unit, knocking $50 off the price! Though it was B-stock, I couldn't tell...it still emitted that smell of "ozone" from new electronics and "new car smell" from the automotive grade fabric covering the cylinder. The unit was scratch-free and looked like it came right off the assembly line. If you get a chance to buy a B-stock item...go for it! You will have no regrets.

    Setup / Calibration

    I placed the sub in a rear corner of my L-shaped 5800 cu-ft basement, approximately 16 feet from the prime listening spot. I chose this corner as the sub is completely conceiled behind an old recliner. I hooked up my BetterCables 12 meter Silver Serpent RCA cable between the line-level input on the 25-31 and the subwoofer pre-out of my Denon AVR-5800. I switched the cross-over to disable (leaving the cross-over duties to the THX-certified receiver). Phase was set to 0 degrees, Auto-on enabled, volume 1/4 up, subsonic filter at 25 Hz, all ports open.

    I entered the Denon's setup mode and set the subwoofer channel to -6 dB, (range is -12 to +12), and disabled the peak-limiter. A quick spin with Avia and my Radio-Shack meter set the 25-31 at 88 dB, with my Paradigm Reference Studio 60's, Studio CC, and Studio ADP's all calibrated to 85 dB reference (00 on my receiver). Factor in the Radio-Shack correction factor of roughly 2-3 dB and the sub is running 5-6 dB hot. Hey, I've got a big room here! [​IMG]

    First Impressions

    By now, I was really anxious to fire this thing up! Not thinking twice, I threw in Fight Club and went straight to the airplane-collision scene. I set my receiver to -10 (10 below calibrated reference) and queued up the scene.....SLAM!!!! I was shocked by the intensity of this scene...I did a quick glance around the room to make sure it wasn't disintegrating! I grabbed my Radio Shack meter and held it at the prime listening spot and reran the scene. On C-weighting, Fast, I hit 113 dB!! That is possibly 115 dB (with correction factor) at 10 below reference, 16 feet away, in a 5800 cu-ft sonic black hole. Did I mention the volume on the sub was only 1/4 of the way up? [​IMG] This is serious bass.

    I ran through LOTR:EE....very DEEEEEP. I felt what can only be described as a kick in the butt about a half-second after the ring hits the ground during the opening sequence. Hmm...never felt that before! The resulting Sauron explosion produced a room-rattling experience that I could feel in my chest and in the couch. I must mention that my basement is a concrete slab, covered with carpet and completely finished. I have read numerous threads about losing couch vibrations when placing a sub on concrete, but I experienced no such thing. The 25-31 PC-Plus has the power to rattle my couch, chest, hind-quarters, and walls...no exaggeration.

    I tried the same scene after re-tuning the sub to 20 Hz by popping in the included port plug and setting the sub-sonic filter to 20 Hz. I can't say that I noticed an appreciable difference. The Sauron explosion was slightly less chest-thumping, but the walls and couch rattled a bit more. I thought I might like that really low stuff, but IMO, the increased rattling of picture frames and other unknowns detracted from the sound quality. I retuned back to 25 Hz and regained the chest-thump, while reducing the rattling slightly. This is all a matter of individual taste, mind you, and it looks like I prefer the higher tune.

    Conclusion

    The investment I made into the 25-31 PC-Plus was WELL worth it! I have never owned a dedicated sub before, as my Studio 60's plunged into the mid-30's. This worked fine for an apartment, but now that my wife and I have purchased a house, the added headroom and sheer power of this sub made a huge difference in my home theater. Upon hearing the sub, my wife asked me if the foundation would be able to handle it..."I guess we'll find out", I said. [​IMG]
     
  2. Ray Nist

    Ray Nist Agent

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    Do you think you would need to recalibrate after plugging a port? I would think you would, as total level may come down a bit.

    --ray
     
  3. Edward J M

    Edward J M Cinematographer

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    Russ:

    Excellent review! [​IMG]

    113-115 dB in a 5800 ft3 room - wow - that's some bass!

    I guess I'm not pushing my 20-39PC+ hard enough - I'm hitting the same levels in my 1800 ft3 room....:b

    Yes, the ring drop has major room decay - I love that scene; it separates the men from the boys in the land of Subwooferdom. I tell owners of "wimpy" subs: If you aren't getting about the same volume on the ring drop as you are on the Sauron reverse sweep explosion, your sub is checking out early.

    That is a KILLER receiver, BTW.

    Enjoy your new PC+!

    Regards,

    Ed
     
  4. Russ_T

    Russ_T Auditioning

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    Ray,

    I forgot to mention in my review that I did indeed boost the level of the sub by 2 dB or so after retuning to 20 Hz. Even with the added volume, the overall impact was still less than with all ports open. I'm afraid any more "goosing" of the amp will push it to the edge...it's pretty hot as is.

    Ed,

    Thanks! I love my new toy! [​IMG]
     
  5. Sean L

    Sean L Stunt Coordinator

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    I have the 25-31PC+ in a 5000+sq ft room (20x15 w/ 20 ft. vaulted ceiling) and it's impressive to say the least. I have it tuned to 20Hz, and it hits hard and deep. But now you have me curious, I think I'm going to try the 25Hz tune and see how I like it.

    Regards,
    Sean in Nor Cal
     
  6. Torgny Nilsson

    Torgny Nilsson Second Unit

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    I just got the same sub, and am amazed at its power! I also thought about plugging one of the ports but can't get the darn top off the sub - it is on real tight. While your review makes me think I may not want to bother, can you tell me how you got the top off?

    If anyone else has decided that it is better to leave all the ports open, or not, please comment.
     
  7. Steve Goolsby

    Steve Goolsby Auditioning

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    I've had one port blocked on my 25-31PC+ for about a month. But after reading this review, I decided to remove the plug to experiment for myself which way was better.

    In my opinion, the sub sounds MUCH better WITHOUT the plug. I did recalibrate (about 3 db hot), and I couldn't believe how much more bass I got without it.

    I had just assumed that it would sound better if I went lower on the tuning, so I had never really compared the sound before and after. (Thanks for the review Russ!) [​IMG]

    By the way, you can GENTLY pry under the lip of top cover with a screwdriver. Once you get it started, you just keep working around it with your fingertips until it comes off.
     
  8. Torgny Nilsson

    Torgny Nilsson Second Unit

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    I thought about using a screwdriver to pry the top off but got paranoid about bending the ring around the top of the sub out of shape. But it sounds like I should just leave the ports as they are. I can't imagine that the sub could sound any better if I blocked one of the ports; I was just going to try it for the heck of it.
     
  9. Russ_T

    Russ_T Auditioning

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    Torgny,

    You won't hurt the cover with a screwdriver...I've pried mine off several times in the last few days and it fits as snug as the first time I took it off. Obviously, don't force it, gentle prying, like Steve said, will get the job done. As far as whether or not to try it, you never know, you might really enjoy the lower tune. I figured out why I couldn't tell much difference....I have a 13.5 dB valley between 20 and 25 Hz, centered around 22 Hz, which totally destroys the benefit of a lower tune in that region. Your room may be flat in that region, allowing you to notice a difference.

    Steve,

    I think some of the added sense of power that I'm getting with all ports open comes from a 7 dB boost around 40 Hz in my room. Other than that, I'm flat from 25 to 63 Hz, dropping off on either side of that range. The engineer in me wants to flatten that response like a pancake, but I can't seem to find a happy medium with different placements. Oh well, even with the peak and valley, I still think it sounds AND feels DARN good! [​IMG]
     
  10. Russ_T

    Russ_T Auditioning

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    Hey all,

    I've been doing some major experimentation with my sub placement and have had awesome results!

    I initially had the sub in the back corner of my basement. After running frequency response plots, I discovered a major peak (7dB) at 40 Hz, bulging the curve upward between 31.5 and 50 Hz. This created a major sense of power, but it was too much after repeated listening sessions....I think this is what they call "boominess". Not only that, but I had a 13.5 dB valley centered at 22 Hz, which destroyed my low end. To give you an idea, I only needed to run the sub 6 dB hot to get close to 115dB peaks.

    I have luckily found a new spot for the sub. It is now along the front wall where the home theater sits, and adjoins the next room (the basement is L shaped). I figured this would be the worst place for it, but it turned out to be the best!

    My frequency response plot is now flat +/- 3 dB between 80 and 20 Hz! ( I have the subsonic filter set at 20 Hz, but still have all ports open). It even has a gentle rise of about 5 dB from 80 down to 20! Ah, the good ol' house curve.

    This resulted in a MUCH cleaner sound from the sub and a more seamless blend with the mains. However, I am now pushing the sub close to its limits, as I'm now running 10 dB hot to obtain 108 dB peaks! (This is at my maximum listening volume of 10 below reference) Don't be discouraged if you think you'll need two if you have a room this size...108 is plenty, and other rooms this large may have flat responses in the corner, which adds another 4 dB or so of headroom. I am nowhere near a corner, so this should give you an idea of what the "little" guy can do! [​IMG]
     
  11. Edward J M

    Edward J M Cinematographer

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    Hi Russ:

    Excellent news on the improved FR!

    Just a friendly warning: Running a 25-31PC+ 10 dB "hot" at 10 dB below reference with the SS filter set to 20 Hz and all three ports open is asking for trouble.

    Assuming you included the RS Correction Factor, you are - in essence - at reference level as far as the sub is concerned.

    With the SS filter set below the tuning point of the enclosure, bottoming the driver is a very real possibility. To be safer at those playback levels, I'd run that SS filter at 25 Hz, even if it means giving up a bit of that deep extension provided by room gain.

    Maybe a quick check with Tom V couldn't hurt - it's better than busting your driver by allowing it to unload below the tuning point.

    Ed
     
  12. Russ_T

    Russ_T Auditioning

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    Ed,

    Thanks for the advice! I crossed my fingers and tried the "lightening ball" explosion THX intro at -10 with those settings and no clacks or hints of strain were evident.

    I'll shoot an e-mail to Tom...never hurts to be safe! [​IMG]

    Russ
     
  13. Jeff_PxR

    Jeff_PxR Stunt Coordinator

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    I, too, just got the same sub. It is awesome--I have listened to several movies and wow!! Fight club was supurb. I watched Tombstone last night and the shotguns ran my dogs howling for the door. And I have tough dogs!![​IMG]
     
  14. Russ_T

    Russ_T Auditioning

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    Hey all,

    I checked with Tom V. regarding setting the subsonic filter to 20 Hz but leaving all ports open and here is what he said,

    "Regarding the subwoofer filter configuration, while the subsonic filter and the tuning configurations are meant to work as we outlined in the SVS manual, excellent results can be found in certain instances by “mismatching” the two settings on the subwoofer. As long as you stay in the 10dB under reference range I don’t think you’ll have any problems."

    There ya go! I'm glad I get to leave it....I'm really enjoying the low-end stuff now that I have a frequency response that will accomodate it! Now if I could only figure out a way to get down to 16 Hz without losing too much punch....oh well, I need to learn to let go and enjoy the dang thing! If I keep this tweaking up I'm going to break something. [​IMG]
     
  15. Edward J M

    Edward J M Cinematographer

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    As long as you explicitly made Tom V aware you are also calibrated 10 dB "hot" on the sub, I guess you're OK! He designed it and he knows best.

    As far as getting to 16 Hz strong, you already know the answer to that: 16-46PC+.

    I know why you went with the 25-31PC+ - it affords the highest SPL above 25 Hz, and that is a big plus (pun intended) for your 5800 ft3 room. Agreed - good choice for the single sub route. Dual 16-46PC+ would give you both the volume AND the ultra deep extension you are looking for. Of course, there is that little problem of money...... :b

    Ed
     
  16. Alan Pummill

    Alan Pummill Screenwriter

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    I finally got to hear a SVS sub a few days ago. It was the 25-31 PCi. We had a HTF Meet at my place, and LaMarcus brought his recently purchased sub to the Meet. We watched several hours of DVD's and listened to CD's also. It is a fantastic sub for both. It out did my Paradigm PW-2200, hands down.

    People here on the HTF tried to tell me that about a year ago, but I didn't listen!

    I WAS WRONG!!

    I wonder how a combo 25-31 PCi/PW-2200 would sound???

    Here is a link about our Local HTF Meet!http://www.hometheaterforum.com/htfo...4&pagenumber=4
     

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