eq'd pb2 ultra sounds cleaner, but considerably quiter

Discussion in 'Speakers' started by Todd smith, Dec 16, 2004.

  1. Todd smith

    Todd smith Supporting Actor

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    I got around to using the peq on the pb2 ultra and it sounds cleaner but the bass peaks are not nearly as loud. I assume this is because I reduced the peak, but I thought I would get more volume than this. It would be ok If I did not here the peaked version. Now I want the volume of the peaked version with the sound of the eq'd version. My bass peaks are now anywhere from 107-112db and before they ranged from about 113-118 so a considerable difference. I recalibrated after eq so that is not the problem. I dont think there is a problem it is just flatter now and not as loud in some areas as well.

    I assume this is normal, right?

    How much volume would a second pb2-ultra give me if I stacked it on top of this one in my 12x17 room?

    How much louder would a b4+ be over dual/single pb2-ultras?
     
  2. Robb Roy

    Robb Roy Supporting Actor

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    Todd,

    If you added a second Ultra, or moved to the B4, you would not see any increase in volume assuming you calibrated and had your volume dial at the same location. All you'd be doing is creating additional headroom. I would recommend double checking your FR, phase and calibration settings, then giving yourself a week or two with the flatter calibration. My guess is you'll find the more natural sound of not having the large peak will grow on you. If you want the sub louder after that, bump up the gain and run it a bit hot.

    -Robb
     
  3. Wayne A. Pflughaupt

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    Todd,

    It’s a bit hard to nail down anything specific without seeing your response chart and knowing things like your placement, room size, and so forth.

    Not knowing any of this I would suggest:
    • Ignore the “correct” calibration and turn the sub up to where it sounds like you want.
    • If you EQ’d your sub for flat response, you might want to try a house curve instead.
    Regards,
    Wayne A. Pflughaupt
     
  4. Todd smith

    Todd smith Supporting Actor

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    what is a house curve?
     
  5. Wayne A. Pflughaupt

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  6. Todd smith

    Todd smith Supporting Actor

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    Thanks Wayne for the excellent information. The problem I have with doing a house curve is my uncorrected spl readings at 15-20hz are about 10-12 DOWN from the rest of my readings.

    A little info about my setup. I am in a 12x17.5 fully enclosed room with 5/8 drywall. One of the short walls and one of the long walls have the foundation behind the studs and drywall. I do have a few broadband bass traps in 3 of the corners of the room which dont change my FR at all, and I also have the first reflection points handled with an acoustic panel on each side wall.

    On the front short wall in the left corner sits an open air equipment rack with my sherbourne amp on bottom, b&k ref50 on second shelf and my 3919 dvd player on top. Next to that sits my jbl s-38 bookshelf speaker on an open bar stool. Next to that sits a 52" dlp tv. On the right side of the tv is the other s-38 on bar stool and there is the s-center on top of the tv. On the rear wall aprox 53" high is 2 shelves mounted on wall which hold 2 other s-38's. On the rear part of the side walls sits 2 more s-38's to complete my 7.1 setup. Five feet out from the rear wall sits a 3-4 person couch (about 2/3 way point of the room which should be a good sound spot from what I have read).

    The Pb2-ultra sits in the rear corner. I started out with the sub in the front corner with my other equipment but my FR chart ranged anywhere from a 50 db reading to a 90db reading from 15-90hz! It looked like the alps! So I tried putting the sub in the rear corner where I am getting much flatter response and with the aid of the peq can get it pretty flat. The uncorected, no eq'd readings are as follows....

    16-58
    20-62
    25-74
    31-82
    35-83
    40-78
    45-74
    50-72
    55-72
    60-72
    65-71
    70-67
    75-68
    80-66
    85-67
    90-67

    The compensated and eq'd numbers are as follows

    16-69.5
    20-68.5
    25-74 best I could do
    31-75 best I could do
    35-73.5 best I could do
    40-71.5
    45-71
    50-69.5
    55-70.5
    60-71.5
    65-71.5
    70-69.5
    75-68.5
    80-69.5
    85-71.5
    90-71.5

    This is where the sub is currently at now and as you can see is pretty flat. I calibrated the sub with avia after doing the peq adjustments to about 3 db hot.

    The problem like I said in the first post is that the sub sounds kind of wimpy in this flat response. my bass peaks are now 107-112 where as before they were higher and more what I thought they would be at. Svs told my this sub should be able to hit 116-122db in my small room and it is pretty far off that right now. When it was in the front of the room with no eq I could get these numbers, but like I said my numbers ranged from 50db to 90db so it was not the overall best spot for the sub.

    I am just a little dissapointed at this point because I thought I would get more volume out of the sub at 3db hot eq'd flat in my small enclosed room. I have tried every possible spot for the sub and this seems to be overall the best one. I was hoping adding another ultra would give me another 5-6 db but it does not sound like it will from what you guys are telling me. I could just turn up the sub, but it is already at 3db hot and the manual does not suggest going louder than this. So what do you think?
     
  7. Edward J M

    Edward J M Cinematographer

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    Todd:

    What tune are you running the subwoofer in?

    Which channel are you referencing when calibrating with Avia?

    Have you tried all five channels with Avia to see the differences between them?

    It is entirely possible (depending on the Avia channel) that the sub is still running flat or even a bit cool. Avia is funny like that because the sub tone uses redirected bass and you can get reinforcement or cancellation from the speaker channel in question as you pan around the room. Try all five channels and note the variation - it will probably be a 5 dB change from the lowest to the highest.

    When you say "compensated" I take it you are adding the RS correction factors to the SPL reading?

    You might want to plot the FR up to 200 Hz and see what the entire curve looks like with the mains in the loop.

    Regardless, if you feel you aren't getting enough oomph from the PB12-Ultra/2, by all means crank up the plate amp volume until you get the impact you want. It is not uncommon for enthusiasts to run the sub 5 dB hot for HT and flat for music. The PB12-Ultra/2 can take it - trust me - crank it up until you are satisfied.

    As long as you don't mismatch the tune switch and the port configuration, that subwoofer is bulletproof. It should/can/will waffle your pants and rearrange items in the room.
     
  8. Todd smith

    Todd smith Supporting Actor

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    Hi Edward,

    I am running the sub in the 1 port block-20hz tune. When I calibrated with avia I used all 5 channels and I am anywhere from 2-3db hot on all channels with the sub. By compensated I do mean I am adding the correction factor for the RS spl meter according to the SVS manual.

    After just reading your review on the ultra it sounds like my room is at play more than anything else. When I had the sub in the front of the room I was able to get numbers similar to yours because (I assume) I had a room induced peak in the 16-35 region. The only problem is having the sub in this location also produced a HUGE null which I dont know how to get rid of besides moving the sub. I cant move the seating position. Putting the sub in the rear eliminated the null, but I dont have the peak either. Overall this is better, but I sure do miss that peak for movies!

    My test disc only goes up to 98hz test tones, but I think avia goes to 200 which I will check out.

    Why would I not get more volume by going to the bigger b4 or adding a second ultra? I thought you always got a db increase with dual subs?

    Thanks for all your help. By the way SVS has been AWESOME as far as the customer service. I had a few issues when I first got this sub and they were verry prompt to solve my problems with absolutely zero problem. I know they dont need anymore hype on these boards, but they deserve every praise they get.
     
  9. Edward J M

    Edward J M Cinematographer

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    Well I think your issue might be three-fold.

    First a flat FR tends to sound anemic to many people, because we are less sensitive to the lowest frequencies (those Fletcher Munson guys). So a bit of room gain below 30 Hz tends to work wonders on HT without adding boom to music.

    If your new position doesn't exhibit gain below 30 Hz, you can certainly adjust the curve with a PEQ. Talk to Wayne Pflughaupt about the concept of a "house curve".

    Second, I still say don't be afraid to crank up that volume control. Even in the 20 Hz tune, that sub has a ton of power and output. You don't need a second sub or a larger sub if the current one has headroom in reserve.

    Third, the 25 Hz tune will give you a few dB more headroom over the 20 Hz tune, if you ever find yourself in the unlikely position of overdriving the sub in the 20 Hz tune. In my mid-size room, I cannot find the limits of that sub in the 25 Hz tune, but it's probably somewhere in the 120 dB region based on the 2 meter ground plane data. Botton line: That sub can get stupid loud in the 25 Hz tune without compression or port noise, so don't be afraid to experiment running it hot in both the 20 Hz and 25 Hz tunes before you resort to upgrading to a larger model.

    Regards,

    Ed
     
  10. Mark Seaton

    Mark Seaton Supporting Actor

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    First, you are quickly seeing why it can take so much subwoofer power to deliver smooth response to very low frequencies in most rooms. I have a few recommendations...

    First, go back and don't be so agressive at cutting the 25-35Hz range. Quite regularly I will allow for a good 5-6dB of rise at this range relative to the crossover frequency. Remember a response that is +6dB at 25Hz and tapers down to relative 0dB at say 80Hz is still +/-3dB. Now, go back and raise the subwoofer level. Given many, many factors, settings made with an SPL meter are still heavily averaged with room for adjustment. The channel test tones are supposed to be approximated to 75dB-C (make sure you are in C weighting). With an 80Hz crossover, a proper subwoofer test signal will also read 75dB when the "proper" relative levels are achieved. If your subwoofer has a rise at lower frequencies, this could skew your setting, resulting in the upper bass being lower than is should be. The goal is to best seam together the response of the subwoofer and main speakers, regardless of what the SPL meter reads. If you are listening at say -10dB when calibrated properly, I would not be suprised at all if you found setting the sub levels 4-6dB hot to sound as you desire, and would possibly make the same setting myself.

    So, to recap:

    1) Let the sub go a little more at the low end. +6dB down here is rarely offensive if the rest of the response is smooth.

    2) Turn it up! Unless you are turning up the level and it isn't getting any louder, you aren't at the sub's limit, only the limit you have imposed with your settings.

    3) Enjoy the process and the learning... it's the cheapest and most rewarding upgrade you will experience!
     
  11. Todd smith

    Todd smith Supporting Actor

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    Excellent info everybody. I will try out these suggestions and bump the gain a little if I still need to. I appreciate the coment on enjoying the process which I forget to do sometimes. Frustration has got the best of me lately, but in the grand scheme of things this is a great problem to have! Thanks again.
     
  12. Wayne A. Pflughaupt

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    What Ed and Mark said. [​IMG]

    Adding a little to their excellent advice, a small room like yours needs a steeper slope compared to larger room, so if by chance the slope Mark recommended still sounds “not quite there,” go ahead and beef it up some more. Like I noted in the links I posted above, I’ve found that getting pure tone (sine waves) low frequency signals to sound the same as higher tones is a good seat-of-the-pants way to determine the slope you need.

    I also see that your readings below 31Hz droop quite a bit, so you might try to flatten things out from that point down – or perhaps a rise not as steep as the one below 31Hz.

    By the way, you don’t have to re-do all your filters to get the house curve. You can induce one by applying a single overlaying filter.

    It takes some trial and error, but a good starting point is a 2-octave filter centered between 300-400Hz. What this does is effectively set up a shelving filter when you cut it. The amount of cut you apply will determine just how much in encroaches into the sub's range. The more you cut, the more it reaches into the sub's domain, so with the filter center so far out you probably want to start with a pretty severe cut, say 15dB. Moving the center frequency back and forth will get the shelving at the point you want it - probably somewhere between 25-30Hz - and the amount of cut applied will determine the slope of the house curve. The bandwidth adjustment can also affect the slope: Wider will soften the curve, narrower will make it steeper (however, get it too narrow and it will start to make response droop at the lowest frequencies, not stay flat). Typically you have to play with all three parameters - bandwidth, frequency center and amplitude - to get the curve you need, but in the end you've effected your house curve with a single filter.

    Regards,
    Wayne A. Pflughaupt
     
  13. dave alan

    dave alan Second Unit

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    All good info except...

    "Remember a response that is +6dB at 25Hz and tapers down to relative 0dB at say 80Hz is still +/-3dB."

    This is actually (+6/-0).
     
  14. Todd smith

    Todd smith Supporting Actor

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    Great info except I have no idea how to do a single overlaying filter between 300-400hz.


    I am now at the frustration level again. I went and rechecked my numbers and they are all different from when I measured them after I did the peq adjustment. The reason they are different is because after I did the peq I checked with avia and I was no longer 3db hot. Since I was no longer at this level I bumped up the gain to get back to the 3db hot, but when I did this it did not bump everything up evenly! So my somewhat good graph now is peaked again. Is this normal? If I go and flatten this out again chances are I will have to bump the gain up again to get 3 db hot which will mess up the graph again. Why is this happening?

    I appreciate the info Wayne, but I am not sure how to do what you are talking about. I wish one of you guys lived in the Denver area so you could swing by and help me out.

    How do I make adjustments in the 300-400hz range?
     
  15. Edward J M

    Edward J M Cinematographer

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    I'm not certain Todd has an external PEQ.

    The PB12-Ultra/2 has a single-band, cut-only PEQ with a bandwidth of 20-80 Hz.

    The Ref 50 has a 3-band cut-only PEQ function. IIRC, it the highest frequency is around 150 Hz, and I doubt it is capable of what Wayne is describing.

    If you don't have an external PEQ Todd, then you probably cannot accomplish what Wayne is discussing. Your best shot is the Ref 50, but I don't think it has a 2 octave notch width or a 300 Hz setting.

    Todd - I think you are worrying too much about the calibration numbers and the shape of the curve below 30 Hz instead of relying on your ears to tell you what sounds good.

    I would only use the PEQ funtion on the PB12-Ultra/2 and the Ref 50 to knock out room peaks in the 35-100 Hz region, because they make the bass sound boomy. Don't use the PEQ to counteract natural room gain below 30 Hz.

    And set the gain on the subwoofer to where ever it sounds and feels the best to you. Don't worry if Avia ends up being 5-6 dB hot; many people like it that hot for HT.

    For music input, use your pre-pro to drop the sub level a few dB - the Ref 50 is easily capable of remembering multiple subwoofer level settings for various inputs.

    A calibration difference of just a few dB can make a big difference in the "personality" of the subwoofer. With your combined PEQ capabilities, there is no reason you can't obtain a very flat curve where it matters for music (above 30 Hz), and then adjust the overall sub level to aggressive for HT and mild mannered/well blended for music.
     
  16. Mark Seaton

    Mark Seaton Supporting Actor

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    Hi Ted,

    There's a reason that some can make a living at installing and optimizing home theaters. Like any skill and trade, there are just as many who are guessing as there are those who really know what they are doing.

    I think Wayne missed earlier in the discussion where you mentioned you were just working with the settings on your PB12-Ultra/2. Your primary adjustments are then the single band parametric, the low pass crossover, and the low frequency settings.

    I can certainly sympathize and relate to your experience. Taking measurements can be frustrating. I have many times been left scratching my head asking how 3 different measurements taken in one location can look so different!!!

    Check for the easy variables. Doors open or closed can have major effects at some frequencies. If things are rattling or vibrating strongly, this can also result in some curious measurements which will vary with testing level. Drop ceilings have given me some really odd looking changes in response as the tiles would begin to "pop" at higher levels.

    I believe Wayne had presumed you were using a multi-band parametric EQ like one of the Bheringer units commonly talked about here. You can certainly do more specific shaping of the response with an outboard unit, but if the response posted above is at all accurate, you had some decent results with the single parametric. If you turn up the level of the sub, you might have gotten much closer to what you wanted. Part of the problem lies in what levels you generally listen at. The higher the level which is comfortable with your system, and the more capable your main speakers, the less elevation of the sub level is commonly desired.
     
  17. Mark Seaton

    Mark Seaton Supporting Actor

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    While I follow the idealogical perspective, there really is no difference. A 6dB window is a 6dB window. +5/-1, +4/-2, or any other combo is mostly a matter of semantics unless you define the "zero" level as something specific. In the ideal some form of passband averaging would define zero. I'd rather just see a response curve than worry about how some arbitrary spec reads.

    Back to your regularly scheduled programing...

    Cheers,
     
  18. Wayne A. Pflughaupt

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    Yes – sorry about that! :b

    Regards,
    Wayne A. Pflughaupt
     
  19. dave alan

    dave alan Second Unit

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    If you had a perfectly flat anechoic FR from 20 Hz to 100 Hz...except for a 10 dB peak at 40 Hz...I certainly wouldn't say that the response was 20 Hz to 100 Hz (+/-5dB).

    I made the point for the reason of underscoring the fact that a so-called FM or 'house' curve is nothing more than a distortion of the in-room frequency response, regardless of whether it's room induced or accomplished by use of EQ.

    Slowly ramping the FR from a given point to the bottom of your system's capability is not a plus or minus situation. It's a boosted curve.

    In the example given, the '0' point was defined at 80 Hz, and everything below that (down to 25 Hz in the example) is ramped up to 6 dB above that point.

    In that same scenario, a low 'E' note on a bass guitar will be 4 dB hotter than the next octave up 'E' note. Some may think that a riff that's played in E with a low 'E' accent (a common riff) sounds better with the low 'E' at 4 dB higher SPL during playback. To each, his own.

    The riff isn't +/- 2 dB...rather, the low 'E' is 4 dB hot (or 6 dB or more, depending on the particular 'house' curve).

    If the 'house' curve is appealing to someone, I would have to agree with Edward. Start the boost at 30ish Hz....below the music bandwidth.
     
  20. Mark Seaton

    Mark Seaton Supporting Actor

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    Dave- While in principal I agree with you, reality tends to make such arguments moot. Test tones commonly used to set the levels of our main speakers will consist of a 500Hz-2kHz, band limited pink noise. This serves reasonably well to get an approximate match of the main speakers which hopefully have a somewhat similar frequency response. If you have ever measured the response of a real speaker in a real room, you know that below 500Hz it is common for the response to look a bit like the rocky mountains without significant smoothing. Looking at real speaker responses we find that many speakers have different tilts or voicings with more or less midbass energy vs. midrange or high frequency energy. So where do you match the subwoofer level to?

    In my experimentations and measuring I have found the best subjective results coming from smooth transitions from region to region. While I most certainly would prefer to see a flat response, the realities of measurements, recordings, and the limitations of speakers makes dead flat response not always the wisest goal. Give me a system with very good acoustics in a larger room with speakers having another 10dB of headroom over what most here consider "plenty" and you will see something much closer to a "flat" response as the optimum setup, but if I had the capability, there would still be a slight lift to the low end down around 25Hz, and likely a slight downward taper above ~2kHz.

    In a couple systems where I have had huge headroom in the subwoofer range and limited headroom in the main speakers (until the next upgrade phase) I have intentionally configured a system to have a nice and smooth shelf starting about 160Hz down to about 70Hz where the system hovered almost 10dB hotter. That's what the owner was happy with, and by making the transition nice and smooth it was not an offensive contour to the response. Bass heavy, yes, but not overly boomy as we often see when we arbitrarily boost the subwoofer level without making any other adjustments.
     

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