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SVS set up help??

Discussion in 'Subwoofers' started by karkus30, Jul 28, 2004.

  1. karkus30

    karkus30
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    Having read Shinobiwans plight. I just had to add a few references about set up. Using test tones on the Denon amp, the sub makes a sound like a lumpy sounding lorry tickover, it sounds like its about to stop then picks up again but louder. This means the SPL meter reads all over the place at 70db its reading anything from -5 to +6. I get the same results with the downloaded sine wave tones and dont have any fancy capture software.

    However if I touch the speaker cone lightly while the test tone is output, its definitely the drive unit thats hiccupping, nothing to do with room acoustics.

    The equipment is an AVC10SE and a PC Ultra sub.

    The whole lot will be moved upstairs in the next few weeks, which will be an aid to the square room syndrome that Im suffering. But that doesnt remove the bad tickover SVS. Is this a fault ?? Ian can you try the test tones through your sub and see if it gives the same results.
     
  2. Kazman

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    With all these issues flying around, could there be a quality control issue with the Ultra Driver right now?

    Think I'll wait before putting any order in for a while until these issues are resolved/explained.
     
  3. karkus30

    karkus30
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    Well , I have e.mailed SVS with the problem. See if its normal or not. There are several posts on different forums relating to difficulties with the Ultra. The other range of subs dont seem to get the same comments, everyone seems more than happy.
     
  4. Ian J

    Ian J
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    For every SVS sub sold in this country a further 100 are sold in USA. If you want to know whether there are quality problems read the American forums as this type of problem would therefore be one hundred fold over there.
     
  5. Jules

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    I don't think the test tone 'test' indicates there is a problem necessarily.

    With every sub I've ever had, the SPL readings always jump all over the place when trying to calibrate the sub.
    I put it down to the timing of room reflections at that frequency, or the inconsistent test tone generator in the amp at low frequencies.
    I've felt the 'burst' or uneven cone movement during calibration too, so again, I don't think this inidactes a fault.

    Subs are just very difficult to calibrate. I've found the test tones give you a 'ball park' figure and the rest is experience.
     
  6. karkus30

    karkus30
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    It could be the test tone generator that causes the effect. Its not due to room reflections, I can actually feel the cone moving and its thumping about every few seconds. Which sub are you using? Im wondering if this is more pronounced on the Ultra ? due to its ability to reach high SPLs. Maybe it wouldnt be noticeable on a smaller less powerful sub. It makes me wonder if the amp has sufficient damping ? Is this why Velo etc go for a servo system to counter this effect.

    It occurs to me that the larger the cone, the more mass and the greater the inertia. Is it difficult for an amplifier to keep control of the coil assembly. Its like waves on a beach, you get two close together and they come further up the shore.
     
  7. Jules

    Jules
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    I've used an old Yamaha Sub and a REL Storm in the past.
    Currently I'm using 2 KEF 45B THX Subs, and with all of them this effect was noticeable to a similar degree with the test tones.

    All of them have been used with my Denon A1SE amp (same brand) and I'm sure this is the culprit.

    I'll have to reserve judgement until my SVS PC Ultra arrives, but I honestly don't think these problems sound like the fault of the subwoofer.
    I certainly hope not anyway.
     
  8. Ian J

    Ian J
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    When they weren't quite so busy building subwoofers to keep up with the demand, Tom V used to be a regular visitor here and would answer questions like this.

    It seems to be an interesting set of question posed here so I'll ask him whether he can spare a few minutes to look in
     
  9. ShinObiWAN

    ShinObiWAN
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    Hi Karkus,

    I don't have a PS Ultra but as you know I do have the passive version, so I don't know how relevant this is but I ran test tones using a PC and the NCH Test Tone generator through my CSU and didn't note any pitch change or change in level when monitoring the output using a real time analyser.

    Could it be mains fluctation, the internal amp or the signal generator itself thats causing the problem you have?
     
  10. Nimby

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    I think you're generalising too much here. I managed a smooth frequency response in my 30 feet long attic room. The needle didn't waver by its own width on test tones. The sound was smooth and continuous.
    (downloaded tones feeding my Naim pre/power amp. Feeding the SVS PCi via speaker cables to the high-level connections)

    I can imagine the cone rising and falling in amplitude on music but cannot see why it should do so on test tones. Unless it's being fed a lower frequency with a higher frequency laid on top. Perhaps as a result of distortion. This might produce an intermodulation effect between the different frequencies. Resulting in frequency doubling. Which might be subsonic in frequency. This might produce a slowly changing "ripple" superimposed on the higher frequency test tone. Or not. :D

    Regarding the cone being too heavy to control: I wonder how it manages to react like lightening to loud signals (like gunfire) and die back to utter silence a microsecond later? If your theory were correct. Then gunshots and bass drums would sound like long booms. Starting slowly, building to a climax and then dying slowly away. That's certainly not what I hear from my own SVS. :)

    Nimby
     
  11. Nimby

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    Could it be the quality of the sound card in the PC?

    Nimby
     
  12. karkus30

    karkus30
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    The test tone that I am talking about is the one in the Denon amplifier, sounds like pink noise to me. If I turn the onboard PQ up to maximum on level and Q at arount 35Hz it seems to help a bit.

    SPL needle is still swinging wildly but its a more occasional kick. Tom has asked me to try a test sweep with the meter on the floor, near the sub, I imagine that will minimize room effects. Thats tonight project !
     
  13. chrisgeary

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    i think everyone here has been assuming you to be using a single frequency test tone, commonly used when calibrating a sub for room response. you are using the internal generator for calibrating speaker levels, which is typically noise made up of many frequencies. at higher frequencies, the SPL meter will sit steadily, but at lower frequencies it will tend to be a little lumpier. the sub cone will seem to move at random too, as frequencies come in and out of phase with each other.

    from what i have read and if i have understood it correctly, there is nothing wrong with your sub at all, its just the normal results of using the noise based test tone for a sub. the cone movement is nothing to worry about, neither is the SPL meter swing, although it makes a reading tricky - be sure to use 'slow' and 'c' weighted.

    hope this helps?
     
  14. Andywilliams

    Andywilliams
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    Hi
    Spl meter readings are very helpful with the speaker set up but when it comes to the sub i fine tune it by ear,you cant get a suitable reading off the meter, most people that have heard my svs seem to think it sounds very good and intergrates very well with my m&ks,So get it set up so it sounds great then forget the technical side and enjoy your sub. :thumbsup:
    Cheers Gonzo.
     
  15. samhain

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    I agree with Jules that a sub or any speaker for that matter is subject to room resonances. There will be certain frequencies within the range of the subwoofer where gains are substantially higher or lower depending on characteristics. The subwoofer I have chosen the Velodyne DD-12 has an inbuilt equaliser on it and as such I can make as flat a line as possible by lowering the peaks and increasing the troughs etc.

    Trial and error I am afraid mate.
     
  16. karkus30

    karkus30
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    Cheers guys, thanks for the replies as they have been very helpful, thats all I needed to know. As it doesnt indicate theres a problem, it must be down to in room freq. response. As Im moving everything upstairs to a more H/C friendly room, it should improve things.

    Its interesting to note that positioning a subwoofer is IMO far more difficult than a standard loudspeaker. I think this becomes even more difficult when you buy a sub with the sort of power and low frequency response that something like the SVS has. TBH, if I was leaving the H/C set up in its current room I would probably sell the sub and buy something with less low end response. Its a tremendous sub, but in less than ideal situations it can exhibit uneven response which becomes annoying as it has to be played at lower levels to avoid excess bass.

    A smaller sub (thats a definition not the actual size) wouldnt give the ultimate SPLs or low end response but would be easier to live with IMO.
     
  17. ShinObiWAN

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    Karkus you really *need* a BFD.

    I'm amazed at the difference mine makes when I hit bypass and I get the unEQ'ed response back - its sounds a little slower a tad boomy even.
    Engage the EQ and the sub just dissappears!

    I wouldn't use any sub without a BFD, especially a big hitter which has the potential to excite room modes to a greater extent than others.

    Really do give it a try, I almost feel like sending you mine to get you hooked and realise what your missing but then I'd be without one!
     
  18. Jack the lad

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    I live in Mansfield, when are you comming around :D :laugh: :laugh:
     
  19. ShinObiWAN

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    Heh,

    Small world, I live in Chesterfield which as you know, is close to Mansfield.
     
  20. AngelEyes

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    Hi Chaps,

    I have been reading this with interest as I hope to get an SVS one day.
    For the uninitiated could you tell me what a 'BFD' is and what it does.

    Thank you for your patience :blush:
     
  21. recruit

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    Hi Angel Eyes,
    It stands for Behringer Feedback Destroyer
    And basically it is a Parametric Equlaizer which lets you adjust Frequencies to suit your rooms acoustics
    Read it here www.snapbug.ws/bfd.htm

    John :)
     
  22. karkus30

    karkus30
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    And where would I purchase such an item and how much would it cost??
     
  23. ShinObiWAN

    ShinObiWAN
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  24. karkus30

    karkus30
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  25. recruit

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    Hi,

    The Model number you are looking for is DSP1124P

    John
     
  26. ShinObiWAN

    ShinObiWAN
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    Link fixed
     
  27. karkus30

    karkus30
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    Must be something up with their site ! I can view the equalisers but no sign of the 1124P. I have found it on Soundmaster direct, but its £119.00 which is a fair hike from £95.00 delivered.
     
  28. Ian J

    Ian J
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  29. ShinObiWAN

    ShinObiWAN
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    Karkus, this link takes you straight to the correct page:

    http://www.bluearan.co.uk/sales/behringer/Behringer Feedback Destroyer Pro DSP1124.htm

    I bought mine from here and they are very quick with delivery - ordered it around 2pm and it arrived the next morning so can't say fairer than that.

    Oh BTW if the link above doesn't work the BFD is listed under Audio Accessories on the Behringer Products page.

    EDIT: Tested link and it works :)
     
  30. karkus30

    karkus30
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    :laugh: still no joy, all I get is a blank page. I cant even look at the Behringer products page. I can look at the Equalisers, but thats all. Maybe theres something on that page my browser doesnt like ?

    Ians link works fine...............Ian, have you used them ???
     

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